jeejee

iTrader: (3)

How would an optimised e85 ignition map look like compared to the same N/A engine / specs on normal petrol ?

And please be a bit more specific then "it has a higher octane rating so it needs to be advanced more"

thanks.

vaticano

iTrader: (8)

I never went back to gas, but from what I have read, if the timing is set up for max power with gas, then no changes are necesary. The biggest changes will be for FI.

jeejee

iTrader: (3)

anybody else care to shed some light on this ?

hellbents10

iTrader: (10)

Right if your engine combination does not require the higher octane then the same timing will be used. Fuel on the other hand is different as you will be using a more e85 as there is less btu's and your b.s.f.c. will be quite a bit higher.

jeejee

iTrader: (3)

Is that something you found out on the dyno, or something you are thinking ?
i ask because i converted all my cars on propane (105-110 octane) and this DOES require a different ignition map vs gas when using the same engine both N/A as forced induction.

When running higher octane in an engine and NOT changing the timing you are actually losing power , when the engine doesn't require the higher octane

hellbents10

iTrader: (10)

I just got done with a ls2 cam only Vette running on e85 the other day. It made the most power with 25 degrees at torque peak and 27-8 at hp peak. It would not make any more power with more timing. Tried all the way to 31. In the lower load areas I did add quite a bit to help with fuel economy.

DanO

Its called "MBT" Maximum Brake Torque timing.

a high octane fuel just allows you to achieve this optimal timing advance. This is the most efficient timing setting for power and BSFC.

Lower octane fuels do not allow this, yet all designs such as; optimal combustion chamber design, direct injection, high EGR... are all targeted to benefit the ability to come closer to or achieve MBT under all conditions. Any variance from MBT is a comprimise..