20 psi @ 94 octane, but what psi @ 91 octane?

[Jarg-gst]

'90 GSX

Mods:
'95 Block with Teflon coated pistons
'94 Head with mild port job
Balance Shafts removed
550cc Injectors
HKS VPC
20G Turbo ported and clipped 10 degrees.
boost controler
'95 ported exhaust manifold w/ 3in turbo-back borla stainless exhaust system
HKS Wastegate w/ dumptube
Front-mount Spearco intercooler
7lb Fidanza aluminum flywheel w/ 2600lb ACT clutch
Unorthodox Racing underdriven crank pulley

This car is run at 20 psi with 94 octane gas. My question is whats a safe boost level to run at 91 octane gas?

Thanks

 

[1QWK4]

Every car is different (mods), I personally would not run more than 17 PSI on pump gas. Do you have an EGT gauge or knock light on the car? I would invest in a logger.

 

[Jarg-gst]

No, not yet.

 

[IPT]

Get a logger. They make tuning SOOO easy. Worth every penny.

 

[Jarg-gst]

Until I one would you say 17 psi on 91 pump gas? Just as a rough estimate until I can get a logger or get it tuned.

 

[candela]

I remember reading somewhere about this, and it ended up for temporary use, 1.5 psi drop for every octane drop. I know its nothing t go bye, as you should tune for whatever you ll use but, its better to be safe.

 

[InferiorWang]

id try 16 or 17 and see how the car feels. If you get a bad feeling while driving, then turn it down further.