Which engine for the C7 Corvette?

[dwightlooi]

Bingo.

If the pushrod was so great, why does the CTS have a DOHC direct injected V6 rather than a pushrod V6?

I won't argue that the Corvette can get away with the pushrod V8 for another generation, maybe two, I am just saying it is better off with DOHC. Likewise for the GMT900s.

Because they were after refinement and consumer perception in that segment more than anything else.

Let's look compare apples to apples for a minute... The 3.9 liter Pushrod V6 made 240hp in the G6. The 3.6 liter high feature V6 (without direct injection and its accompanying compression ratio bump) makes 252. Is that such a huge difference? If the 3.9 had been an aluminum block it'll be smaller and lighter than the 3.6 DOHC too. You can probably get a 4.2~4.5 liter Pushrodder to fit in the same exterior envelop and tip the scales at the same weight as a 3.6 liter V6. In the case of the V8 the difference is even more pronounced. In general, with similar materials and construction, a 6.2 liter pushrod is about the same mass and size as a 4.2 liter DOHC V8.

In any case, when it comes to the Corvette, the DOHC V8 or Turbo-6 is not particularly appealing because it buys no additional performance at an increase in cost. In terms of prestige and consumer perception, it doesn't stand out either. In fact, one can argue that it offers less appeal since the small block like the evolution twin has its swarm of fans who loves it's slightly rude character. Which is why I feel that a DOHC V-12 may make more sense than a DOHC V8.

When it comes to economy, the biggest factor is vehicular weight. The reason being that it takes power to accelerate mass and it takes fuel and air to make power. Next comes the gearing which is especially important at cruise speeds. Which has more wasted energy? A 6 liter 8-pot at turning over 1600 times a minute or a 4 liter 8-pot making 2400 revolutions? In third place comes the frictional losses within a specific engine and its breathing losses. Here, a 2-valve push rod has lower frictional losses, whereas a 4-valve DOHC has lower pumping losses. All else being equal, at cruising speeds and loads, the push rod has the advantage, at power peak the DOHC has the advantage. However, since the push rod engine tends to also be bigger in displacement it is about a wash at cruise with the advantage clearly going to the DOHC engine at the power peak.

What does these all add up to? Well, a light vehicle with a tall gearing can be just as economical as a heavier vehicle with a shorter gearing even if the former has a much bigger displacement motor and a push rod valve train. Even when the vehicles are the same approximate mass, the difference is less significant than most people believe. Case and point?

Chevy Corvette -- 6.2 liter 432hp OHV 2-valve V8 = 16/26mpg (City/Hwy)

Chevy Camaro 3.6 V6 -- 3.6 liter 300hp DOHC 4-valve V6 = 18/29mpg (City/Hwy)

Chevy Camaro SS -- 6.2 liter 420hp OHV 2-valve V8 = 16/24mpg (City/Hwy)

Mercedes C55 -- 5.5 liter 362hp SOHC 3-valve V8 = 16/22 mph (City/Hwy)*

Infiniti G37 -- 3.7 iiter 330hp DOHC 4-valve V6 = 18/26 mpg (City/Hwy)

Honda Accord EX V6 -- 3.5 liter 271hp SOHC 4-valve V6 = 19/29mpg (City/Hwy)

Toyota Camry LE V6 -- 3.5 liter 268hp DOHC 4-valve V6 = 19/28mpg (City Hwy)

* I get about 18mpg on the average in combo local and feeway driving to and from work

Edited September 2, 2009 by Oldsmoboi

[hyperv6]

I was comparing naturally aspirated to naturally aspirated, but if you want to go down the forced induction route the S/C 3800 and Turbo 3800 had a bit of kick around town and geared right could return good fuel economy. Investments into refinement could have made them very competitive engines.... but the car magazines demanded OHC or higher horsepower per litre.

The point I was making was that a pushrod V6 can be every bit as efficient as a 4-cylinder DOHC in a comparable vehicle. You don't have to put the spurs into the V6 Equinox to get around town like you need to with the CRV. The CRV revs high even in normal driving. If you keep the CRV revs below 3,000 like you can in an Equinox, you'll manage to piss off Mable Blue-Hair behind you in her LeSabre. If hearing the engine rev to 6,500 rpm smoothly is an important aspect in your car purchasing decision, perhaps a 160hp 4-cylinder AWD CUV isn't what you are looking for.

I own a 2.8 V6 in a Fiero and a 3800 SC in a 04 GP. Both are good engines compared to where they came from But!!!

THe now that I drive the 3800 SC after a 3.6 there is no comparison. THe 3.6 in the real world get a little better mileage vs the 3800. Also the power is not much different. But the refinement is night and day.

The 3800 SC mileage in the GP is not all that great. In the real world it is 18 and 25 while in the Bu I see low 20's to 30 MPG

The Ford flat head was a hell of a good engine but that doe not mean they should still put it into a 2010 Shelby. If ther eis better technology out there use it.

Edited September 2, 2009 by hyperv6

[cletus8269]

In fact it is more potent than even many SBC and one BBC I owned.

...

those BBC's must have been severely neutered...

[hyperv6]

...

those BBC's must have been severely neutered...

1972 GMC Sprint SP 400 [402]. It would chirp a mean second gear with a stock auto but only got 9 MPG and was a dog. I would have to guess it was a 15 second car at best 100% stock. My 70 350 Monte showed more spunk.

I loved the guy with the stock 69 Chevelle SS that had to run my SBC with a cam. He made sure to get in line at the track to run me. When I clipped him by a full second he would not speak to me after telling me I had to have a BBC since I was missing all that power. I think he had the old 325 HP dog and thought he has a race car.

There were many Great BBC but for every good one there were 5 slow ones.

They all were not LS6's. In fact the best BBC built are the present crate engines today. They have the best of the past and present for a good price and a warranty. We have used many 502's and 572's at work for great effect.

Edited September 4, 2009 by hyperv6

[cletus8269]

I loved the guy with the stock 69 Chevelle SS that had to run my SBC with a cam. He made sure to get in line at the track to run me. When I clipped him by a full second he would not speak to me after telling me I had to have a BBC since I was missing all that power. I think he had the old 325 HP dog and thought he has a race car.

There were many Great BBC but for every good one there were 5 slow ones.

interesting... my dad had a 68 ss396 with the 325. i guess in stock form they werent the greatest but my dad said he could catch all the way up to 3rd and chirp 4th in his. course he was running a tunnel ram setup on his and he had some head work done. they engine shop that rebuilt the motor's bottom end was going to put a cam in it but the shop owner told my grandpa that the cam would make the motor eat parts constantly so they didnt do it. still the street race challenges everywhere dad went day or night got so bad he sold the chevelle and got a truck.

[Chevy Nick]

[sarcasm]I don't know how the Corvette, with its out-of-date pushrod engine, and ancient transverse leaf spring suspension could ever keep up with something on the cutting edge of technology, ie. a Ferrari F430:

Mobil 1 presents the Grand Prix of Mosport GT2 Results:

Pos./Drivers/Car/Laps

1. O'Connell/Magnussen, Chevrolet Corvette C6.R, 117

2. Melo/Kaffer, Ferrari 430 GT, 117

3. Gavin/Beretta, Chevrolet Corvette C6.R, 116

4. Henzler/Werner, Porsche 911 GT3 RSR, 116

5. Bergmeister/Long, Porsche 911 GT3 RSR, 115

6. Farnbacher/James, Panoz Esperante GTLM, 115

7. Law/van Overbeek, Porsche 911 GT3 RSR, 115

8. Feinberg/Hall, Dodge Viper, 113

9. Hand/Auberlen, BMW E92 M3, 110

10. Robertson/Robertson/Murry, Ford GT MK 7, 105

11. Mueller/Milner, BMW E92 M3, 71

This race happened today

http://www.lsxtv.com/forum/corvette-racing...nish-1646.html#

[/sarcasm]

C6.R engine technology: http://www.corvetteracing.com/cars/c6r/engine.shtml

World-class sports car for the common man at a reasonable price

I missed most of the CTS discussion, but the top of the line CTS runs a small block chevy v-8, pushrods included.

[hyperv6]

[sarcasm]I don't know how the Corvette, with its out-of-date pushrod engine, and ancient transverse leaf spring suspension could ever keep up with something on the cutting edge of technology, ie. a Ferrari F430:

http://www.lsxtv.com/forum/corvette-racing...nish-1646.html#

[/sarcasm]

C6.R engine technology: http://www.corvetteracing.com/cars/c6r/engine.shtml

World-class sports car for the common man at a reasonable price

I missed most of the CTS discussion, but the top of the line CTS runs a small block chevy v-8, pushrods included.

It is amazing what old technology and $750,000+ per car can do.

Give me enough money and I could make a little red wagon a winner.

I did see the guys at the GT2 intro at Mid Ohio. Watching them there I think they are still holding back. They do not want to get a rules change before next year. These cars are just so well tuned and sorted out that going a class down is just going to make it easier for them to drive with less power. The less down force is not that much of an issue per what the drivers said at Mid Ohio.

Long Live Jake.

I suspect in the future the Vettes will have either an engine size reduction or more weight. Then they will need more revs. Winners always pay a price in road racing.

[Chevy Nick]

It is amazing what old technology and $750,000+ per car can do.

Give me enough money and I could make a little red wagon a winner.

You don't think the other race teams spend money on their cars?

[hyperv6]

You don't think the other race teams spend money on their cars?

Sure they do and very little on these cars are stock.

Just like calling a top fuel car a push rod engine. It is but other than saying it has push rods and 8 pistons were involved can you compare it to a street engine.

My point is with enough time or money you can make anything fast depending on the rules.

Heck F1 ran very small displacment Turbo DOHC 4 cylinders in the 80's that made well over a thousand HP too.

I know the transverse spring is a tradition but I wonder where the Vette would be with coil overs like Callaway used. We may never know as they have done well with the present set up but it makes one wonder.

[dwightlooi]

I don't think the Pushrod 2-valve vs DOHC 4-valve contest is one over which one is more "advanced". Advanced is a subjective term. The pushrod engine was invented after the overhead cam engine. However, the average DOHC 4-valve design currrently in production also has more technological content such as variable timing, variable valve lift, direct injection, variable intake mannifolds, coil on spark ignition, etc. (all of which an OHV design can also incorporate).

But, all of that are irrelevant. What are relevant are these:-

• Pushrod engines can achieve a higher power-to-weight ratio.
• Pushrod engines can achieve a higher power-to-size ratio.
• Pushrod engines can achieve a higher power-to-cost ratio.
• DOHC 4-valve engines can achieve a higher power-to-displacement ratio.
• DOHC 4-valve engines can achieve a higher degree of NHV refinement.
• DOHC 4-valve engines can achieve attain higher maximum engine speeds.
• Fuel economy is roughly equal for a given level of performance.

[regfootball]

Couldn't? or wouldn't?

On the mpg side of things, the previous gen Malibu V6 could get better highway mileage than a Camry 4-Cylinder.

I also wonder if the imports weren't playing to the test. Sure the 4-cylinders get good EPA scores for mpg, but who drives like that? Even the new EPA system is relatively conservative. You have to spin the hell out of the torqueless wonders that Honda produces even in just around town driving. We're lucky if we get 21mpg average (very typically 250 miles on a 12 gallon fill up) in our CRV. I can't imagine a 3.4 litre Chevy Equinox would be any worse.

todays four cylinders are lively, get good mpg. and the good four cylinders today have better NVH than GM's v6.

face it, GM never invested in making the pushrod v6's up to date. they could neither compete with modern v6's or 4's in total owner satisfaction.

GM should have made an investment in making the pushrod technology stay up to date on NVH, power, revs, and all that.

Edited September 5, 2009 by regfootball

[smk4565]

todays four cylinders are lively, get good mpg. and the good four cylinders today have better NVH than GM's v6.

face it, GM never invested in making the pushrod v6's up to date. they could neither compete with modern v6's or 4's in total owner satisfaction.

GM should have made an investment in making the pushrod technology stay up to date on NVH, power, revs, and all that.

Agreed on the first part, but where GM made it's mistake was around 2004. When the 3.6 V6 debuted (and the 2., GM figured the "high feature" V6s would be maybe 20% of their V6 volume, and the 3500 and 3900 V6s (and few remaining 3800s) would be 80%. Thus the 04-07 Malibu had rough sounding 200 hp V6 compared to Honda's refined SOHC V6 making 240 hp. Now 5 years later, the 3.0 and 3.6 V6s are making their way into all GM V6 vehicles. They should have gone all DOHC V6s 5 years ago, rather than try to get buy with dated, unrefined engines coupled to an equally dated 4-speed transmission.

[hyperv6]

The key today is to make engines smaller and more efficent with out giving up power.

In the past DOHC failed at the low end for power and torque but with the addition of VVT it has given them a very flat torque curve.

Add in the impoved turbo chargers of today with Intercooling Direct Injection, the smaller engines will pave the way to the future of cars getting better mileage and emissions. Companies like Ford and others have not invested into these engines for status but because they had too to meet the future requirements.

GM is only behind and stuck with the push rods as long as they have because they could not afford to do DOHC in the past due to tight money. They did to their credit push the 4 cylinder ahead with the Ecotech as they needed a good solid 4 cylinder.

No one here is saying the LS engines are poor engines. GM has taken them farther than anyone ever thought possible. It is no different than carberators vs fuel Injection. One can do a lot with a carb yet today with emissions and fuel mileage but there comes a time and place it is more cost effective and easier to do it with other systems.

If push rods has such a great future everyone would be moving ahead with them. As it stands few even offer them anymore. If there was a future to them and they were such an easy cheap way to go they would not have spent billions on developing DOHC engines for the future.

If you not even GM on their 4 cylinders are moving down in size. 1.4 Turbo is going to be very common. This past will be seen with many of GM and everyone elses engines. With the ability to get 250 HP to 450 HP out of 2.0-3.6 liters is the way they will go to meet the mileage goals and emmision goals of the goverment.

[regfootball]

just read road and tracks update on their long term MKS ecoboost.

this car is 4400 pounds.

0-60 5.0 seconds.

almost 22 mpg is their current mileage to date. it's like 21.7 or something. this is with them hammering on the throttle. all wheel drive.

now, back to that 13 miles per gallon on the g8 GXP.........

GM will need to start squeezing equivalent hp/litre out of the small block to keep it current in the marketing eye.

[cletus8269]

just read road and tracks update on their long term MKS ecoboost.

this car is 4400 pounds.

0-60 5.0 seconds.

almost 22 mpg is their current mileage to date. it's like 21.7 or something. this is with them hammering on the throttle. all wheel drive.

now, back to that 13 miles per gallon on the g8 GXP.........

GM will need to start squeezing equivalent hp/litre out of the small block to keep it current in the marketing eye.

thats great and all but thats a sedan, this is about super cars. the 26mpg Z06 comes to my mind. what super car with 505hp does that? i am really asking a question here, cause i dont know.

[hyperv6]

The Ecotec is a better engine than the Eco boost 4 cylinder. But GM is losing the fight right now with the marketing that Ford has put out. Ford is just flat wasting GM in marketing all the way around.

GM has some good DI v6 engines but they need to advance them and bring in the turbos asap and market them. GM is going to fall behind in the V6 race too.

When Ford comes out with the Coyote if it is smaller and gets better mileage while making the same or near the same power it will hurt GM. Ford screwed up the first engine but I am willing to bet it will be right this time.

GM has always had top notch engines and trannys. I know they can do a updated engine that will take todays technology and imporve on what they have now in ways of efficentcy.

From a marketing stand point GM would have a hard time with a less efficent engine. Too many people are buying into this green crap but still want their power.

[dwightlooi]

If you not even GM on their 4 cylinders are moving down in size. 1.4 Turbo is going to be very common. This past will be seen with many of GM and everyone elses engines. With the ability to get 250 HP to 450 HP out of 2.0-3.6 liters is the way they will go to meet the mileage goals and emmision goals of the goverment.

I think there is a misconception that smaller displacement equals better economy or that more valves equal better economy. This is not true, in fact sometimes the reverse is true.

For instance, when you drop displacement from say a 3.6 liter V6 to a 2.8 liter V6 you have to ask yourself what happens in the process? Assuming that both engines have the same valve train layout not much has changed there -- same number of sprockets, same number of bearings, same number of cam lobes, same number of followers, same number of valves stems rubbing against the same number of guides. Hence, valvetrain friction remains roughly similar. Now the bores have probably shrunk a little so you have a reduction in wall friction there and the amount of air you are pumping in and out of the engine is reduced so you have reduced pumping losses. The overall improvement in economy is really from these areas and it is slight. It is so slight in fact that because the lower displacement engine also has less torque and power, and is frequently given lower gearing to get it off the line smartly this change in gearing often cancels out the economy gains. More effective is a reduction in cylinder count and making the biggest displacement from the smallest number of cylinders as you can.

Now, you move to forced induction. This is also a mixed bag. A turbocharger gets you additional power from the same engine size, but it also does two things detrimental to fuel economy. The first being that it drops compression ratio. Usually 1 to 2 points. Also, it eliminates whatever fancy intake work you can otherwise implement to achieve resonance charging. In most instances, when you move from a bigger engine without turbo(s) to a smaller one with turbo(s) making the same power, you do not gain fuel economy with all else being equal. When you see a gain, it is usually because you moved from an engine with more cylinders to one with less cutting down on frictional losses. Good examples are Audi's 4.2 liter V8 vs 3.2 liter turbo V6 or GM's own 3.6 liter V6 vs 2.0 liter I4 -- all engines making similar power but the turbocharged unit has less cylinders, less valves, etc.

[hyperv6]

I think there is a misconception that smaller displacement equals better economy or that more valves equal better economy. This is not true, in fact sometimes the reverse is true.

For instance, when you drop displacement from say a 3.6 liter V6 to a 2.8 liter V6 you have to ask yourself what happens in the process? Assuming that both engines have the same valve train layout not much has changed there -- same number of sprockets, same number of bearings, same number of cam lobes, same number of followers, same number of valves stems rubbing against the same number of guides. Hence, valvetrain friction remains roughly similar. Now the bores have probably shrunk a little so you have a reduction in wall friction there and the amount of air you are pumping in and out of the engine is reduced so you have reduced pumping losses. The overall improvement in economy is really from these areas and it is slight. It is so slight in fact that because the lower displacement engine also has less torque and power, and is frequently given lower gearing to get it off the line smartly this change in gearing often cancels out the economy gains. More effective is a reduction in cylinder count and making the biggest displacement from the smallest number of cylinders as you can.

Now, you move to forced induction. This is also a mixed bag. A turbocharger gets you additional power from the same engine size, but it also does two things detrimental to fuel economy. The first being that it drops compression ratio. Usually 1 to 2 points. Also, it eliminates whatever fancy intake work you can otherwise implement to achieve resonance charging. In most instances, when you move from a bigger engine without turbo(s) to a smaller one with turbo(s) making the same power, you do not gain fuel economy with all else being equal. When you see a gain, it is usually because you moved from an engine with more cylinders to one with less cutting down on frictional losses. Good examples are Audi's 4.2 liter V8 vs 3.2 liter turbo V6 or GM's own 3.6 liter V6 vs 2.0 liter I4 -- all engines making similar power but the turbocharged unit has less cylinders, less valves, etc.

Depends on the state of tune.

My 2.0 has a rating of 21/29 260 5 sp and 235/250 HP Automatic stock.

The 2.2 gets 22/32 155 HP

The 2.4 gets 22/30 174 HP

Now with that being said the 2.0 in reality does better than the EPA rating. In stock form I would have to drive it very hard to get less than 20 MPG in non highway driving.

The funny part is with the GM Turbo tune kit. I now have a regular 23 city and 30/31 Highway. I picked up at least 1 MPG over my usual 22 MPG. Now this is not hypermiles. I often see 21 PSI from stop lights.

All the guys with the tune have noticed this with the 2.0 and even GM said it is true in their testing. So in the Automatic I gained 55 HP in first and second gears and 45 in 3rd and 4th gears and picked up more MPG. Hmmm

Not the guys with the other engines also beat the EPA ratings. I have noticed on several GM cars they do better than they are rated anymore since the change in the way they rate them .

VVT, Computers and DI are game changers in the turbo area anymore. Things are not as they once were and comprimised.

If smaller and turbo engines are not the way to go then why are most MFG going to them and not building more pushrod V8? I would like to know. Are they that ignorent?

Edited September 6, 2009 by hyperv6

[smk4565]

thats great and all but thats a sedan, this is about super cars. the 26mpg Z06 comes to my mind. what super car with 505hp does that? i am really asking a question here, cause i dont know.

Z06 gets 15/24 mpg. Base Corvette with manual gets 26 mpg, all good mpg numbers for the performance it offers, thanks to low weight, aerodynamics, and gearing.

19/27 mpg from the Porsche 911 Carrera, but it drops to 16/23 mpg for a 911 Turbo.

Lotus Exige gets 20/26 mpg, add one more mpg for the Elise. The Exige on a racetrack is pretty tough to beat.

[smk4565]

The Ecotec is a better engine than the Eco boost 4 cylinder. But GM is losing the fight right now with the marketing that Ford has put out. Ford is just flat wasting GM in marketing all the way around.

GM has some good DI v6 engines but they need to advance them and bring in the turbos asap and market them. GM is going to fall behind in the V6 race too.

The Ecoboost 4cylinder isn't out yet, so we don't know if Ecotec is better. Agreed though that Ford marketing is laying waste to GM's Howie Long Chevy ads with gray cars in a white/beige showroom.

GM should DI every DOHC engine they make, and a turbo 4 (like Audi/VW's 2.0T) would be nice for the small to mid-size vehicles.

And if they put 2 of those engines together, they have a 4.0-4.8 liter twin turbo V8 for the Vette and Cadillacs.

[regfootball]

if the ford ecoboost was in say, a mustang, with a 6 speed manual. i think we would see about a 4.2-4.3 0-60 if you interpolate the weigght between 4400 pounds and 3600 pounds. i also think that mks that is rated 17/25 and gets 22 in hard driving would prob see 20/30 in the mustang with consistent 25 mpg.

for a tire shredder, that is not bad.

i read yesterday that the 4 cyl 2.0 eco boost will FINALLY be out next year with rating of 240/240 or something like that. seeing as how max torque on the six is available at 1500 rpm, i figure on the ECOBOOST 4 it should make the 230-240 torque at about 2000 rpm. this engine is going in the edge and explorer of all things too so ford is confident in its pulling capacity. i see it going into the fusion and i bet we see 6.0 0-60 with the ecoboost 4 and manual, since the fusion is a pretty light car.

that car will be the spiritual successor to the SHO in my book. and it will prob see EPA ratings of 25/35 with real world mileage consistently around 30.

hows about an ecoboost next gen focus?

Edited September 7, 2009 by regfootball

[hyperv6]

The Ecoboost 4cylinder isn't out yet, so we don't know if Ecotec is better. Agreed though that Ford marketing is laying waste to GM's Howie Long Chevy ads with gray cars in a white/beige showroom.

GM should DI every DOHC engine they make, and a turbo 4 (like Audi/VW's 2.0T) would be nice for the small to mid-size vehicles.

And if they put 2 of those engines together, they have a 4.0-4.8 liter twin turbo V8 for the Vette and Cadillacs.

The numbers are out on the Ecoboost 4 and they are no where near the 2.0 but I expect it to be more available. Hence the word leaking out of GM using the 2.0 more and killing the Cobalt and HHR SS to make them more avaiable for lines that will continue to be built.

DI is going to be on every engine in time as will DOHC. THe question is how long do they delay it.

I would say no merging of engines to make a V8. Used the concepts and ideas learned in the 2.0 and make a clean sheet engine and do it right. Too often GM has cut and added cylinders that just never worked as well as if they did it right.

[smk4565]

Ecoboost 4 is supposed to make 270 hp, that is quite good, it will have the power of The Duratec 3.5. But refinement as well as fuel economy are big factors, if the V6 is smoother and more quite and gets 1 mpg less, people will still take it over the 4-banger.

I agree the engine should be from scratch, but the cylinder size could be the same. I remember when Ford had the 3.0 V6, Jaguar had the 4.0 V8 and Aston Martin had a 6.0 V12, they were all related to each other. GM has 2.0, 3.0 and 2.4 and 3.6 engines so they should be able to come up with 4.0 and 4.8 liter V8s based on engines they already make, which should keep development time and cost somewhat down.

[hyperv6]

Ecoboost 4 is supposed to make 270 hp, that is quite good, it will have the power of The Duratec 3.5. But refinement as well as fuel economy are big factors, if the V6 is smoother and more quite and gets 1 mpg less, people will still take it over the 4-banger.

I agree the engine should be from scratch, but the cylinder size could be the same. I remember when Ford had the 3.0 V6, Jaguar had the 4.0 V8 and Aston Martin had a 6.0 V12, they were all related to each other. GM has 2.0, 3.0 and 2.4 and 3.6 engines so they should be able to come up with 4.0 and 4.8 liter V8s based on engines they already make, which should keep development time and cost somewhat down.

The Ecoboost I have read about was 2.0 230 hp and 240 ft lbs.

The Vette will have to have a V8 as long as GM makes one. It will be smaller in the future with a lighter car as good HP perfromace will be as good or better than it is now.

[regfootball]

c/d fusion 0-60 was around 8 seconds.

230/180=1.27, invert that = .783 * 8.0 = 6.26 seconds 0-60. i will round down to 6.2 seconds. fast enough for me! for a daily commuter.

which would be faster than the/my original sho and damn close to a 3.6 equipped epsilon / auto.

i will bet that it will actually show up with more than 230/240. the v6 came in with more power than originally communicated.

i will guess 25/35 on mpg figures if equipped with a manual trans.

[dwightlooi]

The art of building the most economical engine:-

To build the most economical engine in any given displacement you will want to do the following:-

• Build the biggest engine with the fewest cylinders.
• Maximize the Compression Ratio.
• Use as little cams and valves as you can*.
• Incorporate VVT.
• Make it an Atkinson or Miller Cycle.
• Give it a resonant long intake runner set optimize for the mild acceleration band.
• Incorporate Direct Injection.
• Gear the transmission to produce the lowest acceptable RPMs at 60 mph.
• Ensure that it runs on 87 octane.

* Meaning you'll use an SOHC 2-valve arrangement for an inline engine or Pushrod 2-valve arrangements for a Vee engine.

Eg. If you want the most economical 2.0 liter engine, you'll make it a Direct Injection Inline-3, top it with a SOHC 2-valve head with co-axial dual VVT, give it Atkinson cycle cams, 11.3:1 compression ratio, give it long intake runners which produces resonance charging at 2000~3000 rpm and gear it such at it turns at 2000 rpm at 60 mph (barely able to sustain that speed) without a transmission downshift.

Eg. If you want the most economical 4 liter engine, you'll make it a Direct Injection V6, top it with a pushrod 2-valve head with co-axial dual VVT, give it Atkinson cycle cams, 11.3:1 compression ratio, give it long intake runners which produces resonance charging at 2000~3000 rpm and gear it such at it turns at 1400 rpm at 60 mph (barely able to sustain that speed) without a transmission downshift.

Remember, we are not talking about performance here, or civility, or anything else. Just pure Fuel Economy.

[hyperv6]

The art of building the most economical engine:-

To build the most economical engine in any given displacement you will want to do the following:-

• Build the biggest engine with the fewest cylinders.
• Maximize the Compression Ratio.
• Use as little cams and valves as you can*.
• Incorporate VVT.
• Make it an Atkinson or Miller Cycle.
• Give it a resonant long intake runner set optimize for the mild acceleration band.
• Incorporate Direct Injection.
• Gear the transmission to produce the lowest acceptable RPMs at 60 mph.
• Ensure that it runs on 87 octane.

* Meaning you'll use an SOHC 2-valve arrangement for an inline engine or Pushrod 2-valve arrangements for a Vee engine.

Eg. If you want the most economical 2.0 liter engine, you'll make it a Direct Injection Inline-3, top it with a SOHC 2-valve head with co-axial dual VVT, give it Atkinson cycle cams, 11.3:1 compression ratio, give it long intake runners which produces resonance charging at 2000~3000 rpm and gear it such at it turns at 2000 rpm at 60 mph (barely able to sustain that speed) without a transmission downshift.

Eg. If you want the most economical 4 liter engine, you'll make it a Direct Injection V6, top it with a pushrod 2-valve head with co-axial dual VVT, give it Atkinson cycle cams, 11.3:1 compression ratio, give it long intake runners which produces resonance charging at 2000~3000 rpm and gear it such at it turns at 1400 rpm at 60 mph (barely able to sustain that speed) without a transmission downshift.

Remember, we are not talking about performance here, or civility, or anything else. Just pure Fuel Economy.

Civility or the lack of being the key word.

Edited September 8, 2009 by hyperv6

[hyperv6]

Note the new Mclaren road car engine. It will not only be efficent, powerful and clean.

It will be a twin-turbo 3.8-liter V8 engine producing around 600 horsepower and 433 lb-ft of torque. Note the future will be smaller more efficent, cleaner and no less powerful. GM could do this just as easy and I am sure much cheaper.

[regfootball]

4 valves became prevalent because it helped the engine breathe better i do not see how going back to 2 valves is a good thing.

[dwightlooi]

4 valves became prevalent because it helped the engine breathe better i do not see how going back to 2 valves is a good thing.

Well, yes and no. It depends on what you are after.

For any given bore area, having 4-valves allows you to flow more air. This in turn allow you to burn more fuel and hence make more power. 5-valves do even better (albeit slightly) and some designs combine a 5-valve head with a narrow bore and long stroke to achieve the desired balance between energy recovery from a long stroke engine and adequate breathing to not be too labored at higher revolutions. The VW/Audi 1.8L (I4), 2.8L (V6) and 4.2L (V8) 5-valve engines (1997~2005) comes to mind.

However, one has to understand that 4-valves is not a free lunch and its advantages are largely beneficial only at engine revolutions above what is typically experienced in car cruising down the freeway or puttering placidly around town. The disadvantages of using 4-valves is the additional valve train friction, increased engine mass from larger heads to accommodate the overhead single or (especially) dual cams. In addition, increased flow cross sections also reduces intake velocity which is detrimental to fuel-air mixing leading to increased emissions and reduced power from incomplete combustion unless it is carefully addressed. The increased flow cross section of the valves does not do much for you performance wise until around 4500~5500 rpms (depending on the design).

In the early eighties, when manufacturers first went to 4-valve heads in mass produced engines, many designs like the Toyota 4A-GE and 3S-GE had to resort to separate intake tracts for each valve and butterflies to block off half of them at lower engine speeds to promote intake swirl and complete combustion. In general, the 4-valve engines were weaker than their 2-valve counterparts at lower engine speeds and were no more economical. They did however provide higher output for the displacement. Overtime, manufacturers narrowed the intake port sizes, increased runner lengths and in general toned down their 4-valve designs such that they no longer required complicated implements to run properly from idle and up. However, many engines also no longer realize the performance potential of their 4-valve configuration. For example, a turn of the millennium Toyota 1MZ-FE engine found in the Camry made 192hp @ 5400 rpm out of 3.0 liters (~64 hp per liter). It no longer has the V-RIS swirl promotion system but has relatively mild cams and narrow intake tracts instead. At 5400rpm, a 2-valve head would have been adequate to provide the necessary flow for a similar output.

The reality is that from an economy or performance standpoint, if you are aiming to produce an engine with less than ~70 hp/liter you really don't need a 4-valve design. The LS3 engine in the current Corvette and Camaros is a 68~70hp/liter engine and does NOT in any way sport a radical tune. If you do elect to use a 4-valve design, you pay for it in terms of higher frictional drag (which may cost you cruising economy), greater complexity, higher cost, more weight, bigger size, etc. And, you get paid back tangibly only terms of more refined engine noises. So really, the million dollar question is whether that is your first and foremost priority!