Whats the max boost for 91oct on the stock turbo or the highest you guys have seen?

Thanks.

 

It varies car to car, but if you want to be safe, it's usually going to have a 25psi spike on the hit, and taper off to around 15 or so. Typical 91 octane results with bolt ons (full exhaust, intercooler, intake, boost control solenoid) will vary from 330-350whp on a dyno jet.

 

Thanks for the info. I have my car tune to 29psi and by redline it tappers down to 17psi stock turbo without a catt and zero knock 91oct it also has an ets intake open airfilter.

In evoscan using mode23 to log boost thats the value i get.

 

That sounds about right, of course, you gotta factor timing, backpressure, intake size and afr. the limit on the oem turbo is going to be turbine flow. at some point its going to be choked so much, back pressure will stop it from making anymore boost.

i have a 5" intake, fp red bb turbo, sakura manifold, ams dp, 3.5 exhaust, and 1000cc injectors with a 450lph pump. i run 24psi on a stock engine, with 9-10deg of timing, 11.6 afr, on 93, and it made 498awhp on a dynojet. its been like that for a year now, and so far the engine is healthy.

with the stock turbo, the fuel octane isnt really the issue, its turbine flow and exhaust back pressure that is the limiting factor. plus i think the oem intake becomes a flow restriction at 350-390whp.

just be careful when maxing out the oem turbo. with high boost levels, the thrust loading on the shaft will begin weakening the journal bearings and it can start to have oil blow by. the last thing you want is to have too much shaft rpm, causing either a compressor wheel failure or turbine wheel failure. if the compressor wheel were to explode, its gonna sent debris through the ic piping, ic, and into the engine.

29psi seems a bit dangerous, even with the taper down to 17psi. i guess if it hits 29psi for a really brief amount of time, itll be ok, but its def going to shorten the life of the turbo.

 

Thanks for the info.