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Old 04-26-2007, 02:00 AM   #1
Car hippie
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raising redline... what can my engine handle?

I have a 2006 Boxster. Current redline is 7200 and the rev limiter kicks in at ~7400.


The reason I want a raised redline is because on many auto-cross courses I've done (I've done 6 so far), I have to upshift to 2nd before going into a slalom, which of course slows me down a lot, and then when I come out of the slalom, there is a straight, but I'm at 30mph in 2nd. Downshifting would take too much time also I fear.


I think if I had a higher rev limiter I'd be able to stay in 1st a bit longer.



But I want to know what my engine should be able to handle without potentially causing detriment, or if this would even help me as much as I think it will.


I want to clarify that this is not because I want to redline around the streets and such, because I know that I am probably losing power after 7200rpm since peak HP is made at 6400...




Anyways, what are your thoughts?
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Old 04-26-2007, 02:06 AM   #2
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Quote:
Originally Posted by Car hippie
I have a 2006 Boxster. Current redline is 7200 and the rev limiter kicks in at ~7400.

The reason I want a raised redline is because on many auto-cross courses I've done (I've done 6 so far), I have to upshift to 2nd before going into a slalom, which of course slows me down a lot, and then when I come out of the slalom, there is a straight, but I'm at 30mph in 2nd. Downshifting would take too much time also I fear.

I think if I had a higher rev limiter I'd be able to stay in 1st a bit longer.

But I want to know what my engine should be able to handle without potentially causing detriment, or if this would even help me as much as I think it will.

I want to clarify that this is not because I want to redline around the streets and such, because I know that I am probably losing power after 7200rpm since peak HP is made at 6400...

Anyways, what are your thoughts?
You're actually going slower at any RPM over 6400 especially being that far over the power peak, but shifting is probably worse time wise. Depending upon your class, you need to increase your tire size to gain more ground speed per rpm or decrease your tire size to allow you to stay in a higher gear. All things being equal I'd go smaller. Harder launch, higher gear, more flexibility. Don't be afraid to fan the clutch coming out of corners.
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Old 04-26-2007, 02:14 AM   #3
Car hippie
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So at above 6400 I am going slower than I would be at ~4k in second? If so, yeah, it's not worth it. I don't know if you know the gear ratios


Btw, I have the 5 speed, not the 6 speed, so I have a pretty tall first gear (goes to about 42-43mph) and the optional 18" 'S' wheels as opposed to standard 17s



I need shorter wheels and tires or just tires? I apologize, but I am not familiar with tires and wheels all that much.
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Old 04-26-2007, 02:39 AM   #4
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Tire size, Bronxie.
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Old 04-26-2007, 03:14 AM   #5
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Quote:
Originally Posted by Car hippie
So at above 6400 I am going slower than I would be at ~4k in second? If so, yeah, it's not worth it. I don't know if you know the gear ratios

Btw, I have the 5 speed, not the 6 speed, so I have a pretty tall first gear (goes to about 42-43mph) and the optional 18" 'S' wheels as opposed to standard 17s

I need shorter wheels and tires or just tires? I apologize, but I am not familiar with tires and wheels all that much.
I would go with shorter (smaller outside diameter) tires as wide as you can get away with. Since your car has 18's on it, you MAY not be able to run 17's legally, and changing to 17's may move you from Stock to Street Touring or even Prepared, so while you'll go faster, your competition will also be faster.

As for the gear ratios, I don't care. Without a bunch of other related data it doesn't matter. All I need to know is that right now you're well into the engines over run or in too high of a gear. Shorter tires will allow you to run in a higher gear and be closer to the torque and HP peaks more of the time. How much shorter is dictated (that reminds me of a joke I can get banned for, I should tell it some time) by availability of sizes, experimentation and your wallet.


P.S. What's up with the "Car hippie" screen name? Is it some kind of a dodge to get around a ban happy mod or what?
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Old 04-26-2007, 05:49 AM   #6
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Old 04-26-2007, 11:19 AM   #7
Car hippie
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Quote:
Originally Posted by vwhobo
I would go with shorter (smaller outside diameter) tires as wide as you can get away with. Since your car has 18's on it, you MAY not be able to run 17's legally, and changing to 17's may move you from Stock to Street Touring or even Prepared, so while you'll go faster, your competition will also be faster.

As for the gear ratios, I don't care. Without a bunch of other related data it doesn't matter. All I need to know is that right now you're well into the engines over run or in too high of a gear. Shorter tires will allow you to run in a higher gear and be closer to the torque and HP peaks more of the time. How much shorter is dictated (that reminds me of a joke I can get banned for, I should tell it some time) by availability of sizes, experimentation and your wallet.


P.S. What's up with the "Car hippie" screen name? Is it some kind of a dodge to get around a ban happy mod or what?


That's true about the classes. SCCA will put you into a non-stock class for mostly anything, however, it's possible that if I run shorter street tires, they won't bump me. I'll have to shop and check the availability of such tires.

Thanks


Car hippie was created because I lost my password to Bronxie, but at least I have the added security if I do get banned. (oh wait, no I don't, I can't recover the password if there's no admin that logs in once every 365 days )

Banning here is a joke because these mods can not ban IP addresses so any user can just create a new account. Even if they got an admin to ban an IP address, a user can change their IP in many different ways or even make use of a proxy server. Without an active administrator to continually ban these new IPs, it really is a joke.
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