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PONTIAC, Mich. February 9, 2005; GM engineers have achieved a feat many speculated was not possible. The new LS7 7.0-liter OHV (overhead valve) V-8 engine for the 2006 ZO6 Corvette will not only achieve 500 horsepower but will be capable of running up to 7100 rpm. The previous limit was 6600 rpm in the 6.0-liter LS2.

With this new engine GM is showing multi-valve overhead cam performance is achievable with a two-valve cam-in-block engine. For the new ZO6, higher rpm allows the driver to remain in first gear to just over 60 mph, contributes to higher top speed and improves overall vehicle performance. The LS7 is one of the first automotive OHV production engines in the industry capable of over 7000 rpm.

The new ZO6's sub four-second 0-60 mph time is achieved in part by the extended rpm range and the ability to remain in first gear past 60 mph. The over-190 top speed of the ZO6 is partially due to the speed capability of the engine. As aerodynamic drag becomes a factor at higher speeds, the capability to run higher rpm allows the transmission to be run in a lower gear generating more effective torque at the rear wheels. Also, having the ability to shift all gears at higher speeds improves elapsed times whether on a road course or drag strip.

"For a production engine to run at this high of an rpm blurs the lines even more between OHV and OHC (overhead cam) design," said Dave Muscaro, assistant chief engineer for small block engines. "We took a complete systems approach to achieve the high rpm. We have a tight valvetrain design along with some race-inspired materials for the reciprocating components like titanium intake valves and connecting rods."

OHV engines use pushrods to activate the valves via rocker arms, whereas with OHC engines the valves are typically actuated directly via finger followers. The extra mechanical movement and weight of the components of an OHV valvetrain present challenges to higher rpm. The LS7 design and use of lightweight, stiff components, along with GM's economy of scale, make higher rpm obtainable in a production OHV engine.

"The new LS7 cylinder head gave us the opportunity to design a new high-revving valvetrain," said Jim Hicks, LS7 valvetrain design engineer. "The new valvetrain had to be as stiff and light as possible to assist meeting the engine's aggressive performance targets without compromising idle quality and low emissions. Stiffness is increased with larger diameter pushrods and rocker arms optimized through extensive finite element analysis."

The LS7's 1.8:1 rocker arm ratio and titanium intake valves contribute to a lower effective mass (compared to the LS2 base Corvette engine) in spite of larger and stiffer valvetrain hardware. Idle quality and emissions performance is achieved with the help of a more aggressive cam that provides more lift and duration while still keeping overlap area to a minimum.

"We consulted with our Motorsports group on numerous design aspects of the cylinder head design, said Hicks. "We adopted some of the latest ideas that have been successful in the Nextel Cup and the American Le Mans Series including valve centerline positions, valve angles, valve sizes and rocker arm ratio."

Due to the relatively large bore and stroke (104.8 x 101.6mm) of the LS7, light weight pistons, piston pins, titanium rods and a steel crankshaft are also used to achieve extended rpm. The flat top pistons with race-ready valve reliefs are 482 grams each and use a shortened lightweight piston pin. Each forged titanium rod weighs only 464 grams which is almost 30 percent less than each rod in the LS2. The forged steel crankshaft is stronger, stiffer and designed to handle high-speed loads.

Source: Auto channel
7,100 rpms for pushrod v8....not bad.
 

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holy crap man...seriously, i don't think you can get any better for $75,000 for a nice new car...this thing basicly takes out the ford GT which is 2x it's cost...and most exotics 4x-6x its cost...

if i had money to burn, i would burn it on one of these babies
 

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Not surprising, all it takes are the right parts.
 

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dr_dohc said:
holy crap man...seriously, i don't think you can get any better for $75,000 for a nice new car...this thing basicly takes out the ford GT which is 2x it's cost...and most exotics 4x-6x its cost...

if i had money to burn, i would burn it on one of these babies
Overall the Ford GT will dominate this car, it might comparable in certain categories but the GT will still dominate it. Still a great buy if you have the money, it definitely will dominate the Viper.
 

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i guess they dont have the offical specs on the new vett zo6 yet but last time i check with motor trend with estimates, its suppose to tie or beat the GT in nearly every catagory...guess we'll just have to wait to see the actual numbers...
 

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Discussion Starter #7
dr_dohc said:
i guess they dont have the offical specs on the new vett zo6 yet but last time i check with motor trend with estimates, its suppose to tie or beat the GT in nearly every catagory...guess we'll just have to wait to see the actual numbers...
Should be close. GT has a 50hp advantage, but z06 is about 300lbs lighter. From all indication, both cars should be fairly close in most categories.

That has always been the corvettes bright spot....its ability to hang with or beat supercars and exotics costing 2 to 4 times more.
 

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All I have to say is wow. The Vette just keeps getting better. Best bang for the buck without a doubt. Also you have to remember the Vette does it N/A vs. the GT is SC'ed.
 

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2camvtec said:
All I have to say is wow. The Vette just keeps getting better. Best bang for the buck without a doubt. Also you have to remember the Vette does it N/A vs. the GT is SC'ed.
:stupid
vette is getting better every year...i'm anxious to see how ford would have an answer to this...
 

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Hprelude92 said:
:stupid
vette is getting better every year...i'm anxious to see how ford would have an answer to this...

'06 550hp Mustang Shelby Cobra?????
 

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Discussion Starter #11
Hprelude92 said:
:stupid
vette is getting better every year...i'm anxious to see how ford would have an answer to this...
Ford GT production ends in a year or two. I think we'll see the Ford/Shelby GR-1 come 2007. It is supposed to be cheaper than the GT.

The powertrain will probably be one of these 3.
*Continuation of S/c'ed 5.4L in the GT but tuned for 600+ for GR-1
*N/A 6.4L 605hp v10 in concept car
*N/A 7.0L 600+ hp v8

I think/hope that the 6.4L v10 gets the nod. That's one sweet motor.
 

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Hprelude92 said:
:stupid
vette is getting better every year...i'm anxious to see how ford would have an answer to this...
i dont think ford will answer this. its too expensive and not enough people actually buy the gt
 

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2camvtec said:
All I have to say is wow. The Vette just keeps getting better. Best bang for the buck without a doubt. Also you have to remember the Vette does it N/A vs. the GT is SC'ed.
The Vette also has 1.6 liters over the GT, so the NA vs FI argument isn't that simple.
 

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druuuu said:
i dont think ford will answer this. its too expensive and not enough people actually buy the gt

The GT sold out before it even hit the streets.
 

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Turbomice2 said:
The Vette also has 1.6 liters over the GT, so the NA vs FI argument isn't that simple.

Nope especially when the quality of parts the Vette is using. I know for sure the GT doesn't have titanium rods or valves.
 

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spray004 said:
The GT sold out before it even hit the streets.
that may be true, but i dont see how the GT could make up a big part of Ford's profits. i think that the vette is MUCH more of an asset to chevy than the gt is to ford.
 

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why exactly do they stick with the OHV design anyway......i've never read why.......is it cost, or space or what.......
 

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fizzbob7 said:
why exactly do they stick with the OHV design anyway......i've never read why.......is it cost, or space or what.......
i think its cost. its expensive as hell to develope a new engine. and why would they need to when this one is raking in all that cash?
 

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njn63 said:
they actually developed 2 engines with the new c6 i think. A pushrod and a dohc one and a bunch of people drove them and decided the pushrod one was better. This was without knowledge of which engine was in which car.

but did the DOHC engine have as much attention to detail as the OHV.....it's not a question of which is more efficient and can be better......it's either simply money or the combo of money/"we'll prove ohv-haters wrong"............

you can't argue with thermodynamics
 

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njn63 said:
haha, Ford will answer once Chevy stops making it. Until then they'll just make slower cars and idiots will buy them because they're Ford boys.

That's how Ford operates it seems. They only put out cars to dominate another once the other one is gone. 2003 Cobra, Lightning (pulled once the SRT-10 came out), SVT Focus (SRT-4? I dunno what beat that), etc.

SVT dropped the Lightning so they could focus on the new Cobra. The Lightning will come back once the Cobra has hit the market.

I don't think Ford ever planned to make a big profit off of the GT. Its more of an image car to bolster sales through its other lines like the Mustang. Its more of telling the public, "Hey we can still produce a car that will compete head to head with a Ferrari". Years ago Porsche make a car that sold at a net loss, but it was done for image and marketing.

OHV is a simple design that has been proven throughout the years to be competitive. OHC technology is no where near new to American manufacturers. Hell even Ford had a 427 SOHC engine and even a 427 SOHC 3V engine in the early 60's. Some manufacturers such as GM decide to use OHV technology because its simple and will get the job done effectively.
 
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