X-pipe +/- & position

[steve_k]

Right then in the next few week's i'll (hopefully) be looking at getting an X-pipe for my M20B25 (mildly reworked) & i've been looking at the one's from jetex in stainless steel.

& i was wondering what the pro's & con's of fitting one are & where the best position for it would be?

I was thinking of putting it just on the end of the down pipe's or would it be better off closer to the middle box?

any thought's good or bad are welcome.

disscuss.

[steve_k]

BTTT

come on folk's surely someone on here must have an opinion on X-pipes or experience with them??

[E30BeemerLad]

from what I have seen of x pipes on 6 pot donks, they tend to go after the downpipes and before the first silencer, whether there will be any difference in performance remains to be seen.

[steve_k]

cheer's for that lee

thats the position i thought it would be best to go for.

[DanThe]

Usually they are positioned midway between the manifolds and middlebox

(pilfered pic)

[E30BeemerLad]

Been on the hot tuning website Dan?

[Simon13]

the general rule is they are placed at the hottest point from the collectors. The hotter the gasses the faster they travel and X pipe is there to "scavenge" i can't explain it very well but basically its where one side of the exhaust is pulling the gasses out from the other side.

Your camshaft choice will also effect where this hot point will be. X pipes low you a touch of low end grunt too, but for more up top

[steve_k]

Thanks for the reply's guy's

the general rule is they are placed at the hottest point from the collectors. The hotter the gasses the faster they travel and X pipe is there to "scavenge" i can't explain it very well but basically its where one side of the exhaust is pulling the gasses out from the other side.

Your camshaft choice will also effect where this hot point will be. X pipes low you a touch of low end grunt too, but for more up top

that's what i'd seen on a few websites that where selling them (in the USA ) but i thought i'd ask on here as i knew a few folk would be able to help

Nearly forgot to add the cam i'm using is a cat cams 274dg (ish).

[reggid]

i just bought a BTB3 set and will be modifying the X-pipe position to see if it does what i think it will.

[steve_k]

i just bought a BTB3 set and will be modifying the X-pipe position to see if it does what i think it will.

let me know how you get on please dude

[gooner1]

i just bought a BTB3 set and will be modifying the X-pipe position to see if it does what i think it will.

What do you think it will do?

[Eddie25]

the general rule is they are placed at the hottest point from the collectors. The hotter the gasses the faster they travel and X pipe is there to "scavenge" i can't explain it very well but basically its where one side of the exhaust is pulling the gasses out from the other side.

Your camshaft choice will also effect where this hot point will be. X pipes low you a touch of low end grunt too, but for more up top

+1 i'm sure i've heard a trick the V8 boys use in the states where they apply paint to the exhaust without any x pipe and run it. Where the paint is most burnt aka the hottest point is where they install the X pipe or often H pipe in that case.

[reggid]

i just bought a BTB3 set and will be modifying the X-pipe position to see if it does what i think it will.

What do you think it will do?

closer to the engine the more lowend and topend, the further away the more midrange.

[steve_k]

i just bought a BTB3 set and will be modifying the X-pipe position to see if it does what i think it will.

What do you think it will do?

closer to the engine the more lowend and topend, the further away the more midrange.

well reggid you've just answered my main question with that one statement

[reggid]

What do you think it will do?

closer to the engine the more lowend and topend, the further away the more midrange.

well reggid you've just answered my main question with that one statement

but what it actually does may be completetly different

[steve_k]

closer to the engine the more lowend and topend, the further away the more midrange.

well reggid you've just answered my main question with that one statement

but what it actually does may be completetly different

very true indeed but we'll just have to wait & see

[steve_k]

Well fingers crossed I'll be ordering a X-pipe next Friday & trying it in a few positions between the down pipes & the middle box (got a few meters of T304 grade stainless steel pipe to make up the pipes to link it all up). Just wonder if the arse dyno will notice any difference/improvments after it's been fitted.

[steve_k]

Well fingers crossed I'll be ordering a X-pipe next Friday & trying it in a few positions between the down pipes & the middle box (got a few meters of T304 grade stainless steel pipe to make up the pipes to link it all up). Just wonder if the arse dyno will notice any difference/improvments after it's been fitted.

[shaun_89]

The x-pipe shape, taper angle and length all determine how it affects the engine too!

[steve_k]

The x-pipe shape, taper angle and length all determine how it affects the engine too!

could you explain in a bit more detail??

[steve_k]

The x-pipe shape, taper angle and length all determine how it affects the engine too!

could you explain in a bit more detail??

[shaun_89]

I cant find any good pictures of what i mean online so ill do my best to explain.

The x pipe works in conjunction with header length and collector design to take advantage of exhaust pressure waves to 'pull' exhaust gas out of the cylinder. The combined effect also sucks in intake charge mixture during the valve overlap period.

Obviously this needs alot of dyno time to correctly determine the best dimensions for what your engine needs.

When you bring the two pipes together you need to make every effort to keep the connection as free flowing as possible. If you can imagine two rivers flowing into each other in the shape of an x-pipe, there is going to be turbulance.

Its better to join to two together side by side in a 'Y' formation.
Most straight 6's show a good power increase when the two pipes are joined together over a length of 10-12 inches beside the gearbox.

The angle of the 'Y' pipe affects flow turblence too. A good starting point is around 7-10 degrees into one, so 14-20 included angle.

I could obviously explain this easier with pictures but i hope you know what i mean.

[reggid]

Well fingers crossed I'll be ordering a X-pipe next Friday & trying it in a few positions between the down pipes & the middle box (got a few meters of T304 grade stainless steel pipe to make up the pipes to link it all up). Just wonder if the arse dyno will notice any difference/improvments after it's been fitted.

here is a hint, try putting it about 15" from the end of the primary tubes.........

[steve_k]

Well fingers crossed I'll be ordering a X-pipe next Friday & trying it in a few positions between the down pipes & the middle box (got a few meters of T304 grade stainless steel pipe to make up the pipes to link it all up). Just wonder if the arse dyno will notice any difference/improvments after it's been fitted.

here is a hint, try putting it about 15" from the end of the primary tubes.........

Hmm sounds interesting, do tell

[reggid]

Well fingers crossed I'll be ordering a X-pipe next Friday & trying it in a few positions between the down pipes & the middle box (got a few meters of T304 grade stainless steel pipe to make up the pipes to link it all up). Just wonder if the arse dyno will notice any difference/improvments after it's been fitted.

here is a hint, try putting it about 15" from the end of the primary tubes.........

Hmm sounds interesting, do tell

actually i will tell you what it should be for a more stockish engine, that is for a big hp screamer so ignore that for now.

I am using "pipemax" software which will tell the length and size of pipe for exhaust and inlet, required head flows etc, port and runner CSA depending on your targets.

[steve_k]

[reggid]

http://maxracesoftware.com/pipemax36xp2.htm

it isnt free though

[reggid]

about 420-450mm is closer for a milder M20.

[steve_k]

about 420-450mm is closer for a milder M20.

Thanks for that dude

Just waiting for a dry day so I can get under the car to get everything measured up ready for fitting.

[steve_k]

Well it finaly looks like I'll be getting round to fitting the X-pipe (at long last) & seeing if there is any noticable difference.

forgot to add in the first post that the manifold the X-pipe is being fitted to is a magnex 6 branch (genuine not a copy) if that makes any difference??

fingers crossed I can do it without any faffing about lol.

[e301988325i]

dyno before and after is the only way to prove it!

[steve_k]

dyno before and after is the only way to prove it!

well there is one down the road in clowne so I might pop in before I do anything & see what happens then again after I've fitted it.

[e301988325i]

You've got to, I know it's an extra £50+ for two runs but a subjective, 'it feels faster' just doesn't mean anything unless you can quantify it, timed runs also count but it's very hard to get similar weather conditions whereas a dyno is compensated.

[steve_k]

You've got to, I know it's an extra £50+ for two runs but a subjective, 'it feels faster' just doesn't mean anything unless you can quantify it, timed runs also count but it's very hard to get similar weather conditions whereas a dyno is compensated.

I know what you mean.

I forgot to add that I'm making sure I can change the position of the X-pipe to see what different results I get I;E first run with out it, second run with it fitted at the end of the down pipes, third run with it fitted closer to the middle box & take it from there.

[mpereznoble]

Does the sound change?