Which downpipe?
 

So I'm in the market for a downpipe for my fd and have seen a few different brands and was wondering if anybody has any feedback on any of them or either recommend one. Any suggestions are greatly appreciated, thank you.

which downpipe
 

megan racing offers a 2 piece 3" stainless steel bolt on down pipe...gain 10-16 hp for about 120 bucks i believe. Just throwing it out there.

hks is the way to go in my mind

I have the HKS downpipe in my FD and it was easy to install. Performance gain was noticible. I do highly recommend getting it ceramic coated before you install to reduce heat transfer into the engine bay.

any of the ones mentioned above are a great improvement over stock....

ebay

+1 for the ceramic coated HKS DP. It's a nice unit (and there are always some in the "3rd gen part for sale" section).

Also, I have been told that for the RHD FDs, HKS is almost the only one to fit without any problem (but mine is LHD so I would I know...).

Funny you say that. I have a RHD, and bought a DP from a JDM specialty shop. Oddly enough the DP does not fit! Guess I should have went with the HKS.

Sorry to hear that. The thing is that there is so much reading you need to do if you want to make sure not to make any mistake, and sometime you just want to buy and fit without spending 1000 hours of research on forums. That's what make our cars so adorable :o)

Well it should not be to bad to sell the one you have and find a used HKS (go for the ceramic coated option...).

Please post the results after you install the DP.

By the way, is this a DIY job?

It is to my opinion (but that depends whether you have a garage, time, and if you're a good mechanic - which I am not). I did it with a friend in ~2hours as nothing went wrong. You'll find a lot of information either on this forum or
fd3s.net about the DP change. You'll save some weight too, if I remember correctly the stock pre cat is 22lbs when my HKS DP was ~10lbs (we did weight them after). It become clear as to why you change the guy when you see it out too.

You need to be cautious as you don't want to break any of the turbo studs the DP will attach to (otherwise you're in for some turbo job...).

Good luck this is my favourite mod so far...

If you want to go the cheap route have a local exhaust place just bend the pipe and weld the brackets on for you, that's what the previous owner of my last two cars did and it works just fine.

DO NOT DO THIS!!!!

This kit replaces both the precat (downpipe) and main cat (midpipe). Most cars are not set up with the proper boost control and wastegate sizing to handle this much change in flow. Many blown motors have come from bolting on this kit and no warning or understanding of the supporting mods that it requires.

That said, if you're serious about going straight pipes on your FD, then it's no big deal to pull the turbos and port the wastegate, install an adjustable boost controller, and have a boost gauge to monitor and get things right.

If you're like most people looking to install a downpipe, keep it simple and just buy a downpipe. Many of these 2-piece kits are on the market because they won't fit with the stock cat. Therefore these kits are not the best choice for those individuals.

I would go for a used downpipe from one of these brands: Pettit, HKS, Bonez, PFS, M2, RX7Store, etc. Avoid the eBay ones because the flanges are sometimes warped or the holes don't line up.

Dave

I have a used stainless steel 3" Bonez downpipe from RX7.com. Fitment and quality is known to be among the best.

PM me if interested. I'll sell it for $75 shipped.

Would changing the down pipe and leaving the main cat prevent this over boost situation?

Also, are CA and Federal down pipes the same? Do Fed cars not have a pre-cat?

Peter

yea...if u pull your main cat you better get a fuel managment....!!!! i didnt & blew my motor....kinda funny though cause when i called pineapple & asked them bout this issue they told me not to worry....& i should b fine ... tip from me....do your own research...!!!!!!!

changing JUST the downpipe is usually ok, my first FD was like this and it was fine, it's actually considered a reliability mod. I have no idea what the difference is (if any) between CA and other cars, but I don't think there is one.

I think I read somewhere that JDM cars don't even have the pre-cat we all want to remove in the first place, which shows the exhaust system (back pressure turbo etc) has been designed that way (but with the main cat on...).

:scratch:QUESTION:scratch:
i have a Petit DP mated to my stock main cat and catback.
would changing my main stock cat with Petit Resonated Midpipe or Catless Midpipe with my Petit DP and Stock Catback lead to a blown motor?? i dont have a PFC or haven't moded the wastegate to make it bigger.

Bonez DP or Bonez Highflow Cat is about as best as you will do. Great fitment and quality!

No downpipe...custom a the way from the manifold

Search the 3rd Gen. Section using terms like Boost Creep. Basically it results from having a lack of back-pressure/too much exhaust flow that it overwhelms the stock wastegate on the twins. When that happens, the exhaust pressure "backs up" and is forced through your turbos leading to an unintended over-boost situation. When that happens, the engine runs lean and you get a predetonation. That destroys hard seals and requires a rebuild.
Usually just maintaining a cat...even a hi-flow cat is enough to avoid CREEP. I'm not really familiar with the Pettit Resonated midpipe, but suspect that you would still have sufficient back-pressure and would be OK.....especially with the stock cat-back.


Also, I realize this is an old thread, but for those recommending the HKS downpipe...you DO realize those are for RHD models, right? They're designed to fit with the RHD steering shaft and as such are "squished" at the upstream flange. While HKS is decent quality, intuitively it seems like this woudn't be optimal on LHD models
Also, IMO you want a replacement downpipe with the downstream bracket that allows it to be bolted to the side of the transmission for stability. I believe my DP (on the car when I bought it years ago) is a Bonez and it has that bracket. Otherwise, look for thick flanges, good welds and proven track records. Things no-name Chinese Ebay parts aren't known for.

Jim brings up a good point with the HKS DP. My FD had one installed by the previous owner that I can take pictures of for anybody interested alongside what I believe to be an M2 DP for LHD cars for comparison.

+1 for great info. The Bonez DOES have a bracket/arm to mount next to the transmission about 1/2 way down the length of the car. Many Chinese DP's do not. If you look at the flange size/width of a Bonez compared to a Chinese DP it is about twice as thick.

Downpipe
 

I've never used a stock FD turbo, so going single you always just have to make up your own, I go cheap and just cut and paste on a ebay special. FYI boost creep really doesn't have much to do with the exhaust. If your still using the stock turbos and your pushing enough thru them to get boost creep, they are not going to last long enough to worry about it.

Wrong. It has EVERYTHING to do with exhaust. And you can get it at stock boost levels on the twins (i.e. 10 psi). The stock twin wastegate is relatively small and as mentioned above, can be overwhelmed if there is too little backpressure. And since it's exhaust volumn where talking about, it would proabably have more to do with rpm than psi.
To avoid it you either maintain some backpressure in the system (hi-flow cat is usually enough) or port the wastegate.

so invest in a good high flow cat like Petit and port the wastegat a lil to avoid some boost creep:icon_tup:

The answer is YES, the rotary doesn't like guess work :banghead:!

^^^^^^THIS IS YOUR ANSWER :icon_tup:!

I think you might be confused w/HF Cat vs. Pettit resonated midpipe. Don't put a resonated midpipe on a stock car! Simply get you a Bonez HF cat to go w/your Pettit DP and be done with it!

i think the confused one here is you Sir :lol:

http://shop.pettitracing.com/pettit_.../i-408896.aspx

have a Feed downpipe.But with the HKS you makes definitely nothing wrong.

wow alot of good information should help me out later..

Rx7 store makes a decent downpipe for the price, couple that with their mid pipe and a boost controller to prevent creep and you have some nice gains for cheaper.

WRONG! In another thread you suggested throwing an S5 OMP in the trash without knowing the consequences. Now you're suggesting putting a midpipe on and claiming that a boost controller will protect you from boost creep. It will not. Boost controllers control boost SPIKE. They do NOTHING for boost CREEP, which is caused by people throwing on midpipes without knowing the consequences.
Please do more reading. Your posts are not only wrong, but can cost someone alot of money.

No ya big douche I was being sarcastic about the omp as how is it causing limp mode when hundreds of people don't run an omp whatsoever, maybe you don't know as much as you think. How many 3rd gens have you owned? I've had 3 all running straight exhaust and intake with no boast creep or boost spike. So relate actual facts from the real world please.

An S5 will run in limp mode with no OMP unless you have some sort of solution that takes this into account...such as an RTEK. If you are suggesting otherwise, you are the only person I've ever seen claim this and would also feel you are wrong.

Suggesting someone run a DP and MP with just a boost controller is poor advice. I'm happy that you have had no catastrophic experiences with this combination...someone else may not be so lucky.

While time spent on the forum and posts is not always indicative of knowledge, you are giving the appearance of providing less than solid advice.

It would be interesting to hear your supporting mods for running a straight exhaust and intake with no boost creep or spike. You are apparently the only FD owner in history never to experience these issues.

Please...you weren't being sarcastic....you were simply being wrong. Probably just one of the reasons you've gone through three FDs.
Hundreds of owners do remove the OMP, but not on the stock ECU.

There is absolutely no reason for that. Read and follow the rules for the forums or you will be banned. I issued you an infraction for this and closed your FS thread. Prove yourself as someone that can be trusted and follow the forum rules and common decent human behavior where you don't resort to child like insults to try and make a point.


BTW, Gringo and Sgtblue gave the correct advice and mirrors my own experience with these cars.

You're wrong. Boost creep is basically 'RX-7 101' and you're failing in this rudimentary topic.

3 FDs does not exactly make for a huge sample size, sorry. Believe it or not, there are people on this board who may possibly know a bit more than you. Crazy but true.

You continue to be wrong, and now you're insulting a veteran member.

So, now you've got my attention and I'm not nearly as nice as the other guys posting above me. Just to hammer home the point----- if you don't change your attitude (and what you post) immediately, you'll be shown the door with a quickness.

If it wasn't 100 degrees I'd make a video proving in real life situations those mods and a mbc will not do not creep or spike.....just because I don't have 500000 posts doesn't mean I'm a liar.....did the forum change owners BC it never used to be like this.....can any of you provide a video to counter argue mine? Thanks I'd love to learn something cause I'd hate to blow a motor.

Search under my username and 'boost creep' and you'll get your answer.

Just because YOU haven't had this issue doesn't mean that others won't.

You can't cure a mechanical condition (the OEM wastegate being overwhelmed with too much exhaust flow) with a boost controller. Period. Many many owners have learned the hard way that a well-flowing system with stock twins/stock WG=17+ psi on stock map sensor/fuel=blown motor.

Excuse us if we're kind of cranky after having to explain this for about the 20 millionth time.

Fair enough, I guess the point I was trying to make is that just because it hasn't worked for others doesn't mean it can't work. I duno why it has always worked for me, I spent $11 on a boost controller, $5 in parts from ACE and $6 in ice cream sandwiches and it has not failed me once, but I pushed this 7. That being said, thanks for the welcome and not banning me, I never mind a heated discussion. And I don't need to search you Ive seen your youtube videos..lol

:icon_tup: