EFILive and TTurbo Vette (Long more to come)

[lplott]

Well, the weather is getting nice here in Colorado, I have a week off the end of this month (27 May - 4 June), and it is time to tune this baby up. As you can see below I have all the parts, a great car that is capable of more than it is making at this time, and time plue EFILive to do this tune right.

Setup:
2002 Vette
twin turbos
random tech high flow cats
straight pipes

Custom OS
2bar MAP sensor (GM)
AFR sensor Innovate lc-1 permenantly installed

I have a pretty good tune on the car now (thanks to Mike at Xtreme in Tempe), but before the install of the Custom OS should I:
1. Scan/log AFR and boost pressure.
2. Going to combine the AutoVE and BoostVE logging table into one table just so I can see the two tables all at once.
3. Use the logged AFR under boost to populate the 105+kPa Boost VE table as a starting point for Boost VE tuning? (Should be a good starting point, haven't made any aluminum ashtrays since I got the TTurbo tune)

Here is the hard question:
I am running 91 octane pump gas, a quart of TORCO to 18 gals every tank. I have been reading a lot about knock, and rather to throw fuel at knock or to remove timing to get rid of knock. Since I am running cats I am concerned about how much fuel I inject into the boosted MAP ranges so I don't burn out the cats. From all the reading, it seems to be fairly agreed upon that rather you add more fuel or reduce timing, the RWHP is about the same no matter which way you go.
With this in mind, I am leaning towards removing timing to get rid of any knock if I have to. You guys that have ready access to a dyno, is what I have been reading about fuel vs timing accurate as far a RWHP is concerned in your experience?

More to come as I move through this project...:cheers:

Lots of questions and I appreciate the help.
Lonnie in Colorado Springs

[GMPX]

I am no expert in tuning boosted motors, but I could never understand why on forced induction engines some guys like to get the timing as far advanced as possible, maybe just before knock occurs like on a N/A motor.
In my head I figure you are going to be pumping some serious HP into the engine by means of a turbo or supercharger so why try to gain another 20Hp or less on top of the 500Hp you are making by putting 3 or 4 degrees more timing into it from a 'happy' or safe number? Pulling timing to remove knock (if your AFR's are good) is a better idea than make the mixture too rich.
Now obviously if you run too conservative you will loose power even on a blown engine, but with good fuel I would think maybe 18 - 20 deg total timing under boost, of course there is many variables to that number.
Generally AFR's in the low 12's seems to be good for blown motors, don't go for low 13's like some of the on the edge N/A motors are running.

Go to the Innovate website - http://www.innovatemotorsports.com/ and read the article on the home page about running rich.
Also, check out http://www.efi101.com/forum/ there is plenty of turbo tuning discussions over there, not LS1 based, but the theory is the same.

Cheers,
Ross

[lplott]

Thanks GMPX. That Innovate article has been around in different forms for a few months now. That was the first article that I read that got me to thinking of retarding spark instead of adding fuel to fight knock. I probably will:
1. Set it up initially for 12.3 under boost, do AutoVE.
2. If I get no knock, go to 12.4, do AutoVE.
3. Keep this up till I get knock, retard to get rid of it.
4. Since I don't have a dyno, guess I will probably go with the tune that first produces knock, since that means I have the peak pressure occuring very close to TDC, have the leanest mixture and should be producing the most power.

Maybe if I get this done early enough in the week I can get to Denver, put it on a dyno, load up the last 3 tunes and see which one of these tunes produces the most power. Should be an education.

More to come.
Lonnie:notacrook:

[KAZ MotorSports]

Hey Lonnie...you get things dialed in yet?

[lplott]

KAZ Motorsports,

Still in work. Nitrorocket has been helping me, but his schedule and mine are keeping us busy and tuning the Vette is not currently the top priority.

More to come
Lonnie