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Old 04-16-2021, 12:31 PM   #1
Chi_San
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Default Blouch TD05 16G DBB turbo

This is for an EJ255 Baja. Keep in mind, I've got a TD04 right now.

So, I want an upgrade. I am considering a rebuild, mostly because I've got 170,000 miles on an engine that was apart at 85,000 miles (previous owner), and I'm not 100% confident in the work that was done back then (lots of stuff was either missing, broken, or even sabotaged).

What I want is a smooth power band, with basically flat torque from as low RPM as possible to at least the same point as the TD04 gives up, but without being... Well, the TD04 is really undersized for a 2.5. I could set this thing to make 20 PSI of boost at 2,400 RPM, and it makes over 15 PSI under 2,000 if set to do so (it's currently not, but I still find myself running the engine at 1,700 RPM since it actually makes usable torque there).

So, would a ball bearing TD05 16G give me that stupid torque at 2,500 RPM, or is it going to take longer to spool on a 2.5? Or should I consider a slightly larger setup, like an 18G ball bearing turbo?

In the end, I plan on swapping the gearbox out for a 6MT, since the stock 5MT has already been blown up (previous owner), and yet again, I'm not confident in the shop that repaired it.

Oh, and about the sabotage... I was hitting overboost CONSTANTLY in this thing. After nearly selling the damn thing a bajillion times, I pulled the hoses off the BCS, turbo, and wastegate. The hose with The Pill in it had a hole in it, and it appeared to be deliberate (it was actually possible to see that something was jammed through the hose from one side to the other, as opposed to someone reefing on it with pliers accidentally poking a hole in it). The overboost issues stopped after I replaced the hose, thankfully with one that has a pill in it.
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Old 04-16-2021, 12:38 PM   #2
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There are so many schools of thought when choosing a turbo and you'll get 20 different answers for 20 different people so in my opinion its best to get a few suggestions from whoever is going to be dialing in the tune for your car because they will usually have lots of experience helping folks pick specific turbos.

With all that said, the 16G is a bit small for the 2.5 in my opinion and can actually be a little more harsh on the motor with all that low end torque. I would personally size up when running a 2.5L.

The 18G XTR you are looking at is a very good turbo and is used by lots of folks to make solid power with ball bearing response.

If you are going for a 6mt anyway and plan to build the car to handle the increase in power, I say why not get the 18G XTR. Its only like $1500 anyway which is a pretty good deal for what it is imo

If you want ball bearing for $1000 you can't beat a VF34 from clover turbo. It will spool and perform well but still choke out at high rpm.

Oh and if you're getting tuned for an 18g, throw a 3 port EBCS into the setup and your tuner will appreciate it.

Last edited by K3rm1tth3fr0g; 04-16-2021 at 07:37 PM.
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Old 04-16-2021, 10:26 PM   #3
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There are so many schools of thought when choosing a turbo and you'll get 20 different answers for 20 different people so in my opinion its best to get a few suggestions from whoever is going to be dialing in the tune for your car because they will usually have lots of experience helping folks pick specific turbos.

With all that said, the 16G is a bit small for the 2.5 in my opinion and can actually be a little more harsh on the motor with all that low end torque. I would personally size up when running a 2.5L.

The 18G XTR you are looking at is a very good turbo and is used by lots of folks to make solid power with ball bearing response.

If you are going for a 6mt anyway and plan to build the car to handle the increase in power, I say why not get the 18G XTR. Its only like $1500 anyway which is a pretty good deal for what it is imo

If you want ball bearing for $1000 you can't beat a VF34 from clover turbo. It will spool and perform well but still choke out at high rpm.

Oh and if you're getting tuned for an 18g, throw a 3 port EBCS into the setup and your tuner will appreciate it.
Well, I'm used to the TD04. I'm just worried if I get something larger like the 18G XTR that I won't have enough low end, even with a ball bearing setup. I do a mix of on road and offroad driving, and while I don't rally the piss out of my Baja, there are long, steep roads I do drive on, and having a turbo that makes usable torque under 3,000 RPM is pretty amazing.

As for tuning, I'm getting close to doing the 2004 STi ECU swap. I just gotta find a non-bricked, non-junk ECU, and a new neutral position safety switch.
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Old 04-16-2021, 10:48 PM   #4
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Well, I'm used to the TD04. I'm just worried if I get something larger like the 18G XTR that I won't have enough low end, even with a ball bearing setup. I do a mix of on road and offroad driving, and while I don't rally the piss out of my Baja, there are long, steep roads I do drive on, and having a turbo that makes usable torque under 3,000 RPM is pretty amazing.

As for tuning, I'm getting close to doing the 2004 STi ECU swap. I just gotta find a non-bricked, non-junk ECU, and a new neutral position safety switch.
Just downshift lol.

But seriously If I were you I'd get either a 16gxtr or 18gxtr. You should have usable Torque by 3k.

And if you want to spend a bit less and don't care about top end as much, the VF34 with the ball bearing cartridge will spool similarly 16G XTR and cost less than a BB 16G with similar midrange.

And as for an ECU swap, if you were going that route anyway, my tuner quoted me a 20-40WHP increase JUST from switching to a link ECU FWIW. I know they're over $1k new but they add performance in addition to awesome monitoring.
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Old 04-17-2021, 03:07 AM   #5
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Just downshift lol.

But seriously If I were you I'd get either a 16gxtr or 18gxtr. You should have usable Torque by 3k.

And if you want to spend a bit less and don't care about top end as much, the VF34 with the ball bearing cartridge will spool similarly 16G XTR and cost less than a BB 16G with similar midrange.

And as for an ECU swap, if you were going that route anyway, my tuner quoted me a 20-40WHP increase JUST from switching to a link ECU FWIW. I know they're over $1k new but they add performance in addition to awesome monitoring.
Kinda hard to justify sitting at 3,500 RPM for extended periods of time in first gear. o.x That happened more than a few times in my WRX, since second gear was often times just too tall for the hills/roads I was on. The Baja, on the same hills, is absolutely fine in second gear, even with the same turbo, though... That's a 2.0 vs a 2.5, but it's also a 3,200 lbs car vs a 3,950 lbs truck.

Not set on an ECU yet. The 04 STi ECU is a direct swap, and I can at least go with an AccessPort. The only tuner within 6 hours only deals with AccessPort, and I'm not comfortable with tuning for 1,050cc injectors.

I think I'll go for an 18G XTR. If it doesn't spool low enough, I'll just slap a supercharger on it instead.
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Old 04-17-2021, 07:28 AM   #6
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Kinda hard to justify sitting at 3,500 RPM for extended periods of time in first gear. o.x That happened more than a few times in my WRX, since second gear was often times just too tall for the hills/roads I was on. The Baja, on the same hills, is absolutely fine in second gear, even with the same turbo, though... That's a 2.0 vs a 2.5, but it's also a 3,200 lbs car vs a 3,950 lbs truck.

No that's a 4.44 final drive compared to a 3.9 final drive. The 4.44fd in you Baja acts like shorter gears which Subaru did because of the Baja and Forester having larger overall diameter tires than the WRX.

For your situation I wouldn't recommend the Blouch BB turbos. They don't spool as quick as their JB counterparts. The 16g XTR would be the exception because it's small enough on the 2.5 that it will spool quite quickly. The 16, 18, and 20g XTR turbos aren't true 16, 18, and 20g turbos. It's just that they are close to that size so Blouch named them that way intentionally. The 18g XTR actually spools the same or slightly slower than the 20g XTR. What you do get with the XTR variants is faster transient response. Best bang for the buck for stock location turbo for what you're trying to do; 18g, VF34, 16g XTR in that order. 18g and 16g XTR will spool about the same but the 18g will have more overall power and a broader power band. The VF34 will spool quickest but will run out of steam the quickest as well. To get real pin pointed advice call Blouch. Then call your tuner. Discuss with both of them what your goals and intended uses are and listen to them. They are the ones building and tuning. They will have the best advice.

And unless there is something wrong with your OEM ECU then there's no need to swap in an STi ECU. Both function the same as they both have intake AVCS and DBW. The STi ECU just has the additional capability for the DCCD, but it's easier and more cost efficient to add a DCCDpro controller which also functions better than the OEM DCCD tuning.
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Old 04-17-2021, 09:40 AM   #7
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No that's a 4.44 final drive compared to a 3.9 final drive. The 4.44fd in you Baja acts like shorter gears which Subaru did because of the Baja and Forester having larger overall diameter tires than the WRX.

For your situation I wouldn't recommend the Blouch BB turbos. They don't spool as quick as their JB counterparts. The 16g XTR would be the exception because it's small enough on the 2.5 that it will spool quite quickly. The 16, 18, and 20g XTR turbos aren't true 16, 18, and 20g turbos. It's just that they are close to that size so Blouch named them that way intentionally. The 18g XTR actually spools the same or slightly slower than the 20g XTR. What you do get with the XTR variants is faster transient response. Best bang for the buck for stock location turbo for what you're trying to do; 18g, VF34, 16g XTR in that order. 18g and 16g XTR will spool about the same but the 18g will have more overall power and a broader power band. The VF34 will spool quickest but will run out of steam the quickest as well. To get real pin pointed advice call Blouch. Then call your tuner. Discuss with both of them what your goals and intended uses are and listen to them. They are the ones building and tuning. They will have the best advice.

And unless there is something wrong with your OEM ECU then there's no need to swap in an STi ECU. Both function the same as they both have intake AVCS and DBW. The STi ECU just has the additional capability for the DCCD, but it's easier and more cost efficient to add a DCCDpro controller which also functions better than the OEM DCCD tuning.
Yeah the 18g xtr is just a custom garret cartridge slapped inside a blouch housing and while it's not technically a 18g, its close enough. But from everything I've seen the 18g xtr will spool as fast or faster than the typical 18g with, as you said, better transient response as well.

But I Agree with Snow_bound that blouch and your tuner will have the best insight on your specific goals.

Last edited by K3rm1tth3fr0g; 04-17-2021 at 10:28 AM.
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Old 04-17-2021, 11:00 AM   #8
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Just downshift lol.

But seriously If I were you I'd get either a 16gxtr or 18gxtr. You should have usable Torque by 3k.

And if you want to spend a bit less and don't care about top end as much, the VF34 with the ball bearing cartridge will spool similarly 16G XTR and cost less than a BB 16G with similar midrange.

And as for an ECU swap, if you were going that route anyway, my tuner quoted me a 20-40WHP increase JUST from switching to a link ECU FWIW. I know they're over $1k new but they add performance in addition to awesome monitoring.
Agreed with all said here, if all you're gonna do is a 16g, send me a message and I'll set you up with a billet wheel vf48. That will be like a third the price for pretty much the same result.

I feel like I used to have that notion of prioritizing spool and response. But yeah, you just drive a little differently for your power band. I think you probably have to go bigger than a 30r to really start to be like ok, now the power band is a little specific. Planning out when you can do pulls etc.

Bang for buck hard to beat an FP blue. Access port and a pro tune from Torqued performance...I wouldn't try to reinvent the wheel here with getting cheeky on an STi ecu swap. There's been a tried and true formula for what you're doing since the 2000s.
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Old 04-17-2021, 01:20 PM   #9
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Yeah the 18g xtr is just a custom garret cartridge slapped inside a blouch housing and while it's not technically a 18g, its close enough. But from everything I've seen the 18g xtr will spool as fast or faster than the typical 18g with, as you said, better transient response as well.

But I Agree with Snow_bound that blouch and your tuner will have the best insight on your specific goals.


18g XTR is slower spool than it should be. Even slower than the 20g XTR for some reason. This has been well documented on here and was confirmed when I spoke with Blouch last fall before buying a 20g XTR. I know a few people who have tried them and were not impressed by its lack of initial response.
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Old 04-17-2021, 01:36 PM   #10
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18g XTR is slower spool than it should be. Even slower than the 20g XTR for some reason. This has been well documented on here and was confirmed when I spoke with Blouch last fall before buying a 20g XTR. I know a few people who have tried them and were not impressed by its lack of initial response.
Super weird that a smaller turbine spools slower than the 20g xtr.

I saw an 18g xtr on an EJ207 that spooled really nice with AVCS on here I'll try and find it.
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Old 04-17-2021, 02:44 PM   #11
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Super weird that a smaller turbine spools slower than the 20g xtr.

I saw an 18g xtr on an EJ207 that spooled really nice with AVCS on here I'll try and find it.


If you find it, PM it to me. From what I've read and discussed with Blouch, it has to do with the size of the size of the turbine and compressor wheel. They are actually the same size as the 20g XTR but the 20g housing moves exhaust gases more efficiently.
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Old 04-18-2021, 11:00 AM   #12
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Agreed with all said here, if all you're gonna do is a 16g, send me a message and I'll set you up with a billet wheel vf48. That will be like a third the price for pretty much the same result.

I feel like I used to have that notion of prioritizing spool and response. But yeah, you just drive a little differently for your power band. I think you probably have to go bigger than a 30r to really start to be like ok, now the power band is a little specific. Planning out when you can do pulls etc.

Bang for buck hard to beat an FP blue. Access port and a pro tune from Torqued performance...I wouldn't try to reinvent the wheel here with getting cheeky on an STi ecu swap. There's been a tried and true formula for what you're doing since the 2000s.
Fp blue while a great bang for the buck is pretty big for his application imo, if he was going to spend over $1200 I'd just spend the extra couple hundred and get ball bearing with the 1.5XTR. Yeah it's 49lbs/min vs 57lbs/min but that would be better for his application anyway imo. But a 1.5XTR is still probably bigger than what he wants.

And @snow_bound im still scouring the web for that 18gxtr 207 avcs thread I saw with the decent spool. It may have been on club wrx now that I'm remembering. I'll keep lookin.

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Old 04-18-2021, 02:37 PM   #13
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Something that nobody seems to have picked up on so far: The Baja ECU is NOT compatible with the AccessPort. Using an AccessPort with a Baja requires an ECU swap, or a really risky overwrite.

I would rather buy an AP and a 2004 STi ECU, and have a backup ECU available, than brick my ECU and have to buy an STi ECU anyway.
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Old 04-18-2021, 04:02 PM   #14
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Something that nobody seems to have picked up on so far: The Baja ECU is NOT compatible with the AccessPort. Using an AccessPort with a Baja requires an ECU swap, or a really risky overwrite.

I would rather buy an AP and a 2004 STi ECU, and have a backup ECU available, than brick my ECU and have to buy an STi ECU anyway.


First thought isn't to go through Cobb's products and look for your specific car. However, Cobb does support the Forester XT from those years so you should check with iWire and/or your tuner about compatibility. The Baja and the Forester were very similar. Forester XT ECU would be cheaper (no STi tax) and a good chance it's plug and play with the Baja XT. If it isn't, iWire will definitely be able to let you know what's needed to make it work.
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Old 04-18-2021, 11:19 PM   #15
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First thought isn't to go through Cobb's products and look for your specific car. However, Cobb does support the Forester XT from those years so you should check with iWire and/or your tuner about compatibility. The Baja and the Forester were very similar. Forester XT ECU would be cheaper (no STi tax) and a good chance it's plug and play with the Baja XT. If it isn't, iWire will definitely be able to let you know what's needed to make it work.
The STi and FXT ECU's are both direct drop in replacements for the Baja. However, a FXT Auto ECU won't work, since I don't have an automatic.

Either way, I'd rather go with an STi ECU.

As far as turbo goes, I think I'm leaning more towards the VF34. Second choice is a 16G XTR. Third choice is VF43?

If I came across a VF38 kit, including manifold, UP's, and a functional catted 3" downpipe, I'd probably jump on that. I wonder how a VF38 does on a 2.5 liter? Oof. What would it do with a 2.7 stroker build? That would be quit interesting.
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Old 04-19-2021, 10:11 AM   #16
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Fp blue while a great bang for the buck is pretty big for his application imo, if he was going to spend over $1200 I'd just spend the extra couple hundred and get ball bearing with the 1.5XTR. Yeah it's 49lbs/min vs 57lbs/min but that would be better for his application anyway imo. But a 1.5XTR is still probably bigger than what he wants.
Yeah, I agree but I've never met anyone that was bummed about making more power than they originally "wanted" 99% of the time when you think "this will be enough"...it's not enough and you shoulda gone bigger.

One thing to consider is I believe the 04 STi will support flex fuel via Cobb. I don't think the 04 fxt supports it, only 05+.
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Old 04-19-2021, 10:17 AM   #17
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Yeah, I agree but I've never met anyone that was bummed about making more power than they originally "wanted" 99% of the time when you think "this will be enough"...it's not enough and you shoulda gone bigger.

One thing to consider is I believe the 04 STi will support flex fuel via Cobb. I don't think the 04 fxt supports it, only 05+.
I've met people bummed out about lag.

And I would agree with this generally unless you have a specific goal of wanting low RPM response like it appears OP does.

The FP blue is bigger and uses slower spooling technology than a 1.5XTR, that was my main point. A 1.5XTR can do 400/400 on E85 with a good tune, and OP is using a TD04 right now, it is plenty big and going to a 1.5XTR would be a HUGE difference.

But it appears instead that OP is looking at a VF34 and 16G variants which is valid and makes sense for his use case imo.

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Old 04-24-2021, 03:48 PM   #18
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Actually, I was considering a TD04-19T, but I'd rather get away from that small of a turbo.

So, yes. I'll be doing a VF34. My research shows that you remove the pill when you go with a VF34... This will be fun to tune.
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Old 04-24-2021, 07:09 PM   #19
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Actually, I was considering a TD04-19T, but I'd rather get away from that small of a turbo.

So, yes. I'll be doing a VF34. My research shows that you remove the pill when you go with a VF34... This will be fun to tune.
Good move. The lag shouldn't be too bad on the VF34 and transient response should be pretty good. This turbo was used on the EJ20, so an EJ255 w/ AVCS should spool it up really quick.

Just make sure you get the proper ball bearing oil restrictor.
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Old 04-25-2021, 01:43 PM   #20
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Good move. The lag shouldn't be too bad on the VF34 and transient response should be pretty good. This turbo was used on the EJ20, so an EJ255 w/ AVCS should spool it up really quick.

Just make sure you get the proper ball bearing oil restrictor.
Hoping to do the turbo swap along with a turbo inlet replacement. And maybe a Killer B oil pan/pickup swap as well.

Drove the Baja yesterday, and took it up a logging road that made me quite glad I spent the money on a skid plate...
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Old 04-25-2021, 01:54 PM   #21
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Hoping to do the turbo swap along with a turbo inlet replacement. And maybe a Killer B oil pan/pickup swap as well.

Drove the Baja yesterday, and took it up a logging road that made me quite glad I spent the money on a skid plate...
I definitely encourage you to do all of those, as they are all great upgrades.

I'm about to install a skidplate in my WRX myself. Which brand do you have?

I'm looking into the TBW Performace model.
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Old 04-26-2021, 12:23 PM   #22
Chi_San
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I definitely encourage you to do all of those, as they are all great upgrades.

I'm about to install a skidplate in my WRX myself. Which brand do you have?

I'm looking into the TBW Performace model.
I went with Rallitek, since they were closer to me. I hit an ice rut with it yesterday, and the skid plate did it's job. Probably wouldn't have hurt anything without it, but the ice was very much flatter after...
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Old 10-10-2022, 09:48 PM   #23
Hiryu
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I found this while searching for experiences with the 16G BB turbo...How did this ever turn out for you?

I went from a stock VF39 on my the Murtaya (USDM STi powertrain) up to what I thought would be a slightly slower spooling 18G XT-R ball-bearing turbo, but after tuning it, the power curve was moved back by about 1000RPMs (a bit more than I was expecting--and I hadn't seen the claims that 18G XT-Rs spooled more slowly than 20Gs until this thread....is that with the 8cm turbine housing, or just the 10cm housing?). Granted, the 18G had a lot more power up top and doesn't die off anymore, but I don't spend as much time in those high RPMs and kinda miss the quicker spool.

If I don't get used to the new powerband, I was thinking of either going to a 16G XT-R (and splitting the dif between top end and spool) or maybe just back to a stock VF39 or so. With the car being only 25xx lbs or so, I don't really need a lot of top end and really like the low end torque.
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Old 10-10-2022, 10:44 PM   #24
K3rm1tth3fr0g
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I found this while searching for experiences with the 16G BB turbo...How did this ever turn out for you?



I went from a stock VF39 on my the Murtaya (USDM STi powertrain) up to what I thought would be a slightly slower spooling 18G XT-R ball-bearing turbo, but after tuning it, the power curve was moved back by about 1000RPMs (a bit more than I was expecting--and I hadn't seen the claims that 18G XT-Rs spooled more slowly than 20Gs until this thread....is that with the 8cm turbine housing, or just the 10cm housing?). Granted, the 18G had a lot more power up top and doesn't die off anymore, but I don't spend as much time in those high RPMs and kinda miss the quicker spool.



If I don't get used to the new powerband, I was thinking of either going to a 16G XT-R (and splitting the dif between top end and spool) or maybe just back to a stock VF39 or so. With the car being only 25xx lbs or so, I don't really need a lot of top end and really like the low end torque.
The rear housing is not what caused the 18g xtr to perform poorly. It is outspooled by the 18gxt and the 20gxtr
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Old 10-10-2022, 11:12 PM   #25
benflynn
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320$ g25-550 upgrade/rebuild kit.(for Vf39,52, ect) I was astonished at the spool and top end improvement. Best bang for the $ to 400hp. I was running E85 and external gate. I’ll probably build another for the fxt when I sell it.

E85 will get some of that spool back on anytjing
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