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Old 07-07-2005, 03:19 PM   #1
G.Subramaniam
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Default Going from NA build to Turbo build

I have a NA build
Borla headers
CAI
ProECM torque chip
High flow cat
2.25 Inch Catback
Mild Cams

I am considering switching to turbo of say 4-5 psi
Which of my current mods can I retain

I know that the 2.25 inch catback limits me to 300 hp or less
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Old 07-07-2005, 03:23 PM   #2
gc8impreza00
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right there with ya man -- going from NA to turbo at 5 psi... Ur going to need to get rid of the CAI for sure.. not too sure about the torque chip either... are you wanting a kit or to piece it together yourself?
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Old 07-07-2005, 03:36 PM   #3
G.Subramaniam
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Piece it together
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Old 07-07-2005, 05:08 PM   #4
Matt Monson
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YOu can keep everything but the chip and the CAI...
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Old 07-07-2005, 05:39 PM   #5
G.Subramaniam
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Where exactly does the turbo tap into the exhaust gases to spin
Engine - header - cat convertor - catback ?
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Old 07-07-2005, 08:14 PM   #6
cRayZee
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Quote:
Originally Posted by Matt Monson
YOu can keep everything but the chip and the CAI...

I thought the chip had a built-in voltage limiter so the map sensor does not see boost?

(I guess this would only be useful if the guy decides not to use a standalone)
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Old 07-07-2005, 08:15 PM   #7
cRayZee
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Quote:
Originally Posted by G.Subramaniam
Where exactly does the turbo tap into the exhaust gases to spin
Engine - header - cat convertor - catback ?
Engine - header - up pipe - turbo - downpipe - (cat if u want to have one) - catback/turboback.

ps... please buy my turbokit: http://forums.nasioc.com/forums/showthread.php?t=624573
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Old 07-07-2005, 08:23 PM   #8
G.Subramaniam
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I am curious, when these things blow, as a sizable number seem to do,
the only thing that has to be replaced is the short block ? correct ?
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Old 07-08-2005, 12:19 AM   #9
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Quote:
Originally Posted by G.Subramaniam
I am curious, when these things blow, as a sizable number seem to do,
the only thing that has to be replaced is the short block ? correct ?
they dont all blow, only some

if a turbo is placed on a NA car and tuned right and the boost doesn't go to high it can see many happy miles
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Old 07-08-2005, 01:10 AM   #10
reddevil
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I just blow pistons. So I just replace them.
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Old 07-08-2005, 01:17 AM   #11
no-coast-punk
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It depends how catastrophic the short block failure is. Usually the heads are salvageable but sometimes not.
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Old 07-08-2005, 02:03 AM   #12
gc8impreza00
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with 4-5 psi and a good tune you have a lower risk of blowin the engine than say 8-9psi. Every pieced together kit is different though depending on where you spend your money and how much HP you want to produce... As long as you don't get hit with the boost bug you should be ok.
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Old 07-08-2005, 01:29 PM   #13
Matt Monson
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I've got a $1000 low mileage STi shortblock available that will drop your CR to the 8's and let you run more and more relaible boost...
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Old 07-08-2005, 01:35 PM   #14
G.Subramaniam
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I recently upgraded to your Frankenscoobie idea
EJ25 short block + Ej22 heads for 11:1 compression
Can this take 4-5 psi boost ?
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Old 07-08-2005, 01:59 PM   #15
Matt Monson
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Quote:
Originally Posted by G.Subramaniam
I recently upgraded to your Frankenscoobie idea
EJ25 short block + Ej22 heads for 11:1 compression
Can this take 4-5 psi boost ?
I forgot about that. That's a lot of compression to boost. Not suggested. PM me, I may be able to help you put together a longblock. I've got some core heads in addition to that shortblock.

Or, use your old Ej22 bottom end with some Ej25 heads (which I have) for 8.5:1 cr and boost it that way. But 11:1 is scary for boosting...
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Old 07-08-2005, 02:05 PM   #16
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2.5L displacement and 11:1 compression will give extremely strong low end and no lag
So I am just aiming for 4-5 psi boost, not high boost
( use a very small turbo )
This way you get the best of both NA and turbo
I am thinking of adding a J&S to the minimise risk
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Old 07-08-2005, 02:15 PM   #17
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With that kind of compression, you are going to want a stand alone EM. Detonation will come very easily on that set up without perfect tuning...
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Old 07-08-2005, 02:15 PM   #18
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If you were running beefy connecting rods and pistons 11:1 would be safe. But even a little bump in compression has a radical increase in combustion pressures on boosted engines.
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Old 07-08-2005, 04:38 PM   #19
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I have detroyed three pistons (two motors) by running just 9.5-1 and 8 psi. But that was with a standard NA ecu.
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Old 07-08-2005, 04:54 PM   #20
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Exclamation Not a good idea!!

11:1 + boost= bad news. Your static compression ratio will be sky high! Unless you run primo fuel and have a really good tune. You will detonate.

Even 9:1 You won't notice to much of a lost of bottom end, and it will be a heck of a lot easier to tune.
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Old 07-08-2005, 05:36 PM   #21
G.Subramaniam
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What compression does STI short block + 2.2L heads give ?
9.5??
If so, would this combo give both excellent low end as well as be boost reliable ?
How much low end do I lose by going to STI short block
instead of RS short block

Last edited by G.Subramaniam; 07-08-2005 at 06:21 PM. Reason: error correction
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Old 07-08-2005, 09:27 PM   #22
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Quote:
Originally Posted by G.Subramaniam
What compression does STI short block + 2.2L heads give ?
9.5??
If so, would this combo give both excellent low end as well as be boost reliable ?
How much low end do I lose by going to STI short block
instead of RS short block
MAYBE more like 8.8-9.0.
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Old 07-08-2005, 09:34 PM   #23
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How much low end torque would I lose by going to a CR of 9 as opposed to a CR of 10 or 11
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Old 07-09-2005, 05:37 AM   #24
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It won't make that much difference and you will have more reliable and tuner friendly motor. I would also stay with a 2.5 head preferably a sohc if you want to upgrade valves,cams etc cause it's cheaper and they flow better than the 2.2 heads.
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Old 07-09-2005, 11:47 AM   #25
Matt Monson
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Yeah,
The STI block with your 2.2l heads will be around 9:1. And your driveability off boost will be fine. Most people don't realize that for most of the life of the 911 Porsche was running CR of between 7 and 8.5 on their non-turbo cars, and down in the 6's on the turbos. Only on the modern water cooled cars have they moved up there.

If you boost the car, you want to be hitting somewhere around 12:1 effective CR. As No-coast mentioned, if you start high, even the slightest boost give you huge gains in effective compression. Much easier to tune, and much safer to run something like 9:1 and then boost it. And if you run a small little turbo like a TD04 from a WRX, you will be getting spool up at or below 3000rpms, and have a very useful and effective power band...
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