OverBoosted28

Has anyone made/done their own cross over/X-pipe mod between the stock cat cans? I am contemplating doing it and would hope someone has tackled this and can supply pics :-)
Sorta looking to balance/harmonize the seperate banks. Not sure if there's enough room to get this done between the cans.
Thanks in advance for any help.
Aloha

Mike J

I have been thinking about this over the last year or so as well, and have been gathering pictures of custom systems that mix the sides and doing research for parts - but have not tackled it yet. It would be a winter time project and a good excuse to fire up the TIG welder ... I have been thinking of a few different ways:

- Fabspeed approach using a X with a portal to allow for the sound/exhaust to mix.
- Single large tube containing cats and mixture areas - Knight (on this list) has that on his car, it looks custom fabricated
- mixing box on the stock exhaust where the pipes cross over between the cats
- rebuild the bumper so its a central exhaust which may simplify the routing

One issue is sound, its not clear how the design and size of the mixing chamber should be to allow for a good sound.

I have not heard for instance the Fabspeed solution in person, and will not consider buying their solution until that happens. I have listened to Knight's exhaust, its very good - the idle is wonderful, the lousy sound of two three-cylinder engines is gone. On power it sounds pretty good as well.

There is enough room but it can be challenging because of the angles, a lot of bending and fabrication would be required.

Cheers,

Mike

OverBoosted28

I appreciate it and hope to be able to handle this on my own as well. I think if you can integrate both between the cats, get a balance/equalization of both banks, it'd flow well and sound great. My cans are empty and made elbows (bypass pipes). It's "a tad much" at idle but I don't mind it at all. Once under way, there's no drone, I can converse and still enjoy stereo (stock) with windows down. I have been able to make it past the sound box at turn 5 @ MRLS on the 92 db days. Although, I still haven't been WOT up the hill towards 6 because I don't want to get flagged. So do ya think a straight pipe between the cats would work well?

Mike J

You thinking of a T between the two sides? I thought of that, and I think it has a few kinks to be worked out, but it could work.

The first is sound - I suspect you might need a larger port between the two sides. The second is that that pipe would need a coupling allowing you to uncouple the two sides of the exhaust so you can remove them from the turbos.

I was thinking of a container that connects all four pipes that sits just behind the centerline of the engine. The bigger the container, the larger the mixing chamber. The connectors would need to be clamps of some kind so it can be removed.

The bigger the container, the larger the mixing chamber, the more the exhaust will mix and even out the sound - or at least that is what I think. Hopefully someone will correct me if I am wrong...

Here is a glimpse of the system Knight has:





Bernie, one of our good local wrenches, thought these might be RS Tuning/Schmirle or possibly protomotive.

The stock setup for our reference:



cheers,

Mike

OverBoosted28

I was thinking that (although it would be difficult) you could still remove the whole system as one if you did a solid connection between the two. Looking at "Knights" setup, is basically one solid system and has to be removed as one. So unless I'm not seeing something, you don't need a coupler system to disassemble. Would be a bear to remove by yourself, but should be doable.

Mike J

I do not think the turbos are perfectly square to each other which could cause some binding on the turbos. I have worked on Knight's car and we had to remove a turbo - it was a total pain in the a**. It would have been much easier to have a clamp somewhere along the line.

You can buy nice clamps and weld them in-line without too much trouble anways...

Cheers,

Mike

OverBoosted28

Well, I just got my "Laguna pipes" done. I had opened these and cleaned them out before. It was alright but just a bit civil for my taste. So I made the bypass elbows. Those were great but I was worried about busting sound at the track (92 db max). So here's my solution. A couple of SS 1-3/4" 45 bends, a little fabbing and done! Just gotta get my cross over done now.

Mike J

I have done a set of mufflers, but find I want to control the sound - so if I come in late at night I do not wake up the wife - so I was thinking of the same thing as above (like a LPMM) but with a vacuum/electric valve combined with a cross-over.

I am not getting to a cross-over until later in the year when the weather gets crappy - so please keep us posted, be interesting to see what you come up with! :-)

Cheers,

Mike

Mike J

Did you see this thread? "Tacker" does excellent work!

https://rennlist.com/forums/993-turb...st-clutch.html

Love this fabrication work ...

Basal Skull

Tacker does do nice work..
I've thought about this too, and Bernie wanted to make a set of cross over type exhaust for me when I was doing the motor switch. He was talking about some significant improvements on a 997 he made the exhaust for. I wonder if there's really much performance gain in turbos, I don't think the scavenging type of improvement would be important in turbos? More just for the sound? I have my old engine and exhaust bits sitting on a engine stand, I suppose I can work on it too, but only if I think there will be some improvement or can lose some weight.

Mike J

I really do not know how much power is left on the table with the stock exhaust, but the stock cats (especially if they have mileage on them) are likely restricting some flow. I think having Bernie fab up an exhaust would be much more expensive than just buying a set unless he has some secret sauce that he is not letting you on to.

I know Fabspeed claims more power but they are citing the flow restriction of the cat's as the major contributor, not due to scavenging or impacts of the X pipe - maybe they will chime in here.

I think reducing any restrictions post turbo is the best way to get power - since the turbos naturally supply backpressure. :-)

What exhaust are you running on the Andial engine?

Cheers,

Mike

Mike J

** oops double post ***

Basal Skull

I'm using umw race cats and roock 450 mufflers. The cats and bypasses were a little loud, with these mufflers it's just about right for me. If I could use cross overs and do away with the mufflers (wt/heat), it would be worth it.

Basal Skull

The andial motor came with stock exhaust, I believe the muffler are fisters but it only came with one..

OverBoosted28

I'd seen his thread a while back and was jealous. Incredible work and awesome facility to do it in. It didn't look as though he incorporated any mixing between the banks.
Do ya think there's any other benefit other than smoothing it out at idle?