s
did any of you guys actually read GM's SAE papers? cost is not the reason.
it is one of many benefits to OHV.

post up some sources or stop speculating and spreading your opinions as facts.

 

Since you come here and personally attack folks...yeah.

As for the middle finger...nice one Kid.

 

Please send me your address, so I can send you some funds with which to buy yourself a skin "Thicker than a defective Chinese condom"...Mark

 

I would suggest the same for you. Not doubting what you're saying and frankly I'd love to read those papers.
Having said that, I don't need an SAE paper to tell me that economics plays a considerable role in the selection of OHV for the Vette.
Each generation has had to justify its existence, particularly starting w the C5. McLellan wrote about that. X number of units must be built to justify the BG facility. And X number of units are dependent on a certain price point. And based on the margins GM requires to continue operation, the cost of each unit is locked in. A totally unique power plant is not in the cards or the P&L.
Do the SAE papers suggest GM builds a truck motor as a derivative of a sports car motor? Really?! Color me skeptical.

 

You should probably save em and buy yourself some manners...

 

The papers are all on the SAE website.

The fact is that there are much faster, much quicker, more powerful, more balanced, more fuel efficient, less expensive corvettes released since the C4ZR1.

 

And you attribute that strictly to the engine architecture? How do you explain then the competitiveness of other manufacturers, who DO build DOHC motors, w the LS/LT motors? The LT-5 precisely proves the economics argument. No other GM product used it. It was a single purpose motor with only 6900 examples built adding a cost of $35K in 90's dollars to the price of a Corvette. Hmmm..so I wonder why GM didn't do that again?! Because OHV is sooo much better?
I think I have a couple of other ZR-1 buds that would be happy to show you how much slower a DIY 7.4L LT-5 is than a LS-7.

 

Why is your lt5 not 7.4l?

 

LT-5s were 5.7L stock. That's what mine is and that's the dyno sheet I posted earlier in this thread. But there are different configs of LT-5 done by tuners like Rippie, Lingenfelter, SGC, Henderson, Haibeck that vary from 368-441CID.

 

wow

 

How about we destroke the engine and still run over 550hp at 9K

LT5 C4 ZR1 engine spun up to 9200rpm. Engine was built by Bonefied Customs and runs Bigstuff3 as the management system. Made 550hp and 450ftlbs at 8500rpm. Engine was destroked to a 5.0L to run at the Bonneville salt flats in the D/GT class. Enjoy!

 

This thread delivers.....

 

Saw this statement, you sure it's not variable cams that are flattening the curve?


who cares, its a heavily modified race engine. is that supposed to mean something? does anyone even race at bonneville anymore?

Do you not know the corvette race teams dominate a little thing called lemans? a little bit of a bigger stage against "premiere" competition running DOHC.

running a crappy OHV motor

 

 

It is clear to all but the obtuse, the virtues of DOHC/milt-intake (and exhaust) sets the bar for crankshaft output. And, it is equally evident that GM Power Train has made huge technological strides to optimize the two valve, single cam, push rod architecture; a fabulous achievement in its own right!

So, it isn't so much whether GM's push rods Corvettes today are as good or better than the DOHC world beaters of 24 years ago, but more an issue of opportunity lost! Given the financial realities of GM since 1993, the LSx probably saved Corvette, if not the whole of GM.

However, for many reasons (not all of which were logical) development was halted on the DOHC Corvette project prematurely. I say "prematurely", because of what we die-hard DOHC fans have been able to squeeze out of the architecture since GM halted production of the LT5.

THE DANG THING WAS STARVING FOR AIR!!

Before and after torque curves for an LT5 after porting and exhausts; stock 5.7L bottom and cams and stock idle.



Dyno graph, SAE corrected:



Same car idling...


SO! Taking nothing away from the new LT1s, what irks me and other ZR-1 Brothers is NOT the technological advances represented by the LSx or now the LT1; not at all. But! What could have been if the same effort was poured into developing the DOHC - not instead of, but AS WELL. Unfortunately, we are instead relegated to looking and envying advancements by Ford, and Merc, and Japan for their DOHC developments to gain clues of what should have been for Corvette.

PS: The NA DOHC ZR-1s, cubic inch for cubic inch remain a force to recon with to this day. Ask the Chicago area Corvette clubs that compete at the Crown Point Corvette Club shootouts in the fall, or look at the results of the 1/2 mile WANNAGOFAST shootout in Chicago last spring. (And, you might notice the fastest cars at the 1/2 mile event were FI DOHC V6s and a couple I-4s!! Just reading between the lines....)

 

A lot of DOHC motors are starving for air. the coyotes are the same. add intake and headers and they pick up a lot.

heres a question why DOHC can't get better mpgs??


here is a LS1 with full bolt ons, OEM LS6 cam, and ported intake and exhaust on LS1 heads..not LS6 heads

what's the difference in torque at 3000rpm?

 

this old line again. or hp/l.

what does this unit do for me in real life?

yes and now the LT1 has direct injection and viable cam timing. now we can turn the boost up too.

 

First and foremost GM has done wonders with pushrod motors, but one has to asked where they would be had the economy not tanked and the DOHC motor would have started progressing?

Lingenfelters 415 ZR-1 produced 685 hp and ran 218MPH; beats the new ZR1 to 150 and back down to 0. ZR-1 Snakeskinner was the first to beat the Shelby Cobras 0-100-0(not to mention the car was the first vehicle with carbon fiber/kevlar materials all of which are being used today)......you forget there are not any off the shelf heads you can buy for the LT-5, no high lift cams, springs, no cam phasing, direct injection, weight advantages of a rear differential all things that would come with progression. Christ not to mention advancements in tire compounds!!!

This is technology from 20 years ago and still hangs with new cars with minor mods(from a technoolgy standpoint) porting, cams, headers....

I think the funniest part is no one recognizes that ZR1 was chosen because the LT-5 was a revolutionary venture for GM....notes from Tom Wallace below:


WHY ZR1? "Deciding on a name turned out to be one of the hardest parts of the project," Tom Wallace admits. ZL1 was considered, in recognition of the ultrarare 1969 aluminum big-block package (just two were sold). Z07 was postulated, but then, this car is more than "one better than a Z06," so that was rejected. Saint Zora himself said that "all Corvettes are Super Sports," so SS never got much traction. Blue Devil is fraught with meaning inside GM, not out-but it served as great inspiration for all the blue trim accents. Which left ZR1 as the most sensible choice. This is, after all, a spiritual successor to the C4 ZR1 of 1990. That car sold for the equivalent of $91,000 2007 dollars and represented the state of the automaking art at General Motors in its day. So does this one.

 

What does hp/l buy you? Wow... Well, try this on for size....

The 5.7L, stock cammed LT5 (video), is making 89.12 hp/l w/o all the modern "goodies". Extrapolated to the new 6.2L LT1, it should be making 483 tq/552 hp, not "big woop" 450/450 fwhp. Is the fog lifting yet? No?

Here's the modern torque of the new NA LT1 with all the goodies compared to the 2010 4.5L 458 Ferrari V8 with essentially the same goodies...



What we have is the old L98 vs. LT4 argument. Do you not see a "trend" here????

 

Why are you comparing modified lt5 engines to stock lt1?

Then when you compare stock vs stock it's a car triple in price?