Mazda Rotary Club

hi all,

i\'ve got a standard mazda twin tailpipe exhaust (on the drivers side) on my fd.

i was wondering if it\'s possible to fit another twin on the other side? think it would look damn sexy with the re-amemiya diffuser.

I\'m not technical but would that mean there is to little back pressure???

Am a right or wrong (tehnical poeple) ??

Would somthing like an Apexi ECu deal with it??

I think the petrol tank is in the way. :(

Fish

there\'s always a way thou surely i recall seeing sum very custom & interesting scoobies with both twin rear exhausts on each side, some of which were done relatively cheaply just splitting by the back box & going over to other side which did look a bit strange (http://smilies.jeeptalk.org/contrib/icw/013.gif) if you were low enough to see this.... but otherwise a bit different....
Probably the fav one i have seen was where it split nearer the engine & came out by each side just behind the doors. dunno how popular it was with pedestrians when the flames start coming out thou :rollin lol
Could look good i guess thou & surely wouldn\'t be that much change in back pressure certainly if it was split (http://instagiber.net/smiliesdotcom/contrib/sally/slider.gif)right @ the end & consisted of twisty bits but i guess that\'d all depend on what you\'d got up to that point 5" straight thru maybe & well suffice to say i dunno jack really.
Well other than a twin zaust on one side is Cool (http://smilies.jeeptalk.org/contrib/ruinkai/coolgleamA.gif) not that i\'m biased or owt
Si

Back pressure is not a problem, the fuel tank is the problem.

even with a new fuel tank and its still not easy.

Dont really see the point myself, unless its for a motor with exh ports on both sides of the motor like Vs and boxers, never really understood why they did it on the FC?

There is lots of stuff underneath thats in the way on the FD but as Danny says the f/tank is the biggest problem. You can always get one made up, there are patterns about for tanks that are triangular in order to make space for exits each side.

Cant see they would do power any good though, collecting and then splitting gas again?

QuoteBack pressure is not a problem, the fuel tank is the problem

I stand corrected ;)

Whoever built that exhaust should be shot. A 90 degree bend that sharp will just mess up flow.

There are back boxes with dual outputs that would have suited that install much better. Spintech do a nice line that I would like to try sometime.

QuoteOriginally posted by antnicuk
Back pressure is not a problem, the fuel tank is the problem.

Hi Antony and David,
I can get you some nice stainless bends if you want to sort out the exhaust on your triple.
As Bill has said in his own inimitable way, it is not a very good system and would benefit greatly from some nice mandrel bends welded in place of the sharp angles.You will find it especially important for the supercharged engine as exhaust gas will pile up in the system at revs, exhaust flow being even more important than probably a turbo engine.
Kind regards
Carl;)

Tank is the problem, as I was having one exhaust per rotor, thought I would go all the way, would have thought an improvement as much better flow with twice as much tube, tail pipes are different now.

2

new tail pipes

QuoteOriginally posted by bill shurvinton
Whoever built that exhaust should be shot. A 90 degree bend that sharp will just mess up flow.

Was just about to say the same thing... never seen a 90 degree bend on an exhaust before...!!

ooooohhhhhh loving Gary\'s rear end (http://instagiber.net/smiliesdotcom/otn/love/luvlove.gif) that is awesome!!!!
Si (doing his OJ impression (http://mindscraps.com/s/otn/happy/11zwinky.gif))

QuoteOriginally posted by Luciano
Was just about to say the same thing... never seen a 90 degree bend on an exhaust before...!!

And you both beat me to it , the idea is to get the gasses out as quick as you can those sharp bends are going to try and forces gasses back down.

Bill,
I have one word for you......................... Compromise!

Everything on the car is a compromise, whether it be time, cost effort, availability or space it doesnt matter. In a perfect world it would have round bends, but in a perfect world it would be up and running by now, like carl\'s and gary\'s cars.  

But at least we are all trying and experimenting, unlike some!

The exhaust was made one morning when cris was coming down to wire in the Microtec in desperatly trying to get the car ready for TOTB, it had to have the xhaust so we could road test it while cris was here as he had travelled from bournemouth, it was a sat morning and that was all that was available in out workshop.  But also bear in mind that it is 3 inch pipe  x2 which is huge and a lot bigger than it needs to be so hopefully no matter how tight the bends are the air will find its way out quickly enough.  If it was two 2" pipes, the bends might be smother but still wouldnt flow as much.

Gary
your car is looking good, it would be nice to see it on the road.

Carl,
Many thanks for your offer,  we can get the bends but as mentioned above it was a rush job. Once we get it up and running we can iron out the problems.

QuoteOriginally posted by antnicuk
Bill,
I have one word for you......................... Compromise!

Everything on the car is a compromise, whether it be time, cost effort, availability or space it doesnt matter. In a perfect world it would have round bends, but in a perfect world it would be up and running by now, like carl\'s and gary\'s cars.  

But at least we are all trying and experimenting, unlike some!

The exhaust was made one morning when cris was coming down to wire in the Microtec in desperatly trying to get the car ready for TOTB, it had to have the xhaust so we could road test it while cris was here as he had travelled from bournemouth, it was a sat morning and that was all that was available in out workshop.  But also bear in mind that it is 3 inch pipe  x2 which is huge and a lot bigger than it needs to be so hopefully no matter how tight the bends are the air will find its way out quickly enough.  If it was two 2" pipes, the bends might be smother but still wouldnt flow as much.

Gary
your car is looking good, it would be nice to see it on the road.

Carl,
Many thanks for your offer,  we can get the bends but as mentioned above it was a rush job. Once we get it up and running we can iron out the problems.

Hi Antony,
Even though the tubing is 3 inch it will still be very restrictive.The right angle bends would behave like trying to get exhaust gas through a 1 inch restriction at some revs.
If you get stuck then let me know and I can get you a whole lot of bends.Four 90 degree bends would do the worst of it easily.
2 pipes of 2 inch would be more than enough for your triple to breathe with nice bends in it and much easier to fit for you too.
Anyway my car is not running yet so I know what it is like.
As to Bills comment and your reply,sometimes there are things that should just not be compromised such as your exhaust.
I will say please do not takethe criticism personally though,I think you are doing a great job and look forward to seeing it immensely!
I could get some very well made custom back boxes for you that would be pretty reasonable on cost.Just give me the dimensions if you would like me to help with that.
Kind regards
Carl
:)

Just like to give a big thumbs up to antnicuk, I\'ve made plenty of "prototypes" in my time, just to get something on the road. Nothing like lashing it together in a rush, just to take it all off and replace it with exactly the bit you were looking for 2 weeks later. I even made a subframe out of wood once... don\'t worry, I didn\'t drive it!!:eek:

It\'s bloody obvious the UK is behind the times when it comes to rotarys and it\'s all down to people NOT doing what antnicuk is up to. It\'s high time more people realised it\'s only a car not a space shuttle... if you want it to go fast... make it go fast. All the pontificating and dilly-dallying around won\'t make it a better car... actually doing it will!!!!! In some instances I have to take my hat off to "boy racers", because they have the bollocks to moddify their cars.

My 2p:D

Its a fine balance between a \'prototype\' and downright poor implementation. In this case there may be extenuating circumstances, but if you are preparing a car for a race (as was the case here) putting in something that would clearly loose you power would seem to not be a good thing.

Posting a huge picture of it on a forum without the caveat that it was a rush job and to be replaced at the earliest convenience runs the risk of misleading others into thinking that there is nothing wrong with doing it this way. Which is why I pulled it up.

its sort of spoiling a very nice ship for the metaphorical halfpenny worth of tar.

For what its worth, my two pence worth is that it depends on what the car is being prepared for.

ie if the car is being prepared for a show, then a nice goodlooking twin exit exhaust is important, so if you have to rush a job then losing some performance to make it look good is obviously not a problem.

Although if you\'re preparing a car for a race, looks are pretty much irrelevant, and if you have to rush a job then I\'d forget what it looks like and just make sure it\'s not going to slow me down.  

But I\'m not an expert and I wouldn\'t know how much (if any) power is lost by that exhaust system.   If the cars still like that why don\'t you dyno it now, change the exhaust and then dyno it again, just to see what the difference is..