i just got my t25 back from mjm turbos wow fast turn around like 12 days. ported my out to a t28 and upgraded my turbine and compressor wheel . so now i have a t2/t3 brand new (basicly)fro under 600 jaime@mjmturbos.com tell him mule sent you and u want to same upgrade

So what kinda hp is this good for? and tq? you gonna get it dynoed?

~Ryan :D
Tempted by boost........

Dude I got my T28 from them too. That turbo is great about to go to the track this weekend and find out how great it really is.

Alex
95 Turbo

not sure on the numbers but i want about 300 or so?? it should do that pretty easy

Originally posted by muleman
not sure on the numbers but i want about 300 or so?? it should do that pretty easy

a t25 hogged out to a t28? i think it will die if pushed near 300. generally, 'upgrading' turbos is a bad idea. it can make a little more power at the expense of efficiency and lag. 600 dollars isn't far from a new turbo that can support the power without being 'upgraded'. I wouldn't bother spending that kind of money to overextend a tiny turbo. the factory pulsar t28 is a great turbo right out of the box.

andris

Originally posted by andris

I wouldn't bother spending that kind of money to overextend a tiny turbo. the factory pulsar t28 is a great turbo right out of the box.


And the GTi-R turbo can be had for just a little bit more than $600. Plus it's a new OEM Garrett turbo, not something that some aftermarket company had a chance to screw up. The GTi-R turbo is manufactured by a QS/ISO-9000 company and it has been qualified to Nissan's OEM standards. Aftermarket 'upgrades' are usually built by Mom and Pop outfits with little or no qualification testing.

I also think that trying to 'upgrade' a T-25 is a bad idea. Most of the aftermarket turbo companies do not understand turbos well enough to perform these 'upgrades'. If you read Mike Kojima's turbo article as part of the SCC 'Suck Squish Bang Blow' series, you will see many of the pitfalls of these aftermarket 'upgrades'.

I know nothing about mjm turbos, but I'm guessing that they probably carved your stock T-25 compressor housing and put in a big-trim T-3 compressor wheel. This leaves the compressor with next to no diffuser diameter, which is horrible for the compressor efficiency, although it will flow more than it used to. Then, they probably took your stock 62 trim T-25 turbine wheel and gave it a 15-20 degree clip and stuck it back in the stock 0.64 A/R turbine housing. Clipping the wheel provides a little more flow at the expense of about a 10% loss in turbine efficiency. So, you end up with a lot more lag, an increased propensity for transitional detonation, and just a little more power on the top end.

If you are lucky, they upgraded you to a 76 or 79 trim turbine, but I wouldn't count on that. Even if they did upgrade the wheel, the stock 0.64 A/R housing won't flow nearly as much as the 0.86 A/R housing the GTi-R turbo has.

Hopefully, they have the cabability of component and assembly balancing the turbo to Garrett's OEM spec, but they probably don't, based on what I see from most aftermarket turbo companies. So, your turbo is probably out of balance. The number 2 cause of turbocharger oil seal leaks that I see is turbocharger imbalance (number 1 is improper oil return line routing). This is why about 25% of the aftermarket 'upgrade' turbos I see smoke like hell on the dyno: put them under boost, get some blow-by going on, get the turbo speed up, and the shaft motion from all the imbalance just opens the seal clearances right up, and 'poof', nice big puff of smoke.

MJM turbos may be a very fine outfit, and they may not do any of the monkey shit that I see from so many aftermarket turbo companies. However, I would not invest my hard-earned $600 on an upgraded turbo from them or anyone else unless I knew exactly what they were doing to the turbo.

My experience has been that there are many self-proclaimed experts on turbochargers in the aftermarket. My experience has also been that few of these experts really know a lot about the fundamentals of how a turbo works. I do not mean this as a flame to anyone, but 'buyer beware' when purchasing a turbo. If you are going to try and be innovative, you better arm yourself with some basic knowledge. Otherwise, you risk throwing your money away on something that doesn't really work.

wow thanks for the info but all he use was the exhaust housing (*** that is all i gave him)your right he put a t3 wheel in and use a a/r.80 housing with a 80 trim wheel and it is all brand new garrett part. i was told to run a t28 it would not bolt to a bb manifold so my well good luck everybody with what ever u get

So he didn't rework your stock T-25 into a T-28, then... he carved your stock T-25 turbine housing out to take a bigger trim turbine wheel, and then he put a whole new turbo in there, right?

That's a pretty good way to do it. I think that you will be very happy with the results if you upgrade to the 0.86 A/R turbine housing, though.

yeah that is what he did i still have all the t25 stuff