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overdeveloped beater
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Discussion Starter #1
I know I've read about it before. I'm thinking of going this route in the path to a hi compression N/A 2.5. I know they may not flow as well as a stock 2.5 head, but generous porting can cure that and still leave me well under the astronomical price of the 2.5 heads.

Plus I understand that the 99 and later 2.2 heads can use 2.5 cams. That isn't as much of a concern though as Crower will regrind any cam for a relatively low price.

I guess I need to know what kind of compression I would be looking at with 2.2 heads (not shaved) on a 2.5 motor.

After reading the math geeks thread, I don't think I want to go THAT high in RPMs or compression.
 

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It's a good idea. A guy here in TX has the same thing done.. He beat an M5 on the highway. :devil:

GL with your project.
 

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overdeveloped beater
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Discussion Starter #3
Now THATS the kind of reply I was hoping to see!:biggest:

Should still come in under the price of stock 2.5 heads too if I choose my purchases carefully!!!

Maybe I'll just sell my turbos and do this NOW!
 

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MY00 2.5RS 2Dr BRP
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Storm, can you keep us updated on how your project is going?

This sounds really interesting.
 

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overdeveloped beater
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Discussion Starter #5
I'll post what I find out. It's gonna happen slow though. The 98RS is transforming from a nationals winning STS car into a nationals hopeful DSP car. We're treading new ground with some things and learning alot along the way.

Hopefully this other 2.5 project will come together soon enough to debut next season in SM! Afterall, if it doesn't work out as planned, I can still run a small turbo and make good enough power and not have to change classes (again).
 

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2001 Silverthorn Coupe
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Have you tried the 2.5 cams in a 2.2 (is this a SOHC or a DOHC, you drive a 98, but are talking about 99 and newer heads)? Where did you get that information, thats great. That is definitly a good way to save money using the 2.2 heads.

It might be a wise decision to use the extra money to buy cams from someone who has some Subaru experiance. It would be easier to get what you want without having any need to "experiment". If it didn't get what you want the first time, will it still be cheaper? If it is, you might go that way, but I wouldn't expect it to be right the first time.

cheeRS,

Greg
 

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overdeveloped beater
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Discussion Starter #7
No, I haven't tried the 2.5 cams in a 2.2 head yet. I'm looking into SOHC cams and heads for a shortblock buildup. I read about the 99+ heads and cams from another thread on this site. I haven't actually fitted them to be sure. I can measure the Cobb (or any other maker) cams and use the specs to be ground by the cam grinder of my choice. I have a friend who has the mild cams (SOHC) from Cobb and is currently not running due to catastrophic tensioner pulley failure. I may be able to talk him into letting me measure his cams. I think other makers publish their specs so that's another option. Desktop Dyno is yet another option, though I don't hold much stock in that given the absolutes of the variables involved.

The 98 DOHC won't be touched (yet) since I just co-drive it and SCCA rules limit what we can do in DSP. Alternate intake ideas are being explored. Waiting to hear back from TWM on a setup suitable for our boxers. They do quite well on VW's and Porsches!

I need to find out just how well the 2.2 heads flow since they might do almost as well as a stock 2.5 (optimism here). It's gonna take time and alot of thought to make this work like I want it too. Saving the money is paramount since it would be far too easy to just plunk down the $12-1500 on a set of good 2.5 heads. I DO NOT want to do that. I need to see if this can be done logically, and still make a decent gain.

Section 8 said:
Have you tried the 2.5 cams in a 2.2 (is this a SOHC or a DOHC, you drive a 98, but are talking about 99 and newer heads)? Where did you get that information, thats great. That is definitly a good way to save money using the 2.2 heads.

It might be a wise decision to use the extra money to buy cams from someone who has some Subaru experiance. It would be easier to get what you want without having any need to "experiment". If it didn't get what you want the first time, will it still be cheaper? If it is, you might go that way, but I wouldn't expect it to be right the first time.

cheeRS,

Greg
 

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2001 Impreza 2.5rs Sedan
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I'm just curious why do you want 2.2 heads on a 2.5 block? I understand why the wrx guys put 2.5 heads on a 2.0 block because that will give them more volume, but they will still be able to rev high. With 2.2 heads on a 2.5 block your decreasing the volume, and you arent getting any benifit out of it. Can you enlighten me? Thanx

-Chav
 

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by decreasing the volume in the combustion chamber you are raising the compression. Our engines are built to run on low grade gasoline. We can tak advantage of the jump in compression with higher octain gas. I don't know what the eventual increase in CR is though. THe added power will be more than the little bit of volume lost by making the combustion chamber smaller.

TWM emailed me back when I asked them about a Subaru throttle body setup-

"We just did a custom set up for a guy in England for $7000.00, with enough money anything is possible."

Doesn't sound like they want to do it to me. :mad:

If you are going to be using the stock shortblock, indepedent throttle bodies won't be the best way to extract power from the engine, particularly with a mild grind camshaft. If you have the block apart and have everything ballanced and raise the RPM a bit you can do something, but I don't know how hard I would spin the block as it is from the factory. Unless changing the engine isn't that big of a deal for you, since short blocks are pretty easy to find with minor piston slap for ~$250.00.

I PMed you.

Greg
 

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overdeveloped beater
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Discussion Starter #10
Right on...higher compression is what I was after. I don't want to have to shave heads or blocks or go with different pistons to get higher compression (just yet). Too much to go wrong at my current budget.

Heh...at least YOU GOT a response from TWM. I hate it when folks spit out complete bullshit just to shoo a potential customer away. I could do a hell of a lot more than TWM induction for $7000. I can PROMISE that! I can go to Summit Racing and buy 2 BBK twin Throat TB's for $600 (or cheaper if they got some scratch&dent) and fabricate a pr of plenums to mate them to the heads for maybe $300 at most! That leaves me alot of cash for ECU and fuel components and TUNING!

I realize that mild (or stock) cams wouldn't let the TWM system work to it's potential, but playing with cam timing along with rev limits, fuel delivery and the TWM system could likely see a gain worth exploring. For DSP, I can't change the cams anyway, and that's another project altogether...

As for balancing and raising the rev limit on this hi-comp. project, yes, that's an option. I might as well since the block will be apart. I'm starting with one of those warrantee blocks that had some slap. :biggest: I got 2 more too!

I want to go over all the info I can get before making a decision on what type of cam to run. Stock 2.5 cams probably to start, and then experiment with timing them and after maxing that...theorize on better grinds. Thanks for the helpful info and ideas, Greg.
Section 8 said:
by decreasing the volume in the combustion chamber you are raising the compression. Our engines are built to run on low grade gasoline. We can tak advantage of the jump in compression with higher octain gas. I don't know what the eventual increase in CR is though. THe added power will be more than the little bit of volume lost by making the combustion chamber smaller.

TWM emailed me back when I asked them about a Subaru throttle body setup-

"We just did a custom set up for a guy in England for $7000.00, with enough money anything is possible."

Doesn't sound like they want to do it to me. :mad:

If you are going to be using the stock shortblock, indepedent throttle bodies won't be the best way to extract power from the engine, particularly with a mild grind camshaft. If you have the block apart and have everything ballanced and raise the RPM a bit you can do something, but I don't know how hard I would spin the block as it is from the factory. Unless changing the engine isn't that big of a deal for you, since short blocks are pretty easy to find with minor piston slap for ~$250.00.

I PMed you.

Greg
 

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As for balancing and raising the rev limit on this hi-comp. project, yes, that's an option. I might as well since the block will be apart. I'm starting with one of those warrantee blocks that had some slap. I got 2 more too!

I want to go over all the info I can get before making a decision on what type of cam to run. Stock 2.5 cams probably to start, and then experiment with timing them and after maxing that...theorize on better grinds.
I am starting with a warrenty block too. :lol:

Thats always a good plan.

Now I am confused again. :rolleyes: Which engine are you building? The DOHC or the SOHC? DOHC will react very well to timing the cams differently, but the SOHC will not change much by messing around with cam timing. You may already know this, the DOHC is the best way to go if you cannot change cam grinds, to move the torque curve around.

Greg
 

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2001 Impreza 2.5rs Sedan
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Oh :biggest: Thanx guys! Good luck on your project it sounds like its going to be sweet!

-Chav
 

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overdeveloped beater
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Discussion Starter #14
Sorry for all the confusion. I'm building up an EJ25 from a warrantee block using SOHC 2.2 heads (for price reasons and personal curiosity).

I currently co-drive a 98RS with the DOHC in DSP. We're kinda doing dual duty since the OWNER of the 98RS discusses with me what we should do to his car to make it more of a beast. We split costs of parts, tires, etc...and I do alot of the wrenching while teaching him how to do some of this stuff.

I've been looking for a shortblockto build up and put in my 96L for a long time and ALMOST bought a couple online last year.... Then I took the 98 to the strip and just by chance started talking to a guy who worked at a local dealer. I asked about blocks and we pretty much made a deal I couldn't refuse, so I got 3 blocks with the intention of selling 2 to help finance the 3rd one's cleanup/machinework.

Meanwhile, we still have the 98 that we're trying to make nationally competitive in street prepared, which allows for some interesting mods that nobody else has tried on a Subie yet (to our knowledge). I don't like the fact that already the DSP Imprezas are being referred to as STS cars with Rcompounds. I want to show that one can take an RS and bring it relatively close to the limits of SP rules and do "very well". It really hurts that we can't revert to IT specs as other cars can, they can get very, very light and still make decent power and put it down with authority.

Altering the timing of the cams on the DOHC is part of our plan once we obtain or build adjustable cam gears. At only 33k miles, it's not ready for a new timing belt yet, but once we find a set of gears or a way to make the stock ones adjustable, we'll be in there changing that around.

The project that is the subject of this thread, is going to go into my 96L. I originally wanted to have a 2.5 built up last year to take advantage of DSP rules that clumped ALL Imprezas together. I was hoping to have a stock 2.5 (heads and all) pushing my L chassis with no power anything to DSP contention against the flyweight race bred Fiats and IT BMWS, Acuras, Capris, Neons, etc...

After reading about the prices of 2.5 heads and some peoples dis satisfaction with folks selling RS parts at REASONABLE prices just to keep the "value" of the RS high. I checked into other options and found that the "lowly" 2.2, though sought for it's turbo ready closed deck model, is virtually worthless to most. When I look at the stock power levels it puts out, I can't help but think that with more compression and some more agressive tuning, it might rival some conservatively tuned turbo motors.....Just what most folks are doing while fretting over the transmission longevity or crunching the numbers of lord knows what else. It's my opinion that motors running any amount of boost UNDER 10psi is a waste and should be tuned N/A or re-engineered to hold 10-15psi. Including trannies, axles, brakes, etc...

I'll build up a junkyard dog with very little hi-tech treatments, or expensive electronic gadgetry. Old Skool tuning with basic, time proven fueling control to keep things running reliably. Time may change this plan into something vastly different. I don't know yet. I'll have balancing checked to make sure bearing longevity is not an issue, but nothing extraordinary.

Puck....yeah, the MAP vs MAF is ECU related. It don't care what kind of heads you're running. Go for it if you want. Just know that headgaskets are an area of concern. Price may not be any higher due to the general concensus (or wholesale wool-pulling) that SOHC is "the way to go".
 

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Old thread but I am interested in what is the best setup discussed here. I have a bent valve on a 2.5 DOHC 98. I want to do 2.2 dual port exhasut heads(YEAR?) with DOHC or SOHC. What would be available. I also hear that the 2.5 cams(not sure DOHC or SOHC) when put into a 2.2, make it like a "mild" grid on them. This along with the increased CR means a good amount of gain in power.

Anyone done this? LINKS?
Anyone know what the compression ratio would be?
Anyone know what years were dual port 2.2 and where they SOHC or DOHC?
I have some idea on the last one but want to make sure.

Ideal build from this 2.5 phase 1 block with DOHC 2.2 heads(dual port) with 2.5 cams.

Please comments!
 

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overdeveloped beater
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Discussion Starter #16
Yes, it's been done. EJ25 bottom end with phase II EJ22 heads (singleport type that are otherwise identical to SOHC EJ25 heads) and Delta regrinds will get you a little over 11:1 compression ratio. Still runnable on a stock ECU and pump gas, and a big jump in power/tq across the board.

All EJ22s were SOHC, 95 and older had dual port exhausts and can use any EJ25 header. 96-98 had single port exhausts and need the matching header. 99-01 EJ22's got a redesigned head that is the same as the SOHC EJ25 head, with the exception of the exhaust port. It's also a singleport. The EJ22 cam has .030" less intake lift than the EJ25, but everything else is the same. The SOHC EJ25 cam only drops right into the latest style of EJ22 head, the older style are very different.
 

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info

Do you know which of these run phase 1 vs phase 2 intake manifolds. I have a full stock phase 1 and would like to retain as much of what I have to keep costs down. I have dual port exhaust headers also.

Looks like the hot setup would be:
98 phase 1 block phase 1
99-01 EJ22 SOHC heads phase 2(single port right?)
99-01 cams from 2.5 SOHC phase 2
Phase 2 2.5 head gaskets?
I assume I would need a 99-01 phase 2 intake manifold from a 2.5? or 2.2? and I would need single port headers.
Phase 2 intake manifold gaskets?

Need list:
EJ22 99-01 heads
phase 2 intake, exhaust, head gaskets
phase 2 intake manifold (2.5 or 2.2.. smae or different?)
single port exhaust header


I would be left with to sell phase 1 manifold, and dual port exhaust headers.
 

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overdeveloped beater
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Discussion Starter #18
That pretty much covers it. Although I would use phase I headgaskets. The PN has been updated to get the better design, but the thickness is key on that block. The pistons clear the deck by a small amount.
 

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So phase 1 head gaskets with a phase 2 head and phase 1 block. What do you think of the Cometic gasket? I used that one when my origianl gasket went at 60k.

Stock or Cometic?

Don't plan on turbo at all, I would just swap.

I would also assume using the intake manifold harness from the phase 2. Any other wiring since I am moving from phase 1 to 2 on the heads, an intake. I am going from DOHC to SOHC shouldn't need an ecu or new harness? Please advise. You have been most helpful.
 

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2001 STM Sedan
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storm, message xmoshx. he has a 97 obs with a 2.5 block and 2.2 sohc heads pnp and delta cams tuned with a greddy ultimate. that thing pulls hella hard but the downside is the head gaskets. the cr is around 12:1ish and the stock hg's have a hard time holding the extra pressure. he used sti mls's and everything is koshers. make sure to use the rs headbolts and use 93 octane only or else your detonate really bad.you'll need a good clutch to hold the extra power. an act or fidanza flywheel with an sti pressure plate would probably work out fine. from what i know, you basically have to PnP the heads when you do this to keep the cr in a managable state. a tune is also a huge plus. with these mods he pulls on wrx's most of the time. lol let us know how it goes. the torque specs on this thing should be awesome. perfect for dsp or sm class in auto x.
 
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