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Old 11-03-2001, 03:38 PM   #1
Scooby75
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Default higher redline

I have a turbo 2000 2.5 and REALLY need to get some more high end power. The Low end is crucial but that 62000rpm limiter has got to go. Turbo spools at 2 grand so i've got power, just need the higher RPMs to teach some of the hondas a lesson on the highway. Anyone know someone that can take the redline to 7000 ro 7500RPM or so? I don't know if its just an ECU replacement or new valve train or both.
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Old 11-03-2001, 05:10 PM   #2
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You'll need an aftermarket ECU such as the Tec II.

The stock valvetrain starts to float at about 7200-7400 RPM (IIRC), so if you planned on revving that high, valve springs may be in order.

Quote:
but that 62000rpm limiter has got to go
I just noticed this, but what's wrong with your car...you should be able to go like 100 miles an hour in first with that fuel cut

Last edited by Impreza Rider; 11-03-2001 at 05:19 PM.
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Old 11-03-2001, 05:11 PM   #3
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Both. The stock valvetrain is not up to the task of 7500rpm, especially with boost. Valve float is not your friend.


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Old 11-03-2001, 05:23 PM   #4
Eric SS
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Plus your cam will not make any power that high. If you look at our torque/hp curve, the power starts to dip off way before that (regardless of turbo or NA). If you shift higher, your next gear that you go into will ALSO be above the power curve and you will get even worse performance. Stick with what you have right now and if you want to go higher, get some cams and get some better springs

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Old 11-03-2001, 08:37 PM   #5
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valve timing, perfectly balanced rods n pistons, cams, wallet deeper then the grand canon
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Old 11-03-2001, 09:14 PM   #6
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trust me, power up top without a turbo is weak!
But with a turbo... OMG
get some engine work done (rods or just ARPs) some springs and retainers will help.
and as people have already mentioned engine management is a must
Kian
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Old 11-03-2001, 09:15 PM   #7
Eric SS
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I noticed the same dropoff with my turbo over 6,000

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Old 11-04-2001, 02:24 AM   #8
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I doubt very much that you need to touch the bottom end to hit 7,500-8K. Above that I might start to worry. The top end DOES need work as the springs are too soft and the cams are too small.

I doubt that it would be very expensive to build even a 9 or 10K rpm EJ-25, but the cost goes up alot as you push closer and closer to the theoretical limits of the motor. Which if you do a little math is higher than ANY non-hybrid Honda B-series. I'd guess that a B18C with a B16 crank might be about equal to the EJ-25. Please note that a shorter stroked EJ-22 will run with the best of them, and I don't have the specs but I'd guess the EJ-16 and EJ-18 might have even shorter strokes.
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Old 11-04-2001, 02:34 AM   #9
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You ever heard the saying "If it ain't broken dont fix it" That might be your best bet right now. Just my .02 cents
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Old 11-04-2001, 04:33 AM   #10
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LOL yeah I noticed the 62000 thing right as I hit post reply, DOH!!! (hand slap).
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Old 11-04-2001, 04:38 AM   #11
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Don't worry, I wasn't thinking about doing it any time soon. Hell I was just curious to see if it could be done. I'm planning on getting the Cobb Tuning turbo cams within the next month or two, (paycheck pending). So I'm gonna be one step there. Don't really need the high RPM for autoX and Solo 1 and 2 racing though, which is what I really wanna get into. Gonne be tough on a daily driver, but oh well, gotta do what you love right?
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Old 11-04-2001, 01:17 PM   #12
Eric SS
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Depending on how they layout the Solo 2 course in your area, you might want the higher redline. When I was N/A I would come pretty close to having to shift into 3rd on a lot of our courses. Now that I am turbo, I know I will have to if I don't raise the redline

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Old 11-05-2001, 03:34 AM   #13
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is ignition timing going to be a concern at these rpms? what mgmt would someone use.... I was going to bump up my hybrid because the EJ22T block had a higher redline but i thought against it,,, since it was too much trouble... especially since i'm running piggys...
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Old 11-05-2001, 04:09 AM   #14
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See the first reply in this thread that suggests a TEC-II (obviously, other high quality standalone systems will work, as well).


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Old 11-05-2001, 06:01 AM   #15
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Yes... i appreciate that the TEC 2 will solve all problems... but i'm seeing if the stock crank sensor can handle this.. ie... just using piggy backs or the stock ignition system and a unichip to change timing... since the TEC2 comes with a high res crank sensor its an easy answer... but with its cost involved i was just wondering if the stock on can handle it... and also what are the timing maps like on the stock ECU after the rev limit?
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Old 11-05-2001, 04:32 PM   #16
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Speaking from my limited experience...

People that have over-reved their engines have usually blown the motor. Granted, the cases I have heard of were boosted cars, but this *could* be indicative of lack of maps at higher revolution levels.

Irregardless, there are some factors limiting high rev performance in the 2.5 motor. I have taken the first step in my car, and have installed better valve springs. Stronger valve springs will keep your valves from floating at higher rpm and boost levels, keeping your air mixture true to cam profile.

But the cam itself is a limiting factor. The cam will run out of steam at 6800 to 7000rpm, depending upon other modifications. In my friend's car, where his rev limit is 7k rpm, but has no other rev increasing mods, he runs out of go at about 6750 and you don't really get any benefits from reving past that. In my car with knife edged crank and stronger springs, I can go to 7k rpm before it becomes pointless.

The question you need to ask is how much is enough, and how much do you want to spend? Springs aren't cheap. Cams aren't cheap. Aftermarket ECUs aren't cheap. Its a vicious cycle that is funded by your dwindling disposable income.

I guess this begs the question of why you need more revs. IIRC, top speed in 5th gear at 6200rpm is 140mph! If you need to go faster than this, then I want to know where so I can avoid that road! If it's a track, then try a road course that is tighter. If its a drag strip, then you won't hit those speeds until you break into the 9s anyway. Good luck to you in your quest!

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Old 11-05-2001, 06:10 PM   #17
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Irregardless? Ow.
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Old 11-05-2001, 06:47 PM   #18
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yup DannyAtwork thats what i thought... no point in doing all that for 800 rpm...
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Old 11-06-2001, 01:58 AM   #19
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Well like I said, I wasn't gonna actually do it. Just wondering if it could be done. I just get mad at the Honda owning idiots who brag about being able to take their cars to 8000rpm. Course with a boosted Impreza if you start a race anywhere below 100mph you will walk the dog on just about anything (I have an S2000 stamped on my fender). But I've heard that you can take the car to 8000rpm with an STi Version 5 or 6 ECU and injectors, since they go that high stock. Just one more rumor I suppose. Thanks a bunch.
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