Exhaust manifold design

[Piggy]

As I said, drash on, if you can make us all manifolds in a hour that are nicely tuned to the engine, then I will buy one...

but for most of us, making a tubualr manifold that will have an advantage over a simpler designed log manifold isnt as easy as it would be for you

[Uberderv]

So.... If we can get the flanges made cheap enough we can make whatever style. I saw a bloke making inlet adaptors and turbo plates who might be able to offer summit but can't post in that section yet or pm

[Piggy]

Uberderv, yeah he is will to make flanges for us making manifolds...I just need to get some measurements for my 2.1 head and I wll be sending him some drawings!

[Martin306]

You want a log manifold, for the sake of space, time and money. Putting all that equal length shit down the back of a XUD, c'mon it's tight enough down there already!

[Rippthrough]

Uber doesn't seem to have had much trouble...

[zx_volcane]

Can see what you're saying ripp, if you've got the sense to knock up a log mani form scratch might as well go tuned el.

My simple relocation mani cracked first due to welding it up in far from ideal surroundings, outside in the wind, and then the 2nd time it cracked not on the weld but the material itself sheared.

So agree its not a function of the design, but how it was implemented that caused it to fail in my case.

Would love an el pulse tuned mani - paul are you paying attention :p

Out of interest has anyone got a link to the formulae for working out the lengths / dimensions ..etc based on cam profile, engine size, rev range Sure I've seen it around the internet somewhere.


And if anyone is willing to knock up a short run of exhaust manifold flanges that would be ideal, don't fancy trying to cut one out of steel plate with the plasma, and the quotes I've had so far were pretty expensive.

[darrenjlobb]

Ive got a couple sets of old XUD head exhaust flanges at home which ill never use if anyone wants them

[zx_volcane]

Ive got a couple sets of old XUD head exhaust flanges at home which ill never use if anyone wants them

can you put me down for one please?

[darrenjlobb]

Ok, will dig them out, what i will say though, is there not ideal, had them cut a bit tight so not alot of room, and there not linked, just individual ones, ideally need btrace welding in like i did on my other (see project thread) same flanges used tho as on my other manifold (which londondan has now) worked a treat.

[Paul Baldwin]

Well. That was a bit of a read!

As Tom's said we have discussed a "log" style manifold, mainly for ease of fabrication and space issues as already mentioned. A tuned length manifold would be great in an ideal world but is it really worth it on an xud? I was always under the impression that tuned lengths benefit normally aspirated, high revving petrols the most anyway, when scavenging effects can be maximized to get a few extra ponies?
It's Tom's money too and it's got to be said that buying bends soon stacks up. I don't have access to the raw materials or I could make either up for peanuts with a just a grinder and a welder. Hopefully we'll have less issues next time. The welder I used is kept in an open fronted shed and hasn't been maintained at all for years. Add that to using it outside on a 50m extension lol. The cracking across the material was my fault tho I should think. The bracket had a slight flex in it, one good gusset and sorted All proves you can have a crack at this sort of thing with the absolute barest minimum of kit!
Those flanges would be a great help Darren Saying that, Tom needs some more practice with the plasma cutter :p

[Rippthrough]

Tuned lengths benefit forced induction engines just as much as N/A engines, it' just most people ignore it and wind the boost up instead.

[Martin306]

Tuned lengths benefit forced induction engines just as much as N/A engines, it' just most people ignore it and wind the boost up instead.

And manufacturers Look at Subaru, classic example of unequal length. That's what gives them that unique burble.

[Rippthrough]

Yeah, and they got rid of to gain better efficiency and power...