i recently got to tune a car using race gas (vp c12) for the first time. i was able to raise the timing around 7 degrees over pump gas tune before it wasnt really making more tq, and leaned it out to run an afr around 12.2.

at the same boost level (16psi) the car jumped from the 438 made on pump to 474 on the c12.


what type of typical gains do people see switching to the higher octane leaded fuel? this was my first time using race gas and i just wanted to see if i was in the ballpark

 

That is about right. Sometimes the gains are larger. I have seen 200 horsepower gains by changing to c12 but that was partly due to the ability to increase boost pressure without detonation

 

Race gas, by its lonesome, wont see exponential gains. The gain here is able to reduce the chance of detonation thus can raise timing and boost.

 

yeah i did raise the timing. would have run more boost but the controller was acting up toward the end of the dyno session and i was getting close to running out of money in my pocket to pay for the dyno that day

 

At 13psi I made 435whp with 93...

When I switched fuel to c16 the car picked up 20 horsepower just front switching fuel...

and its said that going from pumps gas to e85... you can pick up 10% on average so that 435whp would have got roughly 40 more horsepower...

 

yeah im not going to be using e85, so i guess its 93 pump for me


and from switching fuel im also going to guess that the tune had to be readjusted for small timing and fueling differences...

 

Just remember, that race fuel helps resist the engine's ability to knock. Gains can change depending upon tuning, turbo and setup. This is a very A-typical question.