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Thread: Turbo size help

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Posts: 31-37 of 37
2012-02-15 13:20:37
#31
Plus the long term cost of a BB over a journal is lots more.

I do t like small frame at all. The smallest turbo I have mounted was a 62-1 about 7 years ago. Then a t66 now I'm running a T76, spools about at 5500rpm but then my power shots straight up
2012-02-15 19:41:19
#32
Guys this isn't a BB vs. journal bearing thread...

Back to the 3076R, it can be had with a T3 housing (which I would do) so the T2 stuff wouldn't be a problem. With a T3 and 0.82 A/R, where would this turbo spool at?
2012-02-15 20:12:37
#33
Originally Posted by ashtonsser
Spool time is based on exhaust energy, weight of the shaft its having to turn and restriction in the shaft.

At any given rpm the exhaust energy is the same given a journal bearing vs BB turbo of the same size.

So take two identical sized turbos one journal one bb, The bb shaft is only going to take very very slightly less energy to turn the shaft compared to the journal bearing.

Here is where the bb shines. Gear changes and respool as the journal bearing shaft will slow down significantly faster while the bb will retain alot of its shaft speed during shifts making respool very quick compared to the journal bearing.

Thats about the only advantage to a BB turbo really.

Its been dyno proven that there is only a 2-300rpm difference in spool time given the same size turbo just one being a journal and one a bb. Again proven.
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That is not how boost onset works. That is not how turbo lag works. That is not how turbo bearings work.

It might be time for my to make another new thread...
2012-02-15 20:12:55
#34
We have a built sr with a 3076 with .63 at spools about 4500 ish don't pay attention
Makes over 400 on pump conservative tune
2012-02-15 20:15:13
#35
Originally Posted by Datspar
Back to the 3076R... With a T3 and 0.82 A/R, where would this turbo spool?
Let me find a dyno chart of that exact setup.

Edit: Here's a RWD SR20DET with that turbo, and stock cams.
http://www.sr20-forum.com/usergallery/15948f01bc031f8b.jpg
Sorry there is no pressure trace, but you can make an educated guess. Looks to be around 4,500 rpm on E85 (cooler/less exhaust energy than gasoline).

It is danmartin's entry in this thread: http://www.sr20-forum.com/tuning/10391-most-powerful-engines-thread-dyno-thread-powerful-cars-tuners.html
Last edited by BenFenner on 2012-02-15 at 20-20-03.
2012-02-15 20:17:25
#36
compound turbo
2012-02-16 22:53:48
#37
Originally Posted by BenFenner
Let me find a dyno chart of that exact setup.

Edit: Here's a RWD SR20DET with that turbo, and stock cams.
http://www.sr20-forum.com/usergallery/15948f01bc031f8b.jpg
Sorry there is no pressure trace, but you can make an educated guess. Looks to be around 4,500 rpm on E85 (cooler/less exhaust energy than gasoline).

It is danmartin's entry in this thread: http://www.sr20-forum.com/tuning/10391-most-powerful-engines-thread-dyno-thread-powerful-cars-tuners.html


Wouldn't spool like that on gas I promise you that unless it has cams then it would with gas
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