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Old 08-25-2010, 09:14 PM   #1
REDrum
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Default NA Engine for Rally "Open Light" class?

So I'm exploring going from Rally America PGT class (turbo) to Open Light (NA). Lots of good reasons to due so, too many to list/compare here... No going open or super production either, so lets not go threre.

So the challenge is how to get a decent NA EJ25X and get it into my 2002 GD?

My performance goals: are ~140 WHP (i.e. ~30 hp over stock), durable enough for 10 events or so, low end Tq and top end powah. Hi flow headers are a given (like TWE 4-2-1)

Phase II SOHC seems to be the most modded with peeps, (plus I have contempt for the Phase I short blocks; (cost me plenty in the late 90s)... I'll be running standalone ECU (Vipec) so OBDII ain't an issue.
Options under consideration:
  • EJ254 w/ <50K on SB (w/AVLS) then add some cams and bolt on mods.
  • Buy any old EJ253 rebuild w/ cams, opened up bearings/rings, hi comp pistons, mild PnP...
  • Or...lurk for decent flowing SOHC heads (PnP'd, AVLS or something JDM) add cams and bolt up to a EJ257 SB with opened up rings/bearings and hi compression pistons, blah-blah-blah

Would like to keep long block costs <$4,000.00.

Not considering E85 or anything higher than 93. Don't want to go much greater than 11:1 compression.

Ideas welcome!
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Old 08-25-2010, 09:49 PM   #2
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i would say with a good built bottom end and cams headers and a good exhaust and a good tune you would be were you want to be. I use to race a scca 240sx with the ka24e sohc motor, the stock output was around 130 to the wheels, we ran a FCW crank and 11.5:1 Compression and 4 down draft carbs and race cams and we put 200+ whp to the ground and spun it to 9000 rpms. SO if this can happen on a non computer controlled motor i am sure you can hit that mark with your computer controlled motor. Also we built one with ITB intake and a Aem standalone and put down 237whp around 30 more with the computer. Good luck with your build.
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Old 08-25-2010, 10:00 PM   #3
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Somthing else to think of the ne 09-10 na motors are putting that much power down stock.
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Old 08-26-2010, 07:07 AM   #4
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I hate to be the bearer of bad news but the 09-10 N/A engines don't put out any more hp than the 06-07's. As a mater of fact, the '10 makes 3hp less than the '06...although it does make 4lb/ft of torque more. Unfortunately, our cars only put about 110hp to the wheels in their stock form. You can thank our wonderful awd for that.
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Old 08-26-2010, 07:17 AM   #5
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I would dodge AVLS and get a motor with normal cams. You won't see any benefit, especially if you're using a 6 speed or rally-geared 5, and it's another complication for tuning and maintenance.

Plus, the AVLS pressure sensors are known to start leaking on a motor which sees high revs/abuse often. I've replaced both mine already, they were leaking a quart per change at 60kmi.

I would also use an NA block, rather than the beefier turbo blocks, because it's a bit lighter and the extra reinforcement won't be necessary, especially if you don't plan to build for race gas.

Definitely focus on the heads, increasing redline as much as possible. Even moreso if you're sticking to a 5spd.



EDIT: bhilly - a factory EFI motor is much harder to get more performance out of, because they're already so good at everything right off the bat.

Last edited by sniper1rfa; 08-26-2010 at 07:25 AM.
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Old 08-27-2010, 07:45 AM   #6
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Thanks guys, please keep it coming.
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Old 08-27-2010, 09:35 AM   #7
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Is this a 2002 WRX you're turning into NA?
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Old 08-27-2010, 10:03 AM   #8
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Quote:
Originally Posted by FuJi K View Post
Is this a 2002 WRX you're turning into NA?
Yup!!!!
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Old 08-27-2010, 06:35 PM   #9
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I ran 10.8 CR on pump gas (91 octane) so I think with 93 octane you could get away with 11.5:1 easily.

Stick with a N/A block, no need for extra strength. Call Delta cams and see if they have any recommendations for you. I love my 2000 grind in my SOHC EJ25 heads with no port work done, I can only imagine what they could do if properly ported and rev'd out to 8k with good springs and retainers. I'm not an expert in AVLS, but I don't think I would use it in your case.



~Josh~
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Old 08-29-2010, 01:28 AM   #10
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Quote:
Originally Posted by REDrum View Post
Yup!!!!
if that's the case, don't worry about going SOHC. Get a set of EJ255 heads like '06+ WRX/FXT or '07+ LGT. Mate that with a higher CR piston'd EJ25 lighter rods motor. Tune via OpenSource with your WRX ECU.
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Old 08-29-2010, 08:59 PM   #11
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^^^ This.

It's already been done if I remember correctly. Might have to search the built motor section or engine management section. I remember reading of a project where someone removed his turbo and added higher compression pistons, then open source tuned the ECU for NA fueling and timing.

Jay
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Old 08-29-2010, 09:15 PM   #12
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you're probably thinking of carl seigler's car. Carl or carl s. on the forums, depending on which forum.

11:1 wisecos, stock STi everything else. It worked OK, but i wouldn't go that route if you're going from PGT to open light, rather than starting in open light and moving to SP or open. Sounds to me like the OP wants a more competitive car, since he's already got a good bit of experience.

Last edited by sniper1rfa; 08-30-2010 at 06:35 AM.
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Old 08-29-2010, 09:19 PM   #13
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You don't need anything exotic for the class. Get a salvaged SOHC engine with delta cams, good equal length headers and exhaust then tune it and learn to carry more momentum in the turns. The best thing about the class is that you don't need a crazy build to be competitive in it.

We tried to run TWE headers and there was no way without dropping the skid plate really low.

J.
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Old 08-29-2010, 09:23 PM   #14
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It might be easier to use the stock heads and put money toward building them. There are a few places that offer CNC combustion chamber work to match up to the 2.5 bore.
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Old 08-31-2010, 12:57 PM   #15
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I've never used them but I've heard a lot of people complain that delta cams in the SOHC motors really push the powerband to the high end. If that's the case, I would try to stay away from them for this type of build.

I'm liking Fuji K's suggestion quite a bit.
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Old 08-31-2010, 02:27 PM   #16
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Too bad they limit the displacement to ~2650cc's. I'd like to see some of the subie 6 cylinders get some competition duty. Open light would be the perfect spot.
Looking at open light results for this past year, certainly looks like the class doesn't have huge numbers. I think a midly modified stock motor, would make YOU more than competitive. I think head work, and equal length headers would put you in pretty good shape, so long as you make sure you are running as light as possible. As your chassis is a bit heavier out of the box than the gc's.
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Old 08-31-2010, 04:02 PM   #17
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Thanks guys, please keep it coming, all good.

Quote:
Originally Posted by sachilles View Post
As your chassis is a bit heavier out of the box than the gc's.
By the time the NA engine goes in it will no longer be "my" chassis... Gunna be swapping seats w/ my 5'-2" co-driver for a year...
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Old 09-01-2010, 03:24 AM   #18
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Quote:
Originally Posted by REDrum View Post
Thanks guys, please keep it coming, all good.



By the time the NA engine goes in it will no longer be "my" chassis... Gunna be swapping seats w/ my 5'-2" co-driver for a year...
I'd have to agree with a couple of the other posters here. your fighting against a couple other cars at most events. Some events (the ones not on the national calendar) recently have only had one OL car at all. If you car about fighting it out with other people in the same class as you consider going G2 (since you said you didnt want to do SP/OC). I'm just not sure spending a whole bunch for a few more HP is really worth it..

I guess if your just doing it for fun then that's cool. Anythings worth doing for the fun of it

I was told PGT was more expensive to run the SP, plus SP has some pretty decent contingency money and OL seems to have jack (sadly).
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Old 09-01-2010, 06:44 AM   #19
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Hey, Have you looked into anything about the intake manifolds? Everyone goes straight to the exhaust, but if theair going into the engine is restricted it won't help. I saw a thread about a N/A build using 05(?) (STI?) components including the entire intake runner and using a 65?mm mustang throttle body.

Just a thought...

Wes.
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Old 09-01-2010, 08:53 AM   #20
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Quote:
Originally Posted by westu37 View Post
Hey, Have you looked into anything about the intake manifolds? Everyone goes straight to the exhaust, but if theair going into the engine is restricted it won't help. I saw a thread about a N/A build using 05(?) (STI?) components including the entire intake runner and using a 65?mm mustang throttle body.

Just a thought...

Wes.
They used an 05 2.5RS intake. It seems to be the clear favorite of most N/A people for power builds.

Also, they used, I believe, 11.2 CR pistons which be the best choice for something like this if you are comfortable running 93 on that high of a CR. To my knowledge, no one makes a high strength 10.0 piston for these motors and you'll definately bust a stock cast RS piston if you try to use one of them.
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Old 09-01-2010, 11:04 AM   #21
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Quote:
Originally Posted by REDrum View Post
Thanks guys, please keep it coming, all good.



By the time the NA engine goes in it will no longer be "my" chassis... Gunna be swapping seats w/ my 5'-2" co-driver for a year...
Oh, very cool. I bet she'll do well.

Will you do any more hill climbs?
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Old 09-01-2010, 11:48 AM   #22
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Quote:
Originally Posted by REDrum View Post
Thanks guys, please keep it coming, all good.



By the time the NA engine goes in it will no longer be "my" chassis... Gunna be swapping seats w/ my 5'-2" co-driver for a year...
That kinda explains the no SP/OC thing. If she's totally new to the drivers seat she won't have enough co-efficients.

I'm just shooting for reliability on our OL car. finish the race without kissing trees or breaking to much.
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