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Old 06-30-2011, 11:26 PM   #1
LTD638
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Default Dom 1.5xtr Build

Unfortunately, due to some financial difficulties, my originally planned GT35r build will have to wait another day....

I still want a quick DD, so i've decided to go with the following set up.. Please chime in with some constructive criticism

Top speed motorsports SS2 short block (cosworth pistons 99.5mm, OE forged rods, OE nitrided Crank)
Blouch 1.5xtr - 8cm exhaust side/3" inlet (After some research, this is the most efficient turbo to run in the stock location.. Seems like bigger turbos experience back pressure prior to the reaching the turbo)
EWG set up - Tial 38mm
ID 850cc Injectors
Walbro 255lph
Grimmspeed EBCS
Spearco TMIC
Invidia Race Headers
ACT XTSS clutch
ACT streetlite flywheel
OE 11mm oil pump
Gates Timing belt/Tensioner kit
Headstuds and bearings

Some optional mods may be: Optimization of Fuel system (finding a way to pump consistent amounts of fuel to each cylinder).. Maybe that can be done by re-routing existing fuel lines, or aftermarket rails and regulator.

I would greatly appreciate some advice.. thanks everyone
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Old 07-02-2011, 01:18 PM   #2
LTD638
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Bump por favor
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Old 07-02-2011, 01:54 PM   #3
LTD638
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After hearing from TSM,
The issue with the larger turbos in stock location is called "Turbo Drive Pressure"...
Can anyone elaborate on this??
And also, I'm thinking of keeping the stock turbo inlet size of 2.360" to keep air density similar to stock...
Any comments would be helpful, thanks
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Old 07-02-2011, 04:42 PM   #4
lil'redwagon
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my limited understanding of drive pressure is: it's the pressure in your exhaust that drives the hotside of the turbo. people talk about a ratio, say 1:1 being ideal, of air pressure in intake manifold, vs. the air pressure in the exhaust. so an example of a 1:1 drive pressure ratio might 25lbs (as measured on top of your uppipe, just before the entrance of the turbo), and 25lbs of boost (as measured in your intake manifold). they say it's best for the engine to have a 1:1 or lower drive pressure. or to put it another way, it's better to have more psi in the intake manifold than in the exhaust. (2:1, 1.5:1, 1.3:1, etc.) it has to do with efficiency ratings, and compressor maps.

here's a good post from a diesel forum (the second post on that page):
http://www.competitiondiesel.com/for...t=67547&page=2

i've never measured drive pressure on my exhaust. but this is what my guess is for what happens on our cars:

subarus have their turbos sitting far away from the heads. this means that the exhaust gasses cool (contract) before reaching the turbo, and it's also a really long way for the gasses to travel before it tries to spin the turbo. this means we have a hard time spooling a large hotside. therefore we end up using turbos with small hotsides. those small hotsides create a lot of back pressure in the exhaust at higher rpms. that back pressure (high drive pressure) ends up choking the motor at higher rpms because at that point, we're trying to pass too much air through the small hotside. a small hotside that we chose because we wanted it to spool earlier.
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Old 07-04-2011, 12:58 PM   #5
LTD638
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Thanks for the response redwagon.

Thats a great explanation!!

I spoke to the folks at TSM... (these guys are too legit to quit, haha)
And after talking to them, the suggestion (after a lot of builds and years of experience) is that the largest turbo to go with in the stock location will flow around 49 lbs/min.
So Dom 1.5xtr fits the bill...

Any more comments will be welcome, thanks
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Old 07-04-2011, 01:57 PM   #6
lil'redwagon
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cool. after reading your original post again, two things stand out:

1) don't the XT-R turbos have a 10cm2 exhaust, not 8cm2? if it's just an 8cm2, then it's just an XT, right?

http://www.bptstore.com/Subaru-WRXST...rger_p_25.html

2) you're going to run an EWG. that should let you control the boost pressure, so your motor won't choke at higher rpms. that's a great way to control a smaller turbo. so why then, does your tuner suggest that you shouldn't go any larger than a 49lb turbo? is it because you're not looking for a lot of power up top, so they're looking for faster spool? it's my understanding that the biggest limitation to a stock location turbo (aside from the intake and intercooler piping) is using the internal wastegate. so if you're using an external wastegate, you could chose a turbo just like any other turbo, no? i bet it's something math-y.

please note: i'm not a motor guy, so these questions are actually for me to learn, not to provoke anything or question the practices of your tuner.
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Old 07-04-2011, 11:52 PM   #7
Concillian
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Quote:
Originally Posted by lil'redwagon View Post
cool. after reading your original post again, two things stand out:

1) don't the XT-R turbos have a 10cm2 exhaust, not 8cm2? if it's just an 8cm2, then it's just an XT, right?

http://www.bptstore.com/Subaru-WRXST...rger_p_25.html
Blouch-speak is:

XT = billet cold wheel
R = ball bearing CHRA

XTRs have traditionally been 10cm hotside, because about the time they moved to the billet wheels, they realized they had cracking issues with their 8cm hotsides for the Garrett CHRAs. By realized, I mean they started getting a significant number of returns. Search enough here and iwsti and you'll see lots of cracked 8cm Blouch turbos for their stock location Garretts. You just don't see a big stink about it, because they seem to take care of their customers and make things right.

From what I can tell, the issue with the 8cm was significant enough that they were forced to stop selling them while they re-designed them to not crack. I suspect re-design was not too difficult, but I bet lead time on a relatively low volume casting like that is very long. So they weren't able to sell 8cm hotsides for the Garrett CHRAs again until recently.

Current 8cm hotsides from Blouch for their DOMxxxx turbos should be solid. Ones prone to cracking mostly on the 2.5r and 3.0r, few to none of the xtr turbos

Last edited by Concillian; 07-05-2011 at 05:49 AM.
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Old 07-05-2011, 12:00 AM   #8
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cant wait to see what type of power this thing makes... do you plan on any meth injection or just a pump gas tune?

other than the light weight flywheel pretty much what i want but went with a different turbo....
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Old 07-05-2011, 03:22 PM   #9
LTD638
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Thanks for the responses guys, much appreciated

Actually, Blouch does make the Dom1.5xtr with an optional 8 or 10cm exhaust housing.
After reading a bit about "turbo drive pressure", it seems like running a larger hot side might contribute to this problem.

LilRed, i was under the same impression that if I would run an EWG, I could go larger.
Actually, I ran this question by TSM, and still have not heard back. I hope to hear from them soon... These guys are extremely knowledgeable about the subject, so I'd like to hear their input on the EWG issue.

The_Smurf, I'm excited as well... My tuner is a genius, so i'm sure i'll be impressed with the final product.... And yes, this will be a pump gas tune, 93 oct.

thanks for the input guys, hope to hear from you later.
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Old 07-06-2011, 06:31 PM   #10
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I had a few more questions, and I was hoping some of you experts can chime in.

With this build I'm concerned about the oil and fuel systems, as well as which injectors to mate up with this turbo.

From some reading, and hear say, I've learned that there are some inconsistencies in the fuel delivery system in these subaru motors... Meaning some cylinders default to receive less fuel than others due to their location in respect to the pressure regulator and relative distance for fuel travel .... If this is true, would supplementing a fuel pressure regulator and upgraded fuel rails help alleviate the issue???

Another issue is the Oil system.. I'm fairly confident (with reassurance from TSM) that the 11mm pump will be the weapon of choice when trying to efficiently lubricate the system.

Now the last issue is the injectors.. I did run this by TSM and my tuner. My tuner has recommended 850cc injectors to mate up with this set up. This seem reasonable considering the size and the flow of this turbo.. I will most likely be tuning this set up to 25lbs on 93 octane.

Well, I'd appreciate any input from you guys
Thanks
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Old 07-07-2011, 02:33 PM   #11
LTD638
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Super Bump!!!!
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Old 07-07-2011, 06:21 PM   #12
lil'redwagon
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so this will be just a powerful DD. my guess is you'll see between 350 and 400whp. that said, you aren't going to be really pushing the limits of the fuel system. and with it a DD, you aren't going to really be pushing it for the oiling either.

with that size turbo, i think the stock fuel rails and regulator should be fine.

11mm oil pump should also be fine.

DW 850cc injectors are working for my Dom3XTR at 25psi and pump 93. so you should be ok unless you want to run e85.
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Old 07-07-2011, 11:08 PM   #13
LTD638
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Thanks for the response LilRed.
Yeah, after hearing back from TSM, stock fuel rails and regulator are solid.
Same with the suggestion for 11mm pump and 850cc injectors.

I hope to have the block in sometime next week, so I'll keep everybody updated.
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Old 07-10-2011, 11:04 PM   #14
nappingcub
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Do you already have the injectors? If not, maybe go for the ID1000s or the DW1000s? You'd have the overhead to go corn fed if you wanted more power down the line, and since you're in the MW, getting the corn power shouldn't be as painful as us poor saps in CA
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Old 07-19-2011, 02:56 PM   #15
LTD638
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Hello.
Just wanted to update everyone on the build.

Still waiting for the SS2 block from TSM.
I'm actually going to be going with an aftermarket fuel rail system (aeromotive)
I understand that the OE rails and regulator are sufficient, but i'd like the peace of mind that these parts can withstand any abuse i throw at it with the Dom1.5xtr

I am contemplating more aggressive cams then OE.. Maybe a Kelford A cam to help the power curve, and just replacing valves, springs and retainers with something more capable.

Anyways, any advice would be appreciated... thanks
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Old 07-19-2011, 04:49 PM   #16
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Kelford R-199-B (Hot street performance cam) would be the way to go IMO. The 264/264s with AVCS on your STi would be VERY nice and great on the street. They are a little more aggressive than the Kelford R-199-A (for a mild turbo upgrade) and IMO a better match for your setup and the 1.5XTR.

I am running the Kelford 264/264 non AVCS cams on my build and love them, very streetable while holding power very will until my 7500rpm redline.
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Old 07-20-2011, 01:51 PM   #17
LTD638
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thanks for the response csmith.
I was thinking either the r-199-a or b.
I'll talk to the builder and see what he thinks I should go with.
I need to keep this this streetable, because it is my DD
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Old 07-20-2011, 08:51 PM   #18
csmithwrx'05
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Quote:
Originally Posted by LTD638 View Post
thanks for the response csmith.
I was thinking either the r-199-a or b.
I'll talk to the builder and see what he thinks I should go with.
I need to keep this this streetable, because it is my DD
No problem. Definitely discuss with your tuner.

Either will be great on the street, but the R-199-B would make better use of your topend with out causing much loss at the lowend, if any b/c they are not too much of grind/agressive (i.e. 272s, 280s, etc.). The R-199-B are pretty much the best cams on the market for a modified street beast like your build IMHO. Arguably they are the best all round grind done by Kelford. My tuner swears by them.

Last edited by csmithwrx'05; 07-20-2011 at 08:57 PM.
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Old 06-20-2012, 05:44 PM   #19
Red MY01
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Hi, just bumping an old thread wondering if there are any results from this build?
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Old 08-01-2012, 10:41 AM   #20
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Also very interested. Building a 3.0XTR, built short block and full exhaust treatment sans headers, looking for results from the camshaft choice.
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Old 08-01-2012, 06:10 PM   #21
SubieEngineer
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Also in for some results... I'm having a similar build done by TopSpeed using the 1.5XTR (10cm).

-TGV Deletes
-Walbro 255
-ID1000s
-ETS TMIC
-1.5 XTR
-Cobb TBE
-GrimmSpeed PNP Manifold, Xpipe, Uppipe
-TopSpeed RR.5 Motor
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Old 08-01-2012, 06:24 PM   #22
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looks like his last login was feb.
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Old 08-02-2012, 10:27 PM   #23
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Quote:
Originally Posted by Bru1212 View Post
looks like his last login was feb.
Yeah, probably no updates, then.
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Old 08-10-2012, 08:29 PM   #24
LTD638
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Whats up guys,
Sorry for the year long delay.
i've posted up the results of this build on the Proven Power Bragging section.
The Car put down 406ft/lbs and 412whp, at 23lbs, on e85.

Just a word of warning.
DO NOT USE TOPSPEED MOTORSPORTS shortblocks.
I couldn't tell you how many adjustments we had to make to the short block just to get it up to cosworth specs.

To continue the discussion, I did end up staying with the OE 07' Cams, just ported and polished the heads, and ported the intake manifold.

Any more questions let me know,
but i'd suggest pulling and building the existing block.
I would go that way the next time around.
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