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Hp?

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Old 07-13-2008, 03:29 PM
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Hp?

OK so i was wondering what is the most HP you can gain from your 8 with it still be practical...

I'm talking just the basic stuff

like how much can you gain from intake ,exhaust and maby some other stuff.

and who has the most horsepower on this forum or fastest track time, etc...


I'm trying to get a check list going of what i will be buying performance wise...
so far i have
(any suggestions would be helpful)

1. Cobb tuner
2. intake
3. exhaust (don't know what brand i don't want a rice pipe)
Old 07-13-2008, 03:30 PM
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ap and catless midpipe are all you need for power gains.

everything else is fluff.

most you can hope for is close to 200 whp. You can't get much higher without FI
Old 07-13-2008, 03:38 PM
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Not much.

Assume you have 100% VE in all RPM's (basically impossible; but assume you have the perfect NA engine) then do this math :

VFR100% = [(Disp)(RPM)]/ 3456 or 1728 rotary
80 cu in * 9000 / 1728 = 417 CFM
VFRactual = (VFR100%)(VE) assume 417 still for best case
MFR = [(2.703)(PAmbient)(VFR)]/[TAmbient + 460]
MFR = 31 lb min air at 80 degrees F.
Horsepower = (MFR)(60)/(A/F Ratio)(BSFC) = about 248 Crank HP at 9000 RPM with a BSFC of .60 and an AFR of 12.5.

So the best you could ever do (theoretically) is 248-ish; and if you get 232 stock.... you figure it out.
Old 07-13-2008, 03:39 PM
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Originally Posted by mysql
ap and catless midpipe are all you need for power gains.

everything else is fluff.

most you can hope for is close to 200 whp. You can't get much higher without FI

hmmm...

i see your rx8 is turbo... how is that going for you? and do you think it was worth it?
Old 07-13-2008, 03:40 PM
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Originally Posted by icey?
hmmm...

i see your rx8 is turbo... how is that going for you? and do you think it was worth it?
ask yourself if doubling the torque and increasing hp by close to twice is worth it

I did a poor *** job on the 3071R clip (went from 47 mph to 75 then back down to 45), but this should give you an idea:

http://youtube.com/watch?v=a0RSPGoHgbw

Last edited by mysql; 07-13-2008 at 03:43 PM.
Old 07-13-2008, 03:42 PM
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Here is a crappy one (night) - but you'll get the idea.

http://youtube.com/watch?v=QVL1IJ_tBb8
Old 07-13-2008, 03:45 PM
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^ I think you linked to the wrong one. This clip is much better:

http://youtube.com/watch?v=GQ2myuLL480
Old 07-13-2008, 03:46 PM
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Yeah prolly - but I just like seeing the 4th gear pull where I am at the end of the run before Paul is even at 4500 RPM.... LOL
Old 07-13-2008, 03:56 PM
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Originally Posted by Kane
Not much.

Assume you have 100% VE in all RPM's (basically impossible; but assume you have the perfect NA engine) then do this math :

VFR100% = [(Disp)(RPM)]/ 3456 or 1728 rotary
80 cu in * 9000 / 1728 = 417 CFM
VFRactual = (VFR100%)(VE) assume 417 still for best case
MFR = [(2.703)(PAmbient)(VFR)]/[TAmbient + 460]
MFR = 31 lb min air at 80 degrees F.
Horsepower = (MFR)(60)/(A/F Ratio)(BSFC) = about 248 Crank HP at 9000 RPM with a BSFC of .60 and an AFR of 12.5.

So the best you could ever do (theoretically) is 248-ish; and if you get 232 stock.... you figure it out.

Then how did TeamRx8 gain almost 40hp NA with a cat?
Old 07-13-2008, 04:01 PM
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Assuming a VE of 100% - which at 9000 RPM I am SURE you will not have.

So if you move from a VE of 60% to a VE of 65% (with your mods); then you will have more power; then you have to factor in drive train losses ( don't forget loss of unsprung weight; etc) - all kinds of stuff to get your Wheel HP number..... but the only way to get to that level of detail is a lot of dyno time.

Last edited by Kane; 07-13-2008 at 04:59 PM.
Old 07-13-2008, 04:57 PM
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hmmm... intresting

i will probably go turbo... one day... haha

iv seen a lot of videos on youtube of turbo rx8's im just trying to figure out the max hp i could get out of an rx8...

any one know how far the tuning limits go as far as N/A...?
Old 07-13-2008, 05:06 PM
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Yes; a VE of 100% (or JUUUUUST over 100%).

Go for it.
Old 07-13-2008, 06:11 PM
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just go turbo u wont regret
Old 07-14-2008, 10:32 AM
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Originally Posted by Kane
Not much.

Assume you have 100% VE in all RPM's (basically impossible; but assume you have the perfect NA engine) then do this math :

VFR100% = [(Disp)(RPM)]/ 3456 or 1728 rotary
80 cu in * 9000 / 1728 = 417 CFM
VFRactual = (VFR100%)(VE) assume 417 still for best case
MFR = [(2.703)(PAmbient)(VFR)]/[TAmbient + 460]
MFR = 31 lb min air at 80 degrees F.
Horsepower = (MFR)(60)/(A/F Ratio)(BSFC) = about 248 Crank HP at 9000 RPM with a BSFC of .60 and an AFR of 12.5.

So the best you could ever do (theoretically) is 248-ish; and if you get 232 stock.... you figure it out.
i think i just had a seizure
Old 07-14-2008, 12:07 PM
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Originally Posted by Revvittupp
Then how did TeamRx8 gain almost 40hp NA with a cat?
I believe that among other things he deleted the AC

If you want a max powah NA rx-8 you need: Cobb AP, Ignition, intake, midpipe, exhaust, & flywheel
Old 07-14-2008, 12:28 PM
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AP ignition and Midpipe should be good for around 210, the others add up to the other 10, and a couple more if you delete AC...
Old 07-14-2008, 01:04 PM
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teamrx8 has a $1000 german built DTM spec cat.

if you want to stay legal and want the benefits of a mid pipe, be prepared to shell out the cash.
Old 07-14-2008, 02:31 PM
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Talking

Racing Beat REV 8 exhaust and Mazsport catless midpipe raised my horsepower by 40 RWHP over the stock exhaust.
But then, I have a Pettit S/C .....
Old 07-14-2008, 02:47 PM
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Originally Posted by dozer
i think i just had a seizure
im gonna throw up.
Old 07-14-2008, 03:11 PM
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You guys asked - I was just giving an answer....
Old 07-14-2008, 03:57 PM
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Originally Posted by Kane
You guys asked - I was just giving an answer....
yes but now we are all depressed



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