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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: Re: advantages of 3" exhaust on supercharged 4ltr
Posted: Mon Jun 01, 2009 5:23 pm 
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You will pick up a small gain, but you'd have to be happy with it for $850.

Alternatively you could put that towards the beginning of a w2a intercooler and smaller pulley. Might cost $1500 but give you 30rwkw instead of 5? In that case much better value. Another option could be a water injection kit, and the necessary tuning to take advantage of it. This often gives 10% more power (if tuned accordingly) and you'd end up with change.

Certainly the exhaust once its on will complement other mods though, and won't cost you more (eg. fuel, maintenance, water/meth, etc). Just some ideas.

Joe

 

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 Post subject: Re: advantages of 3" exhaust on supercharged 4ltr
Posted: Mon Jun 01, 2009 7:51 pm 
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Double post due to Fordmods taking five minutes to update when posting (damn hackers...)

Last edited by fiend on Mon Jun 01, 2009 7:56 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 7:53 pm 
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EVL098 wrote:
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 turbulence and actually slow gas flow down.

I agree with this, having studied this side of thing closely. Backpressure isn't what makes the engine work either, but is a commonly mis-used term. The thing is NOT backpressure ; It is having a thinner pipe that the gas has to fly down very quickly, thus when the valve is shut it creates a bit of a low pressure (vacuum) which then helps suck the next cycle of gas from the chamber. Obviously if you took the extractors off and replaced them with a huge chamber (or just ran engine in a room with no pipes out of head at all) you'd have a very badly running engine. If you had three inch pipes coming straight off each cylinder you'd have a very badly running engine. If you have one inch pipes about three foot long, you have a good running engine. If you then have those running into each other etc etc etc... Etc etc etc... It get's a little complicated now, which is why some people make thousands out of header designs, and I don't.

From rear wheel arch back over axles or similar you could be 2.5" easily as the gases have cooled that much that the actual flow is reduced by then (and yes, this will improve exhaust note over the straight through 3" drone loved by EVO 4 owners in Wellington.)




Obviously I am a novice with no real world experience in such matters, and expect to be blown up via a well placed car bomb first thing in the morning for daring to butt in here.
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 Post subject: Re: advantages of 3" exhaust on supercharged 4ltr
Posted: Mon Jun 01, 2009 8:48 pm 
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Fiend mate don't ever stop is all i can say.
I love your out of the square thinking.
Fact is backpressure is a myth,after the headers it's all a restriction untill the cooling point.That's why a 3inch is better than a 2.5 inch.
The guy that sells the Raptors advocates a 3 inch sport system.
So do i, i only gained 15rwhp but the torque gain was from 1470lb to 1780lb of torque.When you take in to effect that a stock LS1 is only around 1170 it's a good thing.
The thing is untuned so it falls on it's head at 5k but the torque curve is over 1700lb from 1800 revs to that 5000 revs where it pulls timing out .
This made the car much more flexible to drive.

 

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 Post subject: Re: advantages of 3" exhaust on supercharged 4ltr
Posted: Mon Jun 01, 2009 9:11 pm 
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you would definately see a gain, the amount I couldnt tell you. by whacking on forced induction you increase the VE of your motor. a 5 litre V8 with a 2 litre supercharger should be able to put out similar power as a 7 litre v8 (give or take bits here and there- its just an analogy for illustration purposes.) and thus a similar amount of exhaust gas.

so If the raptor (for example- dont know the real figure) is adding an extra 1.5 litres of displacement when on boost you car will have the same exhaust output as a 6 litre or so engine. air in = air out, a motor is for all intents and purposes a self driven air pump. would recomend a high flowing metalcore cat with as low CPI as you can find if you cont already have one.

so 3 inch would be recomended.

 

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 Post subject: Re: advantages of 3" exhaust on supercharged 4ltr
Posted: Mon Jun 01, 2009 9:16 pm 
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Correctamundo.

 

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 Post subject: Re: advantages of 3" exhaust on supercharged 4ltr
Posted: Mon Jun 01, 2009 9:41 pm 
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My stainless system i made was about $650, including magnaflow cat....

Any sort of forced induction, you really need a 3 inch system, but obviously there is plenty running 2 1/2, and happy with it...

Cheers

:D Daz 8-)

 

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 Post subject: Re: advantages of 3" exhaust on supercharged 4ltr
Posted: Mon Jun 01, 2009 9:50 pm 
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while the car is still un tuned running the 2 1/2 system it still has enough grunt to put a smile on ya face..lol
but i would like to extract ever single bit of power from the hand grenade before it explodes.. joke
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 Post subject: Re: advantages of 3" exhaust on supercharged 4ltr
Posted: Mon Jun 01, 2009 10:17 pm 
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meh unless you know a boilermaker/pipe fabricator i wouldn't pay for one troyman.

 

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 Post subject: Re: advantages of 3" exhaust on supercharged 4ltr
Posted: Mon Jun 01, 2009 10:26 pm 
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Get a redback V8 3" over the diff section and have the cat to diff fabricated wont be as expensive

 

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 Post subject: Re: advantages of 3" exhaust on supercharged 4ltr
Posted: Mon Jun 01, 2009 10:46 pm 
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keeping all you thoughts in mind ill point out that the s/s cat converter is $300 of the $800..
ive had 2 quotes so far and the first was $900 and the second was $800..
i dont think ill get it done much cheaper than that...
but ill try a few other places tomorrow..
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 Post subject: Re: advantages of 3" exhaust on supercharged 4ltr
Posted: Tue Jun 02, 2009 12:25 pm 
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Yeah i got my 3" magnaflow cat from tuff car parts on ebay and hes up in qld only cost me $230 including shipping.

Ok with the 3" exhaust on a forced car there is sfa difference when driving around town it will still drive the same, its when you step on it you feel it and id suggest a tune with the exhaust upgrade.

Its all in the tune ..... air in air out......

Breath in then try to breath out through a straw, yes troyman you are a supercharged beast lol you get the idea.

Brad
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 Post subject: Re: advantages of 3" exhaust on supercharged 4ltr
Posted: Tue Jun 02, 2009 6:02 pm 
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also i've seen the twin cam turbo twin exhaust setups on ebay go pretty cheap from other people upgrading, which afaik are dual 2" so therefore sectionally bigger than the 3'' (if size matters) you could possibly pick one up cheap, use as much as possible fabricate as little as possible could turn out a quite an effective cheap mod.

other option could be to unwrap the stock cat, cut the pipes off, get out the die grinder and weld new 3'' inlet/outlet on.

 

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Last edited by low_ryda on Tue Jun 02, 2009 7:03 pm, edited 1 time in total.

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 Post subject: Re: advantages of 3" exhaust on supercharged 4ltr
Posted: Tue Jun 02, 2009 6:10 pm 
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essentially im not out to save money (ive already spent over 5g on the car..lol)
but i dont want to spend un necessary amounts of money for no gains..
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 Post subject: Re: advantages of 3" exhaust on supercharged 4ltr
Posted: Tue Jun 02, 2009 6:20 pm 
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i think for dollars vs gains, the 3" exhaust is going to be pretty bad value at your current power level.
I agree with joexr6 in that I reckon you are better off looking at some form of charge cooling so the tune can be a bit more a agressive, safely.
How much boost is it running now to make 175?

 

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