Exducer affect on HP

mike diesel

mike diesel

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I am curious how much the exducer of the compressor can/will affect horsepower potential.

I just built a compound setup for my duramax using a billet 11 blade s472/87/1.0 as the secondary and a turbonetics custom Y2K as the primary. The turbonetics has a 101/112mm turbine and a billet 6 blade HPC 88mm compressor.

20150318_132440_zpsbyeswhdd.jpg


when researching what turbo I wanted to use as the primary, I was stuck on either a garrett gt4718 and this turbonetics. I ultimately went turbonetics because the turbine seems much better suited in a compound setup than the gt47 93mm turbine did.

The gt4718 is also 88mm but has a 118mm exducer with some billet wheels having 125mm extended tip. When my turbonetics showed up i pulled the compressor cover off expecting to see essentially the same wheel size as the gt4718 which was not the case. It seems like the turbonetics compressor cover has a ton of room that is not utilized. This HPC billet wheel has roughly 112mm exducer. It seems the compressor is cut short which makes the blade height at the exducer very tall.

1 advantage I see is the HPC wheel has less rotating mass but at the same time can't help but think the 112mm exducer is/can affect hp potential.

Would running the wheel down to 118mm+ exducer and having a short blade height flow more air than cutting it short at around 112mm with a much taller blade height? From my research, the HPC wheels don't seem to bad at moving air.
 
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I am curious to see what the turbo experts have to say on this. Back 8 or so years ago when I first got into diesel toys I wanted to upgrade my he351cw to a bigger wheel. I was told it was a waste of money since the 351cw upgrades only increase the inducer size and do nothing with exducer of the compressor wheel. This has always made me think the exducer plays a large role. Curious to see what they say
 
That was a great read. Answered basically every question I could have thought of.
 
My only dislike with that EF5 compressor cover is the diffusor size, the way it is designed will work well for creating flow, but diesel engines do depend on higher pressures than most other applications.
 
I actually bought the turbocharger book in that thread. I haven't had a chance to read through it though so I am still stupid on this stuff and follow the typical flow of what everybody else does LOL

So in a nutshell:

Large exducer = higher pressures

Smaller exducer (comparatively to the large) = more flow

?
 
Correct. I sure there is a point where going too small on the exducer has negative effects.
 
Surprised no one has mentioned wheel trim....ratio of inducer to exducer diameter.....critcal relationship in the equation.
 
CurtisEmery said:
Correct. I sure there is a point where going too small on the exducer has negative effects.
Click to expand...

That point depends how much pressure you need. Larger or higher revving engine needs smaller exducer than small or low revving engine at same hp level.
 
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