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Discussion Starter #1
Hey guys!

I am new to the community here but I am not new to modding! I currently own several vehicles including a heavily modded 4G63 using an HX35 Holset turbocharger. I guess my questions are pretty simple. I recently purchased a Lotus engine with about 20k on it, performance flywheel and clutch, and a Moroso high cap pan. When I modded my 4G63 I kept the stock T25 Garrett turbo. Is the turbo useable on the high revving 2ZZ?

If the T25 is worth using, what fuel pressure and injectors are you guys running on such a light mod?

I am thinking about going ahead and making use of the T25 I have sitting around! So far I love the potential the 2ZZ has to offer.

Thanks in advance!
 

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Gt28 is smallest turbo commonly used. Not sure how t25 compares. There are good threads on how to turbo 2zz motor I run a ff275 turbo kit and like my setup
 

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No big issues with the T25. Just won't get as much HP as bigger ones.
You can run 550's for the injectors if you want to maximize otherwise the stock 440's will work. Frankly if your going to spend some money then get a 2860 with 750's and now you've got enough room to grow you won't have to do anything more until you build the engine.
 

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Discussion Starter #4
Thanks guys! Yeah its a pretty small turbo but I am also not looking for 350+ on my DD. I already have a heavily modded car that gets to get repaired ALL the time. Hard to make big horsepower reliably. I am just looking for a little extra, maybe something equivalent to the stock supercharger, perhaps a little more. Nothing major. Plus the turbo is already kicking around so why not? Better than dropping the $3000 on a stock Lotus supercharger. Not that they aren´t REALLY cool, just the power to cost isnt there to make it worth while for me.

I also have an assortment of turbocharging goodies laying around including TiAL wastegates and BOV, aluminum piping...you know...the basic car nut stuff lol. So this might work out good. Thanks again guys!
 

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I'd expect the T25 to be good for 260hp or less if you stay away from overspeeding it. You could get away with 8psi boost (if you are at sea level) if you bleed it off after 6500rpm. I'd go for it. You should be able to get pretty good throttle response, and the stock motor won't have a problem with that output.
 

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Discussion Starter #6
Thanks man! Might as well get started putting these parts to use! Haha. I found a decent manifold that should be a good combo of reliable and crask-resistant. Its a resin-based cast mani. Wont win any shows but it will hold up! Thanks one thing I learned developing my 4G63...sometimes reliability isnt so pretty! Haha. Anyway I am really appreciative of all the help! Where would you guys tap into the oil supply of the engine to supply the T25 turbo?
 

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Discussion Starter #7
I'd expect the T25 to be good for 260hp or less if you stay away from overspeeding it. You could get away with 8psi boost (if you are at sea level) if you bleed it off after 6500rpm. I'd go for it. You should be able to get pretty good throttle response, and the stock motor won't have a problem with that output.
How would you bleed it off for reliability? I am assuming an MBC but sometimes those arent so reliable. Would you use a solenoid?
 

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How would you bleed it off for reliability? I am assuming an MBC but sometimes those arent so reliable. Would you use a solenoid?
I work exclusively with standalone ECUs and solenoid boost control, so I don't know much about the manual controls. Just looking at the comp map (60 trim), it doesn't go past 25lbm/min. At a PR of 1.5, you would hit that flow at about 7000rpm. I don't know how the turbo would respond to higher rpms at that PR. It may be fine. Otherwise, a PR of less than 1.4 will keep you safe up to redline. At least that is what it looks like to me from the compressor map. I've just got an Excel sheet I use for baselines, so there are enough assumptions in there that the real-world results will vary (I used Elise data to build my baseline, so it should be close with the stock cam and a good intercooler). I'd start off with a PR of 1.5 and see what the intercooler temps do at higher rpm.
 

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Discussion Starter #9
I work exclusively with standalone ECUs and solenoid boost control, so I don't know much about the manual controls. Just looking at the comp map (60 trim), it doesn't go past 25lbm/min. At a PR of 1.5, you would hit that flow at about 7000rpm. I don't know how the turbo would respond to higher rpms at that PR. It may be fine. Otherwise, a PR of less than 1.4 will keep you safe up to redline. At least that is what it looks like to me from the compressor map. I've just got an Excel sheet I use for baselines, so there are enough assumptions in there that the real-world results will vary (I used Elise data to build my baseline, so it should be close with the stock cam and a good intercooler). I'd start off with a PR of 1.5 and see what the intercooler temps do at higher rpm.
Ok, thank you. I dont expect to use an MBC simply because it lacks reliability at times. There is a reason modern turbo systems are solenoid controlled. This should give me a strong base to start with, although, I doubt I will have to go with a standalone in this instance because the stock ECU should be able to work with this? Just a guess. Thanks a lot for your help.
 

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Just remember that because of how small that turbo is, it will present itself as a large restriction to the engine. What this means is that the "PSI" levels will be higher for a given amount of power then a larger turbo. It also means you'll start pushing the limits sooner.

Turbos have come a long way since the T25 was a popular choice 15-20 years ago. Turbo's today with a larger turbine (hot side) can spool just as quickly and be more controllable due to the larger turbine housing. But if you already got it, then I guess you have to consider that. I think expecting 260HP at the wheels out of a T25 is too generous. I'd probably put it closer to 220.
 

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Just remember that because of how small that turbo is, it will present itself as a large restriction to the engine. What this means is that the "PSI" levels will be higher for a given amount of power then a larger turbo. It also means you'll start pushing the limits sooner.



Turbos have come a long way since the T25 was a popular choice 15-20 years ago. Turbo's today with a larger turbine (hot side) can spool just as quickly and be more controllable due to the larger turbine housing. But if you already got it, then I guess you have to consider that. I think expecting 260HP at the wheels out of a T25 is too generous. I'd probably put it closer to 220.

I was thinking 260 crank, so we are on the same page, give or take.


Sent from AutoGuide.com Free App
 

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run it at wastegate pressure and it will hold 8 psi at redline (get an upgraded actuator or it will blow open at high rpms)

you're gonna see about 230-250 whp out of it there

it will spool in the 2000s rpm, 2400ish

400cc injectors are all you'll need

you could use a sidemount intercooler with this turbo since the flow is lower

manual boost control works, but you won't need it since the turbo can't flow up top anyway. Will work just fine if you're going for 15ish psi in the 3-4k range, but then you run the risk of rod damage from torque (300ish ftlbs that soon can cause problems in higher grars) and it will fall off hard above cam switchover
 

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Discussion Starter #13
run it at wastegate pressure and it will hold 8 psi at redline (get an upgraded actuator or it will blow open at high rpms)

you're gonna see about 230-250 whp out of it there

it will spool in the 2000s rpm, 2400ish

400cc injectors are all you'll need

you could use a sidemount intercooler with this turbo since the flow is lower

manual boost control works, but you won't need it since the turbo can't flow up top anyway. Will work just fine if you're going for 15ish psi in the 3-4k range, but then you run the risk of rod damage from torque (300ish ftlbs that soon can cause problems in higher grars) and it will fall off hard above cam switchover
I was thinking about just transplanting the stock setup side mount included right into it. WHat about computer? s imple reflash to the supercharger map will do or what? I know all about how much better modern stuff is. LOL. Trust me, I would love to throw a 16g on it or something from Precision. But I am trying really hard to make this not another project lol. And you are making it harder! lol. All joking aside all great thoughts on this. Much appreciated.
 

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You'll want something tuneable, since you can change boost pressures, and you'd want room for growth later. (also probably want 550cc injectors instead of 400s to be safe)

Radium's AEM setup, the Adaptronic from SSC, the Fastworks Flash, all would work. Depends on if this is just a street car, or you have to conform to certain rules for racing classes.

Dont forget if you do go this route, you'll need better brake pads and you're gonna want a clutch cause it will be a matter of when not if.
 

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This is a big project. hardest part is tuning. i recommend you add air intact temp
sensor. fastworks has a good tuning setup
Ed
 

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Discussion Starter #17
I should clarify: its a project, certainly. But compared to projects I have been involved in the past with, this is very tame. A big project to me is like my 500+whp Talon that I built from the ground up. I refurbished or replaced everything from the front end to the engine internals. It was a great learning tool let me tell you! To me this transplant is par for the course. Of course my familiarity with the 2ZZ is pretty much nilch so I am trying to get informed but overall I think this should be a manageable project in a short time span. Fortunately, I just bought a Foda clutch and lightweight flywheel so my drivetrain should be ready to handle throwing this at it. I will probably upgrade the valvetrain in the process because from what I have read the 2zz has a weak top-side. I just want something fairly tame and reliable. The turbo is, again, just a thought because I have all the stuff to do it and if I play my cards right I can probably do all the addons and get a drivable tune on it in a couple days once I get all the parts I dont have in order. Anyway, again I thank you guys for the feedback and comments.
 

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Discussion Starter #18
P.S. I like the idea of bumping up to the 550s - not necessarily for growth more so I can get the most out of the turbo + reliability. THat seems like the right move.
 

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I should clarify: its a project, certainly. [...] I just want something fairly tame and reliable. The turbo is, again, just a thought because I have all the stuff to do it and if I play my cards right I can probably do all the addons and get a drivable tune on it in a couple days once I get all the parts I dont have in order. Anyway, again I thank you guys for the feedback and comments.
I love seeing more turbo builds on this car and I think your "budget" approach will be really cool.

I've been considering a turbo build myself (or a K-swap, or... who knows!) and it seems like the truly annoying part with these cars is tuning. Sadly, there's no way tune this car like a DSM where $400-600 of tuning gear and a random local tuner (or quick DIY) will cut it.

I started to realize it'll cost $2k to $3k to end up with a tuned car - options I know of include:

Radium AEM hybrid ECU (keeps factory ECU to run dash / HVAC)
Hydra Nemesis hybrid ECU (keeps factory ECU to run dash/HVAC)
EliseParts/GEMS standalone
MWR PIP standalone
EFI X2 standalone (if you can find one)
Unlocked FastWorks package for your stock ECU
Pay Phil to tune with FastWorks (instead of buying unlocked)
I think Jermaine at VF still tunes cars using the factory ECU as well, but I don't think they offer a "tune it yourself" package.

Plus several hours with a specialist tuner or teach yourself (lift + VVT = a lot more variables than the fixed-cam 4G63). It doesn't help that besides the AEM, none of the ECUs offer software that an American tuner is likely to have seen before.

Anyway, I'd love to hear what you end up using to tune... the more DIY turbo builds, the better! :clap:
 

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I too once lived in the land of DSMs.

To build a turbo motor into a big turbo motor is admittedly more complex, but building an N/A car to a turbo car isn't a small feat. You should really approach this as a big turbo motor project, just scale down all the bits that make it all work.

My opinion... the T25 is junk, and if I were to do this build I'd do it right the first time. I think if you were to do that, you'll spend a lot of time and money on it and the giggle factor may not be enough for the effort.
 
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