Boost and timing?

What's a good starting point for timing on a turbo charged 9.5:1, 521" on E85? I've got 40* fixed and pulling back from there, pulling a 1*/psi up to 10psi. Haven't got any real runs on it yet, just been idling around so far..

What heads? Sounds like a lot of timing but depends on combo. My A heads I run 30° and my old CJ heads I ran 36-38 ish. No boost though.

A429 heads. I used to run up it the low 40's with more compression on gas...

If you are just starting out with a boosted combo. I would advise that you set the timing at a fixed degree first. Get your afr under control and boost control working correctly before getting crafty with retard curves.

Are you intercooler or non? Are you efi or blow threw?

I will usually set timing at 30* and tune the rest from there. Continually check the strap on the plugs as you boost and tune the fuel curve. When you get the afr in a happy range at the psi levels and through the rpm curve. Them start adding more timing.

We run a 23 degree 400 inch sbc with a F1X, blow through, on C16 with 34 total. Running a pt3000 water to air I/C. We're making north of 1700 at 26 psi@8400 rpm.

Knowing what type of induction will help a lot. 40* is fine for just driving around (unless you make more power at 30* or any other number) but I would suspect that when you start leaning on it that you'll be a lot less even on the corn.

whatbumper wrote:Knowing what type of induction will help a lot.  40* is fine for just driving around (unless you make more power at 30* or any other number) but I would suspect that when you start leaning on it that you'll be a lot less even on the corn.

Its a 950 C&S blowthru carb. no intercooler

I think the turbocharged section of Yellow Bullet would help a lot. Also, you can simply call Steve Morris and I'm sure he could get you started with some good info. Good luck.

738drvr wrote:I think the turbocharged section of Yellow Bullet would help a lot. Also, you can simply call Steve Morris and I'm sure he could get you started with some good info. Good luck.

I frequent YB and the turbo forums...

Nice read

Heres an update on the issue I'm having with my turbo blowthru E85 setup. Car breaks up at 5500ish rpm. I think this was 38* locked. Im at 44* right now and pulling 1*/#1 at 5 psi and still breaking up. I checked rotor phasing and corrected it. AFR gauge is in the middle and you can see its in the 12 ish range. boost gauge is reading on top of the carb..

https://youtu.be/fYE4_szQ7qQ