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Old 04-13-2010, 02:42 AM   #1
blkjag
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Default Budget Turbo Build

So, I've had a '99 2.5RS for a few years now as a beater project and I'm looking to pull the drivetrain to replace the head gaskets and swap the transmission and rear-end for a 5 spd (it's auto now). I also just ran into someone who is selling an '03-05 wrx longblock real cheap.

What I'd like to know is this:
If I were to take these two engines ('99 N/A 2.5 and the wrx engine) and use them to build a turbo engine what would be the best combination of parts?

I hear that the 2.5 N/A heads flow well but I don't know if there's any modification required to put them on the wrx block. I also don't know what combinations of cranks/rods/pistons will give the best results.

I wouldn't be opposed to a higher compression turbocharged setup requiring higher octane fuel, (I'm working on an E85 lexus engine with 10:1 CR and ~10 psi boost) as long as the engine internals can support it. But, a better-flowing wrx engine (using N/A heads) and maintaining the stock compression ratio would be fine (maybe best for now).

Also, I have fairly extensive experience with engine rebuilds and fabrication work, so I'm not at all intimidated by tapping the holes required for oil and coolant in the N/A heads (if I understand correctly these are cast in the heads, but blocked for N/A motors).

Mostly, I'm just curious to know what options might be available with these parts. Crazy ideas welcome.

Thanks guys.
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Old 04-13-2010, 02:53 AM   #2
blkjag
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Oh, it didn't even occur to me before, but I also have a '96 Legacy 2.2L engine available for parts. So, throw that into the mix too.

And in case anyone wants to suggest it, I'm not at all interested in just buying a full swap. I'm looking for an interesting project with this car.

Thanks again.
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Old 04-13-2010, 11:47 AM   #3
2milehi
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Is the '99 a DOHC or SOHC?
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Old 04-13-2010, 12:42 PM   #4
soobaviator
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'99 is SOHC

Check the EJ205 compression to see if it's good. Maybe you can get away without doing a re-ring/refresh on it which will save some dough. If not you can do it for about $300 if you use your own labor. Simplest and easiest way and the EJ205 will be stronger all around than that 25 for boost. I would not use the 2.5 heads on the 205 compression will be very low... The advantage is that you can keep the 253 manifold however...

Another option is to use the EJ25D short block and re-ring/refresh it. Use the EJ205 heads. The EJ253 has a funky rod length and 48 mm journal crank so there are limited options. If it were me I'd go with the OTS Wiseco's with the WRX heads and stock EJ253 Rods with upgraded bolts. Compression should be something over 9:1 good for a careful pump tune or E85. For the manifold find a take-off EJ205 turbo manifold.

The strength of the EJ253 is limited by the open deck and thin walls (1 mm less than a 205 or 22E) Also the rod journals are 48 mm as opposed to 52 mm for turbo and N/A engines after that year. Just something to think about.

The best deal is to take that 22E, re-ring/refresh and use the 205 heads. You could also use some STI rods if you like without modification. There are a number of piston options including OTS pistons from Wiseco. The '96 22E is phase 1 so the WRX/STI cranks won't work without machining for thrust #5 main. Compression from 8.5-9+ depending on pistons.

Good luck with it!

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Old 04-13-2010, 02:04 PM   #5
blkjag
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Thanks for the replies.

Is there a relatively inexpensive set of pistons (maybe something that's OEM on another engine) that could be used with the EJ205 block and the EJ253 heads to get the compression ratio back up to the 8.5:1 - 9:1 range?

Also, is the EJ22E block really much stronger than the EJ253?

One other question; are timing belts of different lengths required when swapping heads/blocks like this? Or, are all the crank pulleys all pretty similar (so you'd just be able to use the OEM belt for whatever heads you choose).
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Old 04-13-2010, 02:37 PM   #6
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Quote:
Originally Posted by blkjag View Post
Thanks for the replies.

Is there a relatively inexpensive set of pistons (maybe something that's OEM on another engine) that could be used with the EJ205 block and the EJ253 heads to get the compression ratio back up to the 8.5:1 - 9:1 range?

Also, is the EJ22E block really much stronger than the EJ253?

One other question; are timing belts of different lengths required when swapping heads/blocks like this? Or, are all the crank pulleys all pretty similar (so you'd just be able to use the OEM belt for whatever heads you choose).
Drop in Wiseco's and an .027 inch MLS gasket looks like it will get you to 8.5:1, if I may revise and extend my remarks. Quench would be good to go at .043 inches. The Wiseco pistons retail for $450-$550

If you are intent on using the 253 heads and want high compression go with the 22E and the 253 heads. Stock block the compression is over 9:1 with a .051 in MLS gasket. Quench is good at .041 inches on this set-up.

It may be an even shot up to a certain power level but for a given same HP the pressures inside the 253 cylinder will be lower and it has a thinner wall. The 22E has a thicker wall but the cylinder pressures will be higher. The 205 and 22E have the same wall thickness and are open deck. The 205 works for boost to 30 psi. The limits of the 22E should be a bit less than that. The 253 was not designed for boost, especially the heads. It comes down to a calculated risk depending on your power goals.

To my mind I can imagine the 253 cylinders "walking" all over the place with every ignition event under boost so it concerns me. It may not concern you...

SOHC to DOHC the belts are different. Crank sprockets maybe they are but not sure. In any case they are interchangeable on the cranks so no problem switching to the right setup.

How much boost and what turbo?

Last edited by soobaviator; 04-13-2010 at 04:34 PM.
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Old 04-14-2010, 02:42 AM   #7
blkjag
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I'm targeting 250-300 whp (probably closer to 250). I've read some of the threads on this and saw the dyno pulls producing ~250 whp with the EJ205 heads/EJ22E block. I think on the first pull that was shown, the engine ran 22 psi - I don't have plans to go much past that, if at all. I'm not sure what turbo I'll use either, but probably a used OEM subaru or mitsubishi unit, something cheap. I was also playing around with the idea of twin induction using a turbo and an eaton M62 or M90 supercharger (I have one of each sitting around for this type of project).

One thing I'd like to have confirmed: the EJ253 heads should flow better then the EJ205 (due to larger ports and valves), but the valve train can't handle boost above 6,500 rpm or so - does this sound correct?

I guess that would become a trade-off. Do better flowing heads limited to a lower redline beat poorer flowing heads with a higher redline?

From what I've read it seems like I could probably get away with the OEM EJ22E block and rotating assembly and use either the EJ205 or EJ253 heads. (I guess the weak point will be the pistons, since the EJ22E ones look a lot wimpier) Right now I'm tempted to try out the EJ253 heads and see if I can gain enough power from improved port/valve flow to make up for a lower redline. I guess with that setup (if the CR is > 9.1:1) I'll probably run E85 to keep detonation and combustion temp under control (I think the local E85 mix has an octance rating of ~103 these days).

One other nice thing is I wouldn't have to buy the wrx longblock, I could just use the parts I already have.

I'm also thinking about closing the deck with metal epoxy (there was a neat thread on honda tech about this a few years ago and I ran into it again on this forum a few days ago - always thought it was a neat idea).

Any thoughts? Am I crazy to try to get 250 whp on the stock EJ22E pistons?
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Old 04-14-2010, 10:09 AM   #8
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Quote:
Originally Posted by blkjag View Post

One thing I'd like to have confirmed: the EJ253 heads should flow better then the EJ205 (due to larger ports and valves), but the valve train can't handle boost above 6,500 rpm or so - does this sound correct?

I guess that would become a trade-off. Do better flowing heads limited to a lower redline beat poorer flowing heads with a higher redline?

From what I've read it seems like I could probably get away with the OEM EJ22E block and rotating assembly and use either the EJ205 or EJ253 heads. (I guess the weak point will be the pistons, since the EJ22E ones look a lot wimpier) Right now I'm tempted to try out the EJ253 heads and see if I can gain enough power from improved port/valve flow to make up for a lower redline. I guess with that setup (if the CR is > 9.1:1) I'll probably run E85 to keep detonation and combustion temp under control (I think the local E85 mix has an octance rating of ~103 these days).

One other nice thing is I wouldn't have to buy the wrx longblock, I could just use the parts I already have.

I'm also thinking about closing the deck with metal epoxy (there was a neat thread on honda tech about this a few years ago and I ran into it again on this forum a few days ago - always thought it was a neat idea).

Any thoughts? Am I crazy to try to get 250 whp on the stock EJ22E pistons?
EJ253 heads are SOHC the valves are not bigger than the S20 heads and there is no evidence that they "flow better" in a turbo application. The valvetrain itself does not care about boost. It is effected by RPM, friction, inertia and heat.

Phase 1 EJ22E pistons are beefier than the phase 22E pistons. Almost totally different. However both are cast and again not designed for boost. The phase 1 pistons should be stronger for a turbo setup.


Don't even try a DIY closed deck unless you are going to add additional cooling capacity such as an additional oil cooler, oil squirters and larger capacity sump. Unless carefully designed a closed deck EJ turbo motor needs more cooling than a open deck motor.

Just keep it simple, you are not building a LeMans engine or reinventing anything. The simplest combination of parts that works will be the most effective. The S20 WRX heads are turbo heads, that's what they are for. Use them on the block you chose with the requisite gaskets and manifolds. Pick a turbo that suits your performance goals and is within the mechanical limits of the engine parts. I would say 250WHP on pump is pushing the limits with the 22E or 253 bottom end. A WRX TD04L will get you in that range without much difficulty.



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