Ragtop 99

Jazz, it doesn't work that way. Cam shaft positioning, ignition timing, and fueling are optimized around the volumetric efficiency and cylinder pressure that the cam creates. The computer adjusts fueling to deal with results that differ from expected, but its trying to get back to the baseline based upon the stock cam. The ECU won't re optimize itself for a larger cam. A tuner has to do that. A car may run fine with a slightly larger cam in it, but it won't be optimal and it would be a lot of work for small gain. Swap a large cam and the car won't run properly.

Pre Z06, I agree that I would have thought that a 7K redline might have been in order given that increase.

RussM05

The LT1 pretty much was done making power at 6,000. The LT2 has a few hundred more RPM before its all done. That's where the extra 30 or so HP comes from. And it still has a warranty. I would also like a 7000 redline, but that's not in the cards with the stock LT2.

RapidC84B

DOD lifter limitation?

PRE-Z06

The LT2 intake manifold and exhaust manifolds as well as cam are much more efficient at moving air through the engine at higher rpms than the LT1, I wonder if heat and longevity kept the rev limit the same.

PRE-Z06

That very well could be the case

fatsport

I think so.
I also think development costs for the rest of the car had to be astronomical. Keeping the motor cost down, keeping it reliable, and a nice little bump in hp? Good job GM.

That said, it's too bad they started down the DOD route to begin with. Fortunately it can be avoided...
https://www.corvetteforum.com/forums...y-default.html

CPhelps

I believe I've read that 6600 rpm is indeed the limit for the heavier colapsable lifters used for DoD/AFM.

Racer86

If you change the torque curve with a built engine, I worry that the DCT will have drivability problems as it is also computer controlled. It may need to be tuned to match the engine. Thus another problem.

40YRW8

Hib, the complexity of the programming doesn’t concern me nearly as much as the possibility of unwanted and unexpected calibration updates. However, my hope is that GM is well aware of how critical the aftermarket is to the Corvette community and that freezing them out would seriously impact the brand image and sales. I’m betting that once you blow off your warrantee and (more importantly) GM’s product liability, things will be coming down the pipeline. Maybe even with a little “back door” help from GM. OOPS! Forget I said that. Wait, who’s knocking on my door at this hour? Dammit, RUN!!!

40YRW8

Did anyone notice that this profile, even though it isn’t a copy, follows the timing philosophy of the Katech torquer cams? With the shorty headers it looks like they are going for all the exhaust breathing they can get away with. Exhaust timing increases aren’t as dramatic as intake timing but they are much less intrusive to corporate drivability, emission and mileage requirements. This profile looks tailor made for long tube headers.
Gary

JerryU

^^^
I'm sure the GM engineers tested many cam options in small increments. They would have loved to get that extra 5 hp!

Bet Tadge asked many times, "Did you get that extra 5!"

40YRW8

After seeing some dyno sheets it looks like the LS2 is running out of torque above 6000 rpm. You won’t get any more horsepower at 7000 without more or at least the same amount of torque. Of course your car will be a tiny bit faster by staying in a lower gear a little longer but not much. You can raise the torque curve with a noticeable increase in valve timing at the expense of an equivalent amount of low end torque and drivability. Small and acceptable increases can be had with small increases in intake timing. Just as effective for small changes is intake runner length which, I have seen, can be very effective. Would I like more cam and long tube headers? Sure. But GM has to build a car for the consumer world even if it is a hot rod. I think those guys are pretty smart.

40YRW8

I’m not worried about climate change anymore. Al Gore just flew his big private jet to New England and bought a multi-million dollar mansion right on the water. I live in the Arizona desert and I am comforted by the thought that if his doomsday predictions come true at least he will go long before me.

JerryU

Always have to be careful what you ask for! Recall the LT1 Crate Motor gets 535 hp @6300 rpm versus the in the C7 465@6000. However the torque is only 5 ft-lbs more just pushed to a higher rpm. That's with a low restriction exhaust, no CATs, different cam without variable cam timing (as GM pushed that as far as they can without valves hitting pistons.) It also does not have to meet EPA emissions as it's designed for street rods, off road etc. See Pic.

Yep can always get more high rpm power by sacrificing low end torque. In fact, the LT2 does that to some degree versus the LT1 when you look at the power curves!

Note: Gragh with 535 Crate Motor starts at 3000 rpm and is ~40 ft-lbs less at 3000 than the C7 engine. No doubt even a higher percentage lower below 3000 as it does not have variable cam timing!