t25 upgrade to t28
 

So i picked up one of the garret hybrid turbos the T28 (T25 with a t3 compressor and turbine) seems the wheel is about .5" bigger i was just wondering what kind of AFR change you think i will see.. I am running at about 10.8 -10.9 at full boost right now do u think i will run to lean with this turbo. I am scheduled for a retune on the 17th but wanna know if i should risk a ripper with the new turbo. Ill post some pics tommorow if i can find the data cable for my phone.

Re: t25 upgrade to t28
 

Don't risk it. It's only a couple days man. :P

Re: t25 upgrade to t28
 

you can rip it you didnt ge a bigger exhaust turbine did you nor did you raise your boost what fore retune :8

Re: t25 upgrade to t28 WTF???
 

So here is a nother big bag of fukin fail... The Garrett big T28 is a T3 compressor and turbine camparable to the GT28 minus the BB and should be around a 62 trim according to Gpop shop. So if you guys remember i made 176hp with the little T25 at 9psi so i figured i only want another 20 ponies and something like the t28 is bigger so should work and would bolt right up which means i can swap my turbo b4 work. So i install the turbo and first notice im not spooling while ----- footing anymore so there was definatly lag now so i figure i am gonna make a decent amount more power... Got down to Evan's shop get her on the dyno and what do i see full boost at 4800 instead of 3800 and a max power at 9.5psi is ..... 180hp WTF is that ----. I mean it holds power till 7k now but still damn near no power increase doesnt make sence. Jeff didnt see anything wrong with the set up, and Gpop shop said it doesnt make much sence as we all know a 60 trim t3 will usually get these Dseries above 200hp at 10psi and this turbo should have pretty much similar flow characteristics as its a t3 60trim wheel in there. I dont know where to look im just not the happiest guy right now.

Cliffs: bigger turbo, no power gain?

Re: t25 upgrade to t28
 

cuase that turbo is barely any bigger. sounds to me like you should be happy, you gained 5 horse and pulls till redline at the same piddly dick boost level. at 180 horse your probly starting to outflow that t25 hotside. if you wanted 20 horse and it was already on the dyno why didnt you just up the boost a few psi?

you could maybe make 200 hp at 10psi with a straight t3 turbo (bigger than yours) ....you made 180 at 9 psi with a smaller turbo... what doesnt make sense here?

20 hp difference with less boost and a smaller turbo.

Re: t25 upgrade to t28
 

and what motor is this on becuase that spool does seem very late for being a t28, its later than my 57 trim 60/63

Re: t25 upgrade to t28
 

its the Garrett big T28 T3 60 trim wheel it seems alot bigger than the small T25 both compressor and turbine wheel just from looking seems to be close to an inch bigger. It is on the D15b .... i was told the trim size is about 62. i dont know why but it doesnt seem like Evans wants to go above 10lbs even when i suggested getting a bigger map sensor he seems reluctant for some reason.

Re: t25 upgrade to t28
 

then its probly just your hot side holding you back. idk what that turbos from but its not much bigger. and evans probly didnt want your d15b blow up as its already making 180 hp

Re: t25 upgrade to t28
 

http://www.gpopshop.com/mitsdsmturbos.html its not a stock turbo its made by garrett as a high performance turbo... but yeah thats possible but he has done stock block Dseries motors with more power i donno but it still seems like it should have made more power thanx for the reply tho.

Re: t25 upgrade to t28
 

run more boost :6 :y

Re: t25 upgrade to t28
 

when upgrading a t25 into a T28, for any decent power gains, you have to increase the flow of the hot side as well. Otherwise it will over spin and overheat, acting as a exhaust plug as you max it out trying to squeeze out the theoric power gains of that big compressor wheel.

most t25 turbine wheels are too small for any decent power but the largest T28 turbine wheel is similarly sized as a T3 stage1 and when using that wheel with at least .64 a/r, you can take full advantage of any larger compressor such as gt2860R 55 trim which is larger than t3 60 trim and good for up to 310 HP.

The problem with upgrading a T25 with both a larger turbine AND compressor side is the price: new t28 wheels and shafts and the workmanship to put them in can get costly.

Re: t25 upgrade to t28
 

i donno its supposed to be a bigger turbine wheel to, i think from the 60 trim T3 as well but i am getting 1k rpm more lag than b4 so i am pretty sure its a decent size bigger. The guy at Gpop said it should be increadibly similar to the Gt28 minus the little better spool you get with the BB turbo. Are you familiar with the Garrett big T28 it is not modified by the shop it is sent from garrett as a big T28 what kind of power gain would u expect between this turbo and the much smaller T25 Blaast?

Re: t25 upgrade to t28
 

Garrett don'T sell T25 and T28 anymore. they switched to the GT series. Even individual T25/T28 parts are for the most part discontinued at garrett. if you want a non BB turbo, you have to resort using the GT20 and GT22 series.
Ok I just checked and the nice turbine wheel to have on a T28 measures 1.85" X 2.12"
it compares to T3 stage 1 whcih is 1.93" X 2.56"
The wheel used on most recent gt25R and gt28R is 1.8" x 2.12" as well so it'S true that if you have that turbine wheel, you can make similar power than the GT's, even ithout the BB's, provided you use an equivalent sized compressor side, spool up difference due to the ballbearings is really not that bad and mostly not justificative of the twice higher price tag.

Re: t25 upgrade to t28
 

yeah thats why i was surprised with the small gain i saw over the T25 as my compressor and turbine are both much bigger. Its a 60 trim t3 compressor and turbine wheel from what i was told.

Re: t25 upgrade to t28
 

If you want t28-sized turbos, go look at MHI turbos. A big16g has a hotside like a small T3, but can do 350-400whp with the right motor.

The T28 is good for making more torque when it spools, but you're stll limited to the power the turbine can offer. Flow = power, both for intake AND exhaust.

Re: t25 upgrade to t28
 

I wouldn't take a big 16G past ~350 whp across 2WD drivetrain loss, 300 whp AWD. They flow more, but it overspins them and break shafts like no other make of turbo I have ever seen.

Nothing spools like a big 16G, though. Hitchhikkr had one on his 94 LS, ported turbine and O2 housing, the fucker would sling 10 psi at 1000 rpms. It was insane, and the car was HUGELY driveable.

Re: t25 upgrade to t28
 

God I wish I hadnt sold that car. It was the best daily ive ever had.

Re: t25 upgrade to t28
 

Rob, go to my Sweet Vid thread in GD. That is Mister Payne's youtube account, he has a couple videos of your LS. :)