GIRTH!! 4 inches vs 3!! what say yall?

[triniVr4]

does goin with a 4 inch exhaust twk way from performance? and if it does not..does it increase performance?

[bradc]

I would suggest staying with 2.5" or 3" for the downpipes. After those join I don't think it would matter that much if you went with 3" or 4". I think most people here have 3" only though.

[You See]

If the diameter is too large, it'll cause your turbos to overspool. With our standard turbos being so small it will create more power but it'll be a matter of time before they go BANG!

[Bahama Dreamz]

plus you will lose alot of low end. thus wont really take much advantage of the 4 wheel drive to get a nice launch. i had 3 inch straight pipe and it tok alot away from the bottom end

[AllBeItMine]

I would suggest staying with 2.5" or 3" for the downpipes. After those join I don't think it would matter that much if you went with 3" or 4". I think most people here have 3" only though.

wrong :happy:

[AllBeItMine]

If the diameter is too large, it'll cause your turbos to overspool. With our standard turbos being so small it will create more power but it'll be a matter of time before they go BANG!

wrong too :happy:

[You See]

Oh please share your wisdom oh great one! :p

[AllBeItMine]

forget about race cars, or track cars or drag cars with 2 foot long exhausts coming out of behind the front wheel. these spend there lives above 7,000rpm.

for a real world car, no matter if its turbo or NON-turbo, the exhaust system should be designed for how much horsepower the car is generating.

for a standard VR4 with typical mods. 2.5-2.75inch mandlrel meant would be perfect. 3 inch is actually a bit big.

if you going for 350hp mark, 3inch would be fine.

you need to rember the increase in cfm flowing through a pipe gains exponentially as the diameter of the pipe increases also - so you would find a 4 inch exhaust on a 6-700hp car.

[bradc]

ABIM, how big are the downpipes that Lance put on? are they 2" or 2.5"? And after it joins, isn't it 3"

[You See]

mandlrel ...Wrong!

rember ...Also Wrong!
Sorry, hadda find a comeback of some sort! ..lol :rolleyes4

[AllBeItMine]

ABIM, how big are the downpipes that Lance put on? are they 2" or 2.5"? And after it joins, isn't it 3"


on your car? yes. 2.5x2 -> 3.

[Ollpen]

/Hijack

Does this mean that i will not gain performance if i upgrade my exhaust on my stock Legnum?

That would be nice so i dont have to worry about sound :P

[bradc]

on my VR-4 my max power increased from 153kw at the wheels to 159kw at the wheels. After the max power point, the dyno curve with the stock exhausts fell away very quickly, compared to the curve with the exhaust mods. At one point the curve was 12kw away from the standard curve. So there can be quite a big differance with a VR-4

[ANTHONY]

hadda Also very wrong queens english!!............sorry i had to say that old bean/pan/pan




ok ok i'm going

[psbarham]

it all depends on where you want the power , more top end then 3 inch +is spot on , more useable power lower down go for the smaller exhaust , before anybody starts going bullsh!t why did most of the F1 teams copy yamaha and fit a butterfly valve in the exhaust to restrict gasflow for low down grunt ( well ok the FIA took 2 weeks to ban it ) even the wrc boys only run 2 - 21/2 inch exhausts , torque rules as far as they are concerned

[triniVr4]

so, from what im reading, the 3 inch really works for mid range to high end applicaitons...but for street "light to light" usage, th 2.5 is the preferred diameter...


gr8...

[Ollpen]

Saves me heaps of money to hear:P

[AllBeItMine]

yes. but remember - the standard 2.5 inch system is quite restrictive with a number of resonators and a large baffled muffler in the way of the exhaust gases... not the same as a nicely free flowing 2.5inch mandrel system with 1 resonator and a free flow box at the back.

and in response to psbarham comment - the standard vr4 exhaust system has a butterfly in the back box for exactly this purpose, you need to chop open the muffler to see it however.

[psbarham]

yes. but remember - the standard 2.5 inch system is quite restrictive with a number of resonators and a large baffled muffler in the way of the exhaust gases... not the same as a nicely free flowing 2.5inch mandrel system with 1 resonator and a free flow box at the back.

and in response to psbarham comment - the standard vr4 exhaust system has a butterfly in the back box for exactly this purpose, you need to chop open the muffler to see it however.
thats strange my v6 only has one resonator and the back box , but a sh!t load of stupid bends , which is why i'm working on a cunning plan :inquisiti , is the butterfly in the vr4's backbox connected to anything or does it work off of back pressure ?

[AllBeItMine]

thats strange my v6 only has one resonator and the back box , but a sh!t load of stupid bends , which is why i'm working on a cunning plan :inquisiti , is the butterfly in the vr4's backbox connected to anything or does it work off of back pressure ?

its just spring loaded - not vacum actuated like on the audis and porches. there are some pics on here somewhere of somebody modifying it. just can't remember who it was that did it.

and yeah, the vr4 has 2 resonators and a bigger rear muffler... i think.

[Rossco Type-S]

Mine came from Japan with the ralliart exhaust which is 3" or more and has 2 resonators and an absolutely massive muffler.

The difference in performance between the stock car and the mine is huge. The stock car seems slow in comparison. However, my car might have other mods I have not discovered yet.