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Discussion Starter #1 (Edited)
Okay guys help me understand why tere is such a big difference in power between the LS7 in the C6.R and the (C6)Z06. I have looked over the engine specifications and the differences and similarities are shown below. How do the differences account for such a large difference in power?

C6-Z06/ C6.R

Displacement: 7.0/427/ Same
Horsepower: [email protected]/ Horsepower: [email protected]
Torque (lb-ft): [email protected]/ Torque (lb-ft): [email protected]
Bore diameter (in): 4.125/ Same
Crankshaft Stroke (in): 4.00/ Crankshaft Stroke (in): 3.985
Deck Height (in): 9.24/ Same
"V" angle (deg): 90/ Same
Cylinder Bore Spacing (in): 4.40/ Same
Compression: 11.1:1/ Compression: 12.0:1
Cylinder case material: Aluminum/ Same
Cylinder liners: Cast iron/ Cylinder liners: None
Lubrication System: Dry Sump/ Same
Fuel System: Sequential EFI/ Same
Throttle System: Throttle body/ TS: Individual runner
Fuel required: 93 octane/ Fuel required: 100 octane

-RR
 

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im sure alot of it is due to the increased compression (ie need for race fuel). also the cam is probably not made for fuel efficiency and emissions and such. Im sure a cam will wake this car up like nothing else. :thumb:
 

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The numbers you quoted are for the restrictor plate engine. The C6R non restrictor plate puts out close to 675 HP and 650 Tx ( and I have heard rumors of close to 750HP). Compression ratio I have seen is additionally sometimes reported as 12.5:1 and other times 14:1 depending on head chamber size, they run 3 slightly different heads, 30cc, 32cc and 38cc, those would roughly correspond with all of the CR's and chamber sizes. In addition the Valve Angle is a slightly steeper 11 degrees with larger intake runners.,

TheY also run a cast iron liner.

The LS7 head chamber size is 70cc, with a 12 degree Valve angle.

The C6R also runs a more agressive cam, a 5 stage dry sump, Jesel shaft mounted roller rockers with roller tips. The intake manifold runners are twice as long and the intake plenums are twice as big and there are two of them interconnected. There are 8 individual Kinsler FI throttle bodies. There is a Jesel belt drive.

Headers are a 3 step Tri Y with of course NO Cats to deal with and no emissions tuning

So most of the difference is in the heads and cam, intake & TB(s)

Remember, the production engine is still a detuned smogger. I am sure aftermarket will have these putting out +600 HP within 6 mos.
 

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Just curious

How does the C6R manage the detonation issue with such high octane fuel + super high compression? I thought that is a bad combination.

Back to the topic, the 580hp(if true) for the C6R doesn't seem that big of a difference from the LS7. 80HP at the crank can be made up easily by just some simple mods on the LS7, I would think.

Does anyone know why the bigger difference in the TQ #? If anything, the LS7 is a little weak with just 470ft-lb of torque. What is the reason for it NOT to generate a 500+ TQ#? Is it because the small bore/high compression setup? If that is so then how do you explain the relative high TQ# for the C6R.
 

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As as said before, it's all in the camshaft and heads/induction. The extra compression probably adds 10-15HP.

The racecar probably has an camshaft LSA on the order of 108-110 degrees and alot more duration, versus 115+ for the emissions controlled street car. This would make for much higher torque (thus horsepower), but with a much narrower power band. That's why the racecar idles like crap (of course some would call at beautiful) whereas the street car can idle smoothly with the power brakes still working. :)

-Dave C. '04 Z06
 

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Compression will make a huge difference, especially when a cam that has more valve overlap is used. Higher compression becomes a requirement. Basic rule, assuming proper gas ect. is 4% more power per point. Conservative is 3%. Very efficient engines will see almost 4. So, 11:1 to 14:1 os almost or is 3 points. So, 12% multiplied by 525(real power) will yeild additional 63hp plus additional power of a real cam not meant to last 100,000 miles. Like fast ramps ect.

Randy
 

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Thanks Dave and Randy for sharing your thoughts. I just heard from somewhere that high compression and high octane doesn't mix well. It could be I remember it backward.:eek:
 

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There is also the 600 pound difference in weight between the two cars. Plus the torque alone would make a huge difference. Then add the race trans which would probably account for 2 seconds a lap over the manual shifter...
 

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Using a higher Octane rated fuel helps prevent detonation under High compression. the octane rating in fuel is basically a measure of (or = to) a percent by volume scale of iso-octane to heptane. Not all fuels use the same exact chemical mixture so the octane scale is a standard form of measure to describe a fuels resistance to detonate/pre-ignition. Think of it this way, higher is better for high performance engines. This is only because most high performance engines run higher compression or forced induction. high octane race fuel (100+ rated) is used for its stability. Low octane can cause knock which can lead to broken parts/fragging an engine.
 
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