corvette c5 tunes vs. camaro tunes

Hi All,

Its been a while since i've posted and since then i've got a C5 (99 M6).

I'm aware the camaro z28 ls1 has a tune 'break' around 2000, so the 99/00 are very timing aggressive, compared to the 01/02 - basically they de-tuned because of various improvements (and later the LS6 intake). So i'm aware and have stock maps and tuned base maps to improve the later years with better fueling and timing. The SS also has a different tune from what i've seen so far (only slightly - usually auto shift points due to gears)

Now, coming to the corvette c5, ok, so I got a 99 manual, and i've pulled the tune and the timing is even more aggressive than the camaro 99. Basically the timing ramps to 28/29 deg (about 3000rpm) then only has a very slight decrease to about 26/27 (at one rpm cell row at 4400rpm) then back to 28 deg again. The camaros have a much bigger dip over the peak torque area. I know the corvette Z06 also runs conservative timing - but these are >2001 models with LS6 heads and the different cam.

So:
1) Do the standard corvettes have a similar tune break - I do not have a standard tune from any thing newer than a 2000 model - does anyone have one?
2) From experience - is the corvette 99 tune really optimal, its seems to be super high timing (but indeed the fuel is much richer - 11 AFR zone) - ball park - should I expect gains or rather feel gains by leaning to 12.8-12.9 at WOT and dropping timing a couple of degrees - or shaping it a bit (see next point)
3) Should I 'dig' out the timing over peak torque ? - I don't have a dyno - only street tune and wideband. So can do a few drives but its hard where I live now (no long / hidden areas - private roads etc) - so difficult to establish from logging if its 'faster'
4) The O2 shift points are in the >500mv range for corvette vs camaro - position in exhaust is different - but would these be better lower (and improve mpg as a side effect?)
5) The corvette VE is ramped up too, but it actually has a smaller cam than the camaro, so it seems this is too high as well. I need to do auto VE but won't use another licence if I cant get the car noticeably better

thanks in advance guys

Hi maudyZ28,

try post #3 here (the thread title explains it): Tunefiledepot-has-been-replaced



As for 4) above, I set them to 450 mV in all cells, seems to work better with replacement NBO2 sensors.

Hi Joecar,

thanks for that didnt realise some people managed to save files from tune-depot before it was closed.

Any personal impression on the other points, I still think the standard timing is too high and the lack of a dip over peak torque seems worrying - maybe it doesn't 'matter' in the stock the - given they run so rich

My understanding is that the 241 and 243 heads burn faster so they don't need as much spark advance compared to the earlier heads.

241/243s are pretty dang good heads!

Also, you have a high chance of getting some knock now on a stock tune built in 99-early 00s. Why, well gas isnt quite as good anymore and E10 exists almost everywhere. Cleaning up the tune usually nets 10-15rwhp, plus a bit better mpg as you don't go super rich (i.e. 11:1) during WOT.

241 is LS1 and 243 is LS6/LS2. The 241 is the same design as its predecessors except for the casting method which leaves a smoother finish. I'm unaware of any other difference that would have any sort of impact on performance.

I remember the fueling and timing being different between the Camaro and Corvette. Naturally the Corvette was rated higher, so it got more timing and less PE fuel. The thing to remember here is that it also had a less restrictive exhaust system from the factory. I once had a tuner tell me that, generally speaking, when headers are fitted to an LS engine they seem to like an extra 2 degrees of timing. If this is true, and the Camaro's exhaust was sufficiently restrictive, then perhaps this is part of why they were so much more generous with timing advance. Just spitballing here, I have nothing objective to back me up.

The 97-99 cam was very similar to the 01-02 while the 00 cam was unique to that year.

Corvette LS1
YEAR PN DUR LIFT LSA

97-98 12554710 199/207 .472/.479 117
98-99 12560964 199/207 .472/.479 117
2000 12560968 198/209 .500/.500 115.5
01-03 12561721 198/207 .467/.479 116

thanks guys,

Indeed the heads are different between the LS1 and LS2/LS6 (on the Z06) but this is a clear reason for the tune difference (the timing can still be increase with these heads a bit more and make more power - and lean out some) ...

however, I'm really taking about why the tunes were so conservative for the post 2001, the engines for all standard C5s and all camaro and TA were still all LS1 with no major variations. So did it really come down to the LS6 intake that was added in 2001 (ish) adding 20HP, so they made the tune more conservative as not to up the power rating from much, because it gets closer to the Z06.

Then also, basically all I can do with the 99 tune, is probably clean up the fueling really.
And should the timing have a torque spark dip or run flat from 3000 rpm ??

The 2001+ Intake and the newer heads were more noted for the increased torque and GM wanted to keep the base engine for the Corvette at 350HP. They decreased the lift on the intake cycle but still had torque increased by 20 ft-lb as a result. For the 2001 Z06, they used a milder cam than the 2002-2004 Z06 cars because they had not completed all the reliability tests. At that time we had about 6 club members working at the Milford Proving Grounds and we were fortunate to have the lead PowerTrain engineer give us a talk at one of our monthly meetings about all the changes.

Quote:

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Originally Posted by Gordy M

...
At that time we had about 6 club members working at the Milford Proving Grounds and we were fortunate to have the lead PowerTrain engineer give us a talk at one of our monthly meetings about all the changes.

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That's pretty cool :cheers: