Point/Counterpoint: DOHC v OHV
 

As owners of the Hyphened ZR, a great part of our attraction involves the sensation emanating from the turbine like feel of the LT-5 motor. So I have started this thread to devote a space to the yin and yang of engine architecture.
My premise is that GM has done a marvelous job of optimizing the OHV architecture. BUT, I think we're seeing the end of the road for "the little engine that could". The LT-5 represented an alternative that GM abandoned 25 years ago bu that our small community continues to push forward and give a glimpse of what might have been. Just sayin!

Re: Point/Counterpoint: DOHC v OHV
 

Our cars a relic, sure we've done a great job of moving them forward but we're still dealing with something designed and built in the late 1980's. The ease of tuning and modding the lsx is something we can only dream of. The zr-1 had it's time of being king and sadly it's over, but that's to be expected. Time marches on, and that's the way it should be. There are two main things keeping from from jumping into a c6z06. OHC and the interior.

Re: Point/Counterpoint: DOHC v OHV
 

I still value the simplicity and lower weight of the OHV engine, but i usually prefer to drive my lt5 or coyote mustang 5.0 over my LS3 car. I think it just has the extended torque delivery if you need a single simple answer of why dohc is best. I think the question really is going to be about all future engines having a turbo charger and electric assist to cope with emissions. The days of a factory 8000 rpm NA screamer may be over.

I'm over in Europe at the moment and had a chance to drive some 50 mpg cars w turbos. Just about everything will be turbo soon if i had to guess.

Re: Point/Counterpoint: DOHC v OHV
 

Audi is introducing electric turbos which should be a game changer. Interesting Mike that you have the opportunity to get SOTP character from the two platforms. A 5300rpm torque peak with long gear pulls onto a highway makes even a simple drive around fun.

Re: Point/Counterpoint: DOHC v OHV
 

I cant contribute much on the tech side of this conversation, but on a emotional side I can tell you I love this engine relic or not. Mine has over 500hp, runs great, I get to run it to a high rev, sounds great, bullet proof construction and looks like a piece of art. Do I wish it was cost effective to make more power? of course! we all do. I enjoy also owning a piece of automotive history. I find that guys that know cars, not so much the Corvette guys, but the higher end players know and respect our ZR-1. I appreciate this groups constant effort to push the performance envelope. :saluting:

Re: Point/Counterpoint: DOHC v OHV
 

Having sold my supercharged c5 ls motored car, I dont miss it at all. It made more power than my z will ever make but it was just another cookie cutter corvette at a car show. a dime a dozen. as for as the ls7 z06 is not bullet proof. I have seen a few of these cars throw rods and lose oil pressure in recent weeks. there is one sitting at SGC right now without oil pressure. It seems like its not such a surprise for those who know about them. The ls2 and ls3 are not impressive to me. Im not even impressed with the lt4 in the new z06. It is not a hard charger and if it wasnt for the state of the art suspension and aerodynamics and brakes and light weight, that car would have its butt kicked by other comparable hi end muscle cars like the dodges, fords, etc.. Owning a piece of history and feeling the hard charging acceleration of the LT5 is a joy to behold. It may not be the King but it still holds its own especially in the open road. The ZR-1 is not a drag car, road racer, it is a GT. A car that can do well in all types of racing but excels in high speed runs with endurance in mind.

ed ramos #3028

Re: Point/Counterpoint: DOHC v OHV
 

What? What is a "hard charger" and why is the Z06 not one? Which of "the dodges, fords, etc." would be kicking the Z06's butt, were it not for its suspension and aerodynamics? Can you cite any example of a "comparable hi end muscle car"? Are you speaking of the yet-to-be-released GT350 Mustang, or the 1/4-mile-only Hellcats? Could either of those truly be described as "comparable" to the Z06?

The LT5 is a brilliant engine on its own merits; diminishing the LT4 does not elevate it.

Re: Point/Counterpoint: DOHC v OHV
 

Well, two weekends ago I went to the Homestead Nascar track that is 1 mile from my house and they were running all types of cars during a track day event. there were two brand new Z06's on the track too. It seemed like everything passed those cars up. I saw a fox body Mustang with a coyote engine consistently trash the z06's lap after lap. I saw BMWs, mercedes, vipers, etc.. an endless list of cars trashing the z06's lap after lap. A couple of fridays a month they have 1/8 mile nights at the tracks pit road. I saw a new z06 participating and saw a Dodge Challenger Hellcat kill it in the eight mile and another viper trash it too. A modded c6 killed it along with a modded c5 z06. The new z06 cant even top 200 miles per hour while a c6 zr1 can do 209 miles per hour.

If I had a top tier car like any of the ones I mentioned I would not back down to a new z06. Maybe in hard twisties or a tight road course that requires constant severe braking I would not test a z06 but at speed events I would. I am not downing the lt4 to elevate an lt5. it is no comparison 375hp to 650?? I would have liked chevrolet to have thrown the gauntlet and put something out there at least making 700 horse. The mustang had made the super snake 750hp for years and now the hellcats etc...

The hard charger is what a dohc hi performance v8 feels like...it just does not lay down after most cam in block v8's have reached there 6000rmp.. seems like the dohc cars just want to keep on going thus it gives the feeling of a hard charger or constantly accelerating.

I appreciate the handling, braking and down force aerodynamics the z06 bring to the table but am not impressed with its brute power and alot of other competitors arnt either.

ed ramos #3028

Re: Point/Counterpoint: DOHC v OHV
 

You haven't mentioned a single comparable vehicle...only anecdotal examples of highly modified track cars. ANYTHING can be modded. Too bad Chevy stopped at only 650 horsepower; they must be saddened to hear that if they'd just given the LT4 an additional 50 ponies, they could have met your lofty standards.

Perhaps you could name some other PRODUCTION vehicles that are capable of reaching 60 miles per hour from rest in less than 3 seconds, clearing the 1/4 mile in less than 11 seconds, AND completing a lap of the Nurburgring in less than 7 minutes.

Re: Point/Counterpoint: DOHC v OHV
 

Guys,

The idea of the thread was to offer viewpoints re: the engine architectures. Let not take things in a personal direction.
Also, I don't think there has been any indication that a Z06 has gone anywhere near sub 7min at the Ring.

Re: Point/Counterpoint: DOHC v OHV
 

It is certainly not personal with me. I call it as I see it. I will not defend a lousy lt4 car. Its a good car, not a super car. All those vehicles are direct comparisons in specific cases. The ls platform is good no question. i just think chevy fell short on the lt4. what about the ones that just blow up after 10 miles?? I have heard of a couple of those. I just feel no way in hell can a lt4 run 24 hours and average 176mph or complete the 200 hour durability test the lt5 had to endure and survive. 200 hours of flooring the beast time after time again and live. some of these lt4's cant even survive 10 miles of parking lot driving. any way it is just my opinion. by the way the nurburgring vette was involved in a crash so the time was not reported. dont take anything personal it is just my opinion. I have had 7 corvettes but have not bought a new c7 even though it is a nice car and the interior is best improvement. I would wait for the next rendition of the lt4 to see if the improvement made warrants super car status. All corvettes are nice but just a little critical of the so called top vette. long live dohc cars. At least Ford got it right with the coyote!

ed ramos #3028

Re: Point/Counterpoint: DOHC v OHV
 

You are correct about the lap time. I had scanned the story but had not read it completely. Although there are reports of the 2015 Z06 with Z07 package having run a 7:08, a 7:06 and a 6:59, GM will not confirm these reports and on closer examination, I haven't been able to find any confirmed time for the car. Apparently, the Nurburgring has placed a temporary ban on "official" lap times for some reason, so the car is probably running these times, but GM is playing by the 'Ring rules and not sanctioning them. On a speculative basis, a 7-minute lap doesn't seem out of the question to me, since a C6 Z06 ran a 7:22.

Re: Point/Counterpoint: DOHC v OHV
 

Perhaps a more objective analysis could be attained by considering dyno results; in particular "power under the curve".

That said, it is worth mentioning an analysis of results would show the (FBI) ZR-1s produced the fastest 3-car team aggregate 5* out of 6 attempts at the local Crown Point Corvette Club's annual Corvette Shootouts*. The event is made up of Chicago area Corvette clubs, and has been flooded with LSx's, and last fall a couple new LTx's. Various videos showed time and time again the lighter LSx cars jumping out front off the line, but at the 1/8 point the ZR-1s had reeled them in and beating them at the "top end".

*The Team Trophy was not awarded to the ZR-1 team on two occasions; one year the ZR-1s were not registered for trophy runs (but time slips showed they would have won had they been registered), and (for one year only) the trophy was tied into bracket racing rules instead of the aggregate speed of the top 3 club cars.

Analysis of the last two WANNA GO FAST events in Chicago clearly shows two things: 1) Forced induction dominated the 264 cars participating in the (2014) event, and the top 45 out of 264 speeds were all forced induction (with one possible exception), and a good number of them used the DOHC architecture. (See list below)

WANNAGOFAST Monee, IL 6-21,22, 2014:

Nissan GT-R Alpha 16 (Twin Turbo)
2006 Dodge Viper (Nth Moto) (Twin Turbo)
Nissan GT-R Alpha 16 (Twin Turbo)
Nissan GT-R Alpha Omega (Twin Turbo)
2011 Lamborghini Gallardo Superleggera (Twin Turbo)
Nissan GT-R (Twin Turbo)
Nissan GT-R (Twin Turbo)
Mercedes-Benz E63 AMG (Twin Turbo)
2012 Nissan GT-R (Twin Turbo)
1994 Toyota Supra (Turbo)
Nissan GT-R Alpha (Twin Turbo)
2008 Porsche 997 Turbo (Twin Turbo)
2006 Dodge Viper (Twin Turbo)
2009 Nissan GT-R (Twin Turbo)
Toyota Supra (Turbo)
Toyota Supra (Turbo)
2000 Pontiac Trans-Am (Turbo)
Mitsubishi Evo 2 (Turbo)
2010 Nissan GT-R (Twin Turbo)
1997 Toyota Supra (Sound Performance) (Turbo)
2013 Nissan GT-R Black Edition (Alpha) (Twin Turbo)
1985 Oldsmobile Cutlass (Turbo)
2011 Cadillac CTS-V (Vengeance) (S/C)
2006 Lamborghini Gallardo (Heffner/Nth Moto) (Twin Turbo)
2006 Chevrolet Cobalt SS (Turbo)
C5 Corvette (N/A)
2012 Nissan GT-R (Twin Turbo)
2012 Chevrolet Corvette ZR-1 (S/C)
2004 Lamborghini Gallardo Heffner (Twin Turbo)
2010 Corvette ZR-1 (S/C)
2009 Chevrolet Corvette (S/C)
Mercedes-Benz SLS AMG Black Series (F/I)
2009 Chevrolet Corvette ZR-1 (S/C)
2006 Dodge Viper (Twin Turbo)
1993 Mitsubishi 3000GT VR-4 (Turbo)
Nissan GT-R (Twin Turbo)
1998 Chevrolet Corvette (Tigershark) (Turbo)
Dodge Viper (S/C)
2006 Dodge Viper (Twin Turbo)
Nissan GT-R (Twin Turbo)
Nissan 300ZX (Turbo RB26)
2000 Honda S2000 (Turbo)
2003 Chevrolet Corvette (S/C)
2008 Porsche 911 Turbo (Twin Turbo)
1993 Toyota Supra (Turbo)

There's little doubt the 4-valve DOHC architecture has significant advantages over OHV (pushrods), at least in some venues.

Car and Driver article: DOHC vs. OHC:

http://www.caranddriver.com/columns/...mg-slug-it-out

But that said, where the DOHC architecture has a performance advantage, equally evident is the $/hp advantage of the OHV approach.

Mitigating factors?

Kevin makes a good point regarding technological advances. But, his insinuating that (peak?) hp/$ is the quintessential approach to analysis dismisses other virtues that other architectures (DOHC) have, e.g., power under the curve (for one!). How about durability or driveability?

And, so it goes...

Re: Point/Counterpoint: DOHC v OHV
 

Indy 1994
Roger Penske found a loop hole in the Indy rules and
with Mercedes/Illmor built a 209 cubic inch turbo OHV, 2 valve per cylinder, V8
running 1.86 bars abs of boost (that's about 12.6 pounds, not really a big number
in the serious turbo world, a pure race motor, not a stock block...)
that knocked it out of the park! Pole and race win.
Some estimates were over 1100 hp in qualifying trim!
That's about 5hp/cu in!
Rules allowed a little more boost and a few more cubes for OHV motors.
OHV/DOHC???

Re: Point/Counterpoint: DOHC v OHV
 

lt5's were popping in the BG parking lot. No company is perfect and the lt5 is far from it. Is GM worse then most others, I tend to say yes. There's a reason I didn't even look at a gm for my last two daily drivers. I'd still buy a c6z06 tomorrow if I could.

Re: Point/Counterpoint: DOHC v OHV
 

WHAT are you talking about, Kevin:confused:

Re: Point/Counterpoint: DOHC v OHV
 

Kevin is probably referring to the time a young lady in charge of starting the zr-1's and parking them after assembly, would start them in the freezing cold and rev them up big time without warming up the car and thus caused damage with the cam chains etc... they stopped lt5 production for a while until they found out what was being done. The young lady said that is the way she started up her car in the morning so she did the same with these brand new zr1 lt5 dohc cars. These motors were tested in practically every condition except the ultra high revving in the freezing cold. That was the only episode a lt5 blew up in the parking lot. No other v8 had to endure the 200 hour durability test in order for it to be installed and sold in gm cars. I really dont think many lsX engines can withstand 200 continual hours of floorings...I would bet on that. lt5's are not perfect but they are durable and they do make power and they dont really on power adders to make power.

As far as the z06, I like them very much. Unfortunately I have seen recently quite a few having major engine failure. I have talked to very knowledgeable people in the corvette world and they say they are not surprised. It happens more than people know. I love the ls7 427 but now I would be hesitant to buy one. Maybe its there owners abusing them or not maintaining them properly?? who knows.. What I do know is that they are not as durable as an LT5. I am a big fan of the ls7, very big fan and it has been depressing to see some of them lose engine oil pressure. I like thels7 better than the lt4 because of its torque and its natural power.

ed ramos #3028

Re: Point/Counterpoint: DOHC v OHV
 

If anyone has any doubt, I would take a C7Z in a New York second. The car is a technological tour de force. It's amazing what GM has done chassis wise to rival much more expensive hardware. Stuff like the E-Diff is awesome.
I'd love to speculate on what's going in back of the rumored mid-engine tho.

Re: Point/Counterpoint: DOHC v OHV
 

The difference is the internet. We've heard about an isolated number (3, maybe?) of LT4 failures because those of us who pay attention to these things have instantaneous access to such info now due to the existence of the worldwide web. The reason we didn't hear about it back then was because we lacked the instant access to EVERYTHING that we have today, but even the nearly-bulletproof LT5 had its share of failures when new. Because of this, I have decided to FEEL that the LT5 could not withstand a 200-hour durability test, and I have also decided to FEEL that there's no way it could have run 24 hours straight at nearly 176 MPH.

Re: Point/Counterpoint: DOHC v OHV
 

And I suppose you FEEL Elvis and Hitler are still alive? ;)

Re: Point/Counterpoint: DOHC v OHV
 

As I'm sure you can tell, I'm simply illustrating the absurd by being absurd. FEELING that a certain engine is reliable - or that a certain one isn't so - does not make said feeling even remotely true.

Re: Point/Counterpoint: DOHC v OHV
 

I don't really have time write, but will punch this out now anyhow...

I just got back from Arnold, Nebraska on Sunday night. This is the area where the Sand Hills Open Road Challenge was held as well as the Loup to Loup road race. They also had half mile and one mile shootouts.

The winner of the one mile was a modified 2004 Lamborghini putting out 2000 HP. It ran a best of 228 mph through the mile. ...that is another story.

There were three ZR-1's running. They were all modified 350's and I am not sure to which degree. One '90 ZR-1 had Marc's 350/510 package...his actually said 350/515. I believe his one mile run was at 160 mph... that was on older Borla mufflers. The others averaged around 157 mph.

There were three new C7 Z06's there with very experience drivers. A friend of mine had one of them and it has the Z07 package. He had removed the rear wicker extensions from his spoiler.

His car was the fastest of the new Z06's. What did he run??? He was around 165 mph through the mile! He was only five miles per hour faster than the fastest ZR-1!

The stock C6 ZR1's ran faster than the new Z06's.

That is not a put down to the Z06, but there are some issues out there yet for the new car. The Z06 drivers said their car fell flat when hitting fifth gear.

Is this all the aero/down force bits on the car??? Or is this a tuning, supercharger heat issue? I don't know.


One poster here seems down on our "old" ZR-1's. Yes, we are not in a vacuum, but don't cut the ol' LT5 short!

When building the LT5, Chevrolet didn't reverse engineer every part to the cheapest price per widget before failure. They went with world class suppliers on a "we are going to show the world" basis that had the bean counters screaming.

I like the new Corvettes. I like old Corvettes. But, don't deny it... The old ZR-1's are a special breed. Our LT5's don't drop valves. Another friend is scared when his C6 Z06 warranty will go off. Is he going overboard? Maybe. But in the end, I am proud of my LT5!

Re: Point/Counterpoint: DOHC v OHV
 

???? what is he talking about?? decided to feel??? the lt5 did pass the 200 hour durability test and did set the record at nearly 176 mph for 24 hours. You dont have to feel it. It is what it is. How about the lt4?? Has it done anything or set any records?? I am perplexed to hear people trying to poke holes in the lt5 on this forum. This is one place I thought that most people would be in agreement but guess not. If its a joke I dont get it. whatever.

Re: Point/Counterpoint: DOHC v OHV
 

In re-reading my earlier post now, I just wanted to add...in the shootout, the cars each got three runs. The cars mentioned all had very consistant runs. I am not sure how much difference it makes, but the 1990 ZR-1 mentioned had the "ballast" of a passenger. Not sure about the others.

Oh, I was there as a navigator for the road races. Maybe I will enter next year.

Re: Point/Counterpoint: DOHC v OHV
 

Ed,

I started this thread as a means of discussing the pros and cons of the different engine architecture with their inherent advantages and disadvantages. I'd like to keep this on a technical level if possible. Many of us are fans of the C4 ZR-1 due to the unique power delivery we get from the LT-5. Many would like to see GM re-create that and believe that DOHC should be the future direction for Corvette in order for it to take its place among world-class automobiles. So far, GM doesn't seem to agree but they have also done a heck of a job refining the OHV architecture. My premise is that as good as the LT4 platform is, it's near topping out due to inherent limitations.
So your thoughts?

Re: Point/Counterpoint: DOHC v OHV
 

I don't know when GM will break away from OHV V8's, but I feel it is somewhat on topic to point out the LT4's deficiencies as not a totally improved product while we all wish for something a little more exotic. My biggest point is the fact that there were a ton of you tube vids from week one that showed just about everything handing the new Z06's azz to it on roll races. Then came the GM apologists etc...

My take is that GM is holding back...way back... the engine only has a 1.75l supercharger that has to spin faster than the previous ZR1's LS9 unit which was 2.3l. I think it is blowing hot air and running with more internal parasitic drag. All the new cam phasing, direct injection, and all of that just to get the same power as the LS9??

Makes you wonder what the mid cycle refresh is going to bring.

Re: Point/Counterpoint: DOHC v OHV
 

Every LT4 out there is doing the "dependability/reliability" R&D for the corporate folks. The future?

Re: Point/Counterpoint: DOHC v OHV
 

Frankly, I learned my lesson when I bought a brand new 1984 C4 4+3 Z-51. Love the car,
BUT I won't do that again.

Re: Point/Counterpoint: DOHC v OHV
 

GM made a decision for the C5 to develop pushrod V8s and abandon the LT5. Much has been said whether or not that was the correct decision. People have pointed to the power levels of present day LSx engines and said it was the right decision. That can not be established from the data. They can rightly say that their program has been successful and they have achieved good gains in power. However the LT5 was, at the time of the decision, a viable 400+ HP engine.. It took GM 10 years of development to regain that level of power. Further increases came with increases in displacement and FI. All of us know that the existing LT5 was capable of much more. We would all like to have seen what development of the LT5 would have wrought. The supposed superiority of OHV engines in my mind is answered by the racing classes that do not penalize any valve configuration. In those classes OHC engines are dominant. The lone exception is unlimited drag racing. All that being said, we can and do enjoy the unique position that the ZR-1 hold in the Corvette lineage. It does not have to compete with a 25 year newer car. My hope is that GM corrects the LT1/LT4 problems soon. If they are holding back it's not working. Maybe they will adapt OHC heads to the latter block, but I doubt it.

Re: Point/Counterpoint: DOHC v OHV
 

If you want an idea of where the LT-5 could have gone, just look at the Gen2 prototype Graham Behan discussed. 475hp without any displacement increase. And that was 25 years ago. Look at what Mercury Marine is doing with a VERY similar platform. They learned their lesson. If I was GM, I would be partnering w them on "productizing" the LS/LT block w the MM DOHC cylinder heads.The demise of the LT-5 was a combination of "penis envy" on the part of the Powertrain guys, and bean counter myopia from the green eye shade people.
Both of which I think we have seen too often from the RenCen and Warren.
I hope Mary Barra is changing that.

Re: Point/Counterpoint: DOHC v OHV
 

i agree with Mike and Dom and others re their comments and observations relative to the advantages and power delivery of the DOHC vs. OHV. Faced with the superiority of the DOHC architecture, how much longer can GM continue to attempt to mitigate those advantages and embrace what is clearly become a 'damage control' effort (with the OHV architecture)?

Millions was spent on development of the new OHV LT1-4 motors. But, out of the box track performance (and reliability too) has been marginal. And, how much is GM going to bank on the C7's chassis improvements to save the bacon of their latest OHV entry? (Without even touching on the huge swell of reliability issues with LT4's heating PR catastrophe).

In spite of GM hoopla (and excuses), the acid test is going to be performance against European and Japanese in the theater of racing. In view of initial performance (or lack thereof, relative to the latest OHV entries) one has to wonder if we are seeing a repeat of GM's mentality when it stubbornly held to the L98 as being sufficient for Corvette buyers. Or, is there real hope to see an all-out focus on performance as the primary objective?

In the mean time, I've no fear of any match-up with any stock cammed stock-bottomed LS1, or 6.2L LS2, or 3 (LS7s?...maybe them as well, in the right venue?). Just crossing my fingers that GM will endeavor to build a motor and (GT) Corvette capable of the kind of 'take no prisoners' type of car the ZR-1 was when it hit the pavement!:cheers:

EDIT:

I concur w/ Dom's focus on the MM endeavor. However, that effort (last we saw it) was very preliminary; no variable cam/valve timing or direct injection - IIRC. So, that would also need to be considered.

For example, Ford and Mercedes has a pretty good examples of where DOHC might be had GM continued to develop it (C-link).

Re: Point/Counterpoint: DOHC v OHV
 

Has it done anything or set any records??

The LT platform in the C7.R, which was co-developed with the 2015 Z06, won the Triple Crown of endurance races this year: Rolex 24 At Daytona, Mobil 1 Twelve Hours of Sebring and 24 Hours of Le Mans. According to Chevrolet, “the C7.R and the Z06 represent the closest link in modern times between Corvettes built for racing and the road, sharing unprecedented levels of engineering and components including chassis architecture, engine technologies and aerodynamic strategies.” So yes, the new LT platform has done something. But these facts are easy to escape: just FEEL that Chevrolet is lying about the close link between the production LT4 and the LT in the C7.R.

I have always loved and respected the LT5 as a nearly-bulletproof masterpiece, and I think there’s no question that the DOHC architecture is superior and will re-emerge when the small block has finally reached its limit, technologically. But I continue to assert that if the internet and the various Corvette forums that we frequent today existed back in 1990, we would have all heard instantly about the few LT5 failures that occurred and there would have been at least a few people FEELING that the LT5 is unreliable, despite its performance during the record run.

Re: Point/Counterpoint: DOHC v OHV
 

First off, these are all OHV engines....

But comparing pushrod V8's to OHC V8's (whether single or dual cam) isn't a clear cut "this is better and here's why" comparison.

The configuration is largely irrelevant as long as Chevy and Dodge are still putting out pushrod OHV engines that are every bit the equal, if not slightly superior to Ford's modular OHC engines. Let's face it, if someone can build a pushrod engine for a top fuel dragster that makes 10,000 HP, the cam configuration and pushrods aren't the limiting factor. And with variable valve timing we can now compensate for a lot of factors and make a single cam do what it never could in the past.

Direct injection and variable valve timing are far more relevant than cam architecture at this point in time. After that the market is banking on forced induction V6's.

Re: Point/Counterpoint: DOHC v OHV
 

Really? Can you provide data of examples where a NA OHV motor of comparably equal technology and displacement demonstrates equal peak power and superior power under the curve while maintaining a smooth idle? (I referenced the Mercedes M156 6.2L NA as an example of like displacement with like technologies - i.e., cam phasing, etc., and there are others. Example? For example: can you support your claim of comparable OHV being superior to a 25 year old LT5 across the rpm spectrum with a smooth idle?) Point/Counterpoint.

*..."engines that are every bit the equal..."*

Showing us the data to support that claim (w/ comparable displacement) would help to provide some validity to that statement...

How do those very special application BLOWN motors (rebuilt every 1/4 mile run) have any relevance to the architecture discussion at hand??:confused:

Granted, VVT is a modern asset to OHV. However, it is even more of an asset to DOHC architecture as the exhaust valve timing can be independent from intake cam lobe timing. Point/Counterpoint.

Well, I refer (again) to the example of the DOHC Mercedes NA M156 which shares those same technological advances AND displacement with GM's current OHV NA LT1. I dunno, but most of legit true apples to apples comparisons of DOHC vs. OHV, proving superiority of the latter is pretty thin in the evidence side of the argument.

Far as blown V6's goes, one only has to see one of the 1/2 mile or 1 mile shootouts to see the truth of "If you ain't blowin, you ain't goin!" But, those kick-*** Nissan V6s are also DOHC, by the way... But, as Mike already said, hybrids w/ electric FWD may be what really makes DOHC moot - to your Point/Counterpoint.


:cheers:

Re: Point/Counterpoint: DOHC v OHV
 

One of the pros to the DOHC, is that one can use a more aggressive cam grind and still maintain a good idle.
One of the Cons of the DOHC is that the engine even though it is very well designed is not as simple to work on as a pushrod small block. Assuming you don't have 17 miles of hose and tube on your pushrod V8. What I am referring to for one thing is valve guide seals, with a SBC you can fairly easily change them with the engine in the car.
They say push rod engines make better torque, however I do not understand the physics involved with that assumption. I think it goes back to the cam grind utilized in the DOHC engines and stroke of the engine.

Re: Point/Counterpoint: DOHC v OHV
 

Can someone name a modern day GM Powertrain motor which is NOT a V8 and NOT OHC?

Re: Point/Counterpoint: DOHC v OHV
 

the ls engines will keep making power by increasing power adders, turbo, twin turbo, twin superchargers and ramping up boost until the actual materials wont hold. From what I have seen as soon as they starting ramping up power they start adding better internals so it will stay together. At some point I would hope they would entertain the dohc technology and try to get more power that way and not rely so much on just adding boost. Every auto maker is guilty of adding boost to achieve there horsepower goal.

They might consider the camless engine. Using the computer to electronically open and close the valves. This has been something Lotus was trying to develop but at the time there wasnt a device that would open and close the valves fast enough. This was something Dave McLellan spoke about in his book. Camless?? 1 cam, 4 cam and no cam.

ed ramos #3028

Re: Point/Counterpoint: DOHC v OHV
 

The "Waxer vs. Warrior" question.

I was shocked to learn that as many as 1/3 of ZR-1 drivers have never bumped the rev limiter. And, some admit to never exceeding 5500 (!!) rpm! That being the case, unless balancing a nickel on its edge while sitting on the plenum of an idling motor is what excites them, things like which architecture affords what advantage...is pretty moot. :rolleyes: Might as well drive a "Dunwoody Cruiser"! (Our Atlanta friends know what I mean!:p But, translating for those not from around there, think of the movie National Lampoon's "Family Vacation" and the Family Truckster. That car...driven by soccer moms in tennis outfits)

http://www.autoblog.com/photos/family-truckster/

Re: Point/Counterpoint: DOHC v OHV
 

I'm curious as to what you basis for this comment is?


ROI

For the couple hundred or couple thousand people who want a flatter torque curve, with a dead smooth idle and 8000 RPM top end, Chevy isn't going to spend 500,000,000 dollars to retool a plant to build a DOHC V8. And they would piss off more Chevy diehards than they would win over.

You could put the average corvette driver behind the wheel of a 1996 Grand Sport and a 1995 ZR1 and they wouldn't be able to tell you how they felt different. They are selling to the people who are one standard deviation from the center of the bell curve. ZR1 owners are two standard deviations out and Chevy will likely never build an engine that we think would be comparable to the LT5.

Re: Point/Counterpoint: DOHC v OHV
 

I am lucky enough to own both a 1996 Grand Sport and a 1995 ZR-1. I sure can tell you the difference between the two... One has a good engine. The other one does a pretty good impersonation of sex (what is that?), but with your cloths on!