going from 660's > 550's on SAFC2/50trim

[blcknspo0ln]

Talking to a member of a very good DSM shop here in jersey, They recommended me to step down to 550s from 660cc injectors for use with my 50 trim. It will be street tuned to about 21 psi on 93 pump gas.

currently they got it to the tune of 10.8 A/F ratio, and skirting -42% on the HI SAFC compensation.

If you ask me, that's an insane amount of fuel to pull and my timing is suffering. From what data was given, I was hitting 13* peak timing at around 6400 rpms. the only thing Im confused about is I thought that timing was to be advanced in my situation?

anyone believe that I can maximize the potential of this turbo with the 550's and maintain a good IDC? or should I stay with the 660's?

 

[CanadianTSi]

Sounds like you have a boost leak.

Thats how far I had to go when I had a boost leak.

Stay with the 660's.

 

[shleppy]

stay with the 660's. You will easily outflow the 550's at 20psi.

 

[RavenX]

You need to tell those guys what are they smoking by recommending you to step down injectors. Stay with the 660's. Check for boost leaks other than that theres nothing you can do about the timing. I had this same problem and its one of the reason i got rid of the afc. No matter what i did my timing always peaked at 14-15 degrees. The only good side to this is that you can run more boost with such little timing. I find 10.8:1 a little rich especially with such low timing. Try going for 11.0:1 at 20si and check for knock

 

[Zex4g63]

What's your fuel pressure?

 

[DSM90AWD]

As an FYI.. Denso 660s flow anywhere from 700-715cc @ 43psi pressure so if you're calibrating based on a 660cc flow, you are going to be running ~7% richer. More so if your base FP is higher.

If you dont' believe me check with FIC or Cruzin

With my 50-trim and 43psi Base FP I was running over 100% DCs from 5500 RPMs+. Now with my Denso 660s (calibrated via DSMChips EPROM), I'm running 82% DCs at 23psi with room to grow

 

[CanadianTSi]

Being that far into the negative on the S-afc should make your timing go sky high, like 20+, but seeing as it was low this means that you were knocking terribly.

 

[DSM90AWD]

^^Good point. Pulling that much fuel is setting you up on a very aggressive timing map. Likely the high timing is causing you to knock early in the pull which then causes timing to be pulled which richens up your AFRs.

Optimal solution is to get an aftermarket chip calibrated for the 660s or DSMLink.

 

[blcknspo0ln]

You need to tell those guys what are they smoking by recommending you to step down injectors. Stay with the 660's. Check for boost leaks other than that theres nothing you can do about the timing. I had this same problem and its one of the reason i got rid of the afc. No matter what i did my timing always peaked at 14-15 degrees. The only good side to this is that you can run more boost with such little timing. I find 10.8:1 a little rich especially with such low timing. Try going for 11.0:1 at 20si and check for knock

it was a gentleman from DSMotorsports...

anyway, I think i'm just going to bite the bullet and go eprom/chip.. I'll do more research later, but does anyone know off the top of their head if a 97 ECU will work with a chip? or does it need EPROM?

 

[blcknspo0ln]

What's your fuel pressure?

fuel pressure is unknown. i'm running a rewired 190 with no FPR, which research says is unnecessary.

 

[CanadianTSi]

So are you positive you have no boost leaks?

 

[blcknspo0ln]

no, I do have a boost leak. i seriously am doing things ass backwards, it only takes me a whole thread to realize it.

My idle is at -15 vac and you can hear a LOUD hissing come from the 1G TB at IDLE [no pressure at all]. new gaskets + RTV, new shaft seals, cleaned TB. I can't figure it out. anyway.. I'm going to agree with you Canada and go after those boost leaks.. just wish I had the time.

but after my boost leaks are fixed, shouldn't the timing advance arise? If so, teh only solution to it is the ECU chip compensation or link? I've read many threads that guys are pulling ~18* peak timing with crazy adjustments around -45% and supposedly the car runs great.. any insight? thanks for the help

 

[CanadianTSi]

When I ran the time in my sig I had a big boost leak and had to go to around -44 to compensate.

I run my 650's at -35 and that gives me around 18-19 degree's of timing at the top of 3rd.

5 degree's of timing will make your car come alive.

 

[gman991057]

I wouldn't worry about the possibility of a timing advance problem until it IS a problem. After tuning without the boost leak you should get a good amount of timing advance but the car may run mint and won't need any sort of eprom chip. I can't imagine how hard your turbo is working right now, maintaining 21 psi with a boost leak. No wonder your having a hard time tuning. Goodluck