DIY Exhaust for a rotary

[MikeLMR]

Hi Mike,

104db  :rollin
That\'s quiet for a bridgy, it takes a bit of skill with gently building up the revs to keep it that low... the worst I\'ve seen it tested was a few years back at Pembrey when it hit 119db, but the noise scutineer didn\'t really care because it was Truck racing at the same meeting. I can\'t imagine how loud the early race cars must have been with straight through systems and megaphones.

However on a street port noise is a lot more controllable, my RX-4 is 92db at 4500rpm, that\'s running a Janspeed manifold into a 2 inch system, with 2 pre-silencers and Rotechnics rear box, not ideal for maximum power but ok for a standard engine. I\'ve got an old Janspeed manifold lying about somewhere if you want it?

Ray

thanks for the offer Ray, I have a header to work with at the moment (its for an FC) if its looking like its going to totally wrong for the car I might have to take up your kind offer  :Thumbs-up

I suppose 104Dba isn\'t "that" loud ... I didn\'t think Dave\'s Rx3 was too bad at rotorstock actually ... I\'d have a go at using somthing similar on the road  :yes

[MikeLMR]

Mike TTC do exhausts starting at 2inch dia upwards 1.6mm gauge tube in both mild and aluminiumized mild they also do flex in the same diameters. The bends are 90 degree only in the same sizes. If i remember i\'ll fetch the book home and scan the pages tomorrow for you.
Kevin

ace, that sounds just the sort of stuff I\'m after.

I must measure the header pipes I have, they look fairly big, probably 1.75" at least.  merge those into a 2" ?

[kev-yorks]

I\'ll do my best to remember the book and post a copy of the relevant pages Mike then you\'ve got the part numbers which will make life easier when ordering.
Kevin

[RotorHeid]

Mike,
Sorry for not sending email pm!.
The header is for long system,The s/steel mat\'l is 48mm borex1mm thick which will slide into header as I made the system as a "floater" ( don\'t laugh) which means there are no nuts,bolts or flanges, only hangers to support.
The length of system stops at the front of the axle,from there, a 2" collector/ 2"-3" magaphone  is pasted under the ( FC3) back axle to a straight through back box(3" tail pipe).
The back box is  repackable with rockwool and simple tube/ end plate with drill holes muffer which is installed in the tailpipe,Remove it when going to race.
 personally my best choice is to go for long system with two cherry-bomb type( burn it when driving then pack in with s/steel wool) and one backbox.
Leave the splitters in the exhaust ports as it will cut the sharp noise e.g  like chainsaw.

[yoeddynz]

hey ray,
this might be a bit late but do you still have the janspeed manifold you mentioned and is it for a 12A?
cheers
alex

[Ray]

hey ray,
this might be a bit late but do you still have the janspeed manifold you mentioned and is it for a 12A?
cheers
alex

Not sure... it should be at my dad\'s but I need to check to confirm that, I\'ll let you know.

It was definitely of a 12a.

[Ray]

hey ray,
this might be a bit late but do you still have the janspeed manifold you mentioned and is it for a 12A?
cheers
alex

Sorry, can\'t find it! Now I\'m questioning whether I did keep it or if I let it go to the scrappy because the walls had got too thin.

[yoeddynz]

Thanks anyway. Just picked up old \'7 with rusty motor and good engine. It has a very nice solid thick walled large dia manifold that joins about a metre back- looks like a good one to keep and use.
alex