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what's the difference between T25 and T3?


Guest jwmaxse

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Guest jwmaxse

Here's the deal, I just bought an '88 300zx turbo and I know it has the higher compression motor and smaller T25 turbo compared to the older models with the lower compression and larger T3 turbo. I have a working T3 sitting in my bedroom and I'm wondering if it is worth it to put it on. What kind of gains would I see initially? What changes would I need to make to the manifold and downpipe? I also have the downpipe from the T3 and I'm curious if I would need to use that or not.

 

I hear people bashing the T25 all the time and I guess I'm just curious as to why the T3 is so much better.

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Guest bastaad525

T25, faster spool, more responsive, can't run as much boost efficiently, has a lower power cap, less top end push. T3 can be made to spool very fast as well with a good free flowing exhaust setup, will support a bit more boost and power. So it comes down to what you want, really, faster response, or more power. Not sure how dramatically different they are, but since most guys on here are after the big hp numbers (seems I'm the only one content with 200-250hp around here :D ) they would almost ALL prefer the T3, I'm sure.

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Guest Jason84NA-T

I have both my 84T and my 88T. I can say for sure the T3 has far more power potential and only a little more lag. A T3 is an upgrade from the T25, without a doubt. Keep in mind that the T25 equipped W series VG30ET only runs 4-5PSI, and the T3 equipped VG30ET runs 7PSI. Also, since the T3 is more efficient at higher boost, you will get more power from the T3 at any boost setting from roughly 8-13PSI (13 being the limits of the stock fuel system with no modifications). Run good gas and you should have no problems boosting 10PSI+

 

Do you have a t3 from a 300ZX? the housings are different on different T3's... The o2 elbow, and the up-pipe are not the same, so you will need those off a 84-87 model also. Your manifold and downpipe will work fine.

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Guest jwmaxse

Thanks for the info, that's just what I was looking for. I do have a T3 from a 300zx so are you saying I should just be able to bolt it right on? If so, I take it from your post that it is worth it to switch it out until I get a better turbo, which may be over a year away. I am curious as to how much of a difference it will make having the T3 instead of the current one.

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  • 2 weeks later...
Guest Jason84NA-T

it'll make enough difference at higher boost levels to warrant the change, however if you plan on upgrading to a t3/to4e within a year or so, it's not practical to do the work now. Changing the turbo on a Z31 is kind of a pain in the butt. It's almost easier to pull the motor w/ trans.

 

IMO the best turbo for a VG30ET with stock manifolds and internals is a t3/t04e 60 trim w/ stage 3 or 5 exhaust turbine in a .63 a/r exhaust housing. Comp housing A/R of .50 seems to work well for some people, though most opt to go bigger. As Corky Bell says; go a little big, gives you room to grow.

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