38r Specs
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Posting Guru
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From: NW Arkansas
38r Specs
Anyone pulled there 38r apart and measured the wheels?
I have found that the compressor is 66/88 (inducer/exducer) but I cannot find the specs on the exhaust side.
Anyone help me out?
Thanks!
I have found that the compressor is 66/88 (inducer/exducer) but I cannot find the specs on the exhaust side.
Anyone help me out?
Thanks!
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Posting Guru
Joined: Dec 2003
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From: NW Arkansas
bump.. guess I'll track the info down myself..
for further reference
Turbine Exducer 67.69mm
Turbine Inducer 77.47mm
Making a 38r a 66/68 charger
Edit... i wasn't thinking.. the 38r would be a 66/78/1.0 charger.. my brain wasn't working right..
for further reference
Turbine Exducer 67.69mm
Turbine Inducer 77.47mm
Making a 38r a 66/68 charger
Edit... i wasn't thinking.. the 38r would be a 66/78/1.0 charger.. my brain wasn't working right..
Elder User
Joined: Dec 2002
Posts: 797
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From: UT
Are you trying to lower the drive pressure?
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Posting Guru
Joined: Dec 2003
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From: NW Arkansas
No. I was having a discussion with a buddy about how the 38r has better spooling characteristics than a H2e. I was making the point that the 71mm exhaust wheel is a poor choice. The 68mm has quick spool and actually have a much broader map.
By finding the wheel sizes I can now understand why the 38r has a tendency to surge. And that is b/c of the compressor wheel and exhaust wheel being so closely sized.
The 7.3 crowd is too fixated on housing sizes. This can sometimes cause a thumb in the dam effect. The housing being too small will cause bad juju drive pressures, and too large will kill responsiveness. Where as a properly designed charger will have a much larger effect.
By finding the wheel sizes I can now understand why the 38r has a tendency to surge. And that is b/c of the compressor wheel and exhaust wheel being so closely sized.
The 7.3 crowd is too fixated on housing sizes. This can sometimes cause a thumb in the dam effect. The housing being too small will cause bad juju drive pressures, and too large will kill responsiveness. Where as a properly designed charger will have a much larger effect.
Elder User
Joined: Dec 2002
Posts: 797
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From: UT
Gotcha ya. Ya got me by the word "making"...
Looks like the compressor has 56 trim and the turbine has 76 trim.
Is there a map for the 38R?
Edit:
Found one http://www.turbobygarrett.com/turbob...e_Comp_map.pdf
Looks like the compressor has 56 trim and the turbine has 76 trim.
Is there a map for the 38R?
Edit:
Found one http://www.turbobygarrett.com/turbob...e_Comp_map.pdf
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Posting Guru
Joined: Dec 2003
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From: NW Arkansas
I meant to say "making it a 66/68 charger"
you beat me to the map link. The rule of thumb on Garrett BB chargers is you see about 300-400rpm sooner spool up and 30-5-hp vs. a similar sized JB charger
you beat me to the map link. The rule of thumb on Garrett BB chargers is you see about 300-400rpm sooner spool up and 30-5-hp vs. a similar sized JB charger
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Master of Strokes
Joined: Mar 2007
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From: CA
Good post Andy, I have often woundered what a 38r is but no one knew. It is funny how everyone gets so fixed on the housing size vs the wheel size.
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