Secondary compressor restriction

motorwood said:
I pulled it most of last year with the hx55-80 combo. It pulled good for a fairly basic 180 pump and lousy injectors. Im building a pump and bought better injectors and figured id give it a whirl at the local dyno day in march. I was just curious if dowsizing my secondary compressor only, would lay down a better dyno number?
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Your numbers will be more determined by your primary in your situation (as far as turbos anyways) as opposed to the secondary. Going to a smaller secondary will net you faster spool up more than it will anything vs total power.

I assume this is a 12 valve or p-pumped 24 valve. If it were a 6.7 I'd say your 71 mm secondary would be just fine as for street manners as the extra displacement makes it much easier to spool the larger turbos. If it is the case that you're running a 12 or 24 valve I'd probably opt for something in the 65-67 mm compressor range with an appropriate hot side and you'd have better response down low.

I'm not terribly familiar with the Holset turbo's so as for those particular models I can't really suggest one or the other but going off the spec sheet at the top of the Turbo Tech section I'd run something like:

HX55 - 64/98 Comp
73/xx Turbine - 19cm

As for the secondary anyways. Running the smaller turbine housing will help you spool up sooner and then you can gate around it as required as you come up into the higher end on the HX80

Someone more knowledgeable than I about the Holsets may be able to chime in with a better option though
 
I'll bump this back up. I enjoy seeing more information about these Holset turbo's. I'd like to see what motorwood can put together with a smaller secondary as well.
 
Ive opted to stick with the 71mm secondary, but am going with the billet primary wheel. Main reason is its way lighter, hoping that will stop the shaft from spinning inside the wheel. Was curious to discover my HT80 has an "F" trim turbine.
 
I'm sorry if I missed it, but what does the exhaust measure on your turbos? Wheel and housing.
 
4.1" exducer, 31cm housing on first stage. 80mm exducer 25cm internal gated 2nd stage.
 
That 4.1 is even on the smaller side of wheels available correct?
 
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