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Old 09-22-2008, 08:05 PM   #1
atho6
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Default I don't think this has been addressed before...

The general opinion is that the stock 2.5 N/A motor can not handle much boost.

Can the engine be modified with 2.5T components or aftermarket components to lower the compression so that the engine can handle boost?
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Old 09-22-2008, 08:25 PM   #2
reddevil
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It has been addressed....

Anyway, replace the pistons and you can take it to 300-400 whp.

Replace the rods with STI stockers if you can.
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Old 09-23-2008, 02:31 AM   #3
White 2.5rs
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LOL LOL
sorry but this is insane

please lock this thread
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Old 09-23-2008, 07:40 AM   #4
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Sti rods and pistons make for a 350hp block.
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Old 09-23-2008, 09:03 AM   #5
Matt Monson
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Take reddevil's word over chocoholic. Reddevil has built a number of these. Chocoholic has just read about it...
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Old 09-23-2008, 10:33 AM   #6
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Quote:
Originally Posted by Matt Monson View Post
Take reddevil's word over chocoholic. Reddevil has built a number of these. Chocoholic has just read about it...
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Old 09-23-2008, 10:35 AM   #7
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Quote:
Originally Posted by Matt Monson View Post
Take reddevil's word over chocoholic. Reddevil has built a number of these. Chocoholic has just read about it...
I have a EJ251 with STi internals moron.
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Old 09-23-2008, 10:50 AM   #8
Matt Monson
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Quote:
Originally Posted by Chocoholic005 View Post
I have a EJ251 with STi internals moron.
Then you should know better. Though if you haven't pushed it the limit and popped it then you don't really know what it can take. Do a search for Skully. He'll show you what they can take...
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Old 09-23-2008, 11:56 AM   #9
Chocoholic005
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Quote:
Originally Posted by Matt Monson View Post
Then you should know better. Though if you haven't pushed it the limit and popped it then you don't really know what it can take. Do a search for Skully. He'll show you what they can take...
Noone knows what each individual motor can handle. The general assumpition with STi stock pistons is 400. Now some will fail at way more than that, some will fail before. Its impossible to tell the exact point the motor will fail.

I'm not gonna give someone a number that has a high risk attributed too it when they are just starting out. 350 is a little low, yes. But its a good estimate, chances are the motor would not fail because of boost pressure at 350, as apposed to 400 where it would be more likely, and that could get the op in trouble.

I'd rather keep my motor running strong than pop it just to find out what it can take
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Old 09-23-2008, 12:04 PM   #10
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The general assumption is that STi pistons can take 400whp, not 400chp. That's way more than the 350chp you were talking. I stand by my original statement that Doug's advice is far more sound than yours.
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Old 09-23-2008, 12:55 PM   #11
White 2.5rs
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Quote:
Originally Posted by Matt Monson View Post
The general assumption is that STi pistons can take 400whp, not 400chp. That's way more than the 350chp you were talking. I stand by my original statement that Doug's advice is far more sound than yours.
+5
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Old 09-23-2008, 03:32 PM   #12
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Quote:
Originally Posted by Matt Monson View Post
The general assumption is that STi pistons can take 400whp, not 400chp. That's way more than the 350chp you were talking. I stand by my original statement that Doug's advice is far more sound than yours.
I never said it was 350chp, i never said 350bhp, i never said 350whp. You just assumed i was talking about hp at the crank. I assumed everyone would relize that noone talks in chp and would get i ment whp.

I never was saying anything anyone said was wrong. I was smack dab in the middle of the first posts numbers so i dont even know why you said not to listen to me. I was basicly agreeing with him.
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Old 09-23-2008, 09:20 PM   #13
Matt Monson
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You said a 350hp block. Since a block or an engine is not in a car and not subject to driveline loss it was kind of hard to make the leap that you would be talking about whp. Whp requires wheels and blocks don't have them. Plenty of people talk in terms of chp. Just because you say something is so doesn't make it true. Maybe next time just be more clear what you mean.

relize?
ment?
English, do you speak it???
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Old 09-23-2008, 09:29 PM   #14
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The most boost an NA motor has seen without blowing (so far) is 12psi from a garrett gt3076 turbo. Not to say that anybody else will have that kind of reliability, but that seems to be pretty much THE limit for the motor and that's with a standalone and what must be an amazing tune.

The STI internals can be swapped into an RS motor, Brydon has a thread over on RS25 about that, he may also have that thread here as well (this forum).

Last edited by silentt; 09-23-2008 at 10:46 PM.
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Old 09-23-2008, 10:15 PM   #15
VIsubi
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silentt don't be an a$$.never once did he state or assume that he new more than another person he did state that he was studying to be an engineer after someone posted about engineers doing there R&D personally I'm a process refinery operator I know alot about fuels and the making of fuesl and what it takes to go that route you don't think of someone stated something bout fuels here that was 1/2 correct i wouldn't say something your crazy hells yeah i would.. so what if the man is studying to be an engineer...you seem like you use to get people talking bout each other back in high school just like you are now...either way internals will help with the down fall of N/A application..if you don't agree your an idiot because most people do that so they can turbo..forging. There are motors and pistons out there in the array of motors that are turbo charged that aren't even close to forged and they run just fine. Either way just get an STI block or just keep your engine and rebuild it with forged pistons. Also like someone said rods might be a good idea if you can but not needed for force induction. I don't plan on doing high numbers like that and no one should unless they have a good tuner on side at a times notice t otune it....
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Old 09-23-2008, 10:32 PM   #16
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Coco and VI, please use grammar and punctuation. Is it that hard?

Coco- this is like the fourth thread I have seen you post in making yourself look like an idiot. Let the people that have done this and seen the true limits post.
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Old 09-23-2008, 10:43 PM   #17
reddevil
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Quote:
Originally Posted by atho6 View Post
The general opinion is that the stock 2.5 N/A motor can not handle much boost.

Can the engine be modified with 2.5T components or aftermarket components to lower the compression so that the engine can handle boost?
Original question people.......

Yes, yes it can.
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Old 10-22-2008, 07:25 AM   #18
EcksJay
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I typically don't like bumping old threads, but instead of starting my own, I figured I could do a semi-hijack on this one...

So, STI pistons and rods will fit in a Phase2 EJ25 with no issues? What about bearings? Is is a "okay" solution, in that there are better options for what one is doing with the block? How does everything fit together? Are the clearances in the piston face sufficient for the valves, or is it too much? Is the CR too low for good street use?

If one is to spend money on STI internals, are there better aftermarket products in the same or close price range?

So, one would need: Pistons, rings, con-rods, main bearings. What about wrist pins, STI oil pump and water pump? This of course would be for a turbo build (somewhat pointless to mention, since I'd be looking for a lower CR)

What about cams? When I did my 1.8-2.5 swap on my '93L, I installed some delta cam regrinds, and they really woke the car up. Is there anything out there in a REASONABLE price range for the EJ25 turbo applications?

And last but not least, what about the heads? What improvements, if any, should be made to the heads? Valves, valvesprings, retainers?

I think the most attractive thing about this build (and I could be way wrong) is the relative low cost and ease in comparison to a full on STI swap (wiring and everything)

Maybe I should start my own thread....

Last edited by EcksJay; 10-22-2008 at 07:29 AM. Reason: grammar sucked
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