DOHC or SIBC for Corvette C7

[Drew Dowdell]

Yes, but Ford has been quite successful with OHC truck engines for over a decade now.... Toyota's a niche player(in the full size truck market), Ford has long been the market leader.

It's also fairly low on power. A 310 hp Lincoln Navigator? Really?

[CaddyXLR-V]

We will have to wait and see how the tech is applied to the existing engines. What you propose would be far more expensive, and risky than advancing the LS series.

I have no doubt that when/if the LS V8s can no longer be on a par or better than another architecture, they will be replaced. The fact remains that they are more than competitive today, and have great potential for further develpoment. It simply doesn't make sense to abandon such a successful format at this time. When no more potential for the smallblock was there to be had the LS was born. Until that fate compromises the LS, I expect to see GM evolving it over time. Such a progression is what reliability is made of.

DOHC will never be the determining factor in a change to a new V8, someday it may "come with the package", but that's about it. Other technology will be far more important.

OHV is already being phased out of the V6s, and I feel it's only a matter of time before the same happens with the V8s. The only thing slowing that down is that their OHV V8 engines were more advanced than their OHV V6s. I don't think it will happen immediately, but I do think it will happen.

If they OHV layout was really superior, GM would have applied the same LS engine technology to their V6s, and not bothered with the 3.6L and 3.0L V6s.

[Camino LS6]

OHV is already being phased out of the V6s, and I feel it's only a matter of time before the same happens with the V8s. The only thing slowing that down is that their OHV V8 engines were more advanced than their OHV V6s. I don't think it will happen immediately, but I do think it will happen.

If they OHV layout was really superior, GM would have applied the same LS engine technology to their V6s, and not bothered with the 3.6L and 3.0L V6s.

I can't really say on the V6s, the cars they are used in have different requirements. DOHC may make more sense there since the V6s are not simply little V8s as they once were. It really is apples and oranges, and right now OHV V8s are superior in the applications where GM uses them. That's proven by their real-world performance, including economy.

The point is, there is no advantage to be had by going DOHC.

[Justin Bimmer]

4, 6, 8 in V, Flat, or inline configurations are all different engines with different challenges. I doubt a vehicle with a I4 or V6 requries the same power needs/ bands/ or transmission configurations as anything else I listed. Just because the DOHC may be better on an I4 doesn't mean it's better than a OHV V8 in its application.

As mentioned before, apples and oranges.

[SAmadei]

a 4.8L based on the 3.6L in the CTS, with the same hp/l, would have about 405hp. If they made a turbo version based on the 2.0 I4, they could make over 520hp from 4L. I think they would make enough power to make people happy.

I'm not talking specific HP, but power in the general sense, i.e., over the rpm range... coupled with torque or "area under the curve" . Indy cars make ridiculous HP in a small package, but at 10000 rpms... its not going to work in an passenger car. A powerful passenger car engine requires displacement. Displacement alone isn't what causes inefficient fuel economy... reducing it my produce great results on paper, but not in reality. Those turbocharged 301s looked like a good idea at the time, as well.

4.8L is what... 290 ci or so. That's fine. I'm only saying that 5.7 is a nice sweet spot between economy and performance, and it has been for 40ish years. 4.0L is getting too small, and starts overlapping with the V6s.

[dwightlooi]

Before we get carried away with doing everything possible to meet the 35mpg CAFE standard, it is wise to consider what happens if you don't meet CAFE intentionally or unintentionally.

• Trying to meet the CAFE standards is not a legal requirement.
  
• Not meeting CAFE standards does not prevent a company from selling cars.
  
• Not meeting CAFE standards carries a fine of $5.50 per 0.1 mpg per car sold.
  
• Each company actually has two CAFE numbers one for cars and one for trucks. One does not affect the other.
  
• The new standard does not kick in until 2016 -- the Obama administration for all its loony bravado wouldn't be there in 2016.
  
• The new standard is actually for 39mpg for cars and 30 mpg for trucks.
  

It estimated by the clueless folks over at the Obama administration that it'll cost $1600 per car to meet the new CAFE standard. They nonetheless believe that government ought to make that choice of not the consumer or the manufacturer. Bob Lutz said it would cost $6000 per vehicle to meet the standard. Let's split the difference and call it $3800.

Now, let's look at the numbers today. GM's passenger car CAFE numbers today is 31.3. The penalty of doing absolutely nothing is a fine of $5.5 x 7.7 x 10 = $423 per vehicle. This is 1/4th the $1600 the Obama administration thinks it'll cost to meet the standard. It is 1/14th what Maxmium Bob thinks it cost. It's 1/9th if we take the average of the two cost estimates. This is all assuming that fuel economy does not improve at all between now and 2016 in the natural, not particularly deliberate or extreme, course of improvement in automotive technology. Highly unlikely.

Regardless, the ulimate choice is whether to add $400 to the price tag of a vehicle or spend four to fourteen times that to meet some arbitrary wet dream of some politician somewhere. If it's me, I'll simply incorporate the proven, inexpensive, non-performance robbing, technologies which benefit fuel economy as the come along and build cars and engines based strictly on consumer preference and let CAFE compliance fall where it may. Some $200~$400 added to the price tag is quite acceptable compared to going Hybrid across the board when only 10% of buys actually want to pay $2000~6000 more for a green and slow car which will not recover its hybrid premium for a decade.

Edited November 21, 2009 by dwightlooi

[ShadowDog]

Before we get carried away with doing everything possible to meet the 35mpg CAFE standard, it is wise to consider what happens if you don't meet CAFE intentionally or unintentionally.

• Trying to meet the CAFE standards is not a legal requirement.
  
• Not meeting CAFE standards does not prevent a company from selling cars.
  
• Not meeting CAFE standards carries a fine of $5.50 per 0.1 mpg per car sold.
  
• Each company actually has two CAFE numbers one for cars and one for trucks. One does not affect the other.
  
• The new standard does not kick in until 2016 -- the Obama administration for all its loony bravado wouldn't be there in 2016.
  
• The new standard is actually for 39mpg for cars and 30 mpg for trucks.
  

It estimated by the clueless folks over at the Obama administration that it'll cost $1600 per car to meet the new CAFE standard. They nonetheless believe that government ought to make that choice of not the consumer or the manufacturer. Bob Lutz said it would cost $6000 per vehicle to meet the standard. Let's split the difference and call it $3800.

Now, let's look at the numbers today. GM's passenger car CAFE numbers today is 31.3. The penalty of doing absolutely nothing is a fine of $5.5 x 7.7 x 10 = $423 per vehicle. This is 1/4th the $1600 the Obama administration thinks it'll cost to meet the standard. It is 1/14th what Maxmium Bob thinks it cost. It's 1/9th if we take the average of the two cost estimates. This is all assuming that fuel economy does not improve at all between now and 2016 in the natural, not particularly deliberate or extreme, course of improvement in automotive technology. Highly unlikely.

Regardless, the ulimate choice is whether to add $400 to the price tag of a vehicle or spend four to fourteen times that to meet some arbitrary wet dream of some politician somewhere. If it's me, I'll simply incorporate the proven, inexpensive, non-performance robbing, technologies which benefit fuel economy as the come along and build cars and engines based strictly on consumer preference and let CAFE compliance fall where it may. Some $200~$400 added to the price tag is quite acceptable compared to going Hybrid across the board when only 10% of buys actually want to pay $2000~6000 more for a green and slow car which will not recover its hybrid premium for a decade.

That would be a company decision, but a marketing challenge. The most important factor is what the competition would choose to do. For a company to settle with tacking on the 'fine fee' to each vehicle, they would have to be very wary as to what their competitors are doing, especially with the car market. The MPG war is already being waged on commercials. Apparently, auto companies seem to believe this is the most important aspect to buyers looking at a new vehicle. Heck, the majority of the commercials I've seen tend to be promoting the company in its challenge to meet consumer MPG expectations with only a blurb on any individual vehicle. That being said, if the auto companies are correct in their studies on what is really important to the consumer; if their choice is to market against each other in the MPG war; if their goal is to meet the expectations of the consumer by adding value to their vehicles by meeting CAFE standards to gain on market potential, then an auto company cannot afford not to invest in the challenge and doing all of the above and avoiding the potential negative PR by failing to address the matter and, instead, paying out.

Edited November 21, 2009 by ShadowDog

[dwightlooi]

That would be a company decision, but a marketing challenge. The most important factor is what the competition would choose to do. For a company to settle with tacking on the 'fine fee' to each vehicle, they would have to be very wary as to what their competitors are doing, especially with the car market. The MPG war is already being waged on commercials. Apparently, auto companies seem to believe this is the most important aspect to buyers looking at a new vehicle. Heck, the majority of the commercials I've seen tend to be promoting the company in its challenge to meet consumer MPG expectations with only a blurb on any individual vehicle. That being said, if the auto companies are correct in their studies on what is really important to the consumer; if their choice is to market against each other in the MPG war; if their goal is to meet the expectations of the consumer by adding value to their vehicles by meeting CAFE standards to gain on market potential, then an auto company cannot afford not to invest in the challenge and doing all of the above and avoiding the potential negative PR by failing to address the matter and, instead, paying out.

What makes you think that consumers want to spend $4000 more for a 30 MPG car vs say $4000 less for a 26 MPG car with more performance? Right now, 90% of buyers way towards the latter, only 10% of buyers do the Global Warming Coolaid.

[A Horse With No Name]

Americans tastes will change when the price of fuel goes up.

Anyways, does anyone have any verifyable advantadge to a V8 DOHC for the next Corvette?

Seems to me the LS series should do just fine...and no one has given a credible arguement to the contrary IMHO.

Chris

[gm4life]

No, his points aren't valid. There are no benefits to having a pushrod 4-cylinder over a OHC 4-cylinder, there are benefits to having a pushrod V8 over an OHC V8. Thus his point, which he repeats often, is invalid.

GM's V6 pushrods aren't inadaquate because they are pushrods, they are inadequate because they've had relatively zero development dollars thrown at them compared to the HF series.

SMK repeatedly fails to understand that a DOHC and a pushrod of equal displacement will not have equal external dimensions. SMK fails to understand that you will not be able to fit a 6.3 litre DOHC V8 into the space that a 6.3 litre pushrod just barely fits in. Yet he continues to state this as true.

The CTS-V and Corvette do use a pushrod to smack around vehicles way out of their price class . This has been very publicly demonstrated.

Bringing the Koenigsegg into the discussion is just trolling. The Koenigsegg is over $500k. GM could outfit a Corvette with a Pratt & Whitney and still have it cost less. If the factory 638hp of the ZR-1 isn't fast enough for you, Lingenfelter will happily sell you an upgrade to about 680hp for roughly $3k.

So no.. it's not just differences of opinion. He's trolling by repeatedly posting information he knows to be false.

Everyone here is entitled to their own opinion.... however you're not entitled to your own facts.

Agreed 100%. Anyone ever looked a 4.6L Northstar (and the space it takes up) and then looked at a larger small block Chevy, the N* looks HUGE. Those twin cams in each bank take up ALOT of room. OHV allows a larger engine with smaller packaging and still is very efficent. Name me on other sports car that has 436hp and gets over 25mpg?

Edited November 22, 2009 by gm4life

[gm4life]

>>"GM cars always get heavier though"<<

Only GM ?? Back in the day the 3-series used to weigh 2500 or thereabouts, it gained 1000 lbs! How bad does the Accord punish the scale vs. years ago ?

Everything gains weight thru to today, not just GM.

Cars are already half plastic as it is, with aluminum powertrains & wheels and chopped-down proportions and they STILL weigh 3600-4000 lbs. Electronics & air bags aren't made of cotton candy, and they aren't going anywhere. Don't hold your breath expecting a 3800-lbs car to drop 500 lbs- ain't gonna happen.

But it would be nice... I hate all the electronic nannies in cars, like traction control and all that other bull&#036;h&#33;. Don't even get me started on air-bags. Piss on that all I need is a shifter, gas and brake (clutch if needed) and a brain.

Edited November 22, 2009 by gm4life

[hyperv6]

Agreed 100%. Anyone ever looked a 4.6L Northstar (and the space it takes up) and then looked at a larger small block Chevy, the N* looks HUGE. Those twin cams in each bank take up ALOT of room. OHV allows a larger engine with smaller packaging and still is very efficent. Name me on other sports car that has 436hp and gets over 25mpg?

The Nstar is not as big as it appears. I have been involved with many Fiero groups and have friends with both LS and Nstar engines in their Fiero's. Most find the Nstar to be easier to fit into the car. Both are effective engines to put in but the Nstar really fits in nice to a small engine bay in the Fiero.

I would feel the same if I look at the Nstar in my inlaws DTS as it looks crammed in but I also see the same engine in the Fiero and it works well. The Nstar also fit the Cadillac roadster well even with the Supercharger.

[loki]

But it would be nice... I hate all the electronic nannies in cars, like traction control and all that other bull&#036;h&#33;. Don't even get me started on air-bags. Piss on that all I need is a shifter, gas and brake (clutch if needed) and a brain.

you need an Ariel (this right?) Atom for your fun car.

[A Horse With No Name]

I love the Ariel Atom and the Catham Lotus 7...but doubt they would be up GM4life's alley.

Chris

[regfootball]

Well Ford doesn't exactly make the most efficient engines either. Their 5.0L OHV engine was horrible on gas. Our Explorer never got over 14 mpg. A DOHC V8 could share parts and technology with the V6s. While GM says they can use VVT and other technology on their OHV engines, they haven't done it yet. They have with their V6s. They have VVT and DI on multiple DOHC engines now. They wont need to waste the time and money figuring out how to adapt those technologies to OHV engines. And adding those new technologies to OHV might not be as reliable, since no one has done it before. They already spent the time and money developing them for the DOHC V6s.

It creates twice as much work. Instead of developing it once and using it on all their engines, they have to develop it twice.

exactly. same thing with HCCi. which they said is coming at some point too.

personally if GM develops a new DOHC v8 primarily for passenger cars, i think they will gradually work it into some of their 1/2 ton trucks too.

even toyotas cam shredder gets lots of notoriety for its acceleration in truck tests. all toyota has to do is figure out how to make it stay together. and people like to look at acceleration numbers. like it or not, lots of folks need to acknowledge that toyotas v6 and v8 get really good acceleration times, and they basically use the same engine all over.

Edited November 22, 2009 by regfootball

[Camino LS6]

GM will meet CAFE, and the Vette will remain LS-powered.

Someday, maybe, if it makes sense, if GM has some spare cash to throw around, if they can't get the job done without it, Caddy might get a V8 that features DOHC again, but it will be happenstance rather than central to the design.

Don't hold your breath, because there is no imperative for it to happen.

[ShadowDog]

What makes you think that consumers want to spend $4000 more for a 30 MPG car vs say $4000 less for a 26 MPG car with more performance? Right now, 90% of buyers way towards the latter, only 10% of buyers do the Global Warming Coolaid.

I'm not so sure those figures represent the true nature of the final costs. Nevertheless, why is GM so worried about what others are claiming to achieve with their mileage figures by having so much marketing directed to touting its own mileage figures?

[hyperv6]

GM will meet CAFE, and the Vette will remain LS-powered.

Someday, maybe, if it makes sense, if GM has some spare cash to throw around, if they can't get the job done without it, Caddy might get a V8 that features DOHC again, but it will be happenstance rather than central to the design.

Don't hold your breath, because there is no imperative for it to happen.

We should see soon if you are on the money or or off track.

While GM is not fully recovered they are doing many things no one expected by looking into RWD cars and sport models that many just last June kept saying were dead and not coming back under the Goverment Motors banner. Remember when they said the GM perfromace division leliminated direct preoduction car development. Many here even said that was the end. How many times we were told the Zeta was dead and had no future by not only media but also by GM.

In times like these the only thing for sure is things can and will change and when they do it will be swift. So while any of us may be right today we could be very wrong in a month.

If anything the LS based engine will remain for a little while just because unless they reawake a still born project like the N Star replacment it would take time to make a new engine. But on the other hand GM is not sharing future product info as far in advasnce as they used to.

One other option looked at in the past was BMW engines for Cadillac. I never heard how that ended or how that idea was left.

Edited November 22, 2009 by hyperv6

[Camino LS6]

We should see soon if you are on the money or or off track.

While GM is not fully recovered they are doing many things no one expected by looking into RWD cars and sport models that many just last June kept saying were dead and not coming back under the Goverment Motors banner. Remember when they said the GM perfromace division leliminated direct preoduction car development. Many here even said that was the end. How many times we were told the Zeta was dead and had no future by not only media but also by GM.

In times like these the only thing for sure is things can and will change and when they do it will be swift. So while any of us may be right today we could be very wrong in a month.

If anything the LS based engine will remain for a little while just because unless they reawake a still born project like the N Star replacment it would take time to make a new engine. But on the other hand GM is not sharing future product info as far in advasnce as they used to.

One other option looked at in the past was BMW engines for Cadillac. I never heard how that ended or how that idea was left.

Things certainly are fluid at the moment, however I feel certain that the points I make are of an enduring nature.

I'd place money on that.

As I recall, the BMW engine idea was tied to BMW's use of the dual-mode hybrid tech. Haven't heard any news about it since. My gut says that the new GM wouldn't go for that idea.

[aldw]

Any DOHC V8 should be for Cadillac IMHO, as it would serve better in that division than Chevy.

[gm4life]

I love the Ariel Atom and the Catham Lotus 7...but doubt they would be up GM4life's alley.

Chris

Very true I am more of a guy who would try to special order a new Camaro LS with the 6.2L V8, six speed, steel wheels and no extra bull&#036;h&#33; options. You know me so well.

Edited November 22, 2009 by gm4life

[smk4565]

OHV is already being phased out of the V6s, and I feel it's only a matter of time before the same happens with the V8s. The only thing slowing that down is that their OHV V8 engines were more advanced than their OHV V6s. I don't think it will happen immediately, but I do think it will happen.

If they OHV layout was really superior, GM would have applied the same LS engine technology to their V6s, and not bothered with the 3.6L and 3.0L V6s.

Agreed. DOHC will eventually take over completely.

The F150 has SOHC cam now, 5.4 liter with 315 hp, but is going to a DOHC 5.0 liter with 400 hp. I can't believe Ford hasn't announced Ecoboost V6's for the F150 yet. I can see full size pickups offering more V6s in the future to meet CAFE, especially at Ford since the Ecoboost V6 is around 350-360 hp and lb-ft.

[Drew Dowdell]

Agreed. DOHC will eventually take over completely.

The F150 has SOHC cam now, 5.4 liter with 315 hp, but is going to a DOHC 5.0 liter with 400 hp. I can't believe Ford hasn't announced Ecoboost V6's for the F150 yet. I can see full size pickups offering more V6s in the future to meet CAFE, especially at Ford since the Ecoboost V6 is around 350-360 hp and lb-ft.

At what RPM?

[CaddyXLR-V]

At what RPM?

If your asking about the Ecoboost, it is 350 at 1500-5250 rpm.

[smk4565]

4.6L V8: 292 hp @ 5,700 rpm 320 lb-ft @ 4,400 rpm

5.4L V8: 310 hp @ 5,000 rpm 390 lb-ft @ 3,500 rpm

3.5L V6: 365 hp @ 5,550 rpm 350 lb-ft @ 1,500 rpm

The V6 can definitely replace those 2 V8s, and the new 5.0L V8 can be used as the top end engine and for heavy duty applications.

[Drew Dowdell]

I wasn't really convinced, but 350ft/lbsat 1500 is stump ripping

[smk4565]

I wasn't really convinced, but 350ft/lbsat 1500 is stump ripping

I agree, which is why it should be on the F-150. 350 lb-ft at low rpm is more than enough for most pickup drivers, and they have the Coyote V8 for an upgrade. The V6 could be used in the Econoline, then Ford would have a gas mileage advantage in pickups and vans, which would help when selling to utility companies, fleets, businesses, etc.

Getting back to the Corvette, a 2004 Corvette had 350 hp and 360 lb-ft, the ecoboost makes that, a turbo V6 Corvette would still be quick. And the GT-R proves what a turbo V6 can do. The ZR-1 and Audi R8 V10 were on Top Gear tonight, and both were slower around the track than the GT-R.

[Robert Hall]

I agree, which is why it should be on the F-150. 350 lb-ft at low rpm is more than enough for most pickup drivers, and they have the Coyote V8 for an upgrade. The V6 could be used in the Econoline, then Ford would have a gas mileage advantage in pickups and vans, which would help when selling to utility companies, fleets, businesses, etc.

A long time ago Ford sold a lot of F-series pickups with a big straight 6...I could see 6 cyl full size trucks making a comeback.

[A Horse With No Name]

The ecobost thing should be great for Ford. And as much as it pains me to admit it (and it pains me to admit it) Nissan, my least fav. car maker has a winner in the GTR.

Okay, so Maybe I dislike Suzuki and Kia and Daewoo and the Chinese and Tatra and Toyota and a few others more than Nissan.

Chris

[A Horse With No Name]

Very true I am more of a guy who would try to special order a new Camaro LS with the 6.2L V8, six speed, steel wheels and no extra bull&#036;h&#33; options. You know me so well.

It would be cool to get that car in blue and do a knockoff of the 69 Trans Am Penske Camaro's...

THAT would be sweet!

[Camino LS6]

It would be cool to get that car in blue and do a knockoff of the 69 Trans Am Penske Camaro's...

THAT would be sweet!

One of the originals was next to us at a vintage race - deafening even at idle.

[A Horse With No Name]

I've seen them race at Mid Ohio...and been a corner worker when they've gone by at 100+ wide open.

God I'm glad I was born in the twentieth century!

Chris

[Drew Dowdell]

A long time ago Ford sold a lot of F-series pickups with a big straight 6...I could see 6 cyl full size trucks making a comeback.

When did they go out of production? My dad's '93 or '94 F-150 is a 4.9 liter straight six.

[A Horse With No Name]

IIRC the straight six went out of production and Ford switched to a V6 about 1997 or so when they changed to the newer, rounder, uglier bodystyle.

Chris

[Robert Hall]

When did they go out of production? My dad's '93 or '94 F-150 is a 4.9 liter straight six.

I think MY '96..last of the '80 style F-150s. I'm pretty sure the all-new '97 that came out in early '96 had a V6 standard.

[Camino LS6]

The loss of the straight six is a real shame - a victim of packaging issues.

Lots of good ones from many manufacturers over the years.

[A Horse With No Name]

Just say it-B-M-W!

But the cars I loved were the straight six stovebolts of the 40's and 50's. The older I get, the more I love 1950's American cars.

Methinks something like a 1952 fastback Chevy two door with the two tone paint....hmmm. Everyone always thinks I'm nuts for loving them. But having owned both a 1955 and a 1957 Chevrolet Bel Air,I almost would rather have the early 1950's Chev if I were to get another vintage car.

Just LOVE the straight six in those. My 57 came with a six...not many Bel Air two door hardtops were sixes, methinks.

Chris

[Robert Hall]

The loss of the straight six is a real shame - a victim of packaging issues.

Lots of good ones from many manufacturers over the years.

I've owned 2 vehicles w/ them and had experiences w/ a couple others...definitely like them. Alas, it looks like the only way I'll have another new vehicle w/ a straight 6 is to get another BMW.

[Camino LS6]

Chevy 250,292

Jeep 4.0

It's all about the torque...

[A Horse With No Name]

The new 3 is a fantastic car!

Chris

[balthazar]

'Tis correct above: the 300 I-6 was discontinued when the all-new '97s debuted.

Shame- it was a great engine- quite strong. IIRC, Ford enticed some ex-Studebaker engineers over to design their I-6, so the trial-by-fire test run was enormous.

I test drove both a 4.6L & the 5.4L F-150 circa 2003 (both heavier crew cab / 4x4s) and they had nothing in perceived performance over the 300 in my '94... but that was a RWD RC.

[Camino LS6]

The straight sixes always had a consistent competence and reliability about them that V6s never quite matched.

[Lamar]

I've owned 2 vehicles w/ them and had experiences w/ a couple others...definitely like them. Alas, it looks like the only way I'll have another new vehicle w/ a straight 6 is to get another BMW.

Or a Volvo...

[Drew Dowdell]

The straight sixes always had a consistent competence and reliability about them that V6s never quite matched.

My dad's is pushing 200k miles. Just had it's first breakdown.... a broken distributor rotor....