V8 & Twin exhaust question

[mrshin]

So long as the hottest point isn't just form restriction from a nasty bend...

[BeRad]

even still, that shouldnt be in your exhaust. and if it is, its taking pressure/heat off that point therefor helping the problem in that area.

[Wildsupra]

ok so it would seem that if i do run the twin exhaust i will defiantly be using a crossover pipe, maybe justin is right and i should just run a sophisticated sounding single.....hmm i did like the idea of 2 3" pipes exitting the rear of the car at a slight angle though........

Cheers heaps guys, very informative, and being its going on a 1UZ then i definatly wont run them seperately.

Matty

[Mos]

1UZ-FE firing order is 1-8-4-3-6-5-7-2. Left bank is odd, numbered from the front.

1-8-4-3-6-5-7-2
L-R-R-L-R-L-L-R

In a traditional tri-y or 4-2-1 extractrators you group alternate cylinders.
So on the left bank, you will group 1 and 5 together, and 3 and 7 together.
On the right bank, you will group 8 and 6 together, and 4 and 2 together.

You will notice that the time between firings of each cylinder varies on each bank, unlike that of a 4 cylinder which is even.
For instance in the 1 and 5 grouping, there are 4 firing events between 1 and 5 firing. In the 3 and 7 grouping, there are only 2 firing events between them.

The effect is that the pulses come at uneven times out of each bank and unless you group them back together (either back into one, or through an X-pipe) they will continue to be uneven and sound like crap. In terms of performance, I would suggest that if it did not make a difference to exhaust flow and power output, balance pipes wouldn't be used - open pipes obviously don't matter. I guess it makes sense, if you have times of higher and lower pressure, it won't flow as nicely and smoothly as something with more even pressure throughout - the scavenging effect will be more prominent at some firings compared to others.

I'll be running both banks into a single outlet. However, if I were to run twin exhaust I'd use an X-pipe in preference to joining and splitting further down the track.

Mos.

[Wildsupra]

1UZ-FE firing order is 1-8-4-3-6-5-7-2. Left bank is odd, numbered from the front.

1-8-4-3-6-5-7-2
L-R-R-L-R-L-L-R

In a traditional tri-y or 4-2-1 extractrators you group alternate cylinders.
So on the left bank, you will group 1 and 5 together, and 3 and 7 together.
On the right bank, you will group 8 and 6 together, and 4 and 2 together.

You will notice that the time between firings of each cylinder varies on each bank, unlike that of a 4 cylinder which is even.
For instance in the 1 and 5 grouping, there are 4 firing events between 1 and 5 firing. In the 3 and 7 grouping, there are only 2 firing events between them.

The effect is that the pulses come at uneven times out of each bank and unless you group them back together (either back into one, or through an X-pipe) they will continue to be uneven and sound like crap. In terms of performance, I would suggest that if it did not make a difference to exhaust flow and power output, balance pipes wouldn't be used - open pipes obviously don't matter. I guess it makes sense, if you have times of higher and lower pressure, it won't flow as nicely and smoothly as something with more even pressure throughout - the scavenging effect will be more prominent at some firings compared to others.

I'll be running both banks into a single outlet. However, if I were to run twin exhaust I'd use an X-pipe in preference to joining and splitting further down the track.

Mos.

awesome info mate, very much appreciated and very well explained.

Cheers
Matty

[Malicia]

Excellent info Mos.

Using your info it appears that the popular Rush Headers don't really do what they are designed for.



How much would it cost to get new headers made up for the 1uzfe?
I'm not sure I want to spend $5-600 + fitting for an item that isn't doing what I baught it for.

[JustenGT8]

Have you seen the room you have to play with???? You are lucky anyone had a stab at getting anything to fit. Not the best, but for the bucks a hell of a lot better than the stock set surely?

[Wildsupra]

Yeah i must agree with justin there.

Still need to have a close measure up to see if i can get the rush ones to fit in the supra bay......

[petespipes]

Have seen the V8 twin pipes merge together for 400mm then seperate again rather than a cross over pipe,looks nice for flow.I think it may have been a rare shot of an upside down V8 supercar.............

[Wildsupra]

Thats wot i was thinkin, put 2 pipes along side each and cut the guts outta each and basically stretch and seam weld it. Like a big hollow twin inlet outlet muffler.

[Screamn_Sleeka]

Hang on, are you saying that you want a completly exhaust system for each side of a V engine?
Ofcourse u can do that, its easier and cheaper.

But why? you get terrible backfiring!
First hill you go down and try to use engine compression braking you'll wish you put a balance pipe in.

[itchybum1]

With tuned length extractors you won't need a crossover or resonator pipe, i run this setup on my HQ monaro with a twin stainless system. Whereas with tri y's or intermediate's you will obviously have to run one. Tuned length may be more bulky to fit in your application by the sound of things. Although on a stock engine tri's will deliver more low end response than tuned.

[EldarO]

Hang on, are you saying that you want a completly exhaust system for each side of a V engine?
Ofcourse u can do that, its easier and cheaper.

But why? you get terrible backfiring!
First hill you go down and try to use engine compression braking you'll wish you put a balance pipe in.

someone who quite obviously doesnt know matty

"terrible" and "backfiring" are never in the same sentence for matty

mind you, ive only gotten my car to backfire once, the seat was brown and i though half of a flywheel was gonna end up in my ankles

Elmo.

[Screamn_Sleeka]

Well yeah, i dont know what you are trying to achieve here.
Infact, people used to compliment on the sound of the car im talking about, but as far as im concerned they werent the kind of people who have a valid opinion of cars

As for performance i wouldnt have a clue!
I just like it silent and legal.

[Mos]

Excellent info Mos.
Using your info it appears that the popular Rush Headers don't really do what they are designed for.

Yeah, it would appear so, but they'll be way better than stock.

How much would it cost to get new headers made up for the 1uzfe?
I'm not sure I want to spend $5-600 + fitting for an item that isn't doing what I baught it for.

I think the minimum you will be looking at is $1500 for a custom built pair in mild steel, and at least double that in stainless. It's a lot of fiddling around, and then there's the time to weld it all together after you've made all the pieces.

This is my system. The headers have since been ceramic coated.


The headers are obviously limited by packaging constraints. This is where they have to fit.

With tuned length extractors you won't need a crossover or resonator pipe, i run this setup on my HQ monaro with a twin stainless system. Whereas with tri y's or intermediate's you will obviously have to run one. Tuned length may be more bulky to fit in your application by the sound of things. Although on a stock engine tri's will deliver more low end response than tuned.

Tuned to what? If you have an uneven firing order, unless you're making different length primaries for each cylinder (which will only really work at a specific rpm) you will still get uneven pulses regardless of whether it's a 4-2-1 or a 4-1... Is that the sort of thing you're talking about? Or were all your pipes the same length?

Mos.