HP gain from decat and exhaust. - LotusTalk - The Lotus Cars Community
 
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post #1 of 11 (permalink) Old 06-19-2011, 06:25 PM Thread Starter
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HP gain from decat and exhaust.

Any one have any before and after dyno numbers on a NA Elise or Exige when going from stock to a decat and exhaust.
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post #2 of 11 (permalink) Old 06-19-2011, 06:47 PM
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167.31 whp / 121.52 wtor stock
177.17 whp / 126.04 wtor turbo xs intake + forcedfed header + decat + 2bular exhaust (stock ecu)

In other words about 10 whp.

d.a..v...i....d

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410hp 1697lbs. 11.477 @ 123.59 mph
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post #3 of 11 (permalink) Old 06-19-2011, 08:01 PM Thread Starter
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Originally Posted by darkSol View Post
167.31 whp / 121.52 wtor stock
177.17 whp / 126.04 wtor turbo xs intake + forcedfed header + decat + 2bular exhaust (stock ecu)

In other words about 10 whp.
Thanks for the info. Any others?
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post #4 of 11 (permalink) Old 06-19-2011, 08:46 PM
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Originally Posted by Rviscosi View Post
Thanks for the info. Any others?
Not very many people have documented this, as the general consensus is that the gains are so minimal that they aren't worth verifying.

And in all honesty, I'd bet most of DarkSol's increase in peak power came from the header

Edit: heck, it could have been 40 degrees cooler that day

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post #5 of 11 (permalink) Old 06-20-2011, 03:32 AM Thread Starter
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Not very many people have documented this, as the general consensus is that the gains are so minimal that they aren't worth verifying.

And in all honesty, I'd bet most of DarkSol's increase in peak power came from the header

Edit: heck, it could have been 40 degrees cooler that day
That is what the entire premise of this thread is about, to put the speculation to bed. If the cat is as restrictive as they say then my guess would be that what little gain there is, would be from this. 10rwhp in a light car is not bad IMO.

Edit: SAE and STD corrections account for change in atmospheric conditions.

Last edited by Rviscosi; 06-20-2011 at 03:35 AM. Reason: Additional info.
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post #6 of 11 (permalink) Old 06-22-2011, 09:14 AM Thread Starter
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Anyone else have any numbers to add?
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post #7 of 11 (permalink) Old 06-22-2011, 07:56 PM
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I have numbers, but my car is supercharged

** save ~10 lbs gain 1 hp ** EQ: Y=(190*X) / (1984-X) where Y is (HP) and X is (lbs)

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post #8 of 11 (permalink) Old 06-22-2011, 08:56 PM
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A bunch of us dyno'd every exhaust combination imaginable back in the day. Randy Chase spent hours on the dyno trying to squeeze out the tiniest bit of power from different setups.

The gist of it is... an exhaust basically does nothing for power. In an NA car, the decat doesn't really do anything but pollute more.

I have a dyno showing a 9 WHP gain using my PPE header on an NA car. Sticking a decat on with the header showed a 10 WHP gain and a loss in torque... so I just kept a high-flow cat in place with the header.

Supercharged cars are a different story. I run a decat now if that says anything
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post #9 of 11 (permalink) Old 06-23-2011, 04:04 AM Thread Starter
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Originally Posted by Bane View Post
A bunch of us dyno'd every exhaust combination imaginable back in the day. Randy Chase spent hours on the dyno trying to squeeze out the tiniest bit of power from different setups.

The gist of it is... an exhaust basically does nothing for power. In an NA car, the decat doesn't really do anything but pollute more.

I have a dyno showing a 9 WHP gain using my PPE header on an NA car. Sticking a decat on with the header showed a 10 WHP gain and a loss in torque... so I just kept a high-flow cat in place with the header.

Supercharged cars are a different story. I run a decat now if that says anything
Is there a faq on this or thread? I searched but couldn't find anything like that.

Thks
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post #10 of 11 (permalink) Old 06-23-2011, 07:50 AM
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Rviscosi,

No FAQ, what Bane said is correct. You do lose about 28lbs off the rear of the car behind the axel with a BOE exhaust vs. stock though.

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post #11 of 11 (permalink) Old 06-23-2011, 08:06 AM Thread Starter
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Rviscosi,

No FAQ, what Bane said is correct. You do lose about 28lbs off the rear of the car behind the axel with a BOE exhaust vs. stock though.

Well atleast that is a nice bonus.

Thks
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