Katech LT2?
Safety Car
Joined: Nov 2007
Posts: 4,537
Likes: 1,402
From: Bethesda MD
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.
Pre Z06, I agree that I would have thought that a 7K redline might have been in order given that increase.
Melting Slicks
Joined: Jun 2012
Posts: 2,226
Likes: 1,029
From: Thomas Texas
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.
Race Director
Joined: Dec 2006
Posts: 12,322
Likes: 2,872
From: Fort Worth, Texas
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.
Melting Slicks
Joined: Aug 2017
Posts: 2,518
Likes: 942
From: Fl
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
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
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Drifting
Joined: Mar 2006
Posts: 1,869
Likes: 23
From: Oro Valley Arizona
I believe it's unlikely that anyone outside of GM "...gets the keys to tune the car". I believe the days are gone when purveyors of aftermarket calibration tools (HPT, EFILive and etc) could gain insight how a particular GM engine controller is programmed via information leaks or other "backdoor" methods. With the coming of technology such as autonomous vehicles and over the air calibration updates, the levels of encryption car companies are going to use to secure their systems are going to be extensive and are going to be based as much on risk management as they are going to be based on keeping calibration methods proprietary.
Drifting
Joined: Mar 2006
Posts: 1,869
Likes: 23
From: Oro Valley Arizona
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
Gary
E-Ray, 3LZ, ZER, LIFT
Joined: Sep 2007
Posts: 34,860
Likes: 12,292
From: NE South Carolina
^^^
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!"
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!"
Last edited by JerryU; Apr 12, 2020 at 11:27 AM.
Drifting
Joined: Mar 2006
Posts: 1,869
Likes: 23
From: Oro Valley Arizona
I’m surprised they added any with the climate change that’s causing the imminent end of the world soon, seriously though with the 18* extra on the exhaust side I don’t understand why they didn’t let it rev to 7k as that bigger split helps carry the power past peak and the shift/rev limiter is right after peak currently?
Drifting
Joined: Mar 2006
Posts: 1,869
Likes: 23
From: Oro Valley Arizona
I’m surprised they added any with the climate change that’s causing the imminent end of the world soon, seriously though with the 18* extra on the exhaust side I don’t understand why they didn’t let it rev to 7k as that bigger split helps carry the power past peak and the shift/rev limiter is right after peak currently?
E-Ray, 3LZ, ZER, LIFT
Joined: Sep 2007
Posts: 34,860
Likes: 12,292
From: NE South Carolina
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.
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!
Last edited by JerryU; Apr 12, 2020 at 01:39 PM.