Chevrolet Speed -- Concept

[dwightlooi]

Chevrolet Speed - Sports Car for the People

A Simple Formula

• 300 hp
• 3,000 lbs
• 30,000 Dollars

The idea is not to build the best sports car in the world. It is to build the best sports car that the 20~40 demographic can actually afford. It is not the most powerful. It is not the lightest. And it is not the cheapest. But, it is powerful enough to equal a Boxster S at the stop light, it is light enough to approach the FT86 in driving dynamics and, most importantly, it is cheap enough to that a regular college grad can afford one. It is from this car that GM will graduate future Corvette and Cadillac-V owners.

Design & Platform

The Speed is heavily influenced by the Code 130R, but substantially different in most ways. It is not built on a standard Alpha Platform, but a heavily modified version called the Alpha SLC - Short Light Coupe. The wheelbase is shorten by 9.8 inches to 99.5 inches. Height is reduced by 3.8 inches to 52.1 inches. The belt line is dropped by 2.5 inches and the car is a full 23.1 inches shorter in length than the Cadillac ATS. Unlike the Alpha which is engineered to accommodate a wide variety of vehicle configurations and engine types, the Alpha SLC is tailor made for use strictly in 2+2 hardtop coupes powered by a Smallblock V4 engine. In fact, the engine compartment is so short, and the firewall is so far forward, that not even GM's upcoming 3-cylinder Ecotec will fit. Apart from the physical dimensions, the green house has a lot more rake and the nose is a lot shorter. It is almost difficult to imagine this as a RWD vehicle due the exceptionally short hood, but it is -- thanks to the V4 engine. Most importantly, the dramatic reduction in it's load carrying extents (mainly the wheelbase) and enveloped volume allows the vehicle to be approximately 400 pounds lighter than an ATS (300 lbs if you discount the disparity in equipment level and sound insulation).

The Specifications

Powertrain

The design objective calls for maximum power output from the lightest, most compact engine. To this end, a 90 degree V4 engine that is basically a LT1 Smallblock V8 chopped in half is employed. Displacing 3.1L (188 cubic inches), the direct injected pushrod engine is about the same weight as a 2.5 liter DOHC Inline-4, but is only 2¼ cylinders long and significantly lower in height. The engine has two crank pins spaced 360 degrees apart and is supported by three main bearings. It exhibits the good overall balance of a 90 degrees full counter weighted engine, but is not an even fire design. With the crank pins spaced 360 degrees apart, the engine fires twice in 90 degrees of rotation then pauses for 270 degrees before firing twice again. This gives it a characteristically staccato exhaust note (1-1-0-0-1-1-0-0) at idle which turns into a guttural bellow when revved. The engine sounds almost like a Honda VFR750 motorcycle which has the same firing order. Synchronous cam phasing is used as on the Corvette V8 (LT1), but Active Fuel Management (Cylinder Deactivation) is not fitted owing to the impracticality of running the engine on just two cylinders. Direct Injection is employed using a combustion system identical to that on the LT1 V8. The engine offered in naturally aspirated form with 230 bhp @ 6000 rpm with 230 lb-ft @ 4600 rpm, or fortified with an Eaton TVS R1050 (1.05L) supercharger good for 300 bhp @ 6000 rpm with 300 lb-ft @ 3600 rpm.

Eschewing the high costs of an 8-speed automatic or dual clutched manumatics, the transmission choices are relatively traditional. Both the base vehicle and the SS are available with either the GM Hydramatic 6L45 automatic or a Tremec 3160 manual -- both offering 6-speeds and automated rev matching. An electronically controlled active rear differential is optional on the base car, standard on the SS. Stability control is standard on both but launch control is featured only on the SS.

Suspension, Brakes & Tires

Suspension geometry is identical to the Cadillac ATS -- strut fronts, multi-link rears. Magnetorheological shocks are not offered to keep costs down and the Speed relies on traditional coil springs, tube shocks and anti-roll bars to keep vehicular motions under control. Brakes are lifted straight from the ATS with 11.8 x 1.0 inch front rotors on the base car and 12.6 x 1.2 inches on the SS. Both trims get 12.4 x 0.8 inch vented rears. The SS also gets Brembo floating calipers. Rubber on both trim levels are 225/45 R17 with alloy wheels. The base car is fitted with Goodyear Eagle GT All seasons while the SS gets Eagle F1 Asymmetric 2 Maximum Performance summer tires.

The Competition

Edited July 21, 2013 by dwightlooi

[dwightlooi]

Equipment and Amenities

The interior is spartan but not low rent. Navigation is standard, but climate control is manual, seat adjustments and mirror adjustments are manual. The heats are not heated or cooled. A backup camera is standard, but sonar parking sensors and/or dipping side mirrors are not offered. The 240W BOSE audio system offers AM/FM/Sirius radio but does not accept CDs or cassettes, offering instead iPod and USB integration. Featuring just 3-speakers – a pair of 2.5” full range speakers in the A-pillars and an 8” bass/sub-bass driver in the center dash deck – it is similar to the basic Acoustimass 3 setup for rooms. Not exactly Hi-Fi, but lively, distortion free and entertaining. Leather is not offered, but the cloth is of three different textures and the dash and doors are fabric wrapped. Switches and rotary controls have rubberized diamond knurl grip surfaces, are positively indexed and solidly damped. The steering wheel is a 3-spoke design evolved from the Corvette with paddle shifters fitted on the automatic transmission equipped cars. The instrument cluster is elemental – an analog tachometer on the left and speedometer on the right, with a concentric LED fuel gauge inside the speedometer and (on supercharged cars) a concentric LED boost gauge inside the tachometer. Apart from that, the only display in the cluster is a multifunction LCD in the middle which can pull various duties such as trip computer, voltage/oil-pressure/oil-temp/water-temp and warning messages. Regardless of mode, the MFD displays the current gear on the top right corner in a circle. On the automatic transmission cars, a smaller letter on the lower right corner of the circle indicates the current drive mode (P-R-N-D-S-M).

Edited July 21, 2013 by dwightlooi

[hyperv6]

GM is already looking into this an has been investigating how to do such a car. A lot of it depends on a couple things.

The major issue is they would like to do this on what one insider called an Alpha lite platform, though they said it would not be an Alpha and be its own platform. Then once it is build what else could they expand this platform to be used for in the whole of GM. In other words doing a car like this is not an issue but what else can you leverage the platform out over to make it more profitable.

By the time it would arrive the price would be a little higher as to do this it would take at least 5 years.

As for the engine you will have to look at the reality of what is out there and what will be there and a V4 is not really in sight at this point.

While I agree they should look into a car like this and fully expect that this will come to market at some point I do not agree it will fully happen as explained here. There is no right or wrong on dreaming here but with the way things are and how GM works many of these ideas will remain dreams in a car like this.

But over all you have a general idea of what little info that was disclosed.

[dwightlooi]

There is a reason the V4 has a VFR firing order instead of being even fire. The latter would have required a 5 main bearing block, whereas the proposed design is strictly a chopped LT1 leaving three main bearings. Doing this avoids the vast majority of costs associated with developing a new engine. Basically the combustion modeling is identical to the LT1 and does not have to be redone. The pistons, rods, bearings, wrist pins, sprockets, pushrods, lifters, rockers, valves, bolts, coil packs, fuel injectors, fuel pump, water pump, timing chain... basically everything but the block casting and shortened camshaft is identical. Even the block casting is basically a straight forward modification of the V8 block eliminating the center four cylinders. Tooling and production machinery for its assembly is also interchangeable. In fact, doing such an engine is somewhat less work and investment than doing a 5.3 liter version of the Gen V V8 or going from a 2.5 to a 2.0T -- because you are not changing the combustion chamber geometry and do not have to redo the combustion modeling.

Edited July 21, 2013 by dwightlooi

[hyperv6]

And GM has already just made more major investments and has just place more future plans in advancing the Ecotec.

Like it not, agree or not GM has placed their money where they are going so there is little to debate. So in this case for the point of reality you have to work with what is there.

They thought it a good Idea for the same reasons on the Slant 4 Pontiac had and it never went anywhere. V8 engines chopped into 4 cylinder never work out well no matter how you slice it.

Edited July 21, 2013 by hyperv6

[ocnblu]

I support this project. Thanks, Dwight.

[dwightlooi]

They thought it a good Idea for the same reasons on the Slant 4 Pontiac had and it never went anywhere. V8 engines chopped into 4 cylinder never work out well no matter how you slice it.

How so? The V4 has a packaging advantage which cannot be matched by Inline-4 designs or horizontally opposed -- it is how that extremely short hood and chassis is possible. A 90 deg Vee has each pair of cylinders exhibiting the same great balance as a V8 by allowing full counter weights to be used. A Pushrod V4 has a mass, width, height and frictional advantage unmatched by OHC designs. Those are fundamental facts. Why do you think it won't work out?

As far as it not actually being an existing engine, well neither is anything GM hasn't built yet (including the car itself). By that line of reasoning -- if doesn't exist it is impractical -- nothing new would ever be built.

[balthazar]

Pontiac Indy 4 "didn't go anywhere" because gas was 30 cents/gal and V8s were trending, not because of design problems with the Indy 4.
By the same token, the early Tempest unibody 'didn't go anywhere' as it had the same lifespan as the 194 and was replaced with BOF in '64.

That said, it would be interesting to see how well a V4 would perform WRT it's configuration.

[hyperv6]

Pontiac Indy 4 "didn't go anywhere" because gas was 30 cents/gal and V8s were trending, not because of design problems with the Indy 4.

By the same token, the early Tempest unibody 'didn't go anywhere' as it had the same lifespan as the 194 and was replaced with BOF in '64.

That said, it would be interesting to see how well a V4 would perform WRT it's configuration.

I can see you did not spend much time driving one. I have and it was nothing special.

[hyperv6]

They thought it a good Idea for the same reasons on the Slant 4 Pontiac had and it never went anywhere. V8 engines chopped into 4 cylinder never work out well no matter how you slice it.

How so? The V4 has a packaging advantage which cannot be matched by Inline-4 designs or horizontally opposed -- it is how that extremely short hood and chassis is possible. A 90 deg Vee has each pair of cylinders exhibiting the same great balance as a V8 by allowing full counter weights to be used. A Pushrod V4 has a mass, width, height and frictional advantage unmatched by OHC designs. Those are fundamental facts. Why do you think it won't work out?

As far as it not actually being an existing engine, well neither is anything GM hasn't built yet (including the car itself). By that line of reasoning -- if doesn't exist it is impractical -- nothing new would ever be built.

The reality is GM has committed Billions to the inline 4 and I do not see them investing in another 4.

90 degree engines were tight in past FWD cars and will be worse today as space is even more limited. To make the engine viable it would need to be used in both FWD and RWD and I do not see that happening.

A host of Racers over the years have tried to build 4 cylinder engines for different racing classes and they all just never worked out. Some for cost most for issues with NHV that would damage the engine and or drive line. Pink, Crower and Scat have all taken this in and they never lasted.

In most cases where a engine has been cut down there have always been issues. Often even when they are made into a good engine it take time and other things to fix them. Just look at the most successful V6 the 4.3 has had a lot of money and development tossed at it and looking back GM may have been better off now just doing a clean sheet. For many years it is amazing they sold as many as they did as bad as they shook and run.

Not existing is normally in this day and age a sign that they have already visited this and found issues or things that did not make this practical or even a good idea. GM has a long history of chopping engines and do you really think they have not tried this one yet? Keep in mind this company has chopped Pontiac's Chevys and Buicks already and grafted Olds 4 cylinders into V8 and LS engines into V16.

Jumping off a cliff may sound like a good idea but generally most do not be cause there a consequence.

The bottom line is if you think you are the first person to come up with this idea you are not. GM chose an inline 4 that is small and light and suites their need to the point that they have invested Billions.

You are not a GM engineer and you have not had this engine on the stand so to prove it is a viable engine is more than just on paper here. Do you have the loads and how the harmonics of the engine will be? You won't know till you do it. Generally removing cylinders creates as many issues as they solve.

A V4 is not a bad idea in its self but if you want to do one I would recommend looking to what most Motorcycle companies are doing or even boat as they can packaged these engines smaller lighter and extract even smoother power than just cutting cylinders from a V8.

Once you have some real dyno results and maybe you may sway some of us.

Edited July 22, 2013 by hyperv6

[G. David Felt]

And GM has already just made more major investments and has just place more future plans in advancing the Ecotec.

Like it not, agree or not GM has placed their money where they are going so there is little to debate. So in this case for the point of reality you have to work with what is there.

They thought it a good Idea for the same reasons on the Slant 4 Pontiac had and it never went anywhere. V8 engines chopped into 4 cylinder never work out well no matter how you slice it.

Hyper, I have to disagree with you on the V4 reasoning.

GM would not have to invest Billions to Create the V4, one of their licensed Corvette Racing and engine builders have already done the work and has a Solution GM needs to pick up and use.

http://www.katechengines.com/engineering/katech-v4/

If you have Driven a Motus Motorcycle which comes with the Katech V4 engine based on chopping a Corvette V8 in half you would be amazed at how silky smooth and powerful this engine is.

Katech sells a Crate version of the V4 for anyone with almost 400HP/lbs. It really is an amazing engine that is not turbo or supercharged. Proves that the Pushrod V4 cannot only deliver amazing gas mileage but also performance.

Great Idea Dwight, I think this would be a hit for GM and they could easily expand this through other versions for Buick and Cadillac.

[hyperv6]

And GM has already just made more major investments and has just place more future plans in advancing the Ecotec.

Like it not, agree or not GM has placed their money where they are going so there is little to debate. So in this case for the point of reality you have to work with what is there.

They thought it a good Idea for the same reasons on the Slant 4 Pontiac had and it never went anywhere. V8 engines chopped into 4 cylinder never work out well no matter how you slice it.

Hyper, I have to disagree with you on the V4 reasoning.

GM would not have to invest Billions to Create the V4, one of their licensed Corvette Racing and engine builders have already done the work and has a Solution GM needs to pick up and use.

10010941_KATECH_website3.jpg

http://www.katechengines.com/engineering/katech-v4/

v4-dimensions.jpg

If you have Driven a Motus Motorcycle which comes with the Katech V4 engine based on chopping a Corvette V8 in half you would be amazed at how silky smooth and powerful this engine is.

Katech sells a Crate version of the V4 for anyone with almost 400HP/lbs. It really is an amazing engine that is not turbo or supercharged. Proves that the Pushrod V4 cannot only deliver amazing gas mileage but also performance.

Great Idea Dwight, I think this would be a hit for GM and they could easily expand this through other versions for Buick and Cadillac.

I have nothing against the V4 itself but I just do not think or expect GM to change course here with the investment they already have made and are still making. The inline 5 and 6 on paper was a good idea too but it never panned out like they had hoped.

The K Tech is one I missed and looks nice but it is far from an engine I would want to see in a production car. The specs on the rave version match the base turbo Eco numbers and the standard version is below some of the predicted 3 cylinders to come. Also would it has as wide and flat of a torque curve as the Eco turbo that has been the key to its wide acceptance? The low end torque is hard to duplicate in an engine like the V4.

Like I said I have no issue with a 4v in the concept but sorry I do not get excited over some quasi self proclaimed engineer that generally is counter to anything in the market. Generally there is a lot more involved in these things.

Besides do you or do you not think GM has not already investigated this in more ways than anyone with a web thread has even considered? If we were on the inside we would have a clear understanding of what and why they do what they so as there is more to it than hey this is a good idea.

My main point is I do not expect to see this happen. The car I could see happen as GM already as hinted loudly they are looking into it but the engine will be something more of what they already are investing in. I like to speculate but I like to try to keep it realistic as to what could really happen and not some wishful thinking. That is the main difference.

[G. David Felt]

I see and understand the points you are making. I have wondered why a supported Corvette group that clearly has done some R&D has not garnered more attention from GM. Either they have totally been overlooked or GM is watching but not commenting on it.

I would love to hear from some GM Motor engineers on their thoughts about this V4 engine. It would be great if Katech could produce some Torque charts to show how it flows and where in this engine. If it is at a high RPM, then that would tend to show why this motor is popular with motorcycles and why Motus has been successful with it as bike riders do love to rev.

If I had the extra cash, I would love to buy the V4 crate motor and put it into a kit car and see just how efficient I could get it to go on CNG.

[hyperv6]

This deal is a K tech deal and I suspect it was targeted at some racing class more than anything. This is why we have had cut small blocks before as they were intended for Midget Sprints. It was something that just did not work out well and turned into a very expensive engine since so few parts were ready made. blocks and heads had to be cut and custom cranks etc had to be made. They ended up going to a inline 4 and laid it over on the side Offy style. There are many still looking for an engine to replace the old VW engines they used to use in midget sprints.

They also had in many cases a lot of engine failures too. Not sure if it was the design or the tune.

K tech does their own things and Pratt and Miller just pays them to build and tune the engines. I am not even sure if GM has a direct contract for the engines from them or If it is just with P and M.

K tech does some great work with race engines and they also do a lot of custom work too.

The numbers on the engines they have would be ok on a Bike but they are not spectacular compared to the stock Eco. The base V4 is less on power and the race version is about where the base Turbo Eco is. Now on the other hand the weight is fantastic. But it would come in heavier with the things needed for a production style engine.

If I were to do an a V4 I would look to a 60 degree engine as it would fit the FWD applications better. Also I would so a clean sheet engine as you would not have to compromise as much. You could make it push rod or OHC or what ever but I would make sure it was more narrow. Also most 60 degree engines do not require balance shafts and other aids to calm the shake. In todays market you have to have the engine right or it will not look good anymore. The old 4.3 and 3.8 shake just would not get it today anymore and GM did a lot to the 4.3 over the years to fix what was wrong. My first 4.3 was crap an the second one was much better but never got the MPG and power it should have. Today they have fixed most of these issues but little is left of the original engine and today we have pretty close to a total new engine.

I expect to see the Eco 3 cylinder before long also another reason they will keep a inline 4 as it will share parts. I have also heard talk in some markets of a 2 cylinder. We may or may not ever see that and worry about that then.

Anyways I fully expect the car he is predicting as GM has already indicated and while it still needs approved I still expect them to move forward here. The question is just what else would this smaller platform support? A GMC like Jeep or small Ute or pick up? Sports car for Buick?

I just see the engine as not bad but just not anything we will see from GM based on their investments and their moves with product. They have to do more than just dream on the web and find the many ways they need to use these engines and pay for them. If I were making realistic predictions on this car it would be on some kind of Ecotec engine of the future.

[balthazar]

Pontiac Indy 4 "didn't go anywhere" because gas was 30 cents/gal and V8s were trending, not because of design problems with the Indy 4.

By the same token, the early Tempest unibody 'didn't go anywhere' as it had the same lifespan as the 194 and was replaced with BOF in '64.

That said, it would be interesting to see how well a V4 would perform WRT it's configuration.

I can see you did not spend much time driving one. I have and it was nothing special.

I've driven one, yes, so no; you 'can't see' here. 2 friends have 1st gen Tempests currently.

But the claim was not that it was "special" but conversely, that it was insufficient. It was not. Same with this V4 proposal- it's not necessarily 'special', but it offers some considerable advantages worthy of a serious look. Very very little out there in automotive powerplants is "special", but most OEMs/consumers 'just' want reliable, economical & affordable.

[Drew Dowdell]

The main problem I see with the V4 is that it would be almost exclusively a RWD engine which would limit the number of models GM could use it in. You might be able to get it into the Impala or Lacrosse, but FWD models smaller than that most likely wouldn't fit.

[dwightlooi]

I think a point of clarification is in order -- developing a brand new engine architecture is expensive and producing it is even more so because of the need to start an entirely new logistics chain. Developing a variant and/or producing it is generally not.

For example, when GM didn't have the a DOHC 16v engine developing the "Quad 4" was a big deal. I also didn't go that smoothly in the beginning. However, GM has no issue producing the LS7 V8 which was used in a very limited number of even fewer models -- namely the Corvette Z06 and now that this is being phased out the Camaro Z28. They also had no issues doing a 2.0L version of the 2.2 Liter Ecotec fortified with an Eaton M62 supercharger specifically for a few thousand copies of the 1st gen Cobalt SS. Or, does anyone remember, the 4-cylinder 2.8 and 2.9 liter Inline-4s which were cut down versions of the "Atlas" DOHC Inline-6 (LL8) which were used only in Chevy Colorado and GMC Canyon (which accounts from less than 1 in 20 trucks or SUV that GM sold.

The V4 was proposed because it can do what an Inline-4 or Flat-4 turbo cannot. It allows the interior space to be about 6 inches longer with the same wheelbase by allowing the engine compartment to be really, really short. It fits where a flat four of similar displacement won't because of width. It fits a supercharger in the valley of the block in a way that an inline or even 60 deg V engine cannot. It offers about 300hp from 3.1L which at a mild 9 psi of boost, yet exceeds the power level of a 22 psi 2.0T at a similar weight with no turbo lag. It would not have been economical had the LT1 not existed and GM relies on a line of DOHC V8s just like everyone else. But GM has the smallblock card to play that no one else does. It is a application specific engine with very little application outside a compact front engine / rear drive vehicle, but the same can be said of the 2.0 4U-GSE Flat-4 in the FT86 (FR-S / BR-Z). In fact, if you optimize it for regular gas it may make a decent entry level truck engine if GM is interested in making mid-size pickups again. Otherwise, it'll be a limited volume engine like the LS7, LK5, LLV and LSJ, which is fine.

Edited July 22, 2013 by dwightlooi

[hyperv6]

The main problem I see with the V4 is that it would be almost exclusively a RWD engine which would limit the number of models GM could use it in. You might be able to get it into the Impala or Lacrosse, but FWD models smaller than that most likely wouldn't fit.

Someone understands what is in play as this engine would have to satisfy FWD and RWD.

[hyperv6]

I think a point of clarification is in order -- developing a brand new engine architecture is expensive and producing it is even more so because of the need to start an entirely new logistics chain. Developing a variant and/or producing it is generally not.

For example, when GM didn't have the a DOHC 16v engine developing the "Quad 4" was a big deal. I also didn't go that smoothly in the beginning. However, GM has no issue producing the LS7 V8 which was used in a very limited number of even fewer models -- namely the Corvette Z06 and now that this is being phased out the Camaro Z28. They also had no issues doing a 2.0L version of the 2.2 Liter Ecotec fortified with an Eaton M62 supercharger specifically for a few thousand copies of the 1st gen Cobalt SS. Or, does anyone remember, the 4-cylinder 2.8 and 2.9 liter Inline-4s which were cut down versions of the "Atlas" DOHC Inline-6 (LL8) which were used only in Chevy Colorado and GMC Canyon (which accounts from less than 1 in 20 trucks or SUV that GM sold.

The V4 was proposed because it can do what an Inline-4 or Flat-4 turbo cannot. It allows the interior space to be about 6 inches longer with the same wheelbase by allowing the engine compartment to be really, really short. It fits where a flat four of similar displacement won't because of width. It fits a supercharger in the valley of the block in a way that an inline or even 60 deg V engine cannot. It offers about 300hp from 3.1L which at a mild 9 psi of boost, yet exceeds the power level of a 22 psi 2.0T at a similar weight with no turbo lag. It would not have been economical had the LT1 not existed and GM relies on a line of DOHC V8s just like everyone else. But GM has the smallblock card to play that no one else does. It is a application specific engine with very little application outside a compact front engine / rear drive vehicle, but the same can be said of the 2.0 4U-GSE Flat-4 in the FT86 (FR-S / BR-Z). In fact, if you optimize it for regular gas it may make a decent entry level truck engine if GM is interested in making mid-size pickups again. Otherwise, it'll be a limited volume engine like the LS7, LK5, LLV and LSJ, which is fine.

Is there really a need for a hood that is any shorter? If you make it too short you will end up with a car that looks like a Buick Skylark X body FWD. In fact many of GMs FWD cars in the 80's had odd short hoods that did little for styling.

[dwightlooi]

Is there really a need for a hood that is any shorter? If you make it too short you will end up with a car that looks like a Buick Skylark X body FWD. In fact many of GMs FWD cars in the 80's had odd short hoods that did little for styling.

Just look at the illustration above! To each his own tastes when it comes to aesthetics, but those proportions will not be possible with an inline four. It is also not purely a "styling" issue but a functional one.

A car's wheelbase has a lot to do with it's weight since the wheels are the carriers of the entire load. All the structures between the wheels give the car it's torsional and bending strength. With the same rigidity and strength requirements, the shorter the wheelbase the lighter the car. That ~10% reduction in wheel base is responsible for most of the weight loss. But a short wheelbase also means less leg room for the occupants in the passenger cell. A V4 engine -- being 2 1/4 cylinders long -- allow you to move the firewall forward towards the front axle. This allows you to make this a 2+2 vehicle with tight but usable rear seats. If you don't use a V4 the car will have to have more wheelbase (be heavier) or you need to lose the rear seats. From a structural standpoint, the "strongest" design for a unibody is to have the a-pillars terminate at the front strut towers. This is generally impossible in practical cars because of the length of the engine and the desire to have good F/R weight balance. Move the axle further from the firewall and the structure weakens, requiring either weighty reinforcements & bracings, or a sacrifice in platform rigidity and suspension performance. The V4 gets you closest to the ideal triangulation of forces.

Edited July 22, 2013 by dwightlooi

[Drew Dowdell]

eh, put in the camp that the proposed model's proportions aren't all that. I would want a longer hood and lower belt line. The above doesn't do much for me as the first thought that came to mind was "Sonic RS Coupe".... and while a Sonic RS Coupe isn't a bad idea, it isn't something I see people dropping $30k on.

I'm not opposed to a V4 idea, but I do see limitations to its implimentation. It could only be used in the RWD cars, the small trucks, and perhaps the Theta SUVs and large Epsilons. One positive of the V4 is that in the RWD cars already built for the 4-cylinder ecotec, it would improve balance by shifting weight rearward, potentially making cars like the Camaro and CTS front-mid engine cars with the entire engine aft of the front wheel center line.

GM has developed engines with less product line distribution than this before though, so it isn't unprecedented on that front. What is unprecedented is GM doing anything unconventional.

[hyperv6]

Is there really a need for a hood that is any shorter? If you make it too short you will end up with a car that looks like a Buick Skylark X body FWD. In fact many of GMs FWD cars in the 80's had odd short hoods that did little for styling.

Just look at the illustration above! To each his own tastes when it comes to aesthetics, but those proportions will not be possible with an inline four. It is also not purely a "styling" issue but a functional one.

A car's wheelbase has a lot to do with it's weight since the wheels are the carriers of the entire load. All the structures between the wheels give the car it's torsional and bending strength. With the same rigidity and strength requirements, the shorter the wheelbase the lighter the car. That ~10% reduction in wheel base is responsible for most of the weight loss. But a short wheelbase also means less leg room for the occupants in the passenger cell. A V4 engine -- being 2 1/4 cylinders long -- allow you to move the firewall forward towards the front axle. This allows you to make this a 2+2 vehicle with tight but usable rear seats. If you don't use a V4 the car will have to have more wheelbase (be heavier) or you need to lose the rear seats. From a structural standpoint, the "strongest" design for a unibody is to have the a-pillars terminate at the front strut towers. This is generally impossible in practical cars because of the length of the engine and the desire to have good F/R weight balance. Move the axle further from the firewall and the structure weakens, requiring either weighty reinforcements & bracings, or a sacrifice in platform rigidity and suspension performance. The V4 gets you closest to the ideal triangulation of forces.

I think I would be more worried about the transmission tunnel in the car more than the few inched that engine would provide.

Think back to the Monza and the large driveline tunnel in the car and how much space it took up.

Also shorter the wheel base the poorer the ride tends to be. Many cars today have the wheels moved out as far as possible to give better ride and handling.

I think I would look at ways to cut the tranny size or a light weight rear transaxle to remove the large tunnel in the car and create more room where a car like this needs it in the front foot wells.

[dwightlooi]

I think I would be more worried about the transmission tunnel in the car more than the few inched that engine would provide.

Think back to the Monza and the large driveline tunnel in the car and how much space it took up.

Also shorter the wheel base the poorer the ride tends to be. Many cars today have the wheels moved out as far as possible to give better ride and handling.

I think I would look at ways to cut the tranny size or a light weight rear transaxle to remove the large tunnel in the car and create more room where a car like this needs it in the front foot wells.

That is exactly why you want a very short engine. The transmission is widest at the bell housing. Keeping the center of gravity of the engine where it is, if the engine is very short, half the the reduction in length goes towards moving the transmission FORWARD which widens your foot well space. The V4 is basically a foot shorter than the V8 or an I4. Half of that, about 6 inches, goes towards moving the entire firewall forward giving additional foot well width and depth.

The other way of course is to move the transmission to the back and use a rear mounted transaxle.The problem with that is that for most cars the height of the rear bench and or the width between the rear seats are simply not suffcient for that. In a vette this is not a problem because you have no rear seats and an elevated rear platform, but this isn't so four most 2+3 or 2+2 configurations. Another bad thing about a rear mounted transaxle is that you need to carry your engine torque to it with a fast spinning torque tube going the length of the central tunnel. This, like a heavy flywheel, reduces the rev response of your engine. Not much of an issue for a 465lb-ft V8, but in a smaller engine that needle will rise and fall at a slower rate affecting performance and driving experience.

[hyperv6]

I think I would be more worried about the transmission tunnel in the car more than the few inched that engine would provide.

Think back to the Monza and the large driveline tunnel in the car and how much space it took up.

Also shorter the wheel base the poorer the ride tends to be. Many cars today have the wheels moved out as far as possible to give better ride and handling.

I think I would look at ways to cut the tranny size or a light weight rear transaxle to remove the large tunnel in the car and create more room where a car like this needs it in the front foot wells.

That is exactly why you want a very short engine. The transmission is widest at the bell housing. Keeping the center of gravity of the engine where it is, if the engine is very short, half the the reduction in length goes towards moving the transmission FORWARD which widens your foot well space. The V4 is basically a foot shorter than the V8 or an I4. Half of that, about 6 inches, goes towards moving the entire firewall forward giving additional foot well width and depth.

The other way of course is to move the transmission to the back and use a rear mounted transaxle.The problem with that is that for most cars the height of the rear bench and or the width between the rear seats are simply not suffcient for that. In a vette this is not a problem because you have no rear seats and an elevated rear platform, but this isn't so four most 2+3 or 2+2 configurations. Another bad thing about a rear mounted transaxle is that you need to carry your engine torque to it with a fast spinning torque tube going the length of the central tunnel. This, like a heavy flywheel, reduces the rev response of your engine. Not much of an issue for a 465lb-ft V8, but in a smaller engine that needle will rise and fall at a slower rate affecting performance and driving experience.

You move the transmission forward you move the engine forward and you then add length to the nose. Transmission bodies are wide and the bell housing is only part of the problem. The only thing thin on a tranny is the tail shaft.

Sorry this is not an options and defeats the main reason you shortened the engine.

Gee I wonder why you are not working for GM with all these odd Ideas?

[hyperv6]

I see and understand the points you are making. I have wondered why a supported Corvette group that clearly has done some R&D has not garnered more attention from GM. Either they have totally been overlooked or GM is watching but not commenting on it.

I would love to hear from some GM Motor engineers on their thoughts about this V4 engine. It would be great if Katech could produce some Torque charts to show how it flows and where in this engine. If it is at a high RPM, then that would tend to show why this motor is popular with motorcycles and why Motus has been successful with it as bike riders do love to rev.

If I had the extra cash, I would love to buy the V4 crate motor and put it into a kit car and see just how efficient I could get it to go on CNG.

I was interested in the K tech engine and did some digging.

The engine is not really half a LS 350.They like to think of it as a 3/4 version.

In the story I read it said it appears as a half a LS but in truth it has was inspired by three engines. The LS, the Honda 1300 V4 and the Ducati Desmosedici.

The truth is other then some of the general lay out the LS really shares little here. The only shared part is the Cam gear. It shares similar lay out of the ports and valve train but the engine has all different spacing and measurements. Other thean the sprocket it has no shared parts or specifications.

This was intended to be a light weight bike engine and not really anything for a car. They did use a VW dune buggy for testing and I can see a use for this in a sand buggy.

Check out the story in the Sept 2011 Hot Rod as it was the best story on this engine. It is interesting but I think it shows how that to do this right you really need to do more work than just lopping off 4 cylinders.

They even explain the odd firing of this engine as being better to help the rear tire recover between each of the 2 cylinder fires. Take time to read the story as it is neat what they did. Also I can see why GM is not involved as it was not their project or really their engine.

[dwightlooi]

You move the transmission forward you move the engine forward and you then add length to the nose. Transmission bodies are wide and the bell housing is only part of the problem. The only thing thin on a tranny is the tail shaft.

Sorry this is not an options and defeats the main reason you shortened the engine.

Gee I wonder why you are not working for GM with all these odd Ideas?

It's really not that complicated... If you have a four cylinder engine and you remove the front and rear cylinders such that it becomes a 2 cylinder engine, does the center of gravity change? No, it doesn't. However, the nose can be shortened by about the length of one cylinder and the transmission is moved forward by amout one cylinder. Simple? That same goes for when you chop a V8 into a V4. A Smallblock V8 is about 23~24 inches long not counting the accessories. Chop it in two and you save about a foot in overall engine length. Half of that goes towards moving the firewall and transmission forward. The other half goes towards shortening the nose.

[Drew Dowdell]

Regarding the original proposed image, wouldn't a pushrod V4 allow for a lower hood height than a DOHC I-4? Couldn't the nose and indeed the entire beltline be lower?

[hyperv6]

Regarding the original proposed image, wouldn't a pushrod V4 allow for a lower hood height than a DOHC I-4? Couldn't the nose and indeed the entire beltline be lower?

It could be but you can not go too low as you have to account for the hood engine clearance that is required in so many markets now.

Also if the hood clearance was that much of an issue you can lay a Eco over it you like. Many companies will lay inline engines over for lower center of gravity or for hood clearance.

[hyperv6]

You move the transmission forward you move the engine forward and you then add length to the nose. Transmission bodies are wide and the bell housing is only part of the problem. The only thing thin on a tranny is the tail shaft.

Sorry this is not an options and defeats the main reason you shortened the engine.

Gee I wonder why you are not working for GM with all these odd Ideas?

It's really not that complicated... If you have a four cylinder engine and you remove the front and rear cylinders such that it becomes a 2 cylinder engine, does the center of gravity change? No, it doesn't. However, the nose can be shortened by about the length of one cylinder and the transmission is moved forward by amout one cylinder. Simple? That same goes for when you chop a V8 into a V4. A Smallblock V8 is about 23~24 inches long not counting the accessories. Chop it in two and you save about a foot in overall engine length. Half of that goes towards moving the firewall and transmission forward. The other half goes towards shortening the nose.

If you say so.

If it is that good of an idea they could never pass this one up and I am sure the thought has never crossed their mind.

You get GM to build this and I will agree you are right. Deal?

As for the car I peg this at a 75% chance of a business car being approved on what GM is already looking at. The key will be how they can leverage the platform out over other brands and types of product that they can do to offset cost.

[Drew Dowdell]

Regarding the original proposed image, wouldn't a pushrod V4 allow for a lower hood height than a DOHC I-4? Couldn't the nose and indeed the entire beltline be lower?

It could be but you can not go too low as you have to account for the hood engine clearance that is required in so many markets now.

Also if the hood clearance was that much of an issue you can lay a Eco over it you like. Many companies will lay inline engines over for lower center of gravity or for hood clearance.

Hood clearance on a pushdrod V4 would still be lower than the DOHC I-4... and in that picture, it looks taller than the ATS. So, starting with the ATS hood height, which is relatively low, a V4 should be able to be even lower.

[hyperv6]

Regarding the original proposed image, wouldn't a pushrod V4 allow for a lower hood height than a DOHC I-4? Couldn't the nose and indeed the entire beltline be lower?

It could be but you can not go too low as you have to account for the hood engine clearance that is required in so many markets now.

Also if the hood clearance was that much of an issue you can lay a Eco over it you like. Many companies will lay inline engines over for lower center of gravity or for hood clearance.

Hood clearance on a pushdrod V4 would still be lower than the DOHC I-4... and in that picture, it looks taller than the ATS. So, starting with the ATS hood height, which is relatively low, a V4 should be able to be even lower.

Agreed it is a lower engine but my point is the Eco also can be laid over for more clearance if deemed needed.. It has been done by many in OE market and racing with in line engines. In fact in some cases the engines were laid flat. So to be that is a wash for both engines.

[dwightlooi]

Agreed it is a lower engine but my point is the Eco also can be laid over for more clearance if deemed needed.. It has been done by many in OE market and racing with in line engines. In fact in some cases the engines were laid flat. So to be that is a wash for both engines.

All else being constant, a 90 deg V4 is as tall as an inline-4 tilted over at 45 degrees. However, all else is not equal. The proposed engine is a pushrod design whereas the Ecotecs are DOHC mills. DOHC engine have taller, wider and heavier heads. Another problem with tilting an inline engine over is that you bias the weight towards one side since you have to rotate the engine along the axis of the crank shaft and cannot really move that sideways and still keep the drive shaft on the center line.

In any case, the key advantage of the 90 deg V4 is that it is just a tad over 2 cylinders long and it is nowhere near as wide as horizontally opposed fours. These allows the most compact packaging in a longitudinal rear drive application. Being a pushrod design also allows you to exploit this configuration without increasing the number of camshafts and drive sprockets over an inline layout. If you supercharge it, the blower goes neatly in the valley of the engine, something you will find difficult with 60 Vees and impossible with VR4s (15 degree staggered fours). The downside being that a 90 deg V4 design based on a V8 architecture has only two crank journals and you cannot have an even fire engine. This is OK, even attractive -- in the same manner that Ducatis & Harleys are attractive in their own right from their off beat exhaust notes -- in a sporty car or light truck, but is not ideal for a luxury car.

Edited July 26, 2013 by dwightlooi

[Drew Dowdell]

Dwight,

What about a compromise idea? A 15 degree V4 that uses the same pistons as the V8 and triple overhead cam valvetrain. This way, it would allow for the short hood that you're aiming for but also allow for use in most FWD applications as well. The downside is that turbocharging would be more difficult without some creative intake and exhaust routing, but that may be the price to pay for having the engine able to be used in all places where an Ecotec 4-cylinder is today. I just don't see GM building a 4-cylinder that can only be used in RWD cars.

[dwightlooi]

Dwight,

What about a compromise idea? A 15 degree V4 that uses the same pistons as the V8 and triple overhead cam valvetrain. This way, it would allow for the short hood that you're aiming for but also allow for use in most FWD applications as well. The downside is that turbocharging would be more difficult without some creative intake and exhaust routing, but that may be the price to pay for having the engine able to be used in all places where an Ecotec 4-cylinder is today. I just don't see GM building a 4-cylinder that can only be used in RWD cars.

All the narrow angle Vee engines (VR engines) have intakes on one side and exhaust on another. Basically, the intake ports and exhaust ports look like an Inline engine. You'll use just two cams with valve stems of different length allowing one cam to operate all the intake valves and the other all the exhaust valves. The downside is that the block has nothing to do with a V8 block as it'll need 5 main bearings and the combustion chamber will be completely different in geometry. In fact, all the VR motors have piston decks that are NOT perpendicular to the bore. All this means development costs will be like doing a completely new engine architecture.

The key point here is that GM does not really need a "new" 4-cylinder that can be used in FWD applications. It already has the 1.4, 1.6, 1.8, 2.0T and 2.5 engines. A FWD application does not benefit from a reduction in engine length since the engine compartment is wide enough as it is to accommodate an Inline-4. On the other hand, GM can develop a unique large displacement four for RWD applications for very little money which allows the entire package to out perform and look substantially different what is possible by simply using Ecotec fours. In the same vein, Toyota ans Subaru chose to do a 200 hp flat four instead of using an inline four or an existing turbocharged flat four -- and they make excellent examples of both -- for the FT86 because neither would have fulfill the new car's packaging requirements, driving characteristics or weight targets. Desire is one thing, but their ability to do this affordably for a relatively low volume car and a singular application is based on sharing the architecture will the existing Subaru flat fours.

[dwightlooi]

If GM wants to redo a four cylinder for FWD applications, it'll be more worthwhile to look at going to a SOHC 2-valve head with an Atkinson cam grind, cam-in-cam VVT and 14~15:1 compression ratio using direct injection. In doing so, you trade specific output for fuel economy. A naturally aspirated 2.5L so designed has the best chance in beating the MPG numbers of the 1.4T and competing 1.8 and 2.0L engines in FWD compact cars like the Cruze. Output will be ~160 hp which is better than the 1.8L DOHC or 1.4T as currently tuned, and about par with the Focus, Mazda 3 and other 2.0L cars. Basically, this is Skyactiv taken a step further with an increase in displacement, reduction in valve train friction and deeper intake regurgitation.

For applications currently using the 2.5L DOHC four, a turbocharged version of such an engine (aka a Miller Cycle variant) will easily beat the 2.5L DOHC in fuel economy while offering similar performance at 200 hp.

For Hybrids, they can chop that 2.5L Atkinson four down to three cylinders to 1.8L. This will offer the lowest parasitic drag compared to anything on the market while tendering about 120 hp (exactly where the output needs to be).

Another thing they can look at is eliminating the torque converter and/or clutch entirely in mild hybrids. The idea is simple. A converter and/or clutch is really only necessary in automatics for idling and creeping at parking lot speeds. If you remove the need for a car to idle you remove the need for a torque converter or clutch. In a mild hybrid, a 10~20hp / 80~120 lb-ft electric motor can be used to always propel the car from rest. Once below 600 rpm in 1st gear the engine uses AFM to shut off all valves and stops injecting fuel. Idle stop is mandatory and electric propulsion is a given from rest. At 5 mph the engine can decide if it needs to cut in for more power.

Edited July 26, 2013 by dwightlooi

[Drew Dowdell]

The advantage for GM building a VR4 would be that with its shorter length, it could fit in places where the 2.5 does not like in place of the 1.4 in the Sonic and Encore.

[Z-06]

Why is there a notion that this engine will not move a FWD?

[dwightlooi]

Why is there a notion that this engine will not move a FWD?

Because a 90 deg V4 is very short, but wide. When you place it in a transverse setup, it requires much more engine bay length than an inline engine or a 60 degree V6. More importantly though, in a transverse arrangement it has no advantages over an inline-4.

[Z-06]

Why is there a notion that this engine will not move a FWD?

Because a 90 deg V4 is very short, but wide. When you place it in a transverse setup, it requires much more engine bay length than an inline engine or a 60 degree V6. More importantly though, in a transverse arrangement it has no advantages over an inline-4.

But why restrict to transverse setup?

[Drew Dowdell]

Why is there a notion that this engine will not move a FWD?

Because a 90 deg V4 is very short, but wide. When you place it in a transverse setup, it requires much more engine bay length than an inline engine or a 60 degree V6. More importantly though, in a transverse arrangement it has no advantages over an inline-4.

But why restrict to transverse setup?

Ooo. Good question! It could use the same transmission layout as my Toronado or the Dodge Intrepid has.

[dwightlooi]

Why is there a notion that this engine will not move a FWD?

Because a 90 deg V4 is very short, but wide. When you place it in a transverse setup, it requires much more engine bay length than an inline engine or a 60 degree V6. More importantly though, in a transverse arrangement it has no advantages over an inline-4.

But why restrict to transverse setup?

Ooo. Good question! It could use the same transmission layout as my Toronado or the Dodge Intrepid has.

Because...

(1) GM does not have a longitudinal FWD transmission (ala Audi or Subaru) in the Hydramatic lineup

(2) GM FWD Platforms are not designed to take that configuration.

(3) Longitudinal FWD in general is a bad idea from a balance standpoint because it has worse balance than a transverse FWD layout and while having the same footwell intrusion that RWD setups suffer from.

[Z-06]

Explain me why is it bad from a balance point.

[Drew Dowdell]

The balance is bad in Audis, but in other setups, not so much. With a V4, in this setup, you could still have the engine mostly aft of the front wheels. In the intrepid, there doesn't seem to be any more footwell intrusion than any other FWD car.

[dwightlooi]

The balance is bad in Audis, but in other setups, not so much. With a V4, in this setup, you could still have the engine mostly aft of the front wheels. In the intrepid, there doesn't seem to be any more footwell intrusion than any other FWD car.

Actually, no. The Longitudinal FWD transaxles have the differential and output shafts located just behind the torque converter near the bell housing. This is generally inline with the front wheel hubs. It means that generally, the entire entire and usually a part of the transmission (namely the torque converter or clutch assembly) overhangs the front wheel axis.

[balthazar]

Any possibility in reverse-mounting the engine; putting a V4 behind the transaxle & moving the front axle as far forward as possible, with the transaxle out front, in the name of balance? I guess it would make for a really long hood.

[Drew Dowdell]

The balance is bad in Audis, but in other setups, not so much. With a V4, in this setup, you could still have the engine mostly aft of the front wheels. In the intrepid, there doesn't seem to be any more footwell intrusion than any other FWD car.

Actually, no. The Longitudinal FWD transaxles have the differential and output shafts located just behind the torque converter near the bell housing. This is generally inline with the front wheel hubs. It means that generally, the entire entire and usually a part of the transmission (namely the torque converter or clutch assembly) overhangs the front wheel axis.

Not always.

[G. David Felt]

Very cool photo of the Olds engine.

[Drew Dowdell]

Another view.

The front axle line is ahead of the rear two cylinders, so in a V4, the engine/transmission would be primarily to the aft of the front wheels. The caveat is there is no real limitation to how far ahead of the engine you could put the front wheels.... Not that you'd want to, but you could build a rear engine-front wheel drive set up this way.

[G. David Felt]

Very cool drawings, one can see how all the weight would help the tires grip.

[Z-06]

The balance is bad in Audis, but in other setups, not so much. With a V4, in this setup, you could still have the engine mostly aft of the front wheels. In the intrepid, there doesn't seem to be any more footwell intrusion than any other FWD car.

It still does not answer WHY the set up has bad balance. Is it harmonic (NVH) or stability or mechanical?