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Old 07-13-2009, 02:32 PM   #1
stickjohnsonaah
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Default 09 WRX redline... 6,500?? Higher??

I have done a bit of searching today and found that people are saying it is 6,500 as the guages indicate. I don't believe this as this morning on 2 different occasions my car hit 6,700rpm and the 2nd time I made sure it was not inertia from the needle that took it past redline. I was still on the gas when it hit 6,700 then I let out. Is there a possibility my car has a higher redline by mistake? Is this safe?? From what I read for the WRX there is no need to go past 6,500 rpm because the cam doesn't make any more power that high, but it does on the STI. So whats the deal with this? I am going to try this on my way home today in other gears and see what happens.

Thanks for your help.
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Old 07-13-2009, 02:42 PM   #2
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this is normal. its called the rev limiter. almost all cars have one that is a couple hundred rpms above the "red line"
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Old 07-13-2009, 02:49 PM   #3
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That's weird. All the cars I have had the rev limit was set to redline and if you try going past redline you would start bouncing off the rev limiter. I have been driving all dodge performance cars so maybe dodge arts theirs different?? Thanks.
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Old 07-13-2009, 02:50 PM   #4
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It's not the cams, it's the turbo. Well, with what you're referring to anyways.
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Old 07-13-2009, 03:13 PM   #5
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dont know on the 09 if there is usable power up that high.

I always shift at ~6200
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Old 07-13-2009, 03:18 PM   #6
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in my previous cars, i could always bring it up a couple hundred rpm's after the redline starts. my 94 Prelude's redline would start at 6500rpm, but fuel cut/rev limiter was 7200.
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Old 07-13-2009, 03:26 PM   #7
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I could be wrong but there "is" usable power above 6500rpm. The VF52 turbo is not the same as the turbo in the 08wrx. There is power. The question is, how much, and is it worth it to "pass redline" on a stock motor.
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Old 07-13-2009, 06:05 PM   #8
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i have a 09 wrx 265 (canadian), and there really isnt any point in going much higher than 6,000 or so rpm. The power still drops off: you know this by how much your body is returning to normal from its usual state of being thrown into the seat.

Beside there being very little need in driving up into the 6k rpm ranges, yes my car does do about 6700 before the rev limiter kicks in: this is normal.
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Old 07-13-2009, 06:26 PM   #9
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maybe a stage 2 2009 with an EWG would benefit from revving higher than 6000rpm?
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Old 07-13-2009, 06:36 PM   #10
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Quote:
Originally Posted by XX WRX View Post
maybe a stage 2 2009 with an EWG would benefit from revving higher than 6000rpm?
Under modded conditions, you could argue anything. Im more or less commenting on stock performance - which is what i THINK we're talking about here!
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Old 07-13-2009, 06:57 PM   #11
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My 06 had a factory limiter of 6850 IIRC, but the redline on the gauges started at 6500. My limit is now 7200. There's not much power there, but in an autocross it's been helpful once or twice as I didn't need to upshift and then downshift.
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Old 07-13-2009, 07:03 PM   #12
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Ya we are talking about stock. And thanks for all the comments, none of my previous cars we're like this so I was curious. Ill probably shift when I feel the power tapering off
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Old 07-13-2009, 07:07 PM   #13
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Quote:
Originally Posted by AdamMc View Post
Under modded conditions, you could argue anything. Im more or less commenting on stock performance - which is what i THINK we're talking about here!
well yeah but i was providing a possible solution to eliminating the boost taper, therefore making it beneficial to rev to the rev limit.
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Old 07-13-2009, 08:20 PM   #14
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Shift point for maximum acceleration has absolutely NOTHING to do with the power band. It only has to do with torque OUTPUT. Statements like 'shift at X rpm because you don't make power higher than that" means nothing and actually does not make physical sense.

The torque output to the wheels is directly proportional to the force being applied to the ground by the radius of the tire (assuming no wheel spin). Of course Newton tells use that acceleration is proportional to force applied to the ground (by a constant of proportionality being the inverse mass of the object/car). The transmission gears (times the FD ratio but this is constant so lets ignore it for the time being) multiply the torque coming out of the engine by slowing things down...simple energy conservation. When the output torque is high the acceleration is high and when output torque is low, acceleration is lower (lets ignore drag for the time being which does increase proportional to the square of velocity but say for a 0-60 sprint, we can say forget about it...the point is to let you learn about output torque). This is an unarguable fact that is regardless of rpm or horsepower or gear. Also a major note....this shift point does not always and usually does NOT correspond to the torque peak of the engine either.

All of this (along with my assumptions/idealizations....yes all engineers need some to make a point ) shows distinctly that the shift point for the fastest acceleration is the rpm X such that the output torque at rpm X in gear n is greater than or equal to the output torque would be in gear n+1 at the associated rpm in said gear. The instant this is no longer true, shift. If this condition is always true in gear n, then you shift at redline. It's as plain and simple as that for maximum acceleration.

For a relatively peaky engine with a torque peak near redline and a very low geared but close ratioed tranny (B16 civic for instance) it is always going to be making more output torque in gear n than n+1 at gear n's redline in every gear change. This is because not only does gear n+1 not multiply torque (not a big difference as the tranny is relatively close ratioed but it is still less of a multiplication factor) as much as gear n, but 1.6L 4 cyl makes no torque at lower rpms so crap times crap = crap^2. This says you shift peaky, small displacement engines with low gearing at redline...I'd say the bulk of econo box Japanese 4 cyl cars fall into this category.

Lets take a 5.7L Vette with a manual. I don't know what the redline is but let's say 6.5k rpms. The torque band on the 5.7L LSX is relatively flat from say 1500-2000 until it drops off in the higher rpms. Also, the transmission on this car is likely to not be as close ratioed as the Civic in the previous example due to a broad torque band. In this case at redline, the torque output might be lower in gear n than at the associated rpm in gear n+1 after shifting because even though gear n+1 doesn't multiply as much, the torque value is likely higher at the lower rpm. In this event you do NOT want to shift at redline. You must know your tranny gear ratios and a chart of the Torque vs rpm and determine at what rpm in gear n will your output torque hit the point that it is no longer as high as the output torque in gear n+1 at the given vehicle velocity after shifting. With broad torque band vehicles with large displacement engines, this is likely to not be at redline.

For the 2009 WRX:

I don't have the specs for gear ratios (unless it is in the owners manual...will check later) but looking at the torque band, the torque jumps up quickly from idle to say 3300 rpms and then remains flattish above 230 lbft until say 4800 rpms at which point it mildly drops off to say 200 lbft by redline. The transmission ratios are not particularly close because they don't need to be due to the broad torque curve, however without running the numbers I can't make definitive comment (someone get me 1-5 gear ratios). However my inkling is that unless the ratios are insanely far from each other, the EJ255 with the 5spd is not a 'shift at redline engine because it's damn near making peak torque as low as 3300 rpms (within 5-10% of torque peak at least) and this remains the case until about 4800 rpms. A great powerband for a 4 cyl. Mainly due to large displacement plus that swirly thing .

Last edited by 09rexwagon; 07-13-2009 at 08:27 PM.
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Old 07-13-2009, 08:32 PM   #15
theotherguy
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Quote:
Originally Posted by XX WRX View Post
maybe a stage 2 2009 with an EWG would benefit from revving higher than 6000rpm?
You'll run out of fuel on stock injectors.
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Old 07-14-2009, 12:31 AM   #16
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Instead of trying to be super cool and reving to 10K, why don't you concern yourself more with the longevity of your engine.


such abuse early on will only result in a number of costly repairs later. Sure it can go to 6-7K, but there is no real point is pushing the limit, unless you have a need too.
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Old 07-14-2009, 01:21 AM   #17
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Quote:
Originally Posted by DHRDAN View Post
Instead of trying to be super cool and reving to 10K, why don't you concern yourself more with the longevity of your engine.


such abuse early on will only result in a number of costly repairs later. Sure it can go to 6-7K, but there is no real point is pushing the limit, unless you have a need too.
If you upgrade to a larger turbo the WRX 2.5L should make decent useable power 6-7K
the EJ20 had no trouble with 7500 so I don't see why the 2.5L would have any problem with 7000rpm
the 2.5L cams do have slightly higher lift but I don't see this as being enough to cause any problems
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Old 07-14-2009, 02:18 AM   #18
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The rev limiter has a on speed and off speed, so it may cut off at 6900, and kill fuel until below the on speed of say 6700. So where is the rev limiter actually?
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Old 07-14-2009, 07:56 AM   #19
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my perrin stage 2 notes say redline is increased to 6800 rpms. i know that is higher than stock. i also know on a td04 its useless to rev that high. the turbo runs out of steam up high.
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Old 07-14-2009, 09:24 AM   #20
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On a 2009 WRX the default Redline is 6700. Every so many times after you hit, you unlock the 'Redline achievement' awards which bumps up redline.

50 - 6800 RPM
100 - 7000 RPM
250 - 7500 RPM
500 - Nitro, Shocks, and Top Accel. (Must goto your SOA dealer to claim)
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Old 07-14-2009, 12:07 PM   #21
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Quote:
Originally Posted by Celly View Post
On a 2009 WRX the default Redline is 6700. Every so many times after you hit, you unlock the 'Redline achievement' awards which bumps up redline.

50 - 6800 RPM
100 - 7000 RPM
250 - 7500 RPM
500 - Nitro, Shocks, and Top Accel. (Must goto your SOA dealer to claim)
do you gain any GamerPoints for your xbox?
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Old 07-14-2009, 12:15 PM   #22
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Quote:
Originally Posted by 05redrex View Post
The rev limiter has a on speed and off speed, so it may cut off at 6900, and kill fuel until below the on speed of say 6700. So where is the rev limiter actually?
You also have the requested torque table closing the throttle plate as you approach redline, so where is the rev limiter?

Is it where the throttle plate begins to close?
Is it where the throttle plate is 1/2 closed?
Is it where the car hits fuel cut?
Is it where fuel kicks back in?

The world may never know....
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Old 07-14-2009, 03:25 PM   #23
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the one log i've done in my car was 3rd gear 2 - 7k rpm,. there was no "backing off" by the ecu or no feel of the rev limiter, no bounce etc,..
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Old 07-14-2009, 08:45 PM   #24
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quick265 are you stage 1 or 2? Mine won't rev past 6700 so I'm assuming you gotta have some mods.
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Old 07-15-2009, 07:22 AM   #25
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Quote:
Originally Posted by 09rexwagon View Post
MATH SCIENCE MATH ENGINEERING
I'm surprised no one commented on this. Everybody knows that you get a "Perfect Shift!" bonus when you shift just right. Your math is just silly.

But seriously folks, do da maths.
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