red RX-7

Hi everyone,
I just bought a 1993 RX-7 in great shape, i am looking at a downpipe and a mid pipe, I am seeing some for cheap and some like the HKS brand for alot more, please give me some input as i am new at the rotary stuff. i am registered in michigan so emissions is not an issue, any help is appreciated.
-chris

JaNusSolSumnus

I bought the Megan Racing setup from Ebay and really liked its fitment. The only issue I had was during the install of the DP initially as the welds (while of very good quality) did get in the way of the bolts that attached it to the turbo manifold. Once I modified this aspect with some mild grinding it fit perfectly and came back off so far five times without too much effort. The more expensive ones will be a little easier to fit but a lot more strain on the wallet.

Midpipes are all the same IMO... the Megan Racing one fit very well and looked great too with NO leaks. The big differance is going to be stainless steel or aluminized steel (Megan's is stainless) and if you have a hi-flow cat, resonator or nothing...

Beware that a midpipe is asking for trouble on a stock and/or piggyback ECU... I overboosted my car and lost an apex seal. Be it that I was also running a fuel filter that was in dire need of replacement but the caution is there to save you the 2k it has cost me...

Good luck,
~Kris

red RX-7

how would i correct the problem with the mid-pipe, so it would not over boost? boost control?

JaNusSolSumnus

I'm porting my wastegate to eleviate overboost issues, although this requires turbo removal and some daring with removing metal from them. The safest and most effective way (while earning a good bit of poweR) is to get an Apexi PowerFC or some other fully stand-alone ECU and have it tuned at a reputable shop for a full exhaust.

Also assure that your fuel system is in tip-top shape -- fuel filter replacement should be done no later than every 30k, for spirited drivers I suggest 15k and if you have more than 50k on the car I'd reccomend removing the injectors and sending them off for flow testing and cleaning at www.witchhunter.com My suggestions for the fuel system may be slightly overkill but for a car of this nature I find it best not to slack ANYWHERE that deals with the drivetrain. In reality 30k for the fuel filter is norm as is 80k for service intervals on the injectors.

~Kris

red RX-7

thanks for the help!

jpandes

Read this page: http://robrobinette.com/mod_pro_con.htm

You should be careful about running the mid-pipe. The MP will open up your exhaust and you will need to controll your boost & possibly port your wastegate to avoid boost creep. (That's when the wastegate opening is not big enough to vent the excess boost and the boost begins to 'creep' about the desired setting.) With more boost, you'll need to get an ECU. I can't remember if any of the 'rechipped' ECU's are set for running MP's. You might need a PFC to safely run a MP. Oh, an upgrade Fuel Pump might also be a wise upgrade.

Sounds expensive, huh?

If I were you, I'd install the DP and hold-off on installing the MP until you have the other supporting mods. You don;t wan't POP your motor right after you got the car...

Trevrxuk

Hey Chris,
I fitted the Megan racing mid pipe from Ebay last week, very good quality and perfect fit.

Im in the UK so mr car is R/H drive and the down pipe that came with the mid pipe is for a L/H drive RX-7. I dont need it because my car doesn't have a pre-cat like the US models have. So if you want it you can have it free, just pay postage, but I haven't got got a clue how much that would be? Maybe too much to be viable lol.

I didn't get any boost creep after fitting the mid pipe (also have intake and cat-back) but I did get a nasty boost spike upto 15/16 psi on the transition to secondry turbo.
I fitted an HKS EVC to control the boost and it got rid of the spike completely.

If you do a search you will see that many RX owners believe it's safe to run a mid pipe on the stock ECU aslong as boost is controlled to stock levels too. There are some dyno charts (search) that confirm that.

It's well worth doing the mid pipe and getting rid of that power sapping ceramic furnace that weighs a ton! My car feels much happier without it and the power gain is much good fun

ImranRX-7

read what happend to me. https://www.rx7club.com/3rd-generation-specific-1993-2002-16/need-some-help-fellas-think-beast-blew-399849/

You're smart for posting this, I wish I would have. Listen to JaNusSolSumnus, he's right. I had the Power FC, untuned though. Chipped my apex seal. Now I'm undergoing a rebuild. Don't add a no-restriction mid-pipe without getting the wastegate ported and an aftermarket TUNED ecu. Also, a straight-pipe is insanely loud and gets annoying after a while. Get a midpipe with a muffler such as petit-racing's mid-pipe. There very little restriction with these.

Trevrxuk

That's hardluck Imran, hope you got it sorted now.

What was the mileage on the motor, maybe quite high? Good fuel filter and injectors?

I've heard the base map for the Apexi FC is actually leaner than the stock ECU, and it doesn't control boost very well .

Did you ever find out what you spiked to?

rx7will

iTrader: (6)

I got one of those ebay down pipes and i had to cut the flange off and get it rewelded since the flange was not on straight. Now i wish i would had bought a better down pipe.

hotrodrx7

You can probably find a used name brand down/mid-pipe in the parts for sale section of this forum much cheaper than new. Do a search of the seller before you commit to buy.