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Old 04-06-2008, 07:32 PM   #1
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Default What a bummer...small turbos...

So I found out some bad news today. I went to the NE Dyno Day on Saturday and I noticed, that my car had the smallest T25 turbo there! I thought, wtf? why is that so little? So I did some research, and F%&*, I thought it was off an SR20DET or something similar...NO. It's off a freakin Skyhawk, or Grand AM! SO it must go, so if anyone has, or knows of a GT2560 or similar size turbo for sale, let me know. I am looking for something with a .64 turbine / .60 compressor, not .49/.48. Thanks guys.
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Old 04-06-2008, 07:59 PM   #2
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Old 04-06-2008, 08:19 PM   #3
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^what he said. Sam you still running that same turbo?

https://www.miataturbo.net/forum/showthread.php?t=18573
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Old 04-06-2008, 08:31 PM   #4
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I have a .80 compressor and CHRA that would drop right in that turbine of yours. No idea what HP it's efficient to but its tight(shaft play) and its water cooled if you're into that. Pretty sure its the same thing Samnavy has.
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Old 04-06-2008, 11:27 PM   #5
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Wow, I am going to be using that same turbo. Only mine is a factory replacement for a Pontiac Sunbird GT...

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Old 04-07-2008, 12:13 AM   #6
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Dont use that. I was going to use one of those untill corkey from begi told me not to. Sure youll get spool at like 1k rpm but it will run out of breath at like 140 hp haha.



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Wow, I am going to be using that same turbo. Only mine is a factory replacement for a Pontiac Sunbird GT...
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Old 04-07-2008, 12:32 AM   #7
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IIRC, the T2506 from the mid 80's Pontiacs is a .48/.49. I haven't been able to find the size of the compressor wheel, but like most small T25's it's probably good to about 12-14psi and 200whp. You just need a decent exhaust and ECU.

My T25 is from an SR20det and should be good for about 220-230 at 15psi. A stock block SR20det is good for about 250whp at 15psi with an ECU and big exhaust... but it's .4litres bigger and has ten times the headflow we've got.

I've so far only managed 200whp, with a spike to 14.5psi and settling to about 12psi. My peak power came at [email protected] But now that my timing and AE is under control, my EBC is only giving me 12psi dropping to 10psi. As soon as it stops raining, I'm gonna go back out and turn it up to 14psi and make sure it holds 14psi to redline.

I'll let y'all know what butt dyno says. In a week or three, Mike(Icantdo55) and I are going back to see what some good timing can do for power.

If I can make [email protected] and shitty timing... I should be able to make another [email protected], 5* more timing, and COP's at 4mm spark gap.
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Old 04-07-2008, 02:13 AM   #8
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Yeah, from what I researched it should get me to 200whp...barely. That exact same turbo made 175whp at 9-10psi on a single cam 1.6L honda, so I think with a little better displacement, and a better motor overall I might be able to squeeze 200 out of it. And if I cannot, hell, it was a free turbo w/ standard T25 flanges, so a replacement would be easy to setup (bolt it in).
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Old 04-07-2008, 02:20 AM   #9
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Be cautious when swapping in different T25s. The pontiac turbine housing is 1/4 taller so when swapping in the Nissan turbo my DP wouldn't fit. Had to install the Nissan turbo in the Pontiac turbine because the bolt pattern on the nissan was too high. This caused my downpipe to hit parts of the subframe which kept it from fitting at all with the nissan turbine housing.
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Old 04-07-2008, 02:27 AM   #10
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hmmm...

I will have to remember that. I am making my own DP (HKS mani), so if I upgrade I can always cut and add/subtract material to the DP to make it fit. That is odd that it is taller, because it is such a tiny turbo. Also cjernigan, did you ever use a heat shield for the turbo, or is it far enough away from the hood after all is said and done?
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Old 04-07-2008, 02:52 AM   #11
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Quote:
Originally Posted by samnavy View Post
IIRC, the T2506 from the mid 80's Pontiacs is a .48/.49. I haven't been able to find the size of the compressor wheel, but like most small T25's it's probably good to about 12-14psi and 200whp. You just need a decent exhaust and ECU.
I did 202whp at 13psi on a .48/.49. It is an AWESOME little turbo for sub-200whp. 200lb.ft at 3000rpm...
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Old 04-07-2008, 03:02 AM   #12
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Sweet, thats what I like to hear.

I like 0 lag, reminds me of the first boosted car I ever drove. It was a MK4 GTi 1.8T w/ bolt ons and a Revo tune. Not a really fast car, but pulled HARD from any RPM, and felt fast as hell.
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Old 04-07-2008, 01:50 PM   #13
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I like the little .48/.49 turbo I am running now for 1 reason, NO LAG. I have my wastegate set at 8psi, and when I pull out from an intersection, right when my clutch fully engages, there is boost, building to 8psi by 2 grand. It holds 8psi till I hit around 4300 RPM, then the boost starts to drop off. I would like to upgrade to a .80/.64 from an SR20DET, but what RPM will the boost be fully built and will it hold to redline?
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Old 04-07-2008, 02:27 PM   #14
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I also have a .48 / .49 T25. It's small, not sure exactly what car its from. However, I figure if it really runs out of steam I can replace either of the housings without much difficulty, particularly the compressor housing. It has yet to go on the car. I imagine for now it'll be the ideal turbo, once I start getting into the car more I may look to replace it, but that probably won't be until I seriously consider a 9k redline.
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Old 04-07-2008, 04:49 PM   #15
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Quote:
Originally Posted by thirdgen View Post
I would like to upgrade to a .80/.64 from an SR20DET, but what RPM will the boost be fully built and will it hold to redline?
With EBC, I'm hitting 14-15psi by 3300-3400rpm. I'm still fiddling with EBC and have about 2psi worth of dropoff near 7000rpm. I'm sure it'll hold a full 14psi all the way, but the EBC is super sensitive.
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Old 04-09-2008, 05:26 PM   #16
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Small turbos do have that nice torquey feel. I'd like to have boost all in by 2k...
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