Turbo Ls e85 afr and timing
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An indicated 15* on my timing map may only be running 10* actual timing. Then if I plug my 15* number in another engine that reads 6* high, that 15* indicated on the timing map may be 21* actual.
Unless you know your map and the persons timing map you are borrowing from have verified the timing and SYNC'd it 100% correctly... The only right answer is to start at something stupid low like 10* and read the plugs
An indicated 15* on my timing map may only be running 10* actual timing. Then if I plug my 15* number in another engine that reads 6* high, that 15* indicated on the timing map may be 21* actual.
Unless you know your map and the persons timing map you are borrowing from have verified the timing and SYNC'd it 100% correctly... The only right answer is to start at something stupid low like 10* and read the plugs
static comp timing
8.1:1 12.0AFR 20psi 16degrees (would likely take 20deg) 1000rwhp
9.1:1 11.5AFR 20psi 14degrees (would likely take 16 deg) 1000rwhp
9.5:1 11.5:1AFR 20psi 13 degrees (would likely take 16deg) 1000rwhp
10.1:1 11.2AFR 20psi 11 degrees (would likely take 14deg) 950rwhp
10.6:1 11.0AFR 20psi 13 degrees (lifted the heads and blew coolant out too much timing for combo) 1100rwhp
static comp timing
8.1:1 12.0AFR 20psi 16degrees (would likely take 20deg) 1000rwhp
9.1:1 11.5AFR 20psi 14degrees (would likely take 16 deg) 1000rwhp
9.5:1 11.5:1AFR 20psi 13 degrees (would likely take 16deg) 1000rwhp
10.1:1 11.2AFR 20psi 11 degrees (would likely take 14deg) 950rwhp
10.6:1 11.0AFR 20psi 13 degrees (lifted the heads and blew coolant out too much timing for combo) 1100rwhp
No motor (e85 LS or otherwise) “likes” a set amount of timing across the board. The charge temps, part combo, and fuel run will determine MBT timing. ETHANOL BURNS FASTER THAN PUMP FUEL, it generally needs less advance to hit MBT timing. While race gas many need much more. Guys that throw in hotter plugs and a ton of timing at E85 tunes don’t have a clue. Read the plugs, period. There is no other correct answer for a “street tuner”. Every combo will differ. I’ve run as high as 30* and as low as 8* on turbo tunes...
Experienced dyno operators/tuner can gauge when you are approaching the MBT timing limit without reading plugs... But most experienced turbo engine tuners won’t shoot for an MBT timing tune anyway. You don’t want giant cylinder pressure peaks near PK TQ. That’s how U detonate, bend rods, and blow head gaskets. Idea is to tune below MBT timing near peak torque to “cushion” the motor and keep cylinder pressure in check. Then ramp timing back in slowly past PK TQ and pour on power in the upper RPM. “Race” stuff usually stalls past 5k and bleeds off a ton of compression at lower RPM with a huge duration cam. So it will have a much more aggressive timing map in general.









