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advantages of 3" exhaust on supercharged 4ltr 

 

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3" or stay 2 1/2
go 3" exhaust 69%  69%  [ 18 ]
stay 2 1/2 31%  31%  [ 8 ]
Total votes : 26

 

 

 
 Post subject: advantages of 3" exhaust on supercharged 4ltr
Posted: Mon Jun 01, 2009 3:13 pm 
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hi guys
as some know ive now raptor supercharged my ed 4 ltr..
its currently running a 2 1/2" high flow cat,2 1/2 redback system with 1 straight through muffler.
and a few people have recomended i should go 3" exhaust+cat.
what would the main gains be power wise(kw/torque)?
would it gain performance overall or just in the top end?

as centrifugal superchargers build boost with rpm do you think it will loose down low power??
so far the cheapest quote ive got is $800 for 3"cat and exhaust with 1 muffler and resinator..

im not expecting a 100kw gain or anythging silly like that.lol..
but i would be interested in what the gains would be considering a 3" system is almost twice the price of a 2 1/2..
what are your opinions?? :)

Last edited by TROY. on Mon Jun 01, 2009 3:57 pm, edited 1 time in total.

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 Post subject: Re: advantages of 3" exhaust on supercharged 4ltr
Posted: Mon Jun 01, 2009 3:25 pm 
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will lose low down torque but make top end power! depends on if you want a good street car or track car..

 

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 Post subject: Re: advantages of 3" exhaust on supercharged 4ltr
Posted: Mon Jun 01, 2009 3:29 pm 
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Mine picked up power everywhere on the dyno with a 3 inch system.
From zero to redline,the backpressure thing has been mythbusted.

 

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 Post subject: Re: advantages of 3" exhaust on supercharged 4ltr
Posted: Mon Jun 01, 2009 3:36 pm 
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green machine wrote:
will lose low down torque but make top end power! depends on if you want a good street car or track car..


both..
it gets driven all the time so as you know its more of a street car.
but it may be visiting a track every now and then..
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 Post subject: Re: advantages of 3" exhaust on supercharged 4ltr
Posted: Mon Jun 01, 2009 3:36 pm 
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Ive tried dumping the exhaust on my car and it made no noticeable difference so I didnt go ahead with the 3 inch upgrade. Its a different application but its something you could try to see if it makes a worthwhile difference.
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 Post subject: Re: advantages of 3" exhaust on supercharged 4ltr
Posted: Mon Jun 01, 2009 3:39 pm 
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badcooky wrote:
Mine picked up power everywhere on the dyno with a 3 inch system.
From zero to redline,the backpressure thing has been mythbusted.


what sort of gains did you get??
as mine is now down low is fairly good but under boost it almost sounds like the gasses are struggling to get out..
more of a shhhhhh sound mixed with the exhaust note..
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 Post subject: Re: advantages of 3" exhaust on supercharged 4ltr
Posted: Mon Jun 01, 2009 3:48 pm 
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Personally I noticed no difference when changing from 2 1/2" to 3".

 

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 Post subject: Re: advantages of 3" exhaust on supercharged 4ltr
Posted: Mon Jun 01, 2009 3:49 pm 
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can't find the sheets but more everywhere and as the revs rise it gets better.
Something like 10rwkw at peak ,torque was the winner though.

 

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 Post subject: Re: advantages of 3" exhaust on supercharged 4ltr
Posted: Mon Jun 01, 2009 3:59 pm 
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I reckon go the 3" back until the over axle pipe and then drop it back to 2.5".
You wont get droning then and will get a better note , plus keep the gas flow nice.
Remember as exhaust gases cool they physically need less pipe diameter to escape as they are not as dense.
A too bigger pipe diameter all the way through can cause turbalance and actually slow gas flow down.

 

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 Post subject: Re: advantages of 3" exhaust on supercharged 4ltr
Posted: Mon Jun 01, 2009 4:24 pm 
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you will only notice a difference on the rollers and top end..i'd say leave it the way it is and save your money

 

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 Post subject: Re: advantages of 3" exhaust on supercharged 4ltr
Posted: Mon Jun 01, 2009 4:29 pm 
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Worthwhile question when you consider the dollars involved! I have a 3inch exhaust, but think that the advantages of exhausts are often overrated.

Someone commented before about not feeling the difference between 2.5 inch to 3 inch exhaust. Thats the point exactly....from a standard to performance exhaust on a 120rwkw car (eg. standard I6), you've done very well if you pickup 10rwkw. But that's less than a 10% power gain, and usually in a narrow rev range. You'd only just 'feel' a 10% gain in extra acceleration performance.

Changing from 2.5 to 3 inch wouldn't give this gain again. Optimistically you'd get half this, which might be a 5% gain. You'd really have to be trying to 'feel' this gain, and in short time it wouldn't be noticable at all. It would have little effect on acceleration times,etc.

Exhausts are pretty expensive for the the actual gains they give. Aside from the change in exhaust note, they'd be better left as one of the last modifications, though we typically do it first. To make the absolute most of your supercharger, there might be some benefit in 3inch, but I'd spend the $850 on everything else that needs to be done first!

Joe

 

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 Post subject: Re: advantages of 3" exhaust on supercharged 4ltr
Posted: Mon Jun 01, 2009 4:40 pm 
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depends how much power your chasing.

i'm still running a 2.5" exhaust @ 225rwkw

 

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 Post subject: Re: advantages of 3" exhaust on supercharged 4ltr
Posted: Mon Jun 01, 2009 4:46 pm 
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so far it made 175rwkw and 520nm with a fairly poor tune i think i would be lucky to get 200 rwkw?.

im just curious if the 3" exhaust will help get it there..???
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 Post subject: Re: advantages of 3" exhaust on supercharged 4ltr
Posted: Mon Jun 01, 2009 5:04 pm 
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OED666 runs a 3" exhaust N/A, will make gains

 

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 Post subject: Re: advantages of 3" exhaust on supercharged 4ltr
Posted: Mon Jun 01, 2009 5:07 pm 
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you'll pick up some power for sure.
weather its worth the $800 is upto you.

 

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