poor flowing head... crank up the boost?

scottzg · Post by **scottzg** » Mon Jan 12, 2004 7:54 am

Alrighty, so i dont know anything about turboes, and i know there's a good reason not to do this, but i wanna know what it is.

Ok, so you've got a sohc legacy turbo or even worse, a starion (mighty max motor). The head flow just isn't that good. So, why can't you crank up the boost? The volume defeciency will be ameliorated by the air density! Too hard on the valves/valve springs?

vrg3 · Post by **vrg3** » Mon Jan 12, 2004 8:12 am

Increasing boost is harder on everything. Temperatures go up, putting more stress on the cooling system and lubrication. Pressures go up, too, increasing stress on almost everything in the bottom end. Increases in temperature and pressure increase the risk of detonation. Turbine speed goes up, too, so the turbo's working harder.

More boost will take more time to build, too.

But... of course you can crank up the boost. Probably more than half of the turbo owners on this board are running higher-than-stock boost. Some even do it without any other modifications (which I don't think is a good idea). But the result can be superficially the same as the result of improved volumetric efficiency: more power.

scottzg · Post by **scottzg** » Mon Jan 12, 2004 8:36 am

i must be short on vitamins or something... duhhhh.

kinda makes 4v/cyl look less appealing for the sporty sedan market though. The turbo + a naturally peakier engine design makes for "bonus peakiness"

vrg, how many legacies do you have?

vrg3 · Post by **vrg3** » Mon Jan 12, 2004 8:58 am

scottzg wrote:kinda makes 4v/cyl look less appealing for the sporty sedan market though. The turbo + a naturally peakier engine design makes for "bonus peakiness"

You mean that a peakier engine would have higher horsepower numbers on paper?

For whatever reason, Subaru decided to make the EJ22T heads more or less the same as the naturally aspirated ones. Maybe it was because they wanted people in the US to be able to service the turbos despite their rarity, or maybe they didn't want to make a completely different set of parts for a small run of cars...

vrg, how many legacies do you have?

What makes you ask?

At the moment, I have my 93 turbo 5-speed sedan and my cousin has my previous 97 GT automatic sedan (which I and my brother are responsible for maintaining). In the past, while I lived with my family, we had a 91 L auto sedan and a 93 turbo auto sedan. Somewhere in the middle of all that I had a 97 Impreza L 5-speed sedan too.

scottzg · Post by **scottzg** » Mon Jan 12, 2004 6:20 pm

vrg3 wrote:
For whatever reason, Subaru decided to make the EJ22T heads more or less the same as the naturally aspirated ones. Maybe it was because they wanted people in the US to be able to service the turbos despite their rarity, or maybe they didn't want to make a completely different set of parts for a small run of cars...

I kinda figured it was because they wanted the turbo to have more midrange power; heck, most turbo legacies are automatics. I think the Turbo was aimed at people wanting some oomph and a little sportiness but didnt give a rats about ultimate performance. What does the rex get critisized for most here? Being a dog below 3k. The turbo leg, with its sohc, lacking intercooler, and larger displacement, is not so bad in this regard.

A similar example is overseas the starion comes with the 2.0 you find in the eclipse with a strange version of vtec. We got a 2.6L truck motor.

What makes you ask?

I was curious.

georryan · Post by **georryan** » Mon Jan 12, 2004 8:54 pm

Weren't the 22B heads better flowing?? We need to get our hands on them.

boostjunkie · Post by **boostjunkie** » Mon Jan 12, 2004 9:01 pm

The 22b used the STi v4 heads IIRC.

georryan · Post by **georryan** » Tue Jan 13, 2004 8:55 pm

They'd be just as hard to match up with our block as the 2.5's right? I keep forgetting, but the 22B was a semi-closed deck, right?

boostjunkie · Post by **boostjunkie** » Tue Jan 13, 2004 9:08 pm

I cant remember off-hand when subaru switched over from a open-deck block (I'm pretty sure subaru went from closed-deck to open-deck to semi-closed-deck).

georryan · Post by **georryan** » Tue Jan 13, 2004 10:20 pm

yeah that's were I'm at. I know that the 2.5 heads have a hard time matching up, but I don't know how those heads would fair. They'd flow better, that's for sure.

mTk · Post by **mTk** » Tue Jan 13, 2004 11:20 pm

georryan wrote:I keep forgetting, but the 22B was a semi-closed deck, right?

iirc the 22b used the ej22t block. (fully closed)

MK

boostjunkie · Post by **boostjunkie** » Tue Jan 13, 2004 11:24 pm

mTk wrote:
georryan wrote:I keep forgetting, but the 22B was a semi-closed deck, right?
iirc the 22b used the ej22t block. (fully closed)

MK

However, I spoke with someone who was building up his 22b (he found my site on the web and was asking about the ej22g blocks). Apparently, the 22b blocks did NOT come with oil squirters, like our blocks. Everything else was the same. You can imagine my surprise when I come to find out that our block was better than the 22b

ciper · Post by **ciper** » Wed Jan 14, 2004 12:01 am

Just one more reason the legacy turbo was the best engine subaru ever made. How many times do we have to go over that?

NICO · Post by **NICO** » Wed Jan 14, 2004 8:55 am

i second that motion the best subaru ever made, turbo legacy 2.2l ej22t.

totech · Post by **totech** » Wed Jan 14, 2004 4:49 pm

And the best is the 91 with the oil cooler.

ciper · Post by **ciper** » Wed Jan 14, 2004 8:18 pm

Which I have

I have an extra oil cooler if anyone wants. Since we use the same design of filter as most hondas all the oil filter cooler and relocation kits from hondas will work! They are cheap.

vrg3 · Post by **vrg3** » Wed Jan 14, 2004 8:25 pm

ciper, do you have the plumbing that goes with it? I'm interested.

The Subaru OEM oil cooler uses an extra-long filter nipple; without that I wouldn't trust the filter to stay on. Do the Honda kits come with longer filter nipples too? Do they thread right into our block?

I believe Hondas have longer filter nipples than Subarus to begin with; that's why it's better to use a filter properly designed for a Subaru (i.e. Purolator's) rather than a semi-generic one (i.e. Fram's) for proper thread engagement.

ciper · Post by **ciper** » Wed Jan 14, 2004 8:30 pm

I have the cooler and what I think you refer to as the nipple. Do you mean the hollow tube with threads on both ends?

vrg3 · Post by **vrg3** » Wed Jan 14, 2004 8:35 pm

I'm hoping to find everything in this picture:

http://www.graphics.cornell.edu/~v/pics ... cooler.gif

'cept, of course, for the filter and engine block. :) And I'm sure I could find the bolt myself. But I do want the coolant nipple that threads into the block, the hollow tube you're talking about, the vulcanized hoses, and the hard pipe.

ciper · Post by **ciper** » Wed Jan 14, 2004 8:38 pm

No rubber tubes
No block insert
No metal line going to the drivers side of engine.

vrg3 · Post by **vrg3** » Wed Jan 14, 2004 8:48 pm

Hmm... well, I could rig up my own tubing and stuff, I suppose... Splice into the heater circuit or something for the coolant return.

How much do you want for the cooler and the threaded hollow tube? These are off a '91 Legacy Turbo, right?

totech · Post by **totech** » Wed Jan 14, 2004 9:00 pm

ciper wrote:Which I have

I have an extra oil cooler if anyone wants. Since we use the same design of filter as most hondas all the oil filter cooler and relocation kits from hondas will work! They are cheap.

Me too - I have one on each of my 91's!

91's rock

vrg3 · Post by **vrg3** » Wed Jan 14, 2004 10:17 pm

totech - Neither of yours is a spare for sale, though, is it?

MY99 2.5GT · Post by **MY99 2.5GT** » Wed Feb 04, 2004 3:40 pm

boostjunkie wrote:The 22b used the STi v4 heads IIRC.

I have spoken with many people that believed the 22B used the EJ22G block but this is false. I have read in many places that the 22B uses a stroked version of the STI V4 closed deck block. I would like to have a little more information at hand to verify this such as the bore and stroke measurements from the original STI V4 and the 22B.

As far as heads go I once planned to swap SOHC 2.5 heads on my EJ22G but after researching fitment, flow, and cooling capacity I am staying as far away from that combination as possible. My plan now is to build the heads that came with my 22G or find a set of WRX heads and build them.

Brad

evolutionmovement · Post by **evolutionmovement** » Wed Feb 04, 2004 7:21 pm

22B bore x stroke 96.9 x 75.0mm. from You and Your Impreza Turbo

EJ22G bore x stroke 96.9 x 75.0mm from FSM

Steve

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poor flowing head... crank up the boost?

poor flowing head... crank up the boost?