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Old 04-19-2002, 01:02 PM   #1
cRayZee
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Default raising redline?

Well, I saw in another thread people talking about raising the redline...

So who of you have done this? What did you have to do to get this done? Did you upgrade your valvetrain? Upgrade the cams also? I mean, raising the rpm up there sounds like a good idea, but the stock cams just run out of breath near stock readline.

Also, would it still be ok to raise the redline w/ the right valvetrain and cams to handle the higher limit and add a turbo later on?


vic
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Old 04-19-2002, 01:43 PM   #2
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why?
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Old 04-19-2002, 02:16 PM   #3
cRayZee
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why what?


why would iw anna increase my rev limit and turbo it afterwards?


-vic
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Old 04-19-2002, 02:18 PM   #4
rupteur7000
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but why?
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Old 04-19-2002, 02:35 PM   #5
cRayZee
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well....assuming the engine can breathe just fine at a higher rpm, then i can get more power.

Yes, torque is great, but i wanna keep it up goin @ a higher rpm, ya know? Especially if since I autoX, 2nd gear is just too short -- limiting me to under 60 mph. Increasing the rev limiter a couple hundred revs or so would be great.

With turbo, it'll make those gears seem even shorter. Now, w/ turbo w/ good torque, if I can up the rev limit a bit, that'll give me
some more power to play with, once again, assuing the engine can breathe at a higher range and the turbo has no problem with pushing more air at that range also.

-vic
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Old 04-19-2002, 02:37 PM   #6
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no i was just playing with you...

i don't know if the fuel system could handle more rpm.

i am not even sure if anyone makes such kits for the 2.5 L
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Old 04-19-2002, 03:31 PM   #7
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first of all the cams run out of breath @ 5800 RPM and fall flat on their nose...secondly you'd have to upgrade the valvetrain if you plan on spinning those R's w/ boost.

Jeremy

p.s.: you'll need to get the ECU remapped or a uni-chip.
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Old 04-19-2002, 04:23 PM   #8
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yes, i know the stock cams can't do much top end... that's why I'm asking about this. I want to know if people have done something like this. So, i've searched around and seen that the valvetrain can handle up to 7200 rpm or somethin. But i'd probably still like to upgrade them to stronger and ligher material. Just want to know what people think about this or if there have been experiences.

-vic
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Old 04-19-2002, 10:25 PM   #9
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I raised my SOHC 240sx' redline to about 9.5 grand. this is how:

that car was really slow down low it kinda drove like a S2000 actually

New Cam
New Springs
New retainers
New lifters
New rockers (think thats what they are called)
Ported and polished head
New Valves (went all out and got oversized ones )

Not to mention a reprogrammed ECU from JWT

Tachyon racing head services did a nice job for me not too pricey either.

Brad
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Old 04-19-2002, 10:29 PM   #10
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so what are you pumping out now that you raised the redline?
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Old 04-19-2002, 10:37 PM   #11
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Never dynoed it but I ran a best time of 12.9 on cheaters

I also had 11:1 compression too water injected.
Milled Head
JWT Rods and JWT pistons
UOR UD Pulley
Apexi Dual N1
Speedcraft custom made CAI

The motor blew up before I had a chance to have fun with it. the water pump went bad of all things.

Brad
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Old 04-20-2002, 03:41 PM   #12
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You will need to get new cams to make it worthwhile. If you are putting money into head parts you might as well put stiffer springs in there with Cobbs lumpy cam that requires the new springs. This will set you up to 8000-8500 RPM quite well heads wise. How high you will want to rev the stock bottom end, I don't know. You can put light weight pistons in there to ease the load on the stock rods without taking it apart. If you are going to turbo it later, you will not want the lightweight pistons that you would use for a NA engine, with Nitrous, you want a stronger top as with the turbo piston. Put rods, light pistons, and the previous heads together and you can rev it to 8000 NA just fine. You will need a programmable engine managment to do it, and the stock intake manafold starts to really cause problems the higher you go as it does not flow all that much air that well. Head work is almost a necessity for power, but you so not HAVE to do it to make you engine rev, it just would be rather usless not to do it.

The power you would expect from that RPM, and a few more R's?

You need to go with a individual throttlebody set up with the familure velocity stacks ect, and some meaty rods. with all of the requisite head work, with titanium valves. If you are going higher than 8000 you will want to be using the SOHC heads for reliability.

Key word:

Diminishing returns. You have spent alot more than a good low pressure turbo set up with a build bottome end that will be comparable speed wise. The upside is that you do not need to build your transmission, you will not generate enough torque to tear up your gears without being abusive.

You need to know where to stop, and if you plan on going turbo at a later date, skip all of this and just do some head work that is good for both NA and turbo and save your money till it is time to turbo, you end up buying parts twice instead of getting extra things that are really nice with the money. Better yet just keep all of your money and do all the correct things at once. NA and FI engines diverge rapidly in what they need quite early in the tuning game. You don't want to pay for both.

Greg

Last edited by Section 8; 04-20-2002 at 03:48 PM.
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Old 04-20-2002, 03:56 PM   #13
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Oh yea:

If you really want to raise the redline ans spin the piss out of your engine, you will want to destroke it. and use 2.2 or 2.0 cranks. As soon as you split the block, you will want it all ballanced, I am sick of editing the above post and there are still a couple of things missing aside form nonengine parts that I just didn't include like fueling and exhaust. You will need bigger injectors sometime to compensate for the little time that they get to spray before the valve closes again. Things like that.

Greg
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Old 04-20-2002, 07:23 PM   #14
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sweet.thanks, greg

-vic
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Old 04-20-2002, 08:48 PM   #15
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Just remember when you start to do things like changing teh redline and the compression and so forth you need to have good engine management. Before I got the 240's ecu reprogrammed the car ran like a dud... slow as slug.

there are so many gains that you can pull from motor building but they won't do you any good unless you tell the ecu that you changed it all.

Brad
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Old 04-21-2002, 01:56 AM   #16
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The guy that makes the torque chip (IWTU Electronics) has a few cars running prototype modded ECU's with 10% and 15% higher redlines.

Mark Ramirez is running 7,500 rpm on his 2.2L turbo 1998 RS, and TARMAC is running 8,000 rpm on his WRX. Cost is about $500 and they need your ECU for about 3-5 business days.

Still working on the 2000-2002 version which I may test. Will post when they are ready to sell to the public...

Recommended not to go over 7,200 with stock valvetrain on NA, or 6,800 with boost. Pointless to go past 6,500 without cams, and then it is only helpful for some over-run in 1st and 2nd at the autocrosses to avoid shifts in some places.

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Old 05-08-2002, 05:47 PM   #17
cRayZee
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ok, i understand you'd probably need an uprade in cams if you want to raise the redline if going NA. What about in boost? I wanna rev up to 7k rpm or somethin( get better HP without using up so much torque--easier on the tranny) Can I just upgrade my valvetrain and raise the revlimit up to 7k rpm?

-vic
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Old 05-08-2002, 05:50 PM   #18
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I call bull ****n **** on the 12.9 with the 240SX SOHC KA24. BULL ****. There's no way an all motor KA24 is running a 12.9.



Terrin
92 SE-R <----- has the REAL motor, SR20DET
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