Modern turbo to replace stock?
Joined: Aug 2002
Posts: 2,614
Likes: 31
From: Freeland, MI
I don't know alot about turbos, but i would think if you match up the a/r ratio and the flange, you'd be fine
But the bigger question is, why go through the hassle? You honestly wouldn't benefit much from it, the basic turbo design hasn't changed in 30 years
But the bigger question is, why go through the hassle? You honestly wouldn't benefit much from it, the basic turbo design hasn't changed in 30 years
I guess the point would be reliability and efficiency. Stock turbos in good condition are getting a bit harder to come by.
Flanges matching wouldn't be a problem. Worst case scenario would be a new exhaust manifold, downpipe and charge pipe. But those would all be relatively easy to make.
Flanges matching wouldn't be a problem. Worst case scenario would be a new exhaust manifold, downpipe and charge pipe. But those would all be relatively easy to make.
You will need a lot of supporting mods including a new ecu to use a different turbo, especially an EFR...
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I was having a hard time finding a good stock turbo to begin with. I know I can go hybrid and whatnot, but what I was looking for is a modern turbo that I can run on the stock ecu.
Rotary Enthusiast
Joined: Mar 2002
Posts: 818
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From: Phoenix
The Hitachi HT-18 that comes on FC's IS a "modern turbo" in it's design.
The factory turbo is the most reliable unit you can use, it also works best with a stock ECU, it's VERY efficient for the application and it can easily be rebuilt to factory spec.
The only real technological upgrade is a ball bearing turbo, and if you want to keep the stock ECU, I doubt you'll be willing to spend what it takes to get a name brand ball bearing unit.
I think what you're really trying to ask is "what bargain basement turbo can I slap on my car without having to give up anything". The answer is "none".
Only a stock turbo matches the ignition and fuel curves of a stock ECU. The Hitachi HT-18 that comes on FC's IS a "modern turbo" in it's design. The factory turbo is the most reliable unit you can use, it also works best with a stock ECU, it's VERY efficient for the application and it can easily be rebuilt to factory spec. The only real technological upgrade is a ball bearing turbo, and if you want to keep the stock ECU, I doubt you'll be willing to spend what it takes to get a name brand ball bearing unit. I think what you're really trying to ask is "what bargain basement turbo can I slap on my car without having to give up anything". The answer is "none".
This is actually the farthest from the truth.
I have a 91 vert that I built a turbo motor to put in for my wedding. I've spent a ton of hours and a good chunk of change to make this car nice. I'm also trying to keep it as stock as I can, with 'upgrades' only for function (corksport downpipe since the stock downpipe won't fit with the extra vert front subframe) or for reliability.
I had armyofone rebuild an s5 turbo for me, he did a bit of porting to the waste gate so they were even and he also clearanced part of it so the waste gate would open more. Also used a 360 thrust bearing. Considering he did all this and that the twin turbos off the newer fd's are usually replaced with 'more modern single turbos' I figured that the stock ht18 was older technology. That I could find a turbo that isn't almost 30 years old that would be easier to find, and more reliable.
Now, my coupe that I have, will have a bnr stage 4 (sitting in the garage right now) and an adaptronic ecu. But in trying to avoid a standalone or piggyback ecu in the vert.
Oh, I also have a Garrett GTRS eliminator on my daily driver. Which is ball bearing.
Let us entertain the idea.
The TII has Air Flow Meter so you can actually change the VE of the engine with peripherals like turbo and the ECU will adjust.
What you can't do is put a big enough turbo compressor on that you will reach the limit of the stock injector's flow even in the low boost allowed before overboost fuel cut.
The stock S5 manifold/turbo is a really good design being fully divided with dual wastegates and it actually has a really big exhaust wheel per compressor diameter (64mm exhaust wheel and only 63mm compressor wheel).
You could spend a couple thousand dollars and get an EFR 7064 supercore (turbo minus exhaust side/wastegate actuator) and have the S5 turbo housing machined to accept the center section or machine a shim for the center section if the turbo housing is larger.
If you could keep that big 70mm compressor from boost creeping it might work out at 5-6psi boost.
or you might max your AFM and injectors and run lean on the top end,
but most likely it will boost creep and you will hit overboost fuel cut first.
Unfortunately, you can't put a smaller turbo in the stock exhaust housing since the stock exhaust wheel is 64mm.
EFR line has large exhaust wheel sizes per compressor compared to the next best "modern turbo" the Garret GT line.
The problem would be even worse with a GT turbo. A GT30R has a 60mm exhaust wheel so its too small so you have to go up to the GT3576r which has a 68mm exhaust wheel and that big 76mm compressor that will cause problems.
If you go to a T3 undivided or T4 divided manifold/exhaust housing you are going to have crap spool compared to the stock S5 (roughly T25 divided size) manifold/exhaust housing and ofc no more power anyways since you are trying to stay under the limits of your injectors & boost cut with a small compressor.
So basically, no. Trying to upgrade the turbo on stock ECU is crap like everyone else is saying.
I think it would make more sense to get at least an Rtek7 ECU and make the most of the stock S5 turbo by putting the smallest compressor upgrade on it, dynamic seal and better thrust bearings.
Or upgrade the ECU, injectors and turbo (and clutch, and intercooler, and fuel pump, and...) Yeah, it gets expensive.
The TII has Air Flow Meter so you can actually change the VE of the engine with peripherals like turbo and the ECU will adjust.
What you can't do is put a big enough turbo compressor on that you will reach the limit of the stock injector's flow even in the low boost allowed before overboost fuel cut.
The stock S5 manifold/turbo is a really good design being fully divided with dual wastegates and it actually has a really big exhaust wheel per compressor diameter (64mm exhaust wheel and only 63mm compressor wheel).
You could spend a couple thousand dollars and get an EFR 7064 supercore (turbo minus exhaust side/wastegate actuator) and have the S5 turbo housing machined to accept the center section or machine a shim for the center section if the turbo housing is larger.
If you could keep that big 70mm compressor from boost creeping it might work out at 5-6psi boost.
or you might max your AFM and injectors and run lean on the top end,
but most likely it will boost creep and you will hit overboost fuel cut first.
Unfortunately, you can't put a smaller turbo in the stock exhaust housing since the stock exhaust wheel is 64mm.
EFR line has large exhaust wheel sizes per compressor compared to the next best "modern turbo" the Garret GT line.
The problem would be even worse with a GT turbo. A GT30R has a 60mm exhaust wheel so its too small so you have to go up to the GT3576r which has a 68mm exhaust wheel and that big 76mm compressor that will cause problems.
If you go to a T3 undivided or T4 divided manifold/exhaust housing you are going to have crap spool compared to the stock S5 (roughly T25 divided size) manifold/exhaust housing and ofc no more power anyways since you are trying to stay under the limits of your injectors & boost cut with a small compressor.
So basically, no. Trying to upgrade the turbo on stock ECU is crap like everyone else is saying.
I think it would make more sense to get at least an Rtek7 ECU and make the most of the stock S5 turbo by putting the smallest compressor upgrade on it, dynamic seal and better thrust bearings.
Or upgrade the ECU, injectors and turbo (and clutch, and intercooler, and fuel pump, and...) Yeah, it gets expensive.
Let us entertain the idea. The TII has Air Flow Meter so you can actually change the VE of the engine with peripherals like turbo and the ECU will adjust. What you can't do is put a big enough turbo compressor on that you will reach the limit of the stock injector's flow even in the low boost allowed before overboost fuel cut. The stock S5 manifold/turbo is a really good design being fully divided with dual wastegates and it actually has a really big exhaust wheel per compressor diameter (64mm exhaust wheel and only 63mm compressor wheel). You could spend a couple thousand dollars and get an EFR 7064 supercore (turbo minus exhaust side/wastegate actuator) and have the S5 turbo housing machined to accept the center section or machine a shim for the center section if the turbo housing is larger. If you could keep that big 70mm compressor from boost creeping it might work out at 5-6psi boost. or you might max your AFM and injectors and run lean on the top end, but most likely it will boost creep and you will hit overboost fuel cut first. Unfortunately, you can't put a smaller turbo in the stock exhaust housing since the stock exhaust wheel is 64mm. EFR line has large exhaust wheel sizes per compressor compared to the next best "modern turbo" the Garret GT line. The problem would be even worse with a GT turbo. A GT30R has a 60mm exhaust wheel so its too small so you have to go up to the GT3576r which has a 68mm exhaust wheel and that big 76mm compressor that will cause problems. If you go to a T3 undivided or T4 divided manifold/exhaust housing you are going to have crap spool compared to the stock S5 (roughly T25 divided size) manifold/exhaust housing and ofc no more power anyways since you are trying to stay under the limits of your injectors & boost cut with a small compressor. So basically, no. Trying to upgrade the turbo on stock ECU is crap like everyone else is saying. I think it would make more sense to get at least an Rtek7 ECU and make the most of the stock S5 turbo by putting the smallest compressor upgrade on it, dynamic seal and better thrust bearings. Or upgrade the ECU, injectors and turbo (and clutch, and intercooler, and fuel pump, and...) Yeah, it gets expensive.
Ok this is a much better explanation. Thank you. I don't want to get an upgraded ecu because I want it to remain as stock as possible. My other 7 will be the one that is modded to death.
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