hey all, my car (mods in sig) runs perfectly on 95 octane fuel (premixed) boosts cleanly throughout the rev range and feels strong, idles mint etc etc..

However when I put 98 octane or even 100 octane fuel in, the car wont boost past 5-6psi..it does this in every gear and is more prominent when changing down from 4th to 3rd bout 5000rpm. It runs normally in every other aspect of the tune, idle, cruize etc etc...

Timing is at 25 degree's and decreases accordingly as boost increases, fuel maps are perfect, but on the dyno using 98/100 octane it shows very lean afr's around 5-6 psi..

Once I flush out the 98/100 octane and put 95 back in the problems go away and the car runs perfectly again.

Could this be a timing issue?

 

Rotary engines fire 3 times per rotor Every Revolution, Unlike a piston engine that fires 1 time per piston Every 2 Revolutions. Pistons like SLOW Burning Gas to Push on the piston all the way down the cylinder (More Octane). Rotary engines like FAST Burning Gas to spin the Rotor as fast as possible (Less Octane). The LOWEST OCTANE Gas will Burn the Fastest and give you the most HP in a Rotary Engine. Try running the lowest octane gas you can find and add a double shot of pre-mix, to lower the octane a little more, and see what happens.

 

This is only for Non Turbo motors...your right but yea low octane plus turbo motor = Boom!!!

 

Higher octane also requires more advance in timing to fully utilize it due to it's slower burn rate. Contact Rice Racing.