Let me give everyone here a bit of context on my situation before I go into the meat of my question.

My 99 corvette had a 'pioneer' heads/cam setup from the Vette Doctors on it from ~ 3 years back. The cam was a split duration that is nowhere near as stout as what can be gotten today and the heads were 5.7L heads that didn't flow that well compared to what can be had today. The heads were milled about 0.020" and the cam was a 'slow ramp' 222/225 .571/.551 @ 114. I routinely put down about 375RWHP with this combo. Not bad, but not really where I wanted the car to be.

For various reasons that are too lengthy to go into here, I decided to take all of that off of the car and go with a mo better TEA S2 5.3L heads and a TR 224 cam and a bunch of other goodies.

My car is a 6-speed w/ a 3.73 rear in it. I am trying to optimize my PCM tune for my new setup, and in looking through the #'s the Vette Doctors had put in my high-octane table compared to stock, I've got a few questions.

Please refer to this link to see both tables, and the comparison table:

http://www.whitneyroberts.com/wlrtimingtables.htm

What you'll notice in the comparison table (I've got the area in question highlighted in red) is that from 600 RPM to the top of the RPM range in the 0.2 to the 0.4 gms/cyl range, the Vette Doctor code has A LOT of timing pulled from just about everywhere compared to stock.

I'm not ragging on anyone's code... I just want to learn something here and find out *what, if anything* the pulled timing was buying me with a heads/cam setup. <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" /> Should I stick the stock #'s back in with my new setup? If so, do I run a risk of hurting anything in the engine, or am I running a risk of hurting anything/leaving power/tq on the table if I stick to the Vette Doctors timing #'s or vice-versa?

I appreciate any and all comments on this, as I'm really trying to learn more about timing advance and how it relates to the LS1, especially after mods.

<img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />

<small>[ November 22, 2002, 10:05 AM: Message edited by: AllCammedUp ]</small>

 

.2 to .4 g/cyl is going to encompass most of your idle and low RPM driving.

You are not going to see any peak power loss with that canyon in your timing curve, but what you are looseing is a little "seat of the pants" torque and throttle response when you first punch it. Maximum part-throttle timing makes the car feel "peppy".

That is usually where you pull timing when you remove the EGR from a car (F-body). Perhaps they figured the new cam was not giving you the same scavanging / combustion cooling effect, and chose to pull timing in this area to reduce part-throttle KR.

I don't think that you will have problems running the stock timing curves with your new cam. And if you do, just calculate out the g/cyl and RPM that you are seeing the KR. Then pull timing (try a couple degrees at a time) in the appropriate cells.

Gram / Cyl = 15 * MAF(g/sec) / RPM

Good Luck,
Kevin

 

Thanks for the reply, Kevin. That certainly points me in the right direction! <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />

I was planning on doing what you suggested as long as I didn't get an overwhelming reason to stay at the 'magic numbers' the Vette Doctors tune supposedly is/was.