Exhaust fabrication question

[Tom Vogel]

Im getting ready to fab up an exhaust system for my car. Its got an F1R procharged Chev. BB (should do an easy 900-1000hp). I will be exiting 2 1/8" primary to 3 1/2" collectors on Lemons Headers. Ive spent the last couple of years learning to tig weld and have gotten proficient enough to satisfy myself.
I was going to go with 3 1/2" from the collectors to the mufflers (spintech?); and exit to the rear with 3"... also use a 3'' crossover just behind the collectors.
The problem is.... Ive never done an exhaust system myself... so... does anyone have any suggestions on design or know of any links to a site that would give me some design and installation ideas? Im also interested in the best way to suspend the system to allow for torque and twist. Weve strengthened the chassis as best as possible with a cage and boxing, but I know there will be some twist. (oh yeah, we used polyurethane on the engine and tranny mounts)
TIA, Tom

[chicane67]

A question or two...

Why a 3" cross over and not a 3.5" ??... and why not a x-pipe over that of a H-pipe... that has it's limitations ??

I would consider doing 'V-band clamps' at the collector and possibly at the front (or behind if you wish) of the mufflers... that way you can drop that section if you do any drivetrain work and it wont get in the way.

As for hangers, I have used reinforced rubber straps (it looks like strips of tire) or the late model strechy rubber donut type. The strip type I have normally suspended with nuts and bolts... as you can weld a bolt to the muffler case to mount the strap. The donut type, I have used 3/8 round steel barstock... bent into shape... and can also be welded to the muffler.

Burns Stainless has some stuff on their site for pre fabbed X-pipes.

[Tom Vogel]

I was going with the 3" crossover because I figured since it was just for pressure equalization and not flow volume, it woulkd be sufficient.
I was going against the X-pipe because of clearance issues with lowered trailing arm suspension. (I really dont care for the sound of x-pipes on an american v-8... just personal preferance)
I have no problem with buying or using stainless, however, my headers are mild steel and will have to be coated; and I dont think Spintech mufflers are available in stainless and so they will have to be coated as well.... and so I thought... might as well do the whole system in mild steel and coat it all... rather than mix stainless and mild to keep away from disimilar metals and the ensuing corrosion of the stainless in the stainless to mild steel interface.

[chicane67]

...Still the volume is somewhat important as it acts as a plenum (which its volume is also part of tuning)... not of huge importance, but if your going to make the effort you may as well make it work for you. I have found it to be the best to run the same diameter crossover tube(s) as the main diameter from the collector to the muffler inlet... especially in the simplicity of the typical 'H' pipe.

I take it you are reffering to the typical 'Dr Gas' type x-pipes ?? They in my opinion are a joke... but then again, I guess knowledge of the specifics make me so. A true X-pipe is actually much different than what the mainstream has crammed down its throat.

You can get the same Burns X-pipes in mild steel... its just a phone call. Just as most of Spintechs mufflers are also available in stainless... I myself would go mildsteel and coat it just as you have planned to do.

A small info page on the difference: >> Click Here <<

[jackfrost]

A true X-pipe is actually much different than what the mainstream has crammed down its throat.

have you found a source for true x-pipes?

[whytry]

I'll 2nd that.... ^

[Tom Vogel]

A small info page on the difference: >> Click Here <<[/quote]

VERY interesting! Is this your own design?
Thanks, Tom

[PhillipM]

Is this the a representation of the system?

If so, how does this all clear the transmission?

[chicane67]

have you found a source for true x-pipes?

Yes.

A small info page on the difference: >> Click Here <<

VERY interesting! Is this your own design?
Thanks, Tom

Yes... co-conspired. It is a design that I had fabricated back in '89 by the cat who actually sold the "X" pipe design (the one that is the most familiar) to Dr.Gas. That same cat made his name in the Indy car world back in the 70's and 80's as the exhaust go to guy. Ed has sinced retired... but still plays around in his spare time. I use to instrument the system ideas that we could come up with to measure pressures, gas temperatures and frequency... and this system showed the most improvement across the board... by a huge amount. We tried multiple cross over configurations... from the collector area, to even installing crossovers behind the mufflers and even right before the tailpipe. It was a great learning experience... especially since Ed funded all the ideas we could come up with and fabricate. He was a true teacher of the 'art'.

Is this the a representation of the system?

If so, how does this all clear the transmission?

Yeah... that is a better pictorial than the scribble I hastily came up with.

Actually... the last system I put on my personal 67 fit so well, that the bell housing and sub-frame connectors were the lowest things on the bottom of the chassis. The entire system was above the bottom of the front subframe frame rail.

I have done this system in 2.5, 3.0, 3.5 and 4.0". The 4.0" system was on a NovaII... but the 2.5 to 3.5" systems were mostly on 67-70 f-bodies. In fact, the last system I did was a 3.5" system on a 70 1/2 Camaro with a fairly stout 502 cid (it was a co-workers car) and it however... didnt fit quite as well due to the tubing size... but we did 3.5 from the collector to the muffler and 3.0" out of the muffler, out the back.

At the beginning of the turn in (towards chassis centerline) it (the main tubes from the collector) turns in just under the tailshaft of the transmission and as it turns in toward the center... it also goes up toward the shaft tunnel. Then, as it turns down the center of the shaft tunnel... it is side by side until the tubes turn out for the mufflers. The center "X" is then fabricated to fit into the system just under the tail shaft. The "X" in the drawing's from myself or Phillip... are not really to scale and are not really represented all that well... but the pictures show exactly how the tubes are connected.

[Damn True]

You lost me on the orientation.

[chicane67]

Shocking.

I just re-read it... and I feel your pain. I'll try to make some kind of pictorial to explain it... wish me luck.

[Damn True]

Shocking that I require remedial training?

or

Shocking that your explanation obfuscated?

[chicane67]

Tom's explaination = FAIL

[skatinjay27]

man ever time you make a big post you never cease to amaze me with your vaste knowledge... and you alway go over my head lol
thanks for the great info... maybe this is my problem cause ive been though 3 sets of muffler and now i have borla xr-1s on the car and like it but just LIKE it... and ive been thinking its the x-pipe.
so where do we get the true x-pipe section?

[chicane67]

The "X" is a one off fabrication.

Depending on the current installation... all you would have to do is build one on the car as is. Its either that... or you will have to re-fab from the collector to the mufflers to make the fitment.

[Flash68]

Tom, lemme ask you this...

Would you rather have a Dr-Gas style X-pipe or no X-pipe at all if those were your 2 options?

[chicane67]

Uhm... how about you do your self one better than Dr.Gas... an X from Burns Stainless ??








The idea and design behind an "X" is to create a plenum... and unfortunately, I believe the Dr.Gas offerings are a little small in this respect. The Burns stuff is more idea in this respect.

[Flash68]

I love how the X-pipe link on Burns' website appears to be the only non-working link on there. LOL

[Dave@RACEWARE]

Pypes also make a 3.5" x-pipe and mufflers. Their X is normally located 6-8" behind the tail shaft so the tranmission does not come into play. It might be a little wide for a F-body but had worked well on A-body cars we installed them on.

[Tig Man]

The Burns x over is not a true synchronizing crossover! I worked with Boyd Butler, aka Dr Gas, getting the first crossover system to fit the 95 Dayton 500 winner at the shop way back then. The crossover works because of the hole in the middle being sized so that the flow from one side of the inlet splits 50% out of each exit pulling a vacuum on the other inlet. I may not have explained it correctly, but it's not just 100% split of the pipes. On a regular H pipe system we always used a 3" crossover with the 3 1/2" system. Even down to the size of the header tube. Didn't make much difference, even the distance from the collector seamed to not matter much back then.I only wished I had patented the boom tubes. I wouldn't be working now!!

Mark