Having my Exhaust Built
 

I'm going to have a local shop build the new exhaust on my recently acquired '87 Turbo II. After sitting for so many years, the exhaust needs a little work, so I'm going to start fresh.

I want to free up as much power as I can while still being able to pass the New York state inspection, specifically the visual inspection.

Factory Pre-cat (is it worth gutting this?), 3" pipe, 3" in/out magnaflow cat, 3" pipe, then 2.5" pipe from the Y to a pair of turbo mufflers. Probably Super Turbo or Ultra-Flo SS.

And will a set up like this necessitate a retune or cause problems?

Can the pre-cat behind the muffler be replaced with an aftermarket high-flow converter? Would gutting it cause any problems?

Thanks.

"Turbo" mufflers are a poor choice. They don't sound very nice on a rotary.

With any exhaust upgrade, you will end up raising the boost if you don't port the wastegate. A 3" low restriction exhaust will bring it will past 8 PSI, requiring an FCD at the very least.

The precats are mainly there for quick lightoff after startup. They can be eliminated if your emissions test does not include a cold start.

ditch the y pipe and go single sided exhaust... save $ & weight. 3 in all the way thru.

I like the appearance of the dual exhaust in the back, so I ruled out a single exhaust set-up, regardless the impracticality.

I don't want to install a wastegate, and I don't fully understand the 6port issue.

Can the "pre-cat" be replaced with a high-flow cat?

If both cats are replaced with aftermarket cats, will there be a problem related to the ports?

If 3" into 2.5 inches is to big, would 2.5" into 2" be better, yet still provide a safer performance increase?

If you have a TII then you DO NOT have 6-port motor so dont worry about those.

You can replace the pre cat with a stright pipe if you want... wont be any different than gutting it... and I dont think they inspect for pre cats.

Just put that 3 in into the 2.5 and have the wastegate ported like Aaron cake said and get a Fuel cut defender.

Or maybe you you should search the board for someone in your area that knows something about these cars cuz you dont seem too familiar.

your turbo already has a wastegate but its set to work with much less boost. if you put a larger exhaust on the turbo, the turbo will breathe better and more exhaust will flow through it, raising the boost.

theoretically, if you dont port the wastegate out you can get boost creep to the point where you cant even put full throttle on the gas because it will be making too much boost for your fuel system to keep up. modding turbo cars gets expensive fast.

search what a FCD is on here, and what it does, and seach for pics and info on wastegate porting. hope this helps.

For the 20-30 LBs saved, the car is now twice as loud and looks like it's missing a muffler in the back...

Damn right. Single exhausts on RX-7s suck.

Your turbo already has a small internal wastegate. It won't be able to bypass enough exhaust gasses to prevent boost creep once you make the exhaust free-flowing. The solution is to port it. http://www.aaroncake.net/rx-7/s4wastegate.htm . It's not easy or cheap to install an external wastegate on the stock turbo.

As for aux ports, your car does not have them. TIIs are 4 port.

Sure, but there's no reason to. They are only used during a cold start warmup.

2.5" is the diameter of the stock downpipe/cat assembly. I think 2" is about close to the stock catback as well. So essentially you would be recreating the stock setup but with more free flowing components. It will produce less of a boost increase and won't creep as easily as the larger system.

Thanks.

there is no emissions testing on your car in ny

I just passed this morning with a 3" straight pipe and a 6" can

6 inch can? WTF dude!

You may just want to ditch the whole custom exhaust idea and go with a (possibly used) Racing Beat 2.5" system with a high flow cat properly hooked into the airpump. It's not the lightest system out there, but it looks near-stock and is quiet while flowing well. I use a 3" system on my 400whp setup with no cat or presilencer and it is pretty quiet still.

http://www.racingbeat.com/resultset....rtNumber=16418 . http://www.racingbeat.com/photos/16418.jpg

It's pricey new, but there are a lot of them around. You could just get the catback and have a custom downpipe made or look around for one.

http://www.racingbeat.com/resultset....tNumber=S16207 http://www.racingbeat.com/photos/16207.jpg

Don't forget to talk to Mike Lowe (Lowe's automotive) in Sarasota.
He's the local RX7 knowledgable one.
steve

Thanks-
I stopped by Stacey's initially and Big Muffler today.

After all this, I think I've decided that I'm going to just stick with a Cat-back system.
I still want to use this car in the stock SCCA class and I don't want to jeopardize the engine because of the turbo issues.

The next question is, do I just go to a local guy and have them mount up a couple dynomax or magnaflow straight through mufflers for about $350 or pick one out of the catalog and install it in the driveway.

6 inches long, with a 3 inch ID

One shop I saw today was telling me that he was reluctant to work on the RX7s because it "always causes the cars to run bad. Backfiring and stuff."

I asked him the price to install a cat-back system with Dynoflows. He said about $350.
Aluminized steel, crimped bend pipes.

the backfiring is from when you gut the cats. screw the restrictive crush brent pipes--what's the point?

I still think your best bet is to look around for a used Racing Beat catback system, I got mine used for $400 or so shipped (that was the 3" catback). You'll be happy with the sound and the OEM fitment and the OEM look.

the guy at the shop obviously doenst know whats hes talking about. rotaries run rich by design and dont burn all the gas, and throw it out the exhaust like a 2 stroke. its a scavenging system of sorts.

pretty much any rx7 that inst in tip top shape will backfire or flame with a good free flow exhaust and no cats! aluminuzed steel with crimped bends is just the cheap way to do it, and speaking from experience, it wont reduce flow enough to stop the backfireing or flames.

theres a few good twin exit systems on ebay, and racingbeat obviousy makes a great system. if you get the full system, ive heard its very respectable noise wise and doesnt give as much backfireing etc. its designed to work with your car, it wont over exhaust it and it wont be too restrictive.

'what she said.

In general rotary runs exactly the same A/F ratios as a piston engine. They don't run "rich" by design. We tend to run them richer under boost as a precaution under detonation, and silly kids who think they know how to tune often tune unnecessarily rich because they don't know better.

A properly tuned rotary is quite clean, doesn't backfire much, and won't throw flames.

The RB system is hands down the best full exhaust you can get for a TII. Period. But you pay for it...

As Aaron Cake stated, Racing beat is the best exhaust made. I traded a parts car for the non-turbo catback that was 5 years old and it looked great, no major rust and the stainless canisters and tips looked fantastic. I had it for two years and recently traded it for the REV T2. I made ~195HP on the stock turbo/stock boost/street port with the non-turbo RB catback.

The REV T2 I just acquired is the much much older version that is all steel that only has chrome tips and the "RB" logo on them. It still looks great, only minor surface rust on it and the tips polished up very well. Haven't put it on the car yet, though.

Just save your money, and troll the for sale section. They routinely pop up for $350-500 shipped used.

Vince

Here you go: Full REV T2 3" Turbo Back (downpipe/presilencer/y-pipe/mufflers) for $575 shipped buy it now

ebay item # 140237620842

Vince

I've asked about that one already.
The next buyer of that exhaust will be at least the the third owner.
The second owner put at least 30k miles on it.
I'm not about to buy a muffler with that many miles on them.

If I leave it all basically stock, how do the Dynoflow mufflers sound, specifically the ultra-flows, on the turbo rotary? I haven't found a good clip on YOUTUBE yet.

Maybe you didn't read my post. I've bought both of mine used. One was 5 years old, and the one I just got is at least 10 years old. Neither one are worn out.

You will not have to replace one of the Racing Beat mufflers unless you physically damage it (ie road hazard). The type of packing they use in the mufflers doesn't burn out very easily, and the piping is very thick. Their exhaust is built to last. You can't loose buying one used. The one I posted for you is a steal consideing it's a FULL exhaust.

Also, the piping is mandrel bent. Not many shops have a mandrel tubing bender, and if they just use pre-bent mandrel sections it will be very expensive.

I say, save your time and money and buy the one I posted, you will not be able to have one made that fits as well as this one does or sounds as nice.

Vince

go el cheapo with this setup ebay item # 280231127752

3 inch stainless downpipe to muffler for less than $400 shipped

All you really need is the Racing Beat catback and then you can fabricate the rest of it (if that makes financial sense, you'll have to run the numbers), I've never heard of any of their mufflers going bad. I had the 2.5" catback, probably a 7-10 year old one, on my nonturbo. That had some surface rust on it but never had any problems, that was before they went stainless.

The backfiring is especially common on a stock ECU with an atmospheric blowoff valve and no cats. When I switched to a standalone (removed the airflow meter as well, so nothing to get confused by the BOV) I rarely ever backfire now because it doesn't run so rich with the way I've tuned it.