Quote:
Originally Posted by marting
Dougal! and you other guys with know-how;
A local guru said i should get a t 25 with a 60 A/R aprx. (i still don't comletely understand what that is)
And that i would be better of with a slightly biggish turbo than a small one. He said that i could limit it's power on top with the fuel adjustment and the wastegate , and a garrett gt would spool up early enough anyway.
Does anyone agree? I will buy a turbo next week...and if i can find a garrett t25 with A/R between 50 and 60 i guess i'll go for it..
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The only A/R choices I'm aware of with the T25 are the 0.49 which I have and the 0.64.
The 0.49 gives you more low end and a wider usable rpm range. the 0.64 will give you more top end power as it's best efficiency point occurs at higher engine rpm.
I am hesitant to recommend a 0.49 A/R T25 for a 2H unless the driver has all the instruments and drives to them. There's a small chance that an ignorant driver could overspeed the turbo, causing it to die prematurely.
Regarding the GT series, being a later generation product they're more refined and may spool earlier than the older turbos of the same size, but the biggest difference is the bearings used in some models.
Garrett use the suffix "R" to show which ones have bearings in them, these will spool up sooner, the ones without have journal bearings.
So in short
GT2560 = journal bearings
GT2560R = roller/ball bearings and faster spool up.