JD_AMG

http://www.gilbertautoparts.com/Chev...ockV8s/LS1.cfm
http://www.corvetteactioncenter.com/...t4-weight.html
http://www.whiteracingproducts.com/i...oducts_id=1114

Are you seriously that dense? Cost of the engines... A brand new LS2 can be bought for a little over $5,000, while the LT5 when new went in the $20Ks.
And the C6 ZR1 is $106,000 new, nice try though.

Check on the as new price of the C4 ZR1 compared to the C4 Z51, and then compare that to the C5 Z06...
Then why does the LS6 make the same power (and more torque through out the whole rev range) than the LT5 with the same displacement? Your argument is flawed and moronic. A DOHC engine is only going to make more power/torque if it is tuned to do so, your making it sound like it magically gains power from the OHCs.

XxGarbSxX

The production numbers for the Z06 and ZR1 are low enough that cost is likely a high factor.

You can do that kind of tuning with cam-in-block engines as well, it's just harder. You have to grind a new cam instead of a new timing gear.

Irunelevens

In all fairness, the oldest LS6 is still 11 years newer than the release of the LT5. OHC is a more efficient design, but it doesn't mean that every OHC motor will make more power than a pushrod motor.
The point was the ability to do variable valve timing, not just change the timing.

JD_AMG

Exactly my point.
In a racing application where a car would be making north of 1000hp+ I wouldn't mind a V-DOHC engine because the added weight would really be minuscule compared to the power/torque its making. But for the 99.9% rest of the world with street performance cars, a V-OHV engine is more efficient because of weight, size, and cost.

25psi

The weight is 596lbs(page two fully dressed)

The MSRP on the ZR1 is 103,xxx without any options. Show me one person that paid 103k

http://www.automotive.com/2009/101/c...ing/index.html

Its funny you want to bring up the price of a motor when the LS7 is 14k new lol

JD_AMG

Show me one person that paid $70,000 for a GTR

For a 505hp/470ft.lbs, 440lbs engine with dry sump thats really not that bad of a deal.

25psi

I know two people that purchased their gtr at Baker Jackson Nissan(Brad) is the manager and the only one that deals with the GTR. And the MSRP is 83k now, not 73k like it was(which they bought at msrp). Nissan went up on the price.

25psi

Not that bad of a deal, but you're where just complaining about cost

LS1LT1

iTrader: (16)

It's only $12,800.00 (including freight) for the smart shoppers but still.
And that's a lot of motor for that money.

Irunelevens

I'd say that OHC V6s are the industry standard now... Ford/GM/Mopar agrees. The applications where people want smoothness basically require OHC engines now to compete.

25psi

Back to pushrod vs dohc:

Lets clarify this a little bit. First of all, the 1993 lt1 produced 300hp@5000rpm and 340lb-ft@3600rpm. It wasn't until 96 that the lt4 produced 330hp. The lt5 in the 93 zr1 produced 405hp@5900rpm and 400lb-ft@4000rpm. Now that we're comparing apples to apples, there is a 105hp and 60lb-ft difference in output, let alone a narrower powerband, all from the same displacement.

As a matter of fact, now the difference in output is a staggering 35% and in torque 17.6%. If that is not a significant figure, I don't know what is. Ironically, these two engines were put in the same chassis side by side and both corvettes, so i don't see how any vette fan could be biased towards one or the other either.

Fact of matter is, it wasn't until 10 years after the first ZR1 that chevrolet matched the output of the powerplant with the ls6.

Consider this and you would get an idea of what chevy could come up with if they were to consider another dohc v8 for the vette.

JD_AMG

My friend's brother's roomate's uncle knows a guy who bought a ZR1 for MSRP.

Yes, because 405hp LS6 = $7,000ish and 405hp LT5 (new) = $20,000ish.

25psi

I highly doubt an LT5 was 20k in the early 90's

25psi

His name is Brad at Baker Jackson in Houston. Call em.

http://www.mulsannescorner.com/moparv8.html
http://www.mulsannescorner.com/mugenv8.html

Most racing dohc motors are just as light as pushrod motors. So the tech is there.

LS1LT1

iTrader: (16)

Yes, they'd then have a motor that 1) weighs more (more weight = less fuel economy), 2) is physically larger (meaning a less aerodynamic body to put it in = again less fuel efficiency and potentially slower top speeds) and 3) costs more to produce (potentially lower sales).

GM/Chevrolet doesn't use that OHV design by accident or because they don't have enough engineering prowess (because they do)...they use it because they weighed all of their objectives and needs and intentionally chose to use an OHV design.

JD_AMG

I agree they are the industry standard but for different reasons (marketing). "Smoothnes", NVH, feel, all have much more to do with the car and how its built than the engine (motor mounts, firewall, exhaust, transmission, where the engine is mounted etc. etc.). I've driven plenty of OHV's and OHC engines of various displacements and cylinders and can tell you OHC's are not automatically smoother with less NVH. As I'm sure you know the LS6 in the Gen 1 CTS-V is identical to the LS6 in the C5 Z06, but magically the CTS-V's LS6 felt smoother and had less NVH. That same LS6 was also smoother, with less NVH (ignoring the louder exhaust note) than the base CTS's 3.2L DOHC V6. And that same V6 feels no smoother than GM's 3600 OHV V6 (although its more 'crisp' IMO).

25psi

-You are speculating that the increase in weight, could not be negated through the chassis.

-If they use the same trans/gearing, the LT5 would be more fuel efficient

-why would the top speed be less, it would be more with the same exact setup and gearing.

We will see what the future holds for the vette. But I guarantee you in the near future, it will be dohc design. Just like the new V6 Caddies

25psi

I think we should go back to these points. It took GM 10 years to surpass what the LT5 did. 105hp difference with the same displacement. I think this about sums it up.

25psi

The discussion, however, is not about the IMMEDIATE need for dohc V8 power for gm, but the possibility down the road when their pushrod designs are starting to fall short.

The mugen to mopar example was made to clarify my point that dohc engines can and are made compact and lightweight, but that for now it is limited due to material usage and cost. 20 years ago, carbon fibres and space age alloys were seldom seen in anything non exotic, but these days they are much more common (specially the alloys) and this trend will continue.

My1st Truck

iTrader: (8)

Yep, Driven a VW, Mopar or some newer Hondas with OHC? Not smooth at all. Driven a push rod Cadillac? Can't even tell it is running. Marketing is the only thing that makes it better.
Remeber OHC is old too. 1913ish and used in production in the 20's
GM had straight OHC 6s in the 60's.
That debate is crazy, the one that makes the most power with the least moving parts wins.