ISIS T25/T28 replacement turbo v. S15 T28. Input appreciated!

[TAP240]

As the title states, I'm looking for some input on the ISIS T25/T28 turbo replacement option from enjuku (yes I searched and didn't find the results I was looking for). A buddy of mine works for enjuku so he introduced me to this option today. Long story short my S15 T28 is done for, so I took it off the car today and need a turbo ASAP! My current set up is (well was) and SR20det with an S15 T28 turbo..it's tuned with the AEM tru boost, I can change from stock tune, to a 12lb tune, to a 17lb tune; a/f is right where it needs to be in each tune (10.8-11.0 on a hot day and goes to 11.2-11.5 when it cools down at night). The car made 325whp on the dyno with the T28 on 17lbs. My question is, would I still be able to change between tunes and still have the ability to boost at 17lbs with the ISIS replacement turbo (I'll more than likely get the tubular manifold and I'll have to get the o2 housing as well), or will I have to keep the car at the 12lb tune or stock tune? I would imagine that the spool won't be as quick as the S15 turbo, but I don't mind sacrificing a few hundred rpm for the turbo spool. I'm also curious if my dyno numbers will see a drastic difference.
Any insight would be greatly appreciated!

[Croustibat]

1/stay away from crappy cheap chinese turbos. You get what you pay for, and that is what isis sells.

2/get a real tune. Tuning AFRs ? You should be worried about timing, that is what makes power, but also high EGTs that cook oil and turbos, and holes in pistons ...

3/ find what killed your turbo first (i think it comes from point 2 though)

4/ stay away from crappy chinese manifolds, T28 dont produce enough flow to get anything out of them anyway.

5/ if you dont already have one, put a FMIC to cool the charge. An ebay FMIC kit is ok and will net you a tremendous upgrade in both reliability and power, as long as it does not leak.

You should be making more power than that. I am making the same HP with the same turbo, on a CA18DET...

[TAP240]

Originally Posted by Croustibat

1/stay away from crappy cheap chinese turbos. You get what you pay for, and that is what isis sells.

2/get a real tune. Tuning AFRs ? You should be worried about timing, that is what makes power, but also high EGTs that cook oil and turbos, and holes in pistons ...

3/ find what killed your turbo first (i think it comes from point 2 though)

4/ stay away from crappy chinese manifolds, T28 dont produce enough flow to get anything out of them anyway.

5/ if you dont already have one, put a FMIC to cool the charge. An ebay FMIC kit is ok and will net you a tremendous upgrade in both reliability and power, as long as it does not leak.

You should be making more power than that. I am making the same HP with the same turbo, on a CA18DET...

I'm pretty certain that since there were only oil lines run to the turbo, over the course of time that's what caused the turbo to go bad...no coolant was run to it.
I wasn't seeing the amount of power that I should of out of the car anyway; I discovered a huge exhaust leak yesterday when unbolting the turbo....there was only ONE bolt holding the turbo to the o2 housing
And yes, I have a Greddy FMIC.

[ultimateirving]

i have a ISIS RS3871 and for the price its holding up good, boosts way better then t28 could ever hope to, i spike over 20psi because of my old boost controller and its a peppy turbo

[Johannes]

I'll have to agree with the ISIS RS3871. I have it as well and I'm pretty satisfied with it.
As for the fitment, you'll have to drill bigger holes on the oil drain tube to complement with the wider bolt holes on the RS3871.

Here's a link to the ISIS turbo; (I'm guessing it's okay to post links up when it comes to Enjuku cause Enjuku is a Zilvia Advertiser?)

*ISIS RS3871 Turbo - Nissan SR20DET - Enjuku Racing Parts, LLC

[TAP240]

Sounds to me like you guys have had some good experience with ISIS...but that's with the RS38 turbo....
This is the one I'm looking at: *ISIS T25/T28 Replacement Turbo - Nissan SR20DET - Enjuku Racing Parts, LLC
Any input on this turbo? I had the t28 bb, so I'm not necessarily looking to "upgrade"..I wanna stay as close to my previous set up as possible (granted journal bearing and ball bearing will be different, but my principle is still implied...I think)

[TAP240]

After reading a little on the ISIS RS3871, would I be able to use my stock exhaust manifold, and o2 housing...I guess what I'm asking is will it bolt up directly and take the place of my T28 without doing anything else to it? (other than drilling larger bolt holes in the oil return line)
If I were to get the RS38, would it effect my tune at all, or could I bolt up and not have to worry about my tunes being effected to the point where I'll need a re-tune?

[ultimateirving]

I went directly from t28 to rs3871, it is direct replacement, i do run it without a retune currently but i run rich so i could benefit highly.

[TAP240]

Originally Posted by ultimateirving

I went directly from t28 to rs3871, it is direct replacement, i do run it without a retune currently but i run rich so i could benefit highly.

what does your air fuel read in WOT?

[ultimateirving]

10.5! with e85 and 850cc injectors, i have a mail tune tho. need some local dyno work done

[TAP240]

Originally Posted by ultimateirving

10.5! with e85 and 850cc injectors, i have a mail tune tho. need some local dyno work done

damn..that's not as rich as I though you were gonna say, but that is pretty rich. My tune right now, with my previous bb t28 was at about 10.8-11.0 during the hot parts of the day, and when it cools down at night it'll go to around 11.3-11.5 (which is ideal). Tuned with Nistune and AEM tru boost (stock tune, 12lb tune, and 17lb tune). I've got brian crower cams (not sure if that has a major effect), 550cc injectors, wally 255 fuel pump...if I were to install the RS38..what do you think the results would look like (and yes, I know, "every car is different" lol, but based on your experiences with this turbo).

[OkiDori17]

I don't personally have the Isis t25/t28 but a buddy of mine runs one and he loves it. He hasn't had a problem with it so far (he's had it for about 7 months), and he's the type that abuses the hell out of his car.

My .02 is if it's for a daily/weekend warrior then go for it but if you're a hardcore driver abusing it s whole lot then save up for a good Garrett or be like all the cool kids and get a nice Precision (SC6262 dual BB FTW!!! =] )

[ultimateirving]

tap240, when u upgrade you will be able to put those cams to work and really get more out of your tune. Our t28s are tired at anything about 15psi and CANNOT sustain the boost well if ur running up to 7k. The 3871 will push 22psi no problem and u will no doubt love it

[TAP240]

Originally Posted by OkiDori17

I don't personally have the Isis t25/t28 but a buddy of mine runs one and he loves it. He hasn't had a problem with it so far (he's had it for about 7 months), and he's the type that abuses the hell out of his car.

My .02 is if it's for a daily/weekend warrior then go for it but if you're a hardcore driver abusing it s whole lot then save up for a good Garrett or be like all the cool kids and get a nice Precision (SC6262 dual BB FTW!!! =] )

Originally Posted by ultimateirving

tap240, when u upgrade you will be able to put those cams to work and really get more out of your tune. Our t28s are tired at anything about 15psi and CANNOT sustain the boost well if ur running up to 7k. The 3871 will push 22psi no problem and u will no doubt love it

@OkiDori17 I'm definitely not the type to beat my car...I don't plan on keeping the car for much longer than 2 or 3 months (I want to keep it long enough for Import Alliance in Charlotte in July). I just want something that will put my car: one, back on the road, two, get me as close to my previous t28 set up as possible and three, have the car set up worry free for the next owner. Does your buddy just have the tubular manifold with his turbo, or is he using his stock manifold?

@ultimateirving, I don't have the necessary funds to get the car tuned again. I want to keep set up as close to where it is (was) with the t28 and use a turbo that won't call for another tune...I know, me being me, if I DID go bigger turbo (such as the RS), I would really want to get the car re-tuned just out of spite since I know I could pull more out of it..but for the type of driver I am, the current tune is plenty for me. (Not to sound ignorant or anything, I know that some things will be slightly altered from installing a different turbo, but if I keep the turbo as close as possible to the t28, "in theory", I'll be fine)

Another concern of mine is, should I get the ISIS tubular manifold with the t25/28 replacement set up? I know the ISIS replacement turbo will bolt up directly to my stock exhaust manifold..would it be of any merit to go with the tubular manifold, as opposed to the stock manifold? With me wanting to say as close to my last set up as possible..would keeping my stock manifold be the way to go, or could a ball bearing+stock manifold be some-what equally compared to a journal bearing+tubular manifold? (not sure if that question made sense to you guys...I'm trying to formulate my question as clear as possible lol)

[stilmissmysti]

Originally Posted by ultimateirving

I went directly from t28 to rs3871, it is direct replacement, i do run it without a retune currently but i run rich so i could benefit highly.

Originally Posted by ultimateirving

10.5! with e85 and 850cc injectors, i have a mail tune tho. need some local dyno work done

10.5 is lean on e85

Fuel AFRst FARst Equivalence Ratio Lambda
Gasoline stoichiometric 14.7 0.068 1 1
Gasoline max power rich 12.5 0.08 1.176 0.8503
Gasoline max power lean 13.23 0.0755 1.111 0.900
E10 stoichiometric 14.0 - 14.1 ? ?
E85 stoichiometric 9.765 0.10235 1 1
E85 max power rich 6.975 0.1434 1.40 0.7143
E85 max power lean 8.4687 0.118 1.153 0.8673
E100 stoichiometric 9.0078 0.111 1 1
E100 max power rich 6.429 0.155 1.4 0.714
E100 max power lean 7.8 0.128 1.15 0.870


that means you should IDLE and regular driving should be around 9.8 (idle could go much lower like 13's) and WOT should be in the high 6's and any boost should be in the 8.5 range


E-85 pulls more heat than gas and will run leaner (in lambada standards) but you are far short of maximizing your set up
__________________

[Tearlessj]

If it helps any, I bought USED Isis T25/T28 on here for $100. If it failed, it was only $100 so I don't really care. Threw it on my Track car and beat the shit out of it all day. It still works great. The only thing is that it is really laggy.

[smink]

Ive ran the isis T25/T28 replacement for about a year now on my SR and my KA deffinately a little laggy on the SR. Overall not a bad choice though for the price. I suggest getting a braided oil line kit with it. Make absolutely sure you use the tubo nut locking plates from the stock T25 ive seen isis manifold turbo flange studs back out on two different cars.

[TAP240]

Originally Posted by Tearlessj

If it helps any, I bought USED Isis T25/T28 on here for $100. If it failed, it was only $100 so I don't really care. Threw it on my Track car and beat the shit out of it all day. It still works great. The only thing is that it is really laggy.

Originally Posted by smink

Ive ran the isis T25/T28 replacement for about a year now on my SR and my KA deffinately a little laggy on the SR. Overall not a bad choice though for the price. I suggest getting a braided oil line kit with it. Make absolutely sure you use the tubo nut locking plates from the stock T25 ive seen isis manifold turbo flange studs back out on two different cars.

How laggy...compared to a s15 t28 with a huge exhaust leak, I'm thinking I won't see too much of a difference lol. What rpm were you at when you hit full boost?

[TAP240]

Originally Posted by TAP240

damn..that's not as rich as I though you were gonna say, but that is pretty rich. My tune right now, with my previous bb t28 was at about 10.8-11.0 during the hot parts of the day, and when it cools down at night it'll go to around 11.3-11.5 (which is ideal). Tuned with Nistune and AEM tru boost (stock tune, 12lb tune, and 17lb tune). I've got brian crower cams (not sure if that has a major effect), 550cc injectors, wally 255 fuel pump...if I were to install the RS38..what do you think the results would look like (and yes, I know, "every car is different" lol, but based on your experiences with this turbo).

My mistake, I have 750cc injectors, not 550

[nieko]

What happened to your Turbo? It it is genuine Garret, they have a housing program. You send them your old turbo center cartridge and they send you a new center cartridge. I think it is like $300-350. But then you have your brand new s15 turbo again.

[TAP240]

Originally Posted by nieko

What happened to your Turbo? It it is genuine Garret, they have a housing program. You send them your old turbo center cartridge and they send you a new center cartridge. I think it is like $300-350. But then you have your brand new s15 turbo again.

previous owner only ran oil lines and neglected to run coolant lines to it and on top of that didn't use the correct oil feed line. The turbine fins look like a small rock got sucked in, it doesn't spin freely, and there is burnt, caked oil around the back of the turbo. It started clicking beginning of last week, then started making a scratching-like sound under the slightest load, so I pulled it off the day after that started happening.

[jdo180]

looking forward to seeing more actual review on the t25/t28 replacement.
I have one going on a stock srblock with all the normal bolt on mods and will be track driving the car 2 to 3 times monthly as well as 1 to 2 nights a week in the canons..
running at 12psi
with ISIS Turbo line kit
GT Drain setup
tomei Turbine Outlet
megan manifold and MAX inlet
ill let you know what i think ...
Iv had a t25 and specR t28 before so a little to compare it to..
Should have something to say next month ,,we shall see how long it lasts..

[TAP240]

Originally Posted by jdo180

looking forward to seeing more actual review on the t25/t28 replacement.
I have one going on a stock srblock with all the normal bolt on mods and will be track driving the car 2 to 3 times monthly as well as 1 to 2 nights a week in the canons..
running at 12psi
with ISIS Turbo line kit
GT Drain setup
tomei Turbine Outlet
megan manifold and MAX inlet
ill let you know what i think ...
Iv had a t25 and specR t28 before so a little to compare it to..
Should have something to say next month ,,we shall see how long it lasts..

keep me (us) posted on how it turns out man! I've had the s15 bb t28 on each of my 240's this year, loved them. I was on 26lbs with the first one and 17lbs max on my current set up. I'm hoping I can still pull the ISIS on 17lbs with out a problem (my daily tune will be on 12lbs though)
I'm going to go with the ISIS t25/25 replacement set up, with the ISIS tubular manifold, ISIS oil and coolant lines, and ISIS o2 housing...I'm thinking I won't see too much of a difference from my previous set up (had a shitty turbo and huge vac leak I had no clue about)

[ultimateirving]

Get the upgraded turbo, RS3871 for the price its so worth it. ANd room to improve. Plus u dont have to geta retune, like i said i run it as a daily practically just fine.
ALso it comes with a 1year warranty! cant beat that.
you will need a new intake however, i can show you before and after pics

[TAP240]

Originally Posted by ultimateirving

Get the upgraded turbo, RS3871 for the price its so worth it. ANd room to improve. Plus u dont have to geta retune, like i said i run it as a daily practically just fine.
ALso it comes with a 1year warranty! cant beat that.
you will need a new intake however, i can show you before and after pics

going to a bigger turbo like that (granted it isn't a huge leap) I would feel more comfortable getting the car retuned, I've got the crower stage 2 cams and 750cc injectors, so I know I could pull a lot more out of the car than what I was used to seeing, but I'm not necessarily looking for all that; call me crazy, but I'm content with how the car was before the turbo went out lol..

[Matej]

The ISIS turbo is the same generic one that is being sold on Ebay for 200$ shipped.
The only difference is that Enjuku clocked it for a bottom mounted application.

[KiLLeR2001]

BBService | Turbobygarrett

S15 BB Turbo is a GT2560R.

Turbo PN: 466541-4
CHRA PN: 446179-38

Replace the CHRA and enjoy your S15 turbo again.

[Croustibat]

Originally Posted by stilmissmysti

10.5 is lean on e85

Fuel AFRst FARst Equivalence Ratio Lambda
Gasoline stoichiometric 14.7 0.068 1 1
Gasoline max power rich 12.5 0.08 1.176 0.8503
Gasoline max power lean 13.23 0.0755 1.111 0.900
E10 stoichiometric 14.0 - 14.1 ? ?
E85 stoichiometric 9.765 0.10235 1 1
E85 max power rich 6.975 0.1434 1.40 0.7143
E85 max power lean 8.4687 0.118 1.153 0.8673
E100 stoichiometric 9.0078 0.111 1 1
E100 max power rich 6.429 0.155 1.4 0.714
E100 max power lean 7.8 0.128 1.15 0.870


that means you should IDLE and regular driving should be around 9.8 (idle could go much lower like 13's) and WOT should be in the high 6's and any boost should be in the 8.5 range


E-85 pulls more heat than gas and will run leaner (in lambada standards) but you are far short of maximizing your set up
__________________

If you ever had used E85 and a wideband, you would know gauges displays "measured lambda x 14.7", which means stoich will show 14.7, no matter what fuel it is.

10.5 on a gauge display for e85 is quite rich, i usually get good results with 12:1, bit more with 11:1, but richer does not yield anything.

[stilmissmysti]

Originally Posted by Croustibat

If you ever had used E85 and a wideband, you would know gauges displays "measured lambda x 14.7", which means stoich will show 14.7, no matter what fuel it is.

10.5 on a gauge display for e85 is quite rich, i usually get good results with 12:1, bit more with 11:1, but richer does not yield anything.

Thank you for clearing that up for me I have never ran it in any of my cars, but I'm a chemist by trade so it seemed a bit off to me

[smink]

The lag isnt terrible. Im hitting full boost by 3500ish. The Ka deffinately spools it quicker, granted its a larger displacement. For the most part im satisfied with the turbo for dd purposes.