hey guys, sorry to add another exhaust set up in here but this has really got me wondering. I have a series 2 rx7 with a stock 12A. A guy at the local exhaust shop who has done some good work for me before recommends that i put on extractors, 2.5" exhaust with 2 hotdogs, take of the pollution gear and apparently there are like dowls or something in the exhaust ports that reduce air flow which he was going to remove. he wants $470 Australian dollars. Will this give any more power and will what he is saying true? If this will work would any one be prepared to take a guess on how many kilawatts the car has now and what it might end up with after this set up. Any help is greatly appreciated. Sorry guys like i said i'm only new to the rotory world but i love every bit of it

 

ok it sounds like a pretty free flowing exhaust. it will have some benifit but to be honest i doubt if youd be able to feel it as it is a stock motor. But if however you decide to port it a bit, then there will be a greater difference. also the price sounds alright, but you just have to remember that rotors love to chew through anything in the exhaust, jo try and get the bloke to put in good quality hot dogs etc.

im going to get a fairly similar exhaust setup when i get my bridgeport in, it should be good

James

P.S. where in the great down under do you live?? im in perth

 

There are no dowls or diffusers in the exhaust sleve of the 12a. If this guys is telling you that you should remove any thing from the exhaust ports he probbably does not know what he is talking about.

Here is a little exhaust info for you. All rotor housings have an iron sleve pressed in to form the exit path of the exhaust port. This sleve protects the rotor housing from melting while the engine is running. Exhaust gas at the port can reach well above 1500deg, Aluminium melts at about 1300deg. If he is talking about a diffuser, then he is refering to the 2nd gen n/a motors, which does not apply to you, But the diffuser is there to prevent turbulance in the exhaust path, do not remove it.

As for an exhaust system set-up, go with dual pipes all the way out, if you must collect the pipes, then collect them as far back as you can.

Ryan

 

For the 6port engines, removing the 5th and 6th port sleves DOES give you more top-end power, about 5 hp, but it takes away some from the low-end. Now, here in the USA the only 6port engines are the 13b's. BUT in some other countries they did have 6port 12a engines.

I know he said they were in the exhaust ports, but he didn't sound too sure to me, so I think this is what the guy at the shop is talking about.

I'd also go with dual pipes. I would probably use 2 2", 2 1/8", or 2 1/4" pipes all the way back. If you collect, do it just before the pipes go over the axel, or you can run it under the axel, and collect with just enough room to have the muffler fit.

 

I ran duel 2 1/4" pipes back to a 12" long 3" pipe, back to the muffler. Lost a fair amount of lower end power, but above 5k it really comes to life.