Outer Limits 4x4 Board

Hi guys just wondering what your thoughts are on where to place the balance pipe on a dual 2.5" v8 system...

Before cats? after cats?

Also what would be the minimum size for the balance pipe? im looking at fitting 1.5 pipe but would like to go smaller if i can

get a crayon run a line along both pipes, when the motor/exhaust is cold, turn the motor on and the point on each pipe that melts the crayon first, is the ticket to x it over.

the old burn back method.

whats the benifits of having a cross over pipe in my mq shorty its got a holden v8 with twin 2 1/4 pipe no cross over what effects will i have not having one

Was speaking to an exhaust bloke about it a few years ago when considering putting a dual on my statesman.

Apparently it has to do with each bank of the V8 firing one after the other, which pulses high pressure waves down the exhaust pipe. Behind each high pressure pulse there is a vaccuum. A crossover basically utilises the sucking of the vaccuum behind each pressure pulse to draw the exhaust out quicker from the other bank through the crossover.
I can kinda understand that in my head, sorry i cant explain it clearer.
It helps boost low end torque so im told.

Thanks guys.. I was hoping to do it before i start the motor and send the system with the headers for heat proof coating but yeah the burn back meathod sounds the best option to get it right.

Cheers
Dan

PJ.zook wrote:Was speaking to an exhaust bloke about it a few years ago when considering putting a dual on my statesman.

Apparently it has to do with each bank of the V8 firing one after the other, which pulses high pressure waves down the exhaust pipe. Behind each high pressure pulse there is a vaccuum. A crossover basically utilises the sucking of the vaccuum behind each pressure pulse to draw the exhaust out quicker from the other bank through the crossover.
I can kinda understand that in my head, sorry i cant explain it clearer.
It helps boost low end torque so im told.

its also much quieter than duals, because the pulsing from each cylinder bank cancel each other out to a degree, gives it a much nicer note. I can't stand the sound of duals on a v8

80's_delirious wrote:

PJ.zook wrote:Was speaking to an exhaust bloke about it a few years ago when considering putting a dual on my statesman.

Apparently it has to do with each bank of the V8 firing one after the other, which pulses high pressure waves down the exhaust pipe. Behind each high pressure pulse there is a vaccuum. A crossover basically utilises the sucking of the vaccuum behind each pressure pulse to draw the exhaust out quicker from the other bank through the crossover.
I can kinda understand that in my head, sorry i cant explain it clearer.
It helps boost low end torque so im told.

its also much quieter than duals, because the pulsing from each cylinder bank cancel each other out to a degree, gives it a much nicer note. I can't stand the sound of duals on a v8

The only decent sounding 8's must have duel exhausts

cloughy wrote:
The only decent sounding 8's must have duel exhausts

Duals suck except for drag cars and hypo V8's. Duals sound to feral in a bad way, like two Gemini's trying to drag race....

Single FTW

http://www.youtube.com/watch?v=EpjJI4vieXA&

Dual or single it will still sound better than the old 6 its replacing...

I once had a single 3" system on my GT then got a dual system fitted and yep i wasnt happy with it so i made an x pipe for it and gained 40hp at the wheels on the dyno, i can live with that Thats the reason im here asking about a balance pipe so that i dont loose power and it still has the fine tuned sound that a dual system without it cant offer

http://www.youtube.com/watch?v=CCMDUZmhkWM&NR=1
http://www.youtube.com/watch?v=FVi4w_PGvUo

I run twin 2.5in into single 3in from the diff back. Sounds awsome.

Hulksta wrote:Hi guys just wondering what your thoughts are on where to place the balance pipe on a dual 2.5" v8 system...

Before cats? after cats?

Also what would be the minimum size for the balance pipe? im looking at fitting 1.5 pipe but would like to go smaller if i can

The crayon method really is the only effective way of working out where to put it/them.

I've seen a system that apparently worked well with 2 1" balance pipes on 3" twin system. There were 2 hot spots about 4" apart, so they put a pair of balance pipes in diagonally from side to side so they crossed. I suspect that 2 parallel would have worked just as well or possibly better.

I've also seen mention of systems with one balance pipe ahead of the cats and another behind but more often than not it's usually just one behind the cats.

Oh, and for some reason, LPG generally benefits from extractors and balance pipes more than petrol and is usually marginally quieter in the exact same system. Sounds better too.

As for the sound of single versus dual systems, Chevs, Toyota 1UZs and early Ford Windsors and Chrysler V8s usually sound better with a dual system. Clevelands, Holden V8s and Rover V8s always sound like crap so it doesn't really matter whether you have a single system or dual. :p

My 5yo son seems to quite like the twin 2" system on the 350 in my wife's Volvo.

Athol

its been a long time since i've had much to do with v8's.

you need to remember that tuning wise crossover pipe is a compromise.
both banks to a single pipe is best. however very hard to do in most vehicles as they don't have room.
next best is the split each side and dual crossovers in X pattern. unfortunately thats also complicated and most vehicles lack the room.
hence a single crossover pipe is often done as thats all they have room for.

putting a crossover after the cats defeats the purpose somewhat. the cat removes a lot of the pulses ie removes a lot of the tuning ability which is the whole point of the crossover pipe. probably done like that due to lack of room.

but i'm biased, theres nothing nicer than open pipes on a sprint car

Purely for interest's sake, can somebody explain the theory behind this crayon line method.

I understand the "look for the melting" bit - but what causes the hotspot, and will it always form at the same point, regardless of revs?

With the crossover pipe, Does it matter how long it is.

I want to run twin exhausts from my LS1, one under each sill outside the chassis rails. Is there any point having a crossover pipe if it is going to be like nearly 1 metre long?

The exhaust will have cats fitted aswell if that makes a difference

hey hulksta,
heres a few pics of my GQ LWB 454, twin 2.5'' inch system with a 2.5''
x-treme X-JUNCTOIN balance pipe, sounds pretty tough
sorry about all the mud

Athol wrote:

Hulksta wrote:Hi guys just wondering what your thoughts are on where to place the balance pipe on a dual 2.5" v8 system...

Before cats? after cats?

Also what would be the minimum size for the balance pipe? im looking at fitting 1.5 pipe but would like to go smaller if i can

The crayon method really is the only effective way of working out where to put it/them.

I've seen a system that apparently worked well with 2 1" balance pipes on 3" twin system. There were 2 hot spots about 4" apart, so they put a pair of balance pipes in diagonally from side to side so they crossed. I suspect that 2 parallel would have worked just as well or possibly better.

I've also seen mention of systems with one balance pipe ahead of the cats and another behind but more often than not it's usually just one behind the cats.

Oh, and for some reason, LPG generally benefits from extractors and balance pipes more than petrol and is usually marginally quieter in the exact same system. Sounds better too.

As for the sound of single versus dual systems, Chevs, Toyota 1UZs and early Ford Windsors and Chrysler V8s usually sound better with a dual system. Clevelands, Holden V8s and Rover V8s always sound like crap so it doesn't really matter whether you have a single system or dual. :p

My 5yo son seems to quite like the twin 2" system on the 350 in my wife's Volvo.

Athol

are you confusing familys? windsor with duals sounds like a holden (imagine rolling an empty steel drum down a mountain side full of bricks) clevos with dual pipes and balance have the smooth sound.