i know that 14.7:1 is stoic. i was just wondering what my a/fr should be on my bike. im prolly only gonna run 4-5 pounds of boost but the compression is 12.9:1 and the redline is 15,500. there are a select few on the forums who have put turbos on this bike and i am confused as to what my goal afr should be. i plan to retard the timing with a pclll but need a safe afr...any help?

 

I have to build a turbo kit for a local guy for a GSXR1100 drag bike. I will ask him what he is planning for tuning. We have a local guy that just tunes bikes. Big power bikes. The 1100 makes in the 400hp range at the tire.

 

Lots of theories on that - depends on your timing, EGTs, and how close to detonation you are... Probably in the 11 range for AFR, maybe more fuel (less power).
Consider shimming your cyliders with a big base gasket - lowers compression.

 

i have heard of a few guys witha thicker head gasket to lower the compression im having a hard time finding a place that can make or does make them... thanks for all the info guys, i was just curious because i was planning on running 11.0-11.5 but i was checking out other tubo bike dynos that are in the 13's. not sure what supporting fuel mods they have(race fuel, water/meth injection)but i just want to run a few safe,not too costly psi for fun

 

If thats a 1100cc, you could think of it in terms of a H22 when selecting a turbo - half the RPM's at twice the displacement. Since its only 5-6 psi, you may be better off with a larger turbo than you'd think, as most turbos are LESS efficient below 8 psi. But regardless of RPM's and CC's, you will always need a certain amount of AIRFLOW at X psi to make Y horsepower. I'd expect 250-300 whp with anything smaller than a 60trim t3/t04e - but thats me making a complete off the wall guess.

As far as what AFR's should be - is it still a 4-stroke gasoline engine? If so, it follows the same rules as any other, meaning 10:1 to 11:1 AFR's at the most, and ideally 11.5:1 AFR's due to not having good timing control and running high compression (relative to turbocharging norms).