need help with timing curve for turbo motor

[Evan Purple240zt]

Hey guys, I am setting my base programming for timing curves and fuel curves. Tuning fuel is no problem, however, i would like to know what timing curve is reccomended by you guys (something to start with). Let me know exactly what you need to help, and ill provide the information

 

Thanks guys= evan

 

PS... i can set timing retard per boost pressure. How do i know how much, and if i need to retard timing. At this point, i will be running 7psi or so with 420cc injectors.

[Scottie-GNZ]

Here is what worked for me and Patrick.

 

Build an ignition curve that starts at 20* at idle and ramps up to 39* by about 3300, then take 39* up to redline. Then build a retard curve that starts at about 2# boost (whatever is close) and ramp it up to 15* retard at 15# boost (assuming you have a 2-bar).

 

The goal is to have the quick advance to match the boost coming in early and to not runmore than 24* total (advance - retard) at 15# boost. If you want less timing, start at 20* and ramp up to less than 39* or make the numbers in the retard map larger.

[Drax240z]

Sweet, thanks Scottie.

[Evan Purple240zt]

Whoa, too dang simple! thanks scottie.

 

However i have a 3bar.. does that matter?

 

Evan

[TimZ]

quote:

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Originally posted by Evan Purple240zt:

Whoa, too dang simple! thanks scottie.

 

However i have a 3bar.. does that matter?

 

Evan

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No, it doesn't - use the same timing for given actual boost level as Scottie mentioned. The SDS does have a way for you to tell it which MAP sensor you have, right?

[Ron240zxt]

39 degree timing isnt this a little high? There wasnt any problems with patricks car at this level? Hum i guess i got to change my notes again lol

Later All

Ron

[TimZ]

quote:

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Originally posted by Ron240zxt:

39 degree timing isnt this a little high? There wasnt any problems with patricks car at this level?

---

 

I don't know about Patricks car, but that sounds pretty conservative to me. Remember, Scottie said to dial the timing back out with boost, so that you end up with about 24 degrees total timing at 15lbs of boost. The 39 degree number only happens when you are off boost.

 

The 24 degree number is a bit higher than I use, but my timing curve is fairly conservative under boost right now. At 15psi, I'm at about 22 deg total timing.

[Scottie-GNZ]

Update.

 

Got an email from Morgan asking the same thing. I sent him advance and retard maps and he said it really woke his car up. MOF, he said he added a little more advance and the car felt even stronger.

 

Use my numbers as a guideline and adjust accordingly. You might all have have L28Ts but believe me, there are so many variables, every engine will react differently. Turbo size, gas quality, I/C efficiency, exhaust backpresure, etc, all play a little part in making the engines react differently. The SDS has a great tuning feature, the R/L knob. Learn to use it and you will be rewarded. E.g., if you sense a ltlle knock, richen the mixture and see if the knock goes away. If it does, then you have 2 choices, more fuel or less timing. If you have an A/F meter, it can help with that decision.

 

Tim, I would say you are probably a little conservative, BUT, I follow the low-timing/high-boost philosophy myself but never run high boost w/o the most octane I can get. Why I say it might be conservative is that on the street, you only do short bursts of high-boost in 3rd or 4th gears and that is where the real load is, so you can get away with a little more timing.

[Evan Purple240zt]

Thanks guys! Extremely helpful stuff here.

 

I put in a timing map using scotties info and the car seems to run very well. I have to finish the fuel curve now and i will feel safe putting the wastegate spring back in.

 

I drove my car for 3 hours last night with no problems. Things are coming along nicely!!!

 

Thanks again- Evan

[TimZ]

quote:

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Originally posted by Scottie-GNZ:

You might all have have L28Ts but believe me, there are so many variables, every engine will react differently. Turbo size, gas quality, I/C efficiency, exhaust backpresure, etc, all play a little part in making the engines react differently.

---

 

Never have truer words been spoken (okay, never is a strong word - I'm adding some artistic license here ). Timing curves are not too bad to pass around, but fuel maps are pretty much a waste of time. Unless you have a spec engine that is EXACTLY the same as another, the fuel delivery curves probably won't 'trade' very well. Hell, I've had to completely remap my VE curves just from changing my cam timing 3 degrees.

 

Scottie - I agree that my timing on boost is conservative. I had to dial it back to that for the dyno runs that I did last month, because the intake temps were running so high (96 deg ambient). I've left it alone, just because it's still running pretty strong, and it never seems to detonate, now. Also, my EGTs are not through the roof under boost, so I'm going to leave it alone for now.

 

I'm looking at upgrading my TEC PROM, as the newer versions have a feature that can retard timing with increasing intake temps. That way, I could run higher advance in cooler weather, and still not detonate when it gets really hot out.

 

[ July 15, 2001: Message edited by: TimZ ]