looking for a timing curve for a blow thru LS.

it's a new build and need a know good starting point.

LS 5.3
QFT-750 Blow thru
E85
twin GT35

Cheers!

 

15psi with 9.5:1 compression 5.3L LS engine with factory heads and pistons will take about 13* on 93 octane fuel and around 16-18* on E85 at 15psi near redline of 6000-7000rpm. I would start around 15 and compare 16 17 18


Timing is pulled down even lower from that point as boost increasing.
NO LS engine even Naturally aspirated will like much more than 22-24* of timing so keep that in mind LS motors do NOT need or want alot of timing. You may be near 15* of timing by 20psi on E85.

You take it to the Dyno and move the timing around and watch the EGT. Street cars at 3000lbs on a typical dynojet roller will pull out timing until the EGT ramps up and torque drops out then put back a degree or two to bring the EGT back down and you are done.

Race cars run a bit closer to the edge, a degree or two extra over what street cars run, is typical to squeeze the last 5% of torque and power out. But on the street that is dangerous because 1 thing can change like the humidity or ambient temp or the type of driving, up hill, gearing, loading, etc... is HIGHLY variable on the street so you don't want that extra timing in there.

 

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Thanks,
Brand new build..first LS, first Turbo
running E85, stock bottom, stock heads, stock head bolts, stage1 cam.
7lb spring in gates.

No intercooler, HP750 E85
3700LBS

the car will be below 2800RPM 99% of the time.
(2800 gets me 70mph on the highway)
Only raced at track, WOT

I just need a good safe tune-up while i sort it out.

Thanks