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Old 02-09-2008, 04:19 PM   #1
bsikora
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Default Question about stroker kits....

I was just wondering is their any kind of stroker kits out there for a ej25 N/A engine? I am wanting to build a motor for my car. oh by the way i am staying N/A. I dont want a turbo! I was looking to see if their was a Stroker kit so does anyone know? Thanks for the help in advance. Oh by the way please only say something if your going to help. Please no Post whoring. thanks!


Blake
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Old 03-16-2011, 06:28 PM   #2
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old bump... gotta be an easy answer, im sure their is a guru for n/a subby out their somewhere... hell 250hp out of a n/a would be pretty bad ^^^.
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Old 03-16-2011, 06:41 PM   #3
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Why does no one simply Google these things?

Manley makes the cheapest option, although there are some other brands out there. A stroker kit typically bumps displacement from 2.5L to 2.71L by extending the stroke. The crank diameter goes from 79mm to 83mm. The Manley kit uses the same length rods but runs modified pistons with hole located higher up towards the top of the piston to account for the change in stroke. There aren't many options for compression, but you could have Manley make a custom piston if you so desire (example high compression + stroker). The Manley pistons and rods aren't the lightest ones out there (still lighter than stock) if building a very light weight package is important for you. Pricing tends to be pretty similar across vendors, around $2200 for the full kit, $1200 for just the crank alone, but you will need a rod + piston package that is made for the stroked crank.
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Old 03-16-2011, 08:29 PM   #4
zero883xl
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i was more asking if its been done? experience? hp? cost worth gain? lot of what if scenarios on here, but no one seems to have any actual butt dyno experience.
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Old 03-16-2011, 10:19 PM   #5
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Ah. I have not seen it done on a NA motor yet. There are a number of stroked STIs and such, but for the NA, nope.

When I get some spare money that's burning a hole in my pocket, I might at some point look into seeing what the EJ25 can really do when built to a race level. My idea would include the stroker kit, custom high compression pistons, E85, race heads, race cams, and appropriate exhaust header and intake manifolds for the new flow levels. Zzyzx has already built a 300chp NA motor, so there is known potential. It's simply a matter of spending the money, getting the pieces together, and actually building up the motor.

The problem I see with this is that as a NA format, there is no replacement for displacement. It's best to start with as much displacement as we can, and well...the EG33 offers more, and there is hardware available to bore it out to 3.5L. One may even be able to get a custom stroked crank built for it to get it more near 4.0L, and the engine only ways 50 lbs. more for a whole lot more displacement to start with. P&P work and cams get you +300chp pretty easy and more grunt down lower to boot. When we talk big power in the NA format, we always want to start with as big of a package as we can feasibly fit. The EZ36D is super expensive. The EZ30R is too. The EZ30 is getting cheap but also older. The EG33 is super cheap and is well known due to the SVX community building up their motors, both in NA format and forced induction. There's apparently even EG33 based naturally aspirated drag motors doing +450hp (on alcohol I'm sure). However you get the point. You're already going to toss thousands into any motor. Why start with the EJ25 if it's not going to be a forced induction setup?
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Old 03-17-2011, 01:33 AM   #6
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seems like there really should be a market for this, i understand the power wouldnt be a huge unrealistic gain, but maybe 2500-3000 and promise the n/a guys somewhere upwards of 220hp, 220 lb tq? id consider that a good. deal.... must research and see if i can involve others in this scheme...
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Old 03-17-2011, 08:43 AM   #7
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Look no further than what the turbo folks are doing with stroker kits. The pieces are out there, available and in-use.....they're just being used in a low compression, forced induction design. I see custom pistons being the only hangup, if you can call it that.


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Old 03-17-2011, 08:44 AM   #8
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The cost-to-benefits ratio just doesn't make any sense. This isn't like a Windsor motor that you can stroke from 351ci to 427 or even larger, or like a LS motor that you can stroke from 346ci to 427 or even larger. Those are ~23% displacement gains that produce significant power and torque gains. When you're starting with an engine that's already easily capable of 400bhp at the stock displacement, adding 20+% displacement is a healthy return on your investment.

Stroking a 2.5L to a 2.7L is barely a third of that (8.4%). Even if you're making 100hp/L (which is something very few people have done with a N/A EJ25, and I'm not sure any of those have been street-able motors), you'd be gaining ~20hp by spending a couple of thousand bucks on a stroker setup.

I'm with BRR. If you're going to spend the money to stroke anything, stroke an EG33 out to a 3.8 or 4.0 and have some real fun. Stroking a N/A EJ25 just seems like an utter waste of time, effort and $$$ to me.

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Old 03-17-2011, 09:38 AM   #9
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Quote:
Originally Posted by Patrick Olsen View Post
If you're going to spend the money to stroke anything, stroke an EG33 out to a 3.8 or 4.0 and have some real fun.
I'm familiar with a couple of high compression builds, but I can't think of any "civilian" builds with displacement bumps to that degree.

NA definitely stands tallest via displacement, but that's sometimes a stumbling block for street legal builds. It's got to extend beyond NYS that OBD-II vehicles are required to jack into the state DMV and say that they're happy. This is where, in a given OBD-II car, keeping the stock engine management (or more modern OEM) isn't optional - it's obligatory.

If your project consists of a registerable 2.5i that you absolutely, positively, religiously want to keep NA, you need deep pockets, earplugs and a tolerance for disappointment in ROI.

The EG33 definitely has its merits. There are various cams, pistons, rods, etc. available for NA and FI applications, and (wrong forum, I know) they've been boosted DIY by turbo, centrifugal, and twin-screw. I don't know if there are any roots applications, and I honestly don't know where you'd fit a roots supercharger, anyway. In states where OBD-II compliance is a pass/fail for your inspection, I wouldn't consider it an option to stuff one in anything more modern than 1995.

The balls-out EG33 racer you're looking for: Rigoli. Hit it up on YouTube and watch that thing fly off the line - it's obscene. It's like hyperspace.

The right reason to stroke a modern NA EJ25? "I abhor boost", and/or "hp per dollar isn't a concern".

Where did that zzyzx engine go, anyway? Its fame was only longer than the xcceleration FI mill's because it actually found its way into a car. Aaaaand... Don't forget that it was on 108 octane.

Last edited by LetItSnow; 03-17-2011 at 10:11 AM.
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Old 03-17-2011, 10:17 AM   #10
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crower do a 2.7L kit. but not for the N/A's.


they cost about as much as a brand new engine from subaru ($5500 or so iirc).
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Old 03-18-2011, 12:12 AM   #11
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Techworks Engineering can do it. They've stroked a 2.5L up to 2.99L.

If you have to ask about price, you can't afford it.
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Old 03-18-2011, 01:25 AM   #12
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i can afford it. im just trying to find a better combination of parts for 2.5i cars, think i might start a different post and gauge interest.
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Old 03-18-2011, 01:27 AM   #13
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Quote:
Originally Posted by zero883xl View Post
i can afford it. im just trying to find a better combination of parts. think i'll start a new thread and guage interest on a whole kit. just cause some people bought n/a subaru's dont assume we're poor.
It's not just about being poor.

It's about being willing to spend $5000 to gain 30hp.
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Old 03-18-2011, 05:02 AM   #14
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Yeah, the value in it is the tough part to swallow. Really, if you're going to invest money for HP, you want to really go all out. It's not just about stroking the motor because you're already going to pull it, take it apart, and installing a pile of new internals. There's a lot of time and money invested in just that. However, it's not much more to start doing other things like doing head work, upgrading cams and springs, getting custom high compression pistons made, adding coatings, and possibly stepping to a high octane fuel (at least premium, but some of us have E85 (105 octane)) to allow more compression and timing. You start getting to a point that you're building a completely different engine without a whole lot more invested beyond the point you were already going to do. Then the HP numbers start going way up. You can be looking at something that's making 100hp over stock, but it won't be the same engine, and it won't be a matter of just tossing in a stroked crank. However, it will make the high cost meaningful and the car pretty darn fun to drive.
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Old 03-21-2011, 02:19 AM   #15
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Zero, if all you are looking for is 200-230 chp then you do not need a stroker kit. Just bolt 99-00 sohc heads to an STI block. It is a proven combination that most rally guys use, and it is a great daily driver.


the problems with suburu 6-cylinders is the dog legs in the exhaust ports are even more exaggerated then in earlier model 4 cylinder heads. Creating a restriction and high heat during high flow. Also the newer motors are chain driven and will skip timing under high HP.
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