I have the japspeed exhaust system which was purchase from ebay by the previous owner. It has the X pipe in the middle which i believe to be restrictive as it reduces down into an X and looks visibly smaller than two 2.5inch pipes which is what the system starts out as. I believe this may be restricting my top end bhp.

 

Now, can i purchase a centre section from somewhere which doesnt tail into an X that will fit my current setup? which makes and where from? anyone? maybe a H pipe would work?

 

Thanks

i seem to remember....

X = more power and more noise

H = quieter and presumably less power

an "H" pipe is more restrictive than an "X" pipe, the "X" pipe actually helps to draw out the exhaust by creating a "vortex" in the system. if you want to go for 2 indervidual pipes then i'm sure there are companies out there, such as power flow, that will custom build one for you.

I have a z centre h pipe.

an "H" pipe is more restrictive than an "X" pipe, the "X" pipe actually helps to draw out the exhaust by creating a "vortex" in the system. if you want to go for 2 indervidual pipes then i'm sure there are companies out there, such as power flow, that will custom build one for you.

 

You sure though? where is this proved? i suppose its true but not if the "X" is actually smaller than two pipes together which mine seems to be?

Iv'e got a custom made powerflow exhaust on mine and i couldn't be happier, its a very nice sound without being completely mental

X systems usually provide more bhp, there are a few articles lurking, maybe it is just the design of the japspeed one, which would be restrictive with your current setup.

X systems usually provide more bhp, there are a few articles lurking, maybe it is just the design of the japspeed one, which would be restrictive with your current setup.

 

I think this might be the case, its all good having an x pipe but i think the actual x section has to be of equal bore to the rest of the system so realistically 5inchs.

 

anywhere i can find these articles?

http://www.specialtyZ.com/catbacks.htm Available in 2.5" and 3"

 

Edited March 19, 201015 yr by Yowser

anywhere i can find these articles?

 

http://www.boyleworks.com/ta400/psp/exhaust.html

 

http://www.superchevy.com/technical/engines_drivetrain/exhaust/0505phr_exh/index.html

 

Or there's something new out, I think it's called google :D

I think this might be the case, its all good having an x pipe but i think the actual x section has to be of equal bore to the rest of the system so realistically 5inchs.

 

anywhere i can find these articles?

 

When it comes to cross-sectional area, 2.5 + 2.5 does not equal 5.

3.5 diameter is close to double the area of 2.5 diameter.

just what i was going to say

When it comes to cross-sectional area, 2.5 + 2.5 does not equal 5.

3.5 diameter is close to double the area of 2.5 diameter.

 

ah so my exhuast will be fine then... hmmmm......

Are there any problems with an exhaust not having any mixer pipes - like the Mongoose system?

Can this be harmful to the engine in any way? A mechanic I was talking to said it can burn out the valves? Or is this something the balance bar on the car is for?

I'm clueless on this one:(

That properly siamesed Japspeed joint is beautifully made and welded and at the joint part the diameter is more than the single pipe diameter but whether it makes twice the cross sectional area of one pipe I don't know. I can't believe it any more restrictive than those quite crude looking welded jobs that Legrath has pictured above and definitely better than an H pipe. The other advantage of the siamesed joint is that after the joint you effectively have two routes for the gas which is slowing down as it cools so has less restrictional impedance to face.

 

The way it works is also different for turbo and NA. The turbos already mess up the gas flow pulses after they exit the turbos so all that matters is getting the volume of gas out as fast as it will go. For the NA there is a tuning effect that ought to have each cylinders gas pulse pulling the next one out and making the engine breath easier at the top end if the design is right. The NA definitely seems to sound better if the videos on youtube are anything to go by. Before I fitted the Japspeed one on my stockish TT it had a custom made system on using 3.5" diameter pipes cat back with separate systems each side and it was way too loud and droney at speed and too big a diameter with Apexi cans with about 5" ends and honestly no way any faster than than with the Japspeed system. Its still in the back garden. The pipes were too large a diameter to bend so all the bends are welded in.

 

Effectively the cats remain the main impedance to gas flow after the stock exhaust I think.

Jim..... the Xpipe reduction in size will help the exhaust gases flow more then a H pipe and an individual exhaust set-up. When the gas flow hits the X pipe it speeds up and the pressure reduces, (venturi effect) the mixing off x2 gases can be turbulent, but in a close tollerent bore they will be laminar, thus resulting in a fast gas. To sum up, gas flow-smaller bore-faster flow and reduced pressure-fast gas mixture-faster gas expulsion.

Keep the system buddy. Or you can go bigger bore.

HTH

Al.