[Bestswat]

It seems that the general consensus is to go with the 1.5xtr, looking at a few dyno graphs the 1.5xtr pulls all the way to redline. The 18gtx and 71hta might spool a bit earlier by a few hundred rpm's but don't pull as hard to redline as the 1.5xtr or gtx3071. However the 1.5xtr is the pricier of the bunch and for an added 30-40whp it seems a bit hard to justify the cost. Decisions decisions!

 

[Bestswat]

A few curves I found online. These are all stage 2 STi's equipped with a 1.5xtr on a dynojet.

 

[8cd03gro]

Have you driven bigger turbo cars? If you haven't I would strongly recommend driving something with a bigger turbo and feeling the spool difference. If a slightly slower spool doesn't bother you, like it doesn't bother me, it's worth going bigger for more headroom in the future.

Just as a note, Blouch themselves say the 1.5xtr was originally designed for the 2.0 and the 2.5xtr for the 2.5.

 

[TimM]

REV Works stated the difference between the 1.5 and 2.5 was 20 WHP and 400 rpm spool.

I recently added a 1.5 XTR to my high mile 04 STI...along with PW topmount, 850 injectors, and TGV deletes. Picked up 50 CHP (right to 7000 rpm), but gained quite a bit of lag at same boost as the Cobb OTS II program (18).

I do missed the instant on of the VF39. Now saying that, the tuner was very conservative...I wonder if too conservative for low end... I will update it with a fresh engine and boost set to ~23 psi.

The car is certainly much faster now...and works better on the autocross/track.

I think I will be quite satisfied with the result vs reliability for big street miles (current mileage is 179,00 miles).

 

[CNY_STI]

I've got dyno curves in my journal (2nd post) of my 2.5xtr with e85 and 93, running a PnP header. Hopefully in the next two weeks I will have a plot for the 2.5xtr with the holy header and EWG with both fuels as well.

I have heard the 2.5xtr with the 8cm hotside responds nearly the same as the 1.5xtr with more holding power...i have the 10cm hotside which supports better holding in the upper revs but am still at full boost at ~3500 RPM( I picked up about 300 RPM with the PnP header)...food for thought. I can say once it starts to come into boost it hits like a freight train and doesn't stop.

 

[STIhatch]

BorgWarner EFR 7163 Turbo looks to spool fast and has more top end than VF

 

[Bestswat]

I've got dyno curves in my journal (2nd post) of my 2.5xtr with e85 and 93, running a PnP header. Hopefully in the next two weeks I will have a plot for the 2.5xtr with the holy header and EWG with both fuels as well.

I have heard the 2.5xtr with the 8cm hotside responds nearly the same as the 1.5xtr with more holding power...i have the 10cm hotside which supports better holding in the upper revs but am still at full boost at ~3500 RPM( I picked up about 300 RPM with the PnP header)...food for thought. I can say once it starts to come into boost it hits like a freight train and doesn't stop.

Just saw those plots in your journal and that is indeed a much quicker spool than I anticipated in regards to the 2.5xtr. Your numbers appear a little low though, Im sure the Killer B will fix that

 

[Bestswat]

I hope Im not getting myself into too much trouble with an upgraded turbo. Don't really want the motor to go boom so quickly or better yet not at all but I am prepared if it does happen.

 

[BJJMark95]

That Tq Tho... This was also a messed up run becuause this places dyno bay was terrible and had zero air flow. My IATs on this run started in the 135s and ran up to 180s... and get a load of the ambient outside for that day... :/

I don't like going by numbers anymore though because every dyno is different. You will never get the same. What you can do though is get an overall increase given a stock STi base run. When I do that - it normalizes all of my dyno runs (I have been on 4 different dynos and all were different!).

Overall my 1.5 XTR set up put me @ a 60% increase in power over stock on 93 and and 80% increase on E85 - and thats with a conservative safe tune as its my DD. Over 35K miles on my set up so far an zero issues.

 

[8cd03gro]

That torque curve, wtf? You gain and then lose nearly 70 ft-lbs over the course of 500 rpm

 

[STIhatch]

Subaru STi Stock Location EFR Turbo Kit - Full-Race.com

Anyone using this turbo? Looks to have the best balance of spool/power for DD and some track. Looking to upgrade as well.

 

[mheyman]

A few hundred rpm of extra lag is so overrated. At some point the lag becomes annoying on the street, but it's waaayyyy after these size turbos. The gearing is so short in these cars, as long as you're hitting peak boost before about 4,500rpm it is perfectly streetable.

Seems to me it's not just the lag. My car is at full boost well under 4K, but thats not what I feel. It's 10cm 1.5xt. It makes more power everywhere, but it really comes alive not to far from 3 digits in speed and is downright impressive for at least a 40 mph range (never tapped it out - but I'm sure it will do what the gearing and red-line allow) I have might have traded some top end for mid. Perhaps I would have been happier with an 8cm housing. I don't know. Car is a blast anyway though. I'm still very happy.

Added: to next post: Yes 20G should be on the list above FP or Tomei

REV Works stated the difference between the 1.5 and 2.5 was 20 WHP and 400 rpm spool.

Thats a bigger difference in spool than my upgrade from stock to a 1.5!

I recently added a 1.5 XTR to my high mile 04 STI...along with PW topmount, 850 injectors, and TGV deletes. Picked up 50 CHP (right to 7000 rpm), but gained quite a bit of lag at same boost as the Cobb OTS II program (18).

The car is certainly much faster now...and works better on the autocross/track

My numbers indicate app 300 rpm of lag for a "similar" setup. Wrapped ELH and coated turbo might have something to do with it.

Subaru STi Stock Location EFR Turbo Kit - Full-Race.com

Anyone using this turbo? Looks to have the best balance of spool/power for DD and some track. Looking to upgrade as well.

See/ask yamahasho

Interested in how much cooler charge has to be to get 20HP and a HP/lb figure (Toivenen post one but I forget what it was or where.) Will do the calc at home.

 

[StxSti]

blouch 20g xt-r

 

[CNY_STI]

Just saw those plots in your journal and that is indeed a much quicker spool than I anticipated in regards to the 2.5xtr. Your numbers appear a little low though, Im sure the Killer B will fix that

Only reason for low numbers was to not stress the stock motor. Mikey said that with pump and E85 I had a lot more to go but once you go above 350 it starts to challenge the stock block, which isn't currently necessary.

We did one run during tuning the was right around 400 but dialed it back down.

 

[ShinjiML]

Only reason for low numbers was to not stress the stock motor. Mikey said that with pump and E85 I had a lot more to go but once you go above 350 it starts to challenge the stock block, which isn't currently necessary.

We did one run during tuning the was right around 400 but dialed it back down.

Looked at your plots again and wow, your Dom 2.5 seems to spool almost like the stock VF! I swear the other Dom 2.5 plots I saw on EFI's website didn't spool that quickly. It almost looks like a Dom 1.5 boost plot.

 

[H00LiG4N]

I rcently got tuned by Mike B. from EFI aswell
Car is 2.5xtr, 10cm. Putting down 360whp on Their mustang on pump 93 @ 22 psi. hits Target boost @ 3600rpm. Might do E85 to hit that 400+whp and increase spool next spring.

 

[ScottaSTI]

How does the Dom 1.5 do on stock internals? Could you run it with just supporting mods and not doing any internal work?

 

[ShinjiML]

How does the Dom 1.5 do on stock internals? Could you run it with just supporting mods and not doing any internal work?

Basically only needs injectors and fuel pump, can even run on the stock GR/GV TMIC.

That's what Mikey recommended to me when I wanted more power on my stock block. But then again some people run GT35R sized turbos for years with no issues, while others blow their engine in stock form.

 

[Bestswat]

I rcently got tuned by Mike B. from EFI aswell
Car is 2.5xtr, 10cm. Putting down 360whp on Their mustang on pump 93 @ 22 psi. hits Target boost @ 3600rpm. Might do E85 to hit that 400+whp and increase spool next spring.

You got a graph by any chance?

 

[8cd03gro]

Seems to me it's not just the lag. My car is at full boost well under 4K, but thats not what I feel. It's 10cm 1.5xt. It makes more power everywhere, but it really comes alive not to far from 3 digits in speed and is downright impressive for at least a 40 mph range (never tapped it out - but I'm sure it will do what the gearing and red-line allow) I have might have traded some top end for mid. Perhaps I would have been happier with an 8cm housing. I don't know. Car is a blast anyway though. I'm still very happy.

I'm not sure what you mean here in regard to, "it's not just the lag." The feeling of coming alive and top end power will be even more significant on a larger turbo.

As far as EFR turbos go, they're pretty much the best performers on the market imo, if you select the right sizing and the right supporting mods. For me, I love the loud spool and sound of a Tial Q, so the EFR was a no-go. I also feel like the GT series turbos hit harder from a subjective standpoint. There's more of a rush of power. Not the most efficient means of performance, but more fun in my opinion.