[fredmeister]

Originally Posted by spuggy

Fred, do you have dyno charts? Where do you make peak power? This can help highlight if the turbo is running out of flow.

My 3.3 when stock-ish with SC cams and a 3DLZ made peak power quite low (330 FWHP @ 5300 RPM, IIRC), but with a K27/HF, Kokelyn, GHLs - and still with stock ports - made peak HP (and somewhere between 70-95 more of them) @ 5700 RPM.

My guess is that this is limited by the stock ports/ pancake manifold at that point, rather than the K27/HF, and I'd bet that with bigger ports (38mm or bigger) and a better flowing intake manifold (e.g. a 3,2), you could make still more & higher - and maybe want a turbo with more top-end flow still. Or just keep the K27/HF because it spools up nicely for the street, I dunno...

Both my 3DLZ and the K27/HF maintained boost just fine (12.5PSI on a factory wastegate, according to the mech VDO) all the way until power was clearly falling off (e.g. over 6,000 RPM); although it's a red flag if boost falls off, sustaining boost pressure is not an indicator that you're not out of the efficiency island on the compressor map - the 3DLZ was certainly out of puff, I'd think.

You probably need to talk to someone knowledgeable about turbo sizing about what you want/expect. It's all a compromise.

I tend to agree with you from everyting I have read on the forums. Simplifying things, now if I increase the port size to 36mm and match port the manifold and insulator blocks, I could effectively increase the engine efficiency to say 95-100% and therefore flow even more air under boost.

I REALLY WAS HOPING FOR SOMEONE TO POST THE COMPRESSOR MAPS FOR THE K27S AND K27HF TURBOS TO SEE WHERE I LIE.
ANYONE WANT TO SHARE THE INFO?