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Old 03-11-2018, 12:35 AM   #1
biggreen96
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Default Characteristics of stroked ej22t vs destroked 2.5?

I want to build a new motor for my rally car/fun car and I have the ej22t longblock that came out when I put the eg33 in. I realize nothing lasts forever, especially when racing and this junkyard 150k eg33 that I only changed HG's on might let me down. So I want to get something ready to go for that or put it in my OBXT. I have been reading up on the 2.35 combos but still am curious on which one (stroked 2.2 or destroked 2.5) is "better". Why do people go either route?

Is the stroker slower than the destroker rev wise? Would I notice?

Is the stroker going to be more torquey/punchy? Also would I notice?
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Old 03-11-2018, 07:33 AM   #2
kellygnsd
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Destroked 2.35 will be the more rev happy motor. The longer rods equal a slightly better rod/stroke ratio. You will take a low end torque hit with the de-stroker compared to the 2.5 at least. I myself run a destroked 2.35L with +4mm rods. Spins to 8500rpm and HP never falls off.
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Old 03-11-2018, 12:41 PM   #3
jamal
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The 2.1 strokers I've built all drove pretty well. Despite the change in displacement being small they had much better response and torque than a regular 205. For rallyx that might be the better option. The destroked engines on the other hand are meant to rev very high.

However, Wiseco's 2.2 stroker pistons are meant to be used with the phase 1 crank, which has smaller rod bearings (they just took a 2.0/2.2 crank and offset ground the rod journals 4mm smaller to get the extra stroke), and those rods, which are 131.6.

More expensive, but machining the block for #5 thrust and using a newer crank would be better for a stroker, but as far as I can tell you would need pistons custom made. Probably not too difficult or expensive though as you could just say, hey, JE, I want a set of your 2.2 pistons with a shorter compression height and a little more dish.

Also depends on the heads you are using. If they're 2.0 heads a 2.5 bore isn't very good. If they're sti 2.5 heads the 2.2 bore is too small. WRX 2.5 heads have a smaller chamber that doesn't hang off the side of a 2.2 though.

Last edited by jamal; 03-12-2018 at 02:57 AM.
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Old 03-11-2018, 09:50 PM   #4
idin
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Ej22 with Ej207 heads Vs Destroked 2.34 with EJ25 heads (both mildly worked heads plus valves and cams).

Would be very interested to know how they compare...

I imagine spool would not be very different due to 75mm stroke. But no idea about tq delivery.
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Old 03-11-2018, 10:44 PM   #5
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What turbo? The powerband is the major difference between the two. one will make power sooner than the other. You need to match that with the gearing of your tranny.

Better is what you're using it for and where you want the power to be.
Keep the EJ25 as is, run a VF52 and call it a day. Don't make things difficult.

Quote:
Originally Posted by biggreen96 View Post
I want to build a new motor for my rally car/fun car and I have the ej22t longblock that came out when I put the eg33 in. I realize nothing lasts forever, especially when racing and this junkyard 150k eg33 that I only changed HG's on might let me down. So I want to get something ready to go for that or put it in my OBXT. I have been reading up on the 2.35 combos but still am curious on which one (stroked 2.2 or destroked 2.5) is "better". Why do people go either route?

Is the stroker slower than the destroker rev wise? Would I notice?

Is the stroker going to be more torquey/punchy? Also would I notice?
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Old 03-12-2018, 12:35 AM   #6
biggreen96
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Which turbo is a good question.
No matter what I do I like the idea of using as much oem stuff to build the thing. Would it be a waste to put whatever version sti turbo on it? Can those even make 350whp on a 2.35? I read plopping 2.5 sti heads on the ej22t block works just fine.

A decade ago I put a vf39 on the stock ej22t in my old legacy but only ran 14psi, I enjoyed that, but it only made 216whp 235wtq. No real tune, just a wideband and an apexi boost box that allowed me to see if I was maxing the injector duty.

Making things difficult is half the fun!
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Old 03-12-2018, 03:45 PM   #7
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all else being equal (heads, cams, turbo, etc) 2 engines of equal displacement (achieved by different bore/stroke numbers) will make the same torque and HP numbers and the same curves, with maybe a few numbers +/- here or there.

short stroke allows for a higher rev limit because it reduces piston speed.
it also lets you fit a longer rod which is nice for keeping the load on the piston aimed at the crankshaft rather than cocking the piston in the bore and dragging the cylinder wall (minor, but it happens).

more bore is useful at higher rpm because it opens up the space around the intake valves for better cylinder filling vs a tighter, smaller bore.

more stroke can be useful at low rpm because the faster piston speed "pulls" harder against the intake valve, increasing the incoming air velocity
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Old 03-12-2018, 05:07 PM   #8
biggreen96
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Ok, so a 2.35 from stroking the 2.2 would spool faster than a 2.35 from destroking the 2.5 all else being equal(heads turbo fuel etc). That makes sense now.

I think stroker would be the way I would go then. I would rather spend money on a better turbo than head work to rev like crazy.
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Old 03-12-2018, 05:21 PM   #9
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They are both the same displacement, so both should be moving the same air at a given rpm. But with the stroked motor, the piston is accelerating up and down faster which should maybe help with spool and low-mid range power. On the other hand, it is doing so in a smaller bore. Given the same intake/exhaust port size shouldn't airflow and velocity be basically the same?


Like I said, the off the shelf 2.2 stroker pistons from wiseco are meant to be used with 25d crank, rods, and heads. To use better rotating parts, or get the desired compression ratio with different heads, you need custom pistons and/or block machining.

The benefit of a destroked motor comes from the longer rod. There are very few places making +2 or +4mm rods and they aren't cheap.

Meanwhile you could just stick forged pistons in a 2.5 and make more power and torque than either at a given rpm with the same turbo and heads.

Last edited by jamal; 03-12-2018 at 05:49 PM.
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Old 03-12-2018, 07:11 PM   #10
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were it my engine, i'd put the long stroke in the smaller bore.
only ~3.5 mm difference in bore but every little bit helps - smaller bore is easier to get spark timing right and lends itself to HG survivability better.
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Old 03-12-2018, 10:12 PM   #11
idin
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Quote:
Originally Posted by FuJi K View Post
What turbo? The powerband is the major difference between the two. one will make power sooner than the other. You need to match that with the gearing of your tranny.

Better is what you're using it for and where you want the power to be.
Keep the EJ25 as is, run a VF52 and call it a day. Don't make things difficult.
Say Gen 2 GTX 3582 turbo size. And how about GTX 3076 Gen 2?

Power 5-600whp
Road course application
Progressive and usable powerband, as wide as possible

Last edited by idin; 03-12-2018 at 10:34 PM.
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Old 03-14-2018, 09:11 AM   #12
FuJi K
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Quote:
Originally Posted by idin View Post
Say Gen 2 GTX 3582 turbo size. And how about GTX 3076 Gen 2?

Power 5-600whp
Road course application
Progressive and usable powerband, as wide as possible
Rotated setups we've noticed on built 2.5L the turbo starts to come in 3500 and full swing by about 4200rpm. From there it'll pull hard up to 7500rpms. This is with cams like 272 duration. 62mm and larger turbos the built 2.5L we'll pull them to 8000rpms. Full swing in boost is typically 4000-4500.

When you drop the displacement with a 75mm stroke on a 99.5 bore, add about another 500rpms up the rev range to that power band. We did up a 2.1L build with a 62mm and full swing came on about 6000rpms, and from there it pulled to 9000rpms.

These engines aren't limited on revving.
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Old 03-14-2018, 09:29 AM   #13
FuJi K
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Quote:
Originally Posted by biggreen96 View Post
Ok, so a 2.35 from stroking the 2.2 would spool faster than a 2.35 from destroking the 2.5 all else being equal(heads turbo fuel etc). That makes sense now.

I think stroker would be the way I would go then. I would rather spend money on a better turbo than head work to rev like crazy.
I ran my built 22T (9.0:1cr) with stock 75mm stroke with a 20G. I now put a 79mm crank in with a 98mm bore; 2.4L displacement. What can be expected? There isn't anything surprising that's going to come out of the 2.4L setup. I say this because really it isn't going to be any different from the 2.5L we already have. We're talking about a 98mm bore to a 99.5mm bore while running the same 79mm stroke.

Now a destroked 2.5L block setup isn't anything surprising. It's like an EJ22 but just slightly larger bore. The power band moves up the rev range compared to a 2.5L. Its larger 99.5mm bore compared to the EJ20's 92mm helps make more power sooner & also more initial low end torque. This is also why the 22B STi has a lower redline than the EJ207 GC8.

If you don't pull 9000rpms at a minimum, you're not revving like crazy.
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Old 03-18-2018, 08:55 PM   #14
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Quote:
Originally Posted by FuJi K View Post
I ran my built 22T (9.0:1cr) with stock 75mm stroke with a 20G. I now put a 79mm crank in with a 98mm bore; 2.4L displacement. What can be expected? There isn't anything surprising that's going to come out of the 2.4L setup. I say this because really it isn't going to be any different from the 2.5L we already have. We're talking about a 98mm bore to a 99.5mm bore while running the same 79mm stroke.

Now a destroked 2.5L block setup isn't anything surprising. It's like an EJ22 but just slightly larger bore. The power band moves up the rev range compared to a 2.5L. Its larger 99.5mm bore compared to the EJ20's 92mm helps make more power sooner & also more initial low end torque. This is also why the 22B STi has a lower redline than the EJ207 GC8.

If you don't pull 9000rpms at a minimum, you're not revving like crazy.
Thank you.
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