MrJdmJimi

iTrader: (6)

Is there a big difference in power vs spool vs torque .. Just wonder about the pro's and con's on equal and unequal lenth turbo manifolds???

xxNosTankxx

iTrader: (6)

I'm interested in this as well...

Ted B

iTrader: (6)

In a turbo engine, an equal length exhaust manifold more evenly applies exhaust pulse pressure to the turbine. The effect would be to increase spool efficiency and minimize pressure fluctuations inside the manifold, which could impact VE (torque).

MrJdmJimi

iTrader: (6)

what about on a turbo like the hta35r would there big a big loss on that turbo using a unequal manifold?

Magnumpsi

iTrader: (2)

I agree with Ted B but I think that is kind of a broad question as I think that equal length vs unequal really depends on a lot of things.

I know most people think that equal length is the right way but I think there is a lot more that applies to it. Look at Full Race for example they dont build all equal length headers.

Overall cylinder pressure to the turbine would be better on certain set-ups but variables like manifold design, head work and overall VE would be a deciding factor.

Mitch

JC evo1

whats more important; equal runner length or equal runner pressure/back pressure?
I have just had a custom exhaust manifold made, it is not quite equal length, what do you think of the design?

Magnumpsi

iTrader: (2)

Looks good.

I was about to say that it was made backwards until I saw what Evo you have lol.

Mitch

David Buschur

iTrader: (53)

I agree with Mitch. I spent a LOT of time this winter experimenting with headers, length, equal length, diameter, turbine housings etc. I didn't post the results of all the testing nor am I going to. This thread though makes me interested enough to talk about it though.

The Full Race header I was running last year is not even close to being equal length. As a matter of fact if my memory is correct there is about 6" difference in some of the runners, the amount of bends varies a lot per runner too. The header still made excellent power and my car ran 9.65 @151.

I wanted to do some dyno testing and see what I could learn. I built 3 custom headers for my car. I have all the runner lengths and bends per runner in my notes at the shop. I ended up with the most equal length header I built on my car and also the shortest runner length. This ended up being the one I kept, power was the best up to about 5800 rpm and was only down from the best one I tested by 2-3 whp which is hard to judge in the time frame the tests took place.

I would say that from what I learned, being equal length doesn't have a huge effect on the overall power delivery of a header. I did end up making more power and a better overall curve with what I built custom. It would not work though for 99% of EVO owners as it wouldn't fit.

Our production header performs as well as what I have built custom on my car, I just didn't want to run the same thing we seel. There are times I just want my car a little different than the rest. The runners on my car and our production header are less than 1/2" from being exactly equal length per runner. Our production header has runners that are about 4" longer than what is on my car now.

There are things in your turbo kit that will make a MUCH larger difference in the power you make than the length of the runners.

JC evo1

So, what else will effect a manifolds performance? How do things like runner diameter, collector design, wastegate placement change how it works?

Import Junky

iTrader: (7)

Knowing how Dave likes to stay on topic and I'm trying to hi-jack a little I may not get my question answered but here it goes. Dave, your cast manifold kits are extremely popular so how do they compare overall to your tubular ones? Maybe the question has been answered and I need to search but it was worth a shot.

Import Junky

iTrader: (7)

damn I hate working night crew, everybody logs off.

Import Junky

iTrader: (7)

well sorry for trying to hijack, I found what I was looking for.
https://www.evolutionm.net/forums/sh...bular+manifold