MG Sports Cars

Thanks Jim. Earlier replies already convinced me to go w/2 1/4". I'm now just sorting out the pieces I need. I know I need about 10' of straight pipe, 2 90* bends to make an X-pipe (I'm actually thinking that'll be faster/easier to make than an H-pipe), and then some other bends &/or transitions. I'll need to put the car up on stands to figure out if I can go from my headers to the X in a straight shot & from the X to the back where I'll transition back to round in another straight shot. If so, I just need 4 oval to round transitions. The oval bends are expensive so if I need any, I want to figure out the right angles before I order -- they come in 15*, 30* 45*, 60*, 75*, 80*, & 90* and most of those in both 3" & 4.5" centerline bend radius.

Rob,
If you're going stainless, have a look on Columbia's web site. They seem to have a good selection of products and good prices:
[www.mandrel-bends.com]
Ken

Thanks Ken. I'm planning to go with aluminized steel -- once I get it set up I'm going to use Eastwood's ceramic coating on it so no point in springing for SS.

Rob

Make sure you post pictures as you go. Let me know if I can help you with anything

Jim

Rob, Check out Keith Tanner's LS GT exhaust. Not IRS but,centered tank. Also check out Thrush website for mufflers. Look at the Hush Thrush SuperTurbo ,they have a mellow deep tone. Not the welded,chambered,baffled type(Flomaster clone)which is louder.




Edited 2 time(s). Last edit at 03/10/2011 09:40PM by mgb260.

Rob,

Haven't got the Spintech's installed yet. A couple of people that used them on SBF Cobra replicas told me they're quiet with a healthy sound when you get on it. I searched in vain for a sound clip for them. I hope they're not too quiet. OTOH, I hope they're not too loud either.

Bill Jacobson exhaust picture:

Yeah, Bill's is probably closer to what I'm thinking for this next pass. I priced oval pipe -- before I spring for that, I'm going to spend some time under the car (this evening) to decide if 2 1/4" round with the changes that will affod me (vs. the long chambered exhaust tubes I currently have) will be enough. The oval would be cool, but I'm thinking my real problem is that my current exhaust hangs about 1 1/2" lower than it needs to as a starting point & on top of that the chambered tube lengths drive the H-pipe to cross the tranny at a lower spot than it would need to if I could move it back further.

Rob

Are you thinking of making the pipe cutouts in the welded in crossmember wider to accomodate the flattened oval pipe so you could run the oval pipe from the front all the way to behind the battery boxes? If you reweld the piece in the crossmember with a series of MIG tacks strung together it won't screw up the paint very much and you could retouch it easily. You could then merge the ovals into an "X" pipe or have an "H" pipe (oval) just behind the crossmember. . It looks like the highest ground clearance path under your IRS is just inboard of the inner pickup points of the lower control arms. You could make up some triangular cross section pipe in that area to tuck it up even further. If you rubber mount the pipes to the tubular IRS structure you could use minimal clearance and shouldn't have rattle problems. You could then make a sharp bend outward and have mufflers beside the fuel tank with another mount at the exhaust tips.

I haven't decided that yet Jim but that's what I've been thinking about. Until I jack up the car this evening & get under it I don't know for sure how I'm going to run it. I'm thinking I'm going to cut some strips of cardboard to the width of the pipe & tape it to the bottom to sort out the routing & bends. But, basic idea is is to run it fairly tight along the bottom to the battery box area... from there I need to look closer but I think I can turn up there & then go through the IRS between either the LCA & axle or the UCA & axle. Currently it runs under the leading edge of the LCA & then turns up & back from there between the LCA & axle... If I can turn the new tube up before the LCA I'll gain a 2-3" of clearance there (depending on oval or round). I hope to sort this out tonight or tomorrow. After tomorow I won't get a chance to touch it again until next Friday.

Rob, did you look at the shots of the tail pipes on the MG-Roadmaster? They are completely out of the way and go *over* the axle.

JB

Went quiet for about a week -- was in Mexico on a mission trip building a house. Lots of fun (http://cbcbridges.wordpress.com/). Back now & working on the car this weekend.

I decided to go with 2 1/4" oval; ordered the parts yesterday. Took my exhaust off to make measurements to figure out what bend angles I needed & when I reinstalled I was able to pull the existing exhuast up about 1". Still too low but at least it's a little higher till the parts come in. With the oval pipe I'll gain almost another 2" -- close to 3" overall gain vs. prior.

Jim B - I did look at the roadmaster & it looks good. I have an upper control arm (vs. the Jag set up that uses the 1/2 shafts as the UCA) so there's less room. The way mine runs now it goes under the leading edge of the LCS & then turns up & goes between the LCA & 1/2 shaft. That's the best I could do at the time because the chambered exhausts extended about 1-2" past the LCA leading edge. When I re-do it, I'll be able to turn up at the battery shelf & then go through the same area or maybe even above 1/2 shafts; will have to see. I'm planning to make everything up to that turn up & then have a muffler shop bend the pieces that'll go through there. There's a shop nearby with a mandrel bender.

Jim N - Not sure if I'm going to modify the cross member cut-outs, but probably.

just read through all this and just want to say that in my 2008 mustang v6 4.0l automatic ,ford saw fit to install a 2 1/2" exhaust system from the manifolds back to the single muffler.of course i removed the rear section and replaced it with the gt version of the exhaust which is also 2 1/2" and used the gt mufflers.i'd say some people finally learned something about exhaust flow in the last 30 or so years or at least i would hope so.what works on paper does NOT always compute as far as sound goes especially on a street car.the difference between 2.25 and 2.5 inch exhaust is minimal as far as performance goes on a MILD engine but it does affect mpg and sound of the vehicle.i know of several guys who have redone their exaust systems on new stangs time and time again trying to find just the right sound with no drone.drone is an issue with the rear mounted mufflers on these cars.also it can be increased by having an equal exhaust system on a car,meaning if the one side is exactly the same as the other as far as length goes it will set up a resonance and drone.the anwser is to offset one muffler to the other in an undercar muffler layout.having the mufflers at the back there is not much that can be done about it.some guys use x pipes ,some use h pipes and some run true seperated duals with no connection between the two banks.i myself run an x pipe with stock gt muffs and have no problem.for those of you looking for good muffler that sounds great without a huge price try the 2005-2010 mustang gt takeoff mufflers found on ebay .they come with a nice stainless tip already and are free flowing.in fact even the gt 500 used the same mufflers in the early production .the gt500's now use a different muffler.they are shaped to go over a rear axle and are 2.5" in dia. inlet and outlet.that's all ,just thought i would throw that up there.



Edited 1 time(s). Last edit at 03/20/2011 01:27AM by rampant racing.

Rob,

You may already be aware, the Spintechs can be order with oval inlet/outlets.

Rick

Quote: Are you thinking of making the pipe cutouts in the welded in crossmember wider to accomodate the flattened oval pipe so you could run the oval pipe from the front all the way to behind the battery boxes?

I am going to be doing this. Am thinking I'll make a U channel (out of 16Ga) & pie cut the sides of the U in order to enable bending it. Is that strong enough or do I need to do something additional to reinforce?

U-Channel...




Edited 1 time(s). Last edit at 04/04/2011 03:57PM by rficalora.

Rob

I'm sure 16 ga would be strong enough but if you are feeling squeamish you could make the same thing in 3 pieces out of 1/8". By using 3 pieces you could make the side plates much larger and that is what carries the load. Drill some holes in the plates so you can do some plug welds as well as the perimeter welds.

I think what I'm going to do is make the piece the way I showed it... but also another 16Ga piece on each side that gets sandwiched between the existing cross member vertical face & the piece shown above. I'll bend it 90* where it meets the floor like the existing cross member. I think that should provide enough rigidity.

Hey Rob,

The only function of that X member seems to be the termination of the front frame boxes.
If it were my car I would remove whatever portion that is required right up to the floor level.
Taper and cap the ends nicely and call the underside done.
To make up for lost strength nobody said you can't have a x member inside the car.
Weld in a 1" x 2" tube from rocker box to trans tunnel on both sides and your better than new.
Even gives you a nice strong mounting place for the seats.

Hope thats of some use

Cheers
Fred

That's an interesting idea Fred. I have some box pieces I made that raise my seats about 1" in the back & 1 1/2" in the front... this would eliminate those & serve both purposes.