'nother one for our tech.brigade

[reidalpine]

Ok,so I'm looking to make a new free-flowing exhaust system for Roffen (R5TX 1400cc motor)
-thought I'd give it a go and try bending one myself.I have pipe-bending equipment but haven't
the faintest if it'll work. Otherwise I'll have it professionally made.
Unsure if best to go for stainless steel or what. It would be nice to have a Little more sound,but
not so much so I have to blast the stereo on full boob just to mask the exhaust..

(I've got a Devil stainless-system on my Alpine which sound quite nice,doesn't rust but developes
cracks all too often so am not That impressed by it)

Main concern now is to get max torque. I'll probably have another header made(this time by a pro
-Not the crappy Autobleu-copy manuf.for Meca-Parts in France (There's another SAD product !)

How would a rear ,or rather mid-mounted muffler (for my side-outlet)compare to a front/under-
fender one compare? any gain in dropping the front one for a muffler far back as poss? I'm thinking
about the scavenging effect and flow here..

Also-How much do I have to up the diameter to get the free-flow I'm looking for without going Too
big? Any danger of going Too big-bore??I'm not at all familiar with serious exhaust-theory,but thinks
it best to have as non-restricted system as poss to get Good exhaust-speed for effect and highest
internal exhaust-temp in system........

Any/All feedback from the tech-brigade on here would be Greatly appreciated!
Enough ramblin-on from me. Hope all of you have a nice week-end,after you have replied in lenght
the rest of the week-end is yours to enjoy!! -Reid.

 

[malcolm]

You would need a tube bender for exhaust pipe rather than a pipe bender, and even then it is tricky to stop the pipe from buckling. I tend to buy pre-formed sections and weld them together.

The pipe doesn't need to be that big. The main restriction in the R4 and R5 exhausts is the silencer. A straight through silencer works well. I think I used 42mm pipe for mine. http://www.renault4.co.uk/r5-exhaust.htm and http://www.renault4.co.uk/gordini-exhaust.htm

The silencer is better at the rear - the gas has cooled down by then and will be running a bit more slowly. Also the speed of sound will be lower with the cooler temperature so a short silencer at the back works just as well as one twice as long at the front.

I wouldn't bother making a manifold. The TX one seems fine.

 

[reidalpine]

Hi Malcolm-Thanx for response! So I see you think I would be ok in using the orig.manifold-I would have thouht it would be a bit on the tight side
but as said I'm no pro at this..At the moment I'm breaking the motor in and with my careful approach I haven't seen any problms with it,but of-
course haven't "opened it up" any yet.
-I see your point re buying pre-formed bends etc,so might go that route..
Have an Abarth-silencer on hand so could be tempted to buy that as it is rear-mounted,but could be seen as Naff as it's got 2 megaphone outlets

I've used exhaust-bandages b4 to cool underbonnet and have good exhaust-flow but they totally cooked the exhaust-pipes to the point these dis-
integrated (flaked) to the point they broke in smallflakey bits..Looked like war-ration dried bisquit so won't go there again..
42mm pipes sounds close to what I had in mind too -Easy to connect to manifold aswell..

I'm putting on my thinking-cap again.. -Reid.

 

[uaz04]

Hi Malcolm-Thanx for response! So I see you think I would be ok in using the orig.manifold-I would have thouht it would be a bit on the tight side
but as said I'm no pro at this..At the moment I'm breaking the motor in and with my careful approach I haven't seen any problms with it,but of-
course haven't "opened it up" any yet.
-I see your point re buying pre-formed bends etc,so might go that route..
Have an Abarth-silencer on hand so could be tempted to buy that as it is rear-mounted,but could be seen as Naff as it's got 2 megaphone outlets

I've used exhaust-bandages b4 to cool underbonnet and have good exhaust-flow but they totally cooked the exhaust-pipes to the point these dis-
integrated (flaked) to the point they broke in smallflakey bits..Looked like war-ration dried bisquit so won't go there again..
42mm pipes sounds close to what I had in mind too -Easy to connect to manifold aswell..

I'm putting on my thinking-cap again..
-Reid.

I'm facing the same dilemma this week, so I have to ask...what did you finally decide upon, and how did it turn out? I've also got a 1.4 [TS] motor, and I feel it necessary to increase the tube size to 42 or 45 mm.
Michael