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Old 08-03-2000, 11:13 AM   #1
MikeYOX
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Question Imprezer- What's wrong with the EJ20?

You said you'd never put one in your car in a recent post.
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Old 08-03-2000, 01:11 PM   #2
Imprezer
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Very simple, because I have a 2.5L high compression engine that is turbo charged and has a very good engine management system which makes sure that my EJ25 works at its peak potential safely. Why go down to EJ20 with low compression for more $ and more headache? Yeah yeah yeah, WRX, real turbo engine, closed deck, yappidy yap yap. Until my EJ25 blows up in peices, which I doubt it ever will, I won't even think about EJ20.

Oh, boy, someone is already knocking on my door and wants to kick my EJ25 butt.
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Old 08-03-2000, 01:53 PM   #3
ColinL
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I've noted that many ProRally guys are still favoring the WRX STi motor for its endurance. I agree with Alex and Shiv here, the EJ25 can make the same power and more torque as the EJ20 and will be less stressed due to it's higher displacement.

Of course Group N limits you to 2.0L... but I don't think the SCCA Open class has such a limit. I could (easily) be mistaken though.
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Old 08-03-2000, 02:12 PM   #4
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Imprezer, could you please elaborate on your cars set up?
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Old 08-03-2000, 02:17 PM   #5
North Ursalia
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I think my biggest consideration would be how hard the EJ20 is to get in the first place. The 2.5 is EVERYWHERE in the US- you can get one from a dealership if you have to. If you blow the EJ20, how soon will you have another? Think of how scare the engine is, never mind spare parts if you should need them.
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Old 08-03-2000, 02:18 PM   #6
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MY99 Impreza 2.5 RS

CUSCO WRX Equal Lengh Tubular Manifold
CUSCO WRX Catless 3.5" Downpipe
CUSCO WRX 3.5 Downpipe Back Exhaust System
IHI VF-22 Ball Bearing & Watercooled Turbocharger
Modified Fuel Delivery System
VPS Forced Induction TEC II Kit
Custom True Cold Air Box
Custom Intercooler w/ waterspray

Thats about it. There are few other things, but these are the most important ones.
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Old 08-03-2000, 02:19 PM   #7
Jude DeMeis
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Don't forget the STi EJ20 has a forged steel crank and twincam heads with solid valve lifters granting an awesome 8000rpm redline with no valve float.
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Old 08-03-2000, 02:24 PM   #8
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Yeah, I know. I didn't want to list it all so I refered to the rest of the differences as yappidy yap yap. Sorry if I was unclear, hehe.
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Old 08-03-2000, 02:26 PM   #9
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Jude, you might search for Jay_UK's teardown and analysis of his STI4 versus a regular 220HP UK 2.0L turbo. He seems to think there isn't much difference except the heads.

The '98RS had solid lifters and DOHC if we choose to go that route. But there should be no need to rev to 8000 RPM, that's actually one of the durability points in the EJ25's favor.
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Old 08-03-2000, 02:26 PM   #10
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nice!
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Old 08-03-2000, 02:46 PM   #11
Jude DeMeis
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Both you and the guy from UK are simply wrong. Fact: Only STi motors come with solid lifters and forged steel cranks. They also have special pistons.

As for 8000rpm, it's very useful as you can hold a gear longer which is worth serious time in a short race (e.g. autocross): Rather than waste time grabbing third gear, you can stay in 2nd to 8000rpm. It also makes the engine more resistant to accidental overeving. I once saw a racer misshift and overrev a Lotus Esprit (solid lifters) to 10000 rpm. Don't try that with an EJ25...
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Old 08-03-2000, 02:52 PM   #12
Joel Gat, 1.8L
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So if you care about the heads so much, bolt the heads to the EJ25. Another great mod to a great engine

Joel - and yes, the heads fit and should be as easy to find as the blocks - not very at all (the STi R/RA heads or blocks, that is).
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Old 08-03-2000, 02:55 PM   #13
ColinL
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I'll take the high road and not get into a petty debate since I personally didn't disassemble the engines.

However, your comment on RPM is ridiculous. A particular NUMBER does not matter, it is HOW BROAD of a torque curve you have. If you can make power from 2500-6500 RPM, why is that so bad compared to 4000-8000?

I'd not roll my dice on any engine surviving a mechanical overrev. The Lotus driver was lucky.
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Old 08-03-2000, 03:22 PM   #14
Jude DeMeis
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Colin, unless you change your final drive ratio, the 6500rpm redline is going to require upshifting the car more often during an autocross. With the same gearbox, the 8000rpm limit allows you to hold 1st and 2nd in situations where the other car would either bounce off the 6500 rev limiter or require a .3 second upshift (and then, of course, a downshift). Sure, if you change the final drive to 3.34 you will be even, but then require ~20% more torque to overcome the taller gear...
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Old 08-03-2000, 03:33 PM   #15
ColinL
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Yes, but you'll be downshifting the higher revving, lower displacement engine more often in the slow transitions.
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Old 08-03-2000, 03:43 PM   #16
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ColinL, FYI for SCCA ProRally Open class, you can have up to 3000cc displacement turbocharged, 5100cc non-turbo OHC, or 6375cc non-turbo pushrod. You have to run a 36mm or 40mm restrictor, though, which keeps horsepower under 400, or so .
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Old 08-03-2000, 04:01 PM   #17
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I have a Phase-1 EJ20 closed-deck block, two Phase II EJ25 blocks, and one Phase-1 EJ25 block apart in my shop right now so I have compared them.

In fact, I think it's about time I finish Part 3 of the engine-build series.

Here's a picture of some DOHC lifters, wanna guess where I got them from?



I have a set of WRX heads and a WRX intake manifold getting prepared to go on the flow bench this weekend so we'll know once and for all if there is any advantage.

Cheers,
Trey
CobbTuning.com
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Old 08-03-2000, 04:12 PM   #18
Jay_UK
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Oh bugger...

I dont know what I'm doing or anything about Subies...

Thanks for pointing that out...

J.
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Old 08-03-2000, 04:24 PM   #19
Gambit
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Imprezer can you tally up the cost of what yo had to do to make sure your EJ25 runs without hiccup? Thanks.
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Old 08-03-2000, 04:24 PM   #20
Matt Monson
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Question

Hmmm? (Scratching head) Do you spend a lot of time in 1st or 2nd at an auto-x?

Correct me if I'm wrong, but isn't part of why our gearing is different than the WRX is the different torque curves of the respective engines?
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Old 08-04-2000, 12:45 AM   #21
MikeYOX
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Have a Nice Day?

What have I started?!?!?!

This is some good stuff though. Thanks a lot.
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Old 08-04-2000, 02:35 AM   #22
Jay_UK
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Hi there...

The myth about the subie being the best thing since sliced bread is poop.

The EJ25 uses the same design of bottom end as our cars.

Yes depending on the MY, the head design changed... and our cars run a different compression.. but thats it.

The thing about STI having special pistons.. is sort of true..you can order them as an option from the factory.

I'm looking at a 2.5 bottom end.. with new internals...bolted upto solid lifter heads...

I'll be running 8.5 - 9:1 compression

You cant beat capacity. I have raised my compression in my STI.. from the standard 8:1

I know of a guy running 9:1 (maybe 9.5:1 - cant remeber) in his 22B.

The choice of compression against boost is dependant on what you want from the actual engine.. and in turn the gearing...

So.. if I was/when to rebuild my engine from scratch... I will get a 2.5... make it closed deck (to be safe - although I believe open is strong enough for most people).. and let the magic begin.

I believe the RS/2.5 guys will get the same (if not more) power than our cars.... *flame suit on* lol

J.
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Old 08-04-2000, 07:09 AM   #23
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Smile

I agree with Jay. EJ25 has nearly identical block (minus a few minor diffs which can be added to the EJ25 if desired), same type crank, same high quality rods, great cylinder heads, etc. Throw in some good pistons and go for it.

And even if you want SERIOUS power, the EJ25 still makes for a good base. We're building one now where we are closing the deck, reinforcing the block, adding the piston cooling sprayers (customer's request), etc.

For what some of you guys go and spend to get a smaller displacement motor, we could easily build up the EJ25 to handle as much, if not more, than a STi-spec EJ20 could handle. Even with turbos, there's still no replacement for displacement.

Plus, the EJ25s are torque monsters! I've seen a dyno sheet of a properly built EJ25 setup and the car made 506 HP @ 6500 with 19psi of boost. That equates to over 400 ft/lbs of torque @ 6500 and that's not even max torque! The smaller displacement engines don't make more torque, they just carry the torque at a higher RPM to make the HP numbers. And this particular EJ25 still uses stock crank, stock oil pump, etc and is very reliable. You'll have more problems keeping a gearbox under it than anything else.

Not that I'm anti-EJ20. They're great motors. I just think some of us have this misperception about the EJ25 which might have been fostered by some misinformation put out early on by others who really never even looked inside on of these motors.

Cheers,
Trey
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Old 08-04-2000, 07:45 AM   #24
STi Sev
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Hello,

Quote:
posted by gambit
Imprezer can you tally up the cost of what yo had to do to make sure your EJ25 runs without hiccup? Thanks.



You do NOT want to know how much that kit costs.. If it's even available to the immediate public...

I disagree with the 2.5L Turbocharging...
You see what happening to all these cars. Busted gears, blown tranny, so unless you change the tranny, gears, heads, SOMETHING.. I STILL think 2.0L is the best engine turbocharged out there.

Try showing me a 2.5L DAILY DRIVEN like how I Drive it (100 miles a day) run for over 100,000 miles. Show me this, and I'll eat my car

Don't get me wrong. I LOVE My 2.5RS, but what most people don't understand is speed is only limited by reliability. If your car doesn't RUN how you gonna drive that "2.5L Monster"?

Balance is the key.

-Sev the *******

[This message has been edited by STi Sev (edited August 04, 2000).]
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Old 08-04-2000, 07:54 AM   #25
efoo
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Sev - almost all the failures we've seen were in the transmission, just like you said in your post. Not the engine.

The engine itself has been proven to be able to handle the power, IMHO.

Of course, a car is more than just an engine. If you seriously change one part of it, you've got to change the other parts too to match. So yes, people likely need upgraded transmissions. But you'd still have the same problem with a 2.0L engine, if you swapped into a RS. The engine itself isn't the problem here.

-Edwin
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