*Trim Calculation*

MDCmotorsports

MDCmotorsports

Offical SM Expert: Turbochargers
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Mar 31, 2005
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Trim smim LOL.

Great info IJ! But I just did the trim calculation on my holset hy35w (dodge ram cummins turbo diesel) and it comes out to a 45 trim.

BUWHAHAHAHAHHA.

That turbo flows enough air for 30+ psi and over 450hp.
 
Joel W.

Joel W.

Just A Jedi
Nov 7, 2005
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ya i thought i did enough research before i bought it, but typically i find out afterwords that i didnt have a clue... i really aprectiate all your help on this topic, great thread..
 
I

IJ.

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Mar 30, 2005
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Jon: Very welcome!

Probably find your Turbo is for a 6+ litre motor :)

Joel: There's a LOT of "black art" involved with Turbo sizing that's really just math, once you find the formulas it almost makes sense I just wish they would settle on 1 set of end user terminology to describe them.

I used to struggle through all of the calculations when doing a match in the old days now I just use "years of experience" to get close but fell on my butt with the GT series as they just don't react the same as the older small frame Turbos!

2nd GT was the charm :).
 
Joel W.

Joel W.

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ok so to stick with this topic and get my brain belts smoking.. i read about all these 60 plus trim or (A/R) ??? turbos (monster hp) and now the smaller 45trim from MDC's post, my question is does changing the trim just mean its going to bite or grab more air, more aggressivly than say if it was a smaller trim.. pretending that the wheels were roughty the same EX diameter? man does that even make sense... (smoke cloudy haze)
 
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I

IJ.

Grumpy Old Man
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That's actually a perfect way to describe it Joel!

In Jon's case I'm only guessing his Turbo is for a much larger motor to be moving enough air for 450hp at such a small trim!
 
MDCmotorsports

MDCmotorsports

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Well another thing to think of too....

Possibly the larger trim means a tad more lag because you are after all trying to rotate a larger mass. Larger wheel takes longer to spin.

IJ, that Holset turbo made 450hp on a 2.2 ltr toyota.

:)
 
I

IJ.

Grumpy Old Man
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Jon: what is this "Lag" you speak of? ;)

Diesel turbo's are usually pretty big on the exhaust wheel and smaller than a gas turbo on the compressor side so I wonder what it's response was like on the 2.2?
 
MDCmotorsports

MDCmotorsports

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The guy told me full spool by 4200rpm.

I had one on my supra, and had full spool by 3200-3600rpm.

Specs on the holset....

Compressor minor/major: 2.077"(52.75mm)/3.0645"(77.84mm)
Turbine minor/major: 2.2825"(57.98mm)/2.5670"(65.20mm)
 
MDCmotorsports

MDCmotorsports

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IJ. What the crap are you still doing awake!

Any who, I have found that most Holset turbos are pretty balanced. Its the air research and garrett diesel turbos that are NOT MATCHED. I have seen some of the garrett turbos with 100mm turbines, and 50mm compressor wheels.

WTF!?!?
 
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