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Old 07-15-2012, 07:45 PM   #1
y4gUDp2s
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Default EJ22 - small turbo for high altitude?

I've got an EJ22 in a 97 Impreza, and overall I've been quite happy with it. The other day though, I was driving up to about 10,000ft, and my little engine really started flagging. I practically had to floor it to get going faster than 45mph, and I would start slowing down if I ever let the rpm fall below 3k. I'm pretty darn sure it got worse with altitude.

I'm not a speed junkie, but it got me thinking- what if I slapped on a dinky turbo? Not because I need gobs of power, no. I don't want to redo the maps and the pistons and worry about my open deck. Just something to keep my intake pressure at least around 1atm (sea level), so I don't lose power. Ideally all I'd need would be a pair of manifolds, a turbo, and perhaps a pressure regulator. I'd probably want the turbo to kick in around 2k, and peak around 3k. No engine management, no intercooler.

Would this be particularly expensive? Impossible? Waste of time?

My past experience tells me, mods don't pay off But besides suffering in silence, my main alternative is selling this guy and upgrading- which would be a 2000+ Impreza, and that's a big jump in price, especially now that I'm thinking turbo. I can afford it, but it seems silly for a beater.

So, I thought, maybe if I keep the scope small and the goals (truly) modest, it might work out?
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Old 07-15-2012, 11:00 PM   #2
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Basically a turbo normalized engine. This is fairly common on aircraft engines. You would have to devise some sort of boost control to limit manifolds pressure to around 30" Hg absolute. It's not hard to make something top do that on an engine that stays at a constant rpm/power setting but for a car that will be accel and shifting gears it will not be easy
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Old 07-15-2012, 11:12 PM   #3
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Quote:
Originally Posted by RaceFaceXC View Post
Basically a turbo normalized engine. This is fairly common on aircraft engines.
Good to hear it's not a totally wacky idea.

Quote:
Originally Posted by RaceFaceXC View Post
You would have to devise some sort of boost control to limit manifolds pressure to around 30" Hg absolute. It's not hard to make something top do that on an engine that stays at a constant rpm/power setting but for a car that will be accel and shifting gears it will not be easy
I might be able to handle this part on my own. You'd basically just need a fast-acting valve with sufficient flow and a pressure sensor, right?

Edit: Hmm, maybe an intercooler wouldn't be so easily waivable. At 10,000ft, I'm reading it's about 0.75atm. This means about 33% boost in pressure, aka 33% boost in temperature. If it's a toasty day, that means 100F -> 290F, presuming I still know how to use the ideal gas law and Kelvins.

Last edited by y4gUDp2s; 07-15-2012 at 11:54 PM.
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Old 07-15-2012, 11:34 PM   #4
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Have you considered going with an Avo turbo kit or something along that line, Im not sure what the year cut off is for the older kit they put out but they have a solid kit that is only pushing something like 6psi. Its small enough to not have to rebuild the motor but enough to get your power up.
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Old 07-15-2012, 11:50 PM   #5
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Have you considered going with an Avo turbo kit or something along that line, Im not sure what the year cut off is for the older kit they put out but they have a solid kit that is only pushing something like 6psi. Its small enough to not have to rebuild the motor but enough to get your power up.
Well, a kit would be nice and all, but this is not a car worth investing $3.5K. If that's my only option for turbos, I'm either buying a WRX or keeping what I got. Probably keeping what I got

(Normally I'm quite happy with what I got, I was just highly unamused by her hillclimb performance!)
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Old 07-15-2012, 11:59 PM   #6
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What about a supercharger? It doesn't seem like you'd see as great an advantage in altitude performance as a turbo, but it also may cost less??? I don't know anything about it....just shooting dumb ideas out like always.

http://www.rs25.com/forums/f7/t10710...ur-subaru.html
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Old 07-16-2012, 12:32 AM   #7
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Fair enough, it is a bit pricy but still cheaper then a WRX if its a car you want to put the coin into.
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Old 07-16-2012, 01:11 AM   #8
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youll need exhuast manifold, turbo, intercooler, fuel injectors, fuel pump, and a tune...pretty pricey if you ask me
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Old 07-16-2012, 01:21 AM   #9
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Originally Posted by klaus_b2 View Post
youll need exhuast manifold, turbo, intercooler, fuel injectors, fuel pump, and a tune...pretty pricey if you ask me
Man, I'm not going for power! All I want is stock performance at 10,000ft. If I have a system that keeps the manifold at 1atm (air pressure at sea level) I don't need upgraded fueling, because as far as the car is concerned, it's just driving at sea level.

If I wanted MOAR POWAH, then yes, you're right and I know that. If I was sitting here trying to get 250hp out of an EJ22, I'd be an idiot. Rather, the issue is that at sea level I have 135hp but by the time I reach 10,000ft, I have considerably less, because air pressure is low. If we presume a 33% reduction in air pressure means a respective decrease in power (because the engine takes in less air with every stroke) I'm making 90hp.
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Old 07-16-2012, 02:47 AM   #10
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1 atmosphere (or 1 bar) is 14.5038psi. So I really don't think you want to shot for that. Your n/a car will not ever see positive pressure in your intake manifold.It has only ever seen vacuum. The 91-94 turbo legacy only had ~8psi stock and it had upgraded injectors. But that may have been subaru being safe(they did make it closed deck for no reason). But you can probably pick up one of those for pennies(vf-10/11). Heck you can probably pick up most of need parts from an old turbo leg. Oh and unless u go custom turbo piping u will need a turbo crossmembers(once again turbo leg works). Also with the small amount of boost you want, you will NOT need an intercooler. The stock turbo leg did not have one.
Ok, enough about turbo legacy...
Good luck!

Last edited by PENGUIN_JF1BJ_EJ22T; 07-16-2012 at 02:55 AM.
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Old 07-17-2012, 11:28 PM   #11
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1 atmosphere (or 1 bar) is 14.5038psi. So I really don't think you want to shot for that. Your n/a car will not ever see positive pressure in your intake manifold.It has only ever seen vacuum.
Frak, you're right. Completely forgot about that. Also forgot that vacuum varies with throttle angle and load... How do I know what I should shoot for? I'm reading normal manifold vacuum under load is around 20", or about 1/3 of atmospheric. So, maybe 5psi?

Quote:
Originally Posted by PENGUIN_JF1BJ_EJ22T View Post
The 91-94 turbo legacy only had ~8psi stock and it had upgraded injectors. But that may have been subaru being safe(they did make it closed deck for no reason). But you can probably pick up one of those for pennies(vf-10/11). Heck you can probably pick up most of need parts from an old turbo leg. Oh and unless u go custom turbo piping u will need a turbo crossmembers(once again turbo leg works). Also with the small amount of boost you want, you will NOT need an intercooler. The stock turbo leg did not have one.
Ok, enough about turbo legacy...
Good luck!
This is great info. Thanks! I'll see if I can't find a junkyard that has some, if I can get my head under the hood I'll get a better idea what I can use...

Last edited by y4gUDp2s; 07-17-2012 at 11:37 PM.
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Old 07-18-2012, 01:46 AM   #12
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Quote:
Originally Posted by y4gUDp2s View Post
Man, I'm not going for power! All I want is stock performance at 10,000ft. If I have a system that keeps the manifold at 1atm (air pressure at sea level) I don't need upgraded fueling, because as far as the car is concerned, it's just driving at sea level.

If I wanted MOAR POWAH, then yes, you're right and I know that. If I was sitting here trying to get 250hp out of an EJ22, I'd be an idiot. Rather, the issue is that at sea level I have 135hp but by the time I reach 10,000ft, I have considerably less, because air pressure is low. If we presume a 33% reduction in air pressure means a respective decrease in power (because the engine takes in less air with every stroke) I'm making 90hp.
oh lol read it wrong. in that case, i know nothing about altitude or anything like that to help haha
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Old 07-18-2012, 02:01 AM   #13
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Quote:
Originally Posted by PENGUIN_JF1BJ_EJ22T View Post
1 atmosphere (or 1 bar) is 14.5038psi. So I really don't think you want to shot for that. Your n/a car will not ever see positive pressure in your intake manifold.It has only ever seen vacuum. The 91-94 turbo legacy only had ~8psi stock and it had upgraded injectors. But that may have been subaru being safe(they did make it closed deck for no reason). But you can probably pick up one of those for pennies(vf-10/11). Heck you can probably pick up most of need parts from an old turbo leg. Oh and unless u go custom turbo piping u will need a turbo crossmembers(once again turbo leg works). Also with the small amount of boost you want, you will NOT need an intercooler. The stock turbo leg did not have one.
Ok, enough about turbo legacy...
Good luck!
You're confusing absolute and relative pressure. The OP (who is confused about which tech subforum this thread should have been in ) is trying to maintain 14.7 psi of ABSOLUTE pressure, which means 3-4 psi of boost at high altitude. Very doable, except that an unmanaged system that has a 30% pressure ratio is going to make 5-6 psi at sea level, which may or may not be dangerous.
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Old 07-18-2012, 02:03 AM   #14
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your issue imo is the newer denso ecu you use (unless you got by with an older jecs). they don't like their map sensors reading boost.
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Old 07-18-2012, 02:26 AM   #15
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Quote:
Originally Posted by BAN SUVS

You're confusing absolute and relative pressure. The OP (who is confused about which tech subforum this thread should have been in ) is trying to maintain 14.7 psi of ABSOLUTE pressure, which means 3-4 psi of boost at high altitude. Very doable, except that an unmanaged system that has a 30% pressure ratio is going to make 5-6 psi at sea level, whichu may or may not be dangerous.
Um no, I am not confused. But thanks for flaming 2 people in one post (me amd the "OP")and still providing no useful info!
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Old 07-18-2012, 07:43 AM   #16
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Quote:
Originally Posted by PENGUIN_JF1BJ_EJ22T
Um no, I am not confused. But thanks for flaming 2 people in one post (me amd the "OP")and still providing no useful info!
Yes you are. While 14.x psi is what the atm pressure is at sea level, boost is RELATIVE to that. So a car that boosts 5 psi on the boost gauge has about 19 psi ABSOLUTE. If you paid attention in 7th grade physics you would know that. (FYI, that is a flame)

If you thought ban suvs comment was a flame you have not been here very long. He was simply clarifing misleading advice.
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Old 07-18-2012, 11:01 AM   #17
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Quote:
Originally Posted by RaceFaceXC

Yes you are. While 14.x psi is what the atm pressure is at sea level, boost is RELATIVE to that. So a car that boosts 5 psi on the boost gauge has about 19 psi ABSOLUTE. If you paid attention in 7th grade physics you would know that. (FYI, that is a flame)

If you thought ban suvs comment was a flame you have not been here very long. He was simply clarifing misleading advice.
Hey ass hat, how many factory subaru boost gauges read Absolute pressure? And you have been on nasioc 8 months longer then me, I just search and read and usually don't post cause of the asshattery. But I guess u talk before u get the facts. i am sure this was a first....
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Old 07-18-2012, 12:43 PM   #18
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Quote:
Originally Posted by PENGUIN_JF1BJ_EJ22T View Post
Hey ass hat, how many factory subaru boost gauges read Absolute pressure?
None. But what's that got to do with anything?


Quote:
Originally Posted by PENGUIN_JF1BJ_EJ22T View Post
And you have been on nasioc 8 months longer then me, I just search and read and usually don't post cause of the asshattery. But I guess u talk before u get the facts. i am sure this was a first....
It's amusing that you think a signu date has dick to do with what he does or does not know. You need a new system for determining bona fides.
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Old 07-18-2012, 01:37 PM   #19
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I say this with every intention of being helpful, but if you want to boost your car you are in the wrong forum. About 4 more forums down there is a whole forum committed to doing what you want to do and there's a ton more knowledge there about doing it.

Personally, if I were driving your car, I would put an intake on it and a set of Delta cams in the heads and call it done. That's good for 15hp and will offset most of what is bothering you for less than $500.

If you do want to continue down the turbo path, when you get to the aftermarket forced induction forum, look for Subachad's stuff. If you can find one of his exhaust systems on the used market, it's right up the alley you are talking about. Or an old JC Sport/PDM kit, but those are more few and far between these days...
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Old 07-18-2012, 08:58 PM   #20
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Originally Posted by BAN SUVS
It's amusing that you think a signu date has dick to do with what he does or does not know. You need a new system for determining bona fides.
That's the problem, you and your fan boy keep amusing things!

Note how a real "bona fide", Mr. Monson tells the "op" he is in the wrong forum, and then provides useful info.
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Old 07-18-2012, 10:24 PM   #21
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The OP got useful info when it was pointed out that you are wrong. It is perfectly reasonable for him to want a small turbo to make up for altitude losses, and at 10,000 feet, 3 psi of boost is effectively not boost. In fact, as dozens if not hundreds of early EJ series owners have learned, a small VF or TD04 turbo on wastegate boost will run fine with no other mods, if you use premium fuel.
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Old 07-19-2012, 02:47 AM   #22
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I say this with every intention of being helpful, but if you want to boost your car you are in the wrong forum. About 4 more forums down there is a whole forum committed to doing what you want to do and there's a ton more knowledge there about doing it.
I wasn't sure, 'cause it's currently NA...

Is it possible for a mod to move the thread to the other forum? I wouldn't mind.

Quote:
Originally Posted by Matt Monson View Post
Personally, if I were driving your car, I would put an intake on it and a set of Delta cams in the heads and call it done. That's good for 15hp and will offset most of what is bothering you for less than $500.
Hmm... I like the idea of cams in that they are simple and I need to replace my t-belt soon anyway, but do I need to send them my cores to be ground? Can't have the car out of service more than a little while.

I'm skeptical whether cams could buy me 15hp, but I'll give 'em a call at least. I'm reading that high altitude favors high lift/low duration, so maybe there's a little extra to be had by using the right profile, besides just using bigger cams.

Pros: Loping idle

Cons: Fuel economy?

Quote:
Originally Posted by Matt Monson View Post
If you do want to continue down the turbo path, when you get to the aftermarket forced induction forum, look for Subachad's stuff. If you can find one of his exhaust systems on the used market, it's right up the alley you are talking about. Or an old JC Sport/PDM kit, but those are more few and far between these days...
Thanks! I'll look around.
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