Re: Point/Counterpoint: DOHC v OHV
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Re: Point/Counterpoint: DOHC v OHV
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ed ramos #3028 |
Re: Point/Counterpoint: DOHC v OHV
An article that's very much "on point" with our discussion here. Be worth following it. Coyote v LS3.
http://www.enginelabs.com/engine-tec...gine-shootout/ |
Re: Point/Counterpoint: DOHC v OHV
Unfortunately, I think, it’s “on point” in more ways than one. IMHO, this article is not a good argument for a DOHC platform. First, they had to handicap it by starting with a truck engine for the Coyote, because a truly-comparable Mustang engine is far too expensive to be built vs. the LS3. That’s red flag #1. Then, they acknowledge that the Camaro’s (and Corvette’s) pushrod LS3 produces more power in stock form than the Mustang’s DOHC Coyote in stock form, so they handicap it again by throwing a HP per liter parameter into their testing criteria to save the Coyote’s bacon. Ouch, that’s red flag #2. Does anyone who’s being truly objective really care about HP per liter, as opposed to just the amount of power produced? HP per liter, in a case like this, is nothing more than a BS qualifier, an excuse, vis-*-vis, “Well, maybe my Mustang only has 420HP but it’s NOT FAIR, because your Camaro has more cubic inches!” And just as an aside, the smaller displacement Coyote is a MUCH larger and somewhat heavier engine than the LS3, which begins to shine a light on the potential packaging limitations of a modern DOHC layout. This is important, because if GM designs a Corvette around such a large and heavy engine, then it also needs to consider how that car's dynamics may suffer, especially in this age of rapidly rising CAFE standards, thanks to the greenies.
Please understand that, as I’ve said before, I love the LT5…wouldn’t have owned a Z unless that was fully true. But it seems to me that we’re generally falling into 2 camps here: those who really want GM to move back toward DOHC power for the Corvette, and those who believe that it’s generally not currently viable from a cost perspective. Regardless the final dyno numbers, I think that the entire premise of this particular article does a better job of validating the latter group’s argument. |
Re: Point/Counterpoint: DOHC v OHV
The Coyote is only 430 lbs if I recall correctly. It is certainly not the cheapest way to make an 11 second street toy, but there are a couple of useful advantages that I consider:
1) True dual cam VVT. The powerband from 300 cubic inches is really amazing and you don't have to always shift to keep it above 4000 rpms like you do on an LS engine when you get caught on the dull part of the low rpm power curve. 2) no surge of massive torque to blow off the rear tires as with large displacements. I find that this type of engine easier to drive a car at its limits than a big inch one. 3) There are sometimes intangible properties like an engines willing to change speed and rev although with the coyotes borrowed long stroke from the modular engines, the advantage might be for the LS. Just like diesels- they might have 800 lb/ft of torque, but they are locomotive slow to rev up. My mustang is geared so much lower than my vettes- it certainly seems faster to rev out- the 5.0 engine takes it in stride and seems balanced better. (maybe not better than the LT5, but certainly than the LS3). conclusion: the transmission might be the more important discussion, but true variable valve timing raises the area under the curve for torque so that coupled with close ratio gearing is really hard to beat. |
Re: Point/Counterpoint: DOHC v OHV
The article was not cited in order to score points for the OHC motor. It was put there as a source of greater objectivity than may be displayed on this forum, and that includes me. I am interested in seeing what they come up with.
What would be a really interesting "comparo" would be taking an LSsomething and dropping the MMR DOHC LS heads on it. Same block, but different valvetrain architecture and even same induction. THAT would make for a very interesting test. |
Re: Point/Counterpoint: DOHC v OHV
In a pure scientific (DOHC v OHV) discussion, when making comparisons of examples with varying degrees of critical variables, there has to be some mollification of differences - especially in something as critical as displacement. Another example is comparing a NASCAR motor to one designed to me emissions and perform equally well in city type stop and go traffic with the AC turned on as it does at WOT.
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I agree that you're spot on when considering power/$$ and marketing. I mean after all, about 1/3 of ZR-1 owners admit to never pushing their LT5s beyond Gen-I SBC capabilities. The LT5's characteristics are pretty much moot if limited to 5500 or 6000 rpm. But, $$ wise, the ZR-1 was X2 the price of the base Corvette when new, and pretty much the same is true today, except for some NCRS garage queens that push that to X3 perhaps. So, for some, and that includes all of us, $$ isn't the deciding factor, but rather determines how long one (like me) has to wait to be able to afford one! And, one could question my saying so, but the "FBI" has taken home the team trophy for the fastest aggregate of 3 cars at a local Corvette drag race shootout event, 3 out of the last 4 years, plus the first year when we won but didn't register for trophies. [I] I dunno... But, it might be a clue? (And there's no more scoffing from C5 or C6 owners when a "lowly C4" with a ZR-1 badge on it comes to the line against one of their LSx bretheren... So, the burning question is, what would be possible if GM did build contemporary DOHC V8? I'm w/ Dom: what does the LSx do with a set of MMR DOHC heads on it?? And, why are so many manufactures moving to the DOHC architecture w/ VVT and DI in spite of the drawbacks?? |
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Re: Point/Counterpoint: DOHC v OHV
wow, reading only the first few pages and cracking up I have to add that I have a 91 Zr1 and my brother has a 2004 Z06 so i have experienced both DOHC and OHV engines/layouts. The z06 has more down low torque, more of a throw you back in your seat at low or any rpms where our LT5s have to rev up to get that adrenaline feel. His engine is hundreds of lbs less and way cheaper to build, maintain etc. Given our cars were KING until the C5 z06 came out. the z06 is faster and handles better but the LT5 has more potential. I have ported plenum/IH catback and a tune and I was neck and neck with the stock c5 z06 but he eats me up in the twisties. At the end of the day I love my car more bc of its rarity, group of people, car guys that actually know what a zr1 is, no blind spots, and I **** on my bro every chance i get by saying i can take my top off.....plus his girlfriend likes my car more lol. Long live the KING:proud:
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Re: Point/Counterpoint: DOHC v OHV
Your interior doesn't look like it was vacuum formed out of sheet plastic either.
Again, match up to his 405hp, then run beyond the 1/8 mile. See what happens. |
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true that Dave M "pushed the boundaries" and wen't world class when corvette was about to go extinct.
I like his style! Hoping the "new ZR-1" will be a DOHC mid engine TT car. if so I'll be saving my butter and egg money and buying a used one (after it's under 100k buy in) as for the ford. I'm not a fan but I respect what they've done with the new VooDoo flat crank engine emerging with well over 500 poinies and a legit 8k plus red line. that to me is more exciting than slapping a blower on (heavy up top too isn't it!) I love all corvettes, but GM does have the engineering talent to build another world beater. I don't think the new Z06 is it. hopefully the new ZR-1 will be! GM again needs a "flag ship" give me that rear engine maint nightmare with a stout electic motor up front and let's give that "La Ferrari" (jeez what an uninspiring name) a run for it's money at a fraction of the cost. not easy to do but that's exactly what the old ZR-1 did and it's time to do it again! now where is that bean counter stick, oh, it left with Dave M !!!! |
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Most Corvette owners don't even know what it was. It was a blip on the radar. If they had stuck with it there is no doubt that the Corvette would be a faster car today because of it. It would also be 50% more expensive. |
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And, as they were leaving, one said he wanted to get a ZR-1 soon as he could afford it. It was refreshing!:-D |
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A young driver who knows what the LT5 is today is rare. |
Re: Point/Counterpoint: DOHC v OHV
Car people on the other side of the pond knew and admired the LT5. This comes from friends/family (Italy, Portugal, Greece, Hungary) who live there. They thought GM/Corvette finally was stepping up. I'm still always amazed at Corvette guys who don't know anything about the C4 ZR-1/ LT5. It's not like the ZR-1 was a regular C4 with a decal pkg. & paint.
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Re: Point/Counterpoint: DOHC v OHV
Most of the people who appear to have an appreciation of the LT-5 re in fact younger people, even younger than the Millenials. And don't forget how the
ZR-1 was introduced. It was in Europe and w the European press. Maybe we could ask our European brethren their view. The V angle and bore spacing also indicated a proliferation of the LT-5 motor into other models. The fact that Powertrain doesn't even have an example of the LT-5 in the HQ speaks volumes about silo thinking that exists through this day. You can't tell me McClellan isn't a bit bitter about the LT-5 altho he'd never say anything like that. And costs would have been dramatically reduced with volume. If the LS wasn't a truck motor, you wouldn't have $50K C7s today either. |
Re: Point/Counterpoint: DOHC v OHV
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I think this is due in part to the fact that many of the original buyers weren't car guys per se, they were buying them for investments. When that investment didn't pan out, they sold them to the second owners who were car guys. |
Re: Point/Counterpoint: DOHC v OHV
If you are a younger car enthusiast, the C4 ZR-1 represents an absolute steal in terms of performance and exclusivity. Particularly if you do your own wrenching. Some of the same reasons I'd love to have a Ford GT or a Pantera.
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They are cost effective to own in stock form, but aren't cost effective to modify at all. They aren't cost effective to repair or rebuild either. If you want cost effective you buy a high mileage or blown C5, pull the engine and drop in a low mileage salvage engine. The money I'll have into rebuilding the LT5 I'm working on, to stock form, would buy me a mid mileage LS3. |
Re: Point/Counterpoint: DOHC v OHV
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Re: Point/Counterpoint: DOHC v OHV
Very nice. Probably the only car I would have to consider as a trade for my Z.
Is that Hilborn injection I see? |
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Re: Point/Counterpoint: DOHC v OHV
Pantera an affordable exotic.
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