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Series I Major Horsepower Upgrades This is the place to discuss Super Chargers and Turbos, Nitrous, Porting, etc

I have a really NOOB question

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Old Jan 6, 2009 | 07:40 PM
  #1  
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I have a really NOOB question

alright guys. forgive me for asking such a question but i can't seem to find an answer.

Can you tune a turbo to make peak power at 9k? i don't care if it doesn't make as much power, i just want to know if it can be tuned to make peak at 9k or 9500 instead of 7k or 7500
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Old Jan 6, 2009 | 07:57 PM
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why?
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Old Jan 6, 2009 | 07:58 PM
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flow
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Old Jan 6, 2009 | 08:02 PM
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why? because it would bother me having the ability to go to 9.5k but not having power past 7 or 8... i would just rather make peak at 9k... its make the fun factor go up for me
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Old Jan 6, 2009 | 08:03 PM
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Originally Posted by Charles R. Hill
Yes but performance will suffer at RPMs below that.
you mean my powerband will be (for ex from like 5-9 instead of 3-7
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Old Jan 6, 2009 | 08:04 PM
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yeah but your thinkin about it backwards,,, your thinking about 9.5k NA rpms vs. 7.5-8k Turbo rpms
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Old Jan 6, 2009 | 08:08 PM
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well i mean.... our cars already make peak power at like 8 or 8500 so going all the way to 9 or 9500 is kinda pointless and that already bothers me... i couldn't imaging magnifying that
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Old Jan 6, 2009 | 08:17 PM
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relevant quote

Originally Posted by staticlag
Turbos on the renesis don't make peak power at 9K because of the side port design. When the engine is turning that fast the exhaust can't exit fast enough because of the restriction. When it can't completely exit then you have some leftover exhaust in the engine for the next cycle, this takes up room for fresh fuel and air mixture. This problem is inherent to the engine and cannot be fixed without some crazy port work.

This exhaust gas buildup contributes to the overheating & seal failures we see on FI engines.
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Old Jan 6, 2009 | 08:22 PM
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yea thats why before you turn the car off rev it up to 3 or 4 rpms for about 5 sec so it will let the left over exhaust build up out, thats what a mazda dealer told me
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Old Jan 6, 2009 | 08:23 PM
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mmm... so it IS possible, but it would be healthier for the engine if i just stuck to the 7-8k like every1 else does
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Old Jan 6, 2009 | 08:45 PM
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Originally Posted by hossg
yea thats why before you turn the car off rev it up to 3 or 4 rpms for about 5 sec so it will let the left over exhaust build up out, thats what a mazda dealer told me
the extra reving before shutoff is the exhale the carbon build up and minisquel leftover fuel, by reving it and cutting the fuel your ensuring that theres no leftover fuel that would lead to carbon build up
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Old Jan 6, 2009 | 09:10 PM
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I bring it up to 4k every time before shutting her down... why? dont remember...
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Old Jan 6, 2009 | 09:16 PM
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its not pointless to shift at 9k+ NA
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Old Jan 6, 2009 | 10:51 PM
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Oi!

https://www.rx8club.com/series-i-major-horsepower-upgrades-93/rpms-turbos-163785/
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Old Jan 6, 2009 | 11:06 PM
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Originally Posted by Charles R. Hill
Yes but performance will suffer at RPMs below that.
Charles is completly correct. The goal with any forced induction system is to put you at max torque output as soon as possible. This requires that the turbo/SC be able to provide boost early in the power band.

To have a turbo create power through 9k RPM's would mean using a larger turbo which wouldn't be sized properly for the renesis. If you were in a race with another RX8 which had a quicker spooling time you'd lose every time and probably be making less peak horsepower.

In short, what you're asking for could be done but the results would be the opposite of what you'd be looking for.
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Old Jan 6, 2009 | 11:22 PM
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i'll post it again....

if you can make more power at a lesser RPM why would you want to intentionally reduce power in the sub-9K range, or make modifications that would result in less total area under the curve? Just so you can spin to 9K and smile about it? its unnecessary stress on the bearings
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Old Jan 7, 2009 | 12:12 AM
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Originally Posted by Charles R. Hill
One with which I disagree.
I don't necessarily buy into the recirculated exhaust gas and seal failure part, but do you have another theory as to the limiting factor at higher RPMs? The exhaust ports seem like the most likely candidate to me.
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Old Jan 7, 2009 | 06:29 PM
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it is def possible with a large enough turbo and good tuning but NA peak power is somewhere between 8k and 8.5k so ur really not changin the power band any with a turbo....but yes possible but would not b a great everyda driver i nkow taht!
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Old Jan 7, 2009 | 07:34 PM
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alright, thanks for all the replies guys.
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