What engine upgrades or modifications would I need to run about 350hp on a DOHC EJ25? I assume that the internals, cams, complete valve train and more would have to be changed, but what specific parts would be best to use? What about the ignition system, fuel systemand intake system?

Thanks in advance.

Are you talking about 350hp at the wheels or the crank?

Cause if you meant the crank...I think all you basically need is the Tec-II to run about that amount if I remember correctly.

Crank horsepower.

I think the pistons should be in your list of upgrades because IIRC the '98 pistons had a striking resemblance to pancakes (meaning almost no piston skirt). This resulted in piston wobble forcing a premature end to the block.

I would hit up the Fuel management fairly hard with BIG injectors. Then look to a water/air IC, and plenty of aux engine cooling as a safety. Running a better ignition, and other usual aids.

I would avoid internals as much as possible, but as stated before there may be no way to get around the factory pistons in some years.

Basicly no detonation = no HP limit.

One thing to note is that on the stock valve train figure on a 5,000-5,500 RPM HP peak, or you will have problems with flaoting valves at higher boost.

[This message has been edited by XT6Wagon (edited December 22, 2000).]

Thanks.

What kind of rev limit would I be looking at with better valve springs and retainers?

WOW! 5000 to 5500 horsepower? I'd like to see that on a 2.5 liter engine... http://www.i-club.com/ubb-files/wink.gif

But, no detonation does not equal unlimited horsepower. There is a fundamental limit to how much pressure and force the internals of an engine can take. Proper fuel management will allow you to come closer to that limit without throwing a piston (or bending a rod, etc.), but it can't fix everything. Good internals will greatly increase the life of an engine at any exaggerated HP level (such as the 350HP of which you speak). I'm not saying it can't be done on stock internals, but you just have to look at the issues (such as the weak pistons on a '98).

Even if you had exceptionally robust internals, the head will lift at some point-- it is aluminum and so is the block. Closed deck would help, and there are a few other tricks you could try. (bigger head bolts, head bolt anchors...)

At that point we're well into the $20k plus motors, so I think we can safely say that whoever has that kind of cash will get the job done. Have you seen the 7 second "Focus" dragster? estimated 1500HP from a cosworth inline four, built by Ken Duttweiler. Don't wanna see that pricetag...

At that point we're well into the $20k plus motors, so I think we can safely say that whoever has that kind of cash will get the job done. Have you seen the 7 second "Focus" dragster? estimated 1500HP from a cosworth inline four, built by Ken Duttweiler. Don't wanna see that pricetag...


http://www.i-club.com/ubb-files/frown.gif Damn. I don't have that much for an engine.

Didn't SCC build a 300hp EJ25? What internals did they use? I read Shiv's report on that car and what it took to get to 300, but it didn't list the internal engine modifications.

Project Impreza (SCC) was done on a '99 Imp which had, now I am assuming here, the Phase II block. Chances are that your running a Phase I block (although Phase II is possible, go figure). I think in the phase change, they revamped a bearing or two and corrected the piston skirt problem. Please correct me if I am wrong; I haven't read up on that info lately.

Woah, there... Back up the horsies a few thousand dollars. While a 1500HP EJ25 is probably (OK, definitely) a 20K+ plus motor, that's not the kind of horsepower Mike is hoping for. Depending on the things you do (just pistons, pistons and rods, pistons and rods and crank work, etc.) and who does it (you or an engine builder) you could be talking a couple thousand dollars or several thousand dollars. How much are you willing to spend? I'd pick some budget that you think makes sense and start shopping around for parts. Think about whether it's worth having a good engine builder assemble the thing (I think it is, but I'm also definitely NOT a professional engine builder). Once you have a better understanding for how much things cost, you can add or subtract the miscellaneous bits until you have the compromise that works for you (yes, it will be a compromise or else it would be a 20K+ motor).

Wow - the same MikeYOX who was quoted in SCC - hehehe.

Here's what I'd plan on, and please note it's full driveline:

Vishnu TEC-II Turbo kit (turbo and managment) - $5959
Act Clutch - ~$400
Rallispec Oil Cooler - $300
Stronger Valve Springs - ?
High flow fuel pump - ~$140
J&E Pistons - ~$700
Crower Rods - ~$700

Now, with the Vishnu kit, you get the engine management AND the big injectors - cool deal. With the fuel pump you shouldn't need to worry about fuel starvation. The valve springs, pistons, and rods should let you rev that puppy up to 7500 revs with the TEC-II running the show. With that setup I'd be pretty confident to run a bulletproof 350 hp. The only other weak link would be the tranny.

Basil

For the question about a 99 pistons having a skirt is incorrect. The 99 also does not have a skirt. I would recommend talking to Trey at Cobb tunning. I do not think you will hit your goal of 350hp because the turbo if it is a T3/04E it will be maxed out at 22psi or 1.2 bar. If you go to Turbonetics web site you will learn more about what i'm saying. You can turn the boost up hire,but you will wear the turbo more and will just making more heat. It is inefficent to go above 22psi. You will need a bigger turbo.

thanks,
Greg

Yeah, I'd better contact Trey.

Perhaps it would be better if I stuck with "just" 300hp? I'll see what happens.

[This message has been edited by MikeYOX (edited December 22, 2000).]

FWIW seems that 12k will buy you a well built turbo.
Cams $500
heads $2200
conrod $800
pistons $750
closing deck $950
shivs turbo $5950
thats $11150
Add some in for install, etc.
Probably can drop the head work and save some money there.
Seem legit to everyone?

Those numbers look right but you forgot labor.

Labor?? BAH! Do it yourself http://www.i-club.com/ubb-files/biggrin.gif

Numbers look good, but I have to disagree with the closed deck - I don't think you'd need a closed deck for 350 hp. I also have to question the necessity of cams. Don't get me wrong, I'd love them, but I don't really think they're gonna be neccesary.

Labour should run about $400 for the installation of the turbo, not sure about the rest.

Basil

[This message has been edited by Basil (edited December 22, 2000).]

I don't own an Impreza yet. I'm planning on buying one specifically for the purpose of modifying it.

FWIW seems that 12k will buy you a well built turbo.
Cams $500
heads $2200
conrod $800
pistons $750
closing deck $950
shivs turbo $5950
thats $11150
Add some in for install, etc.
Probably can drop the head work and save some money there.
Seem legit to everyone?

That sounds like a good idea. I'll have to add $3K for the Cobb Tuning Gear Kit obviously. I doubt the stock trans will hold up to 350hp on a reliable basis.

I'll check with some of the tuners to see what kind of labor I would be looking at. I'm betting at least $5,000.

Thanks again guys. http://www.i-club.com/ubb-files/smile.gif