Hi all-

I've had one generation or other of RX7 for over a decade now, and have had my 3rd gen for about 6 years. So far I haven't made may attempts on repairing or upgrading the 7, but now I'd like to try my hand at doing some work on the car myself.

I have a several questions:

1) How difficult is adding a downpipe for someone new to mechanics? I'm extremely good with electronics, but with autos the limit of my experience is brake pads and oil changes.

2) Are there any online resources with good instructions for installing a downpipe? I've seen many posts on the subject but nothing that lists out the steps to install.

3) Does anyone have experience trying to get an FD with a downpipe through emissions in Memphis, TN? I plan to leave the mid-cat in, but I'm not sure it will pass - I've seen mixed results in other threads but none specific to this area.

I'd appreciate any help on the subject. I did quite a bit of searching but didn't really find these specific answers. You all seem extremely knowledgeable and generally friendly - if I've missed posts that explained this I apologize in advance.

I'm posting a pic of my melted pre-cat for your amusement...

 

isnt it aslong as you have the main cat and your air pump you should be able to pass emissions with a downpipe.. that should of been the first thing changed in the car

 

Changing the downpipe isn't THAT hard to do as long as you

1.) set aside a good chunk of time...like a whole weekend just to be extra safe. You can't rush this.

2.) Make sure to really soak ALL fasteners in PB Blaster at leat 4 hours or so before you start (read that as overnight)

3.) Have tons of patience

4.) Have new gaskets for both ends of the downpipe

5.) Have the right tools (wrenches, sockets and extensions, magnetic stick)

6.) Make DAMN sure to cover all openings as you expose them so as to prevent dropping items down pipes, etc...

Other than that, it's pretty straightforward. It was the first mod I did to my FD when I got it 9 months ago and looking back it really wasn't that bad.....just time consuming (much like every other mechanical repair adventure under the hood of the FD)

 

It is pretty easy. Jack up the car, soak the bolts in WD40 or any other lube for a whlie and have LOTS of patience. I pass smog in CA with it and my RB duals and as you know to pass emissions in CA is the hardest thing in the world so you should be able to pass with a breeze.

 

yeah its patience to work in a REALLY tiny spot. its gonna take you about 12 HOURS in all id say.

 

Wow.. 12 hours to a weekend for labor in your driveway, or on 4-point lift in a shop with any tool you could ever imagine needing??

I'm really glad this question was brought up.. I will be doing mine in a couple days.

 

1. Get a DP that fits well. Many need filing/grinding/different DP-to-turbo flange bolts to make them fit. IMO, the HKS and several other brands that are reputed to fit well are worth a few extra $ to eliminate the PITA factor. I installed an HKS w/o difficulty.
2. My FD passed emissions in OH w/ excellent readings with no pre-cat. The main cat and air pump are stock.
3. It may be melted, but you also appear to have a significant oil leak. Diagnose and fix that while you're under there. The oil pan may be the culprit - they often leak, and oil pan work is easier while the DP is off. Here is a thread with some oil-pan-sealing tips: https://www.rx7club.com/3rd-gen-archives-73/easier-oil-pan-removal-305386/

 

SixSigma,

You can always just take it to a shop that does any kind of exhaust work. Way back before I had a house and some real tools, I had Midas install my entire exhaust replacement (DP, Hi-Flo cat and catback) for not much money.

The exhaust work is not "rotary specific" so any shop that does exhaust work can handle it.

 

The oil leak MIGHT be from your turbos. As long as they boost fine and don't smoke, it may be something to just live with for now.

Since you still have the original studs, it's a good bet that one or more will break during removal. That's when the PITA factor can really kick in. Especially without a lift and some tools you probably don't have.
I'm not sure about MIDAS, but if you have a trusted shop as previously suggested, that might be a better choice. I also agree with getting the quality DP, stainless if possible. You should notice a nice performance bump too. Good luck.

 

lol, it's just a pipe with bolts. Nothing special that any exhaust shop hasn't seen before.

 

Maybe your MIDAS is better than my local one. I've dealt "professionally" with several of their employees. Probably not a good choice.... for me. I've also seen some pretty crude work come out there. Destroyed exhaust headers from careless drilling, and some sort of asbestos paste stuffed into seams to keep them from leaking on a friend's Chevrolet.

 

I think that's a *safe* estimate, just in case something goes wrong. In reality, the downpipe was my first ever project on an FD as well and it took maybe 3-4 hours to do. You have to remove some of the I/C piping and the ABS heat shield, and some of the nuts are hard to get at but it's really not bad if you have to right tools, some mechanical experience, and nothing breaks on you. In my case it also helped that two of the studs decided to come out instead of the nuts they attach to. This made fitting the downpipe in place muuuuch easier for me ;P

 

That's true of any shop. The name of the shop is just a name; what makes a shop good or not is their workers. I have delt with the same thing getting alignments; I use a Goodyear close by but no other Goodyear within 50 miles will put my car on their rack. Not all shops of the same name are of the same quality.

 

Maybe I could have stated it better, but the purpose of that post wasn't to bad mouth ANY shop necessarily. (you just got me going about my local MIDAS shop ) Given the author's statements that he'd only done brakes and oil changes, I assumed he'd been taking it somewhere for other repairs through the years. The suggestion I was trying to make was to take it to a "trusted shop". As you indicated, it's just a pipe with some bolts on it. IMO, it doesn't HAVE to be an exhaust shop. Like changing the fuel filter, it's one of those jobs that's alot easier with a lift, but nothing technically special about it.

 

I did mine a few years back, got it from rx7.com, nice fit and SS. The flanges are cast and the O2 sensor hole is cast iron. There are full SS models available as well as regular galvanized metal. Some use standard bolts while others have their own connecting bolts. Your exhaut manifold gasket can be reused-once, perhaps twice - it is very expensive so be careful. Get a new gasket at the CAT - it is not that bad cost wise. Emission will be no issue and the only thing the precat did was help with a cold start emission test-that an implode and engine or two - cold start emmission is only done in car certification when new not by state test sites. Unless the guy doing the test is an FD expert he will not even know you put a DP on the car. I would highly suggest getting access to a real lift. I would never want to try this on my back - I am not as young as as once was-and even then I ran for the lift - an uncle and friends in the business. All it took was a case of beer - good beer. You just need to reach up pretty far and it is a tight fit. If you can do a brake job and replace spark plugs this is not that hard a job-one step up. It seems more daunting than it really is. It is basically 6 hard to remove bolts and about 10 other bolts/nuts. Penatrating oil is fine at the manifold- soak em good and they will come out. If the exhaut bolts at the cat stick heat them up - depending on age/rust they may need to be cut . You can use a propane torch on the exhaust bolts and nuts - get them red hot and they should unbolt - gloves and safety goggles if you need to go this route. Cutting is a last resort - a shop with a lift should have a torch. If you have the $$ and the car is older consider putting in a new 02 sensor - it will never be any simpler than now - you must unhook the lead to take out the precat and re-install the 02 sensor. THe DP does come with directions which explain pretty well what you are going to need to do. If you buy it from a good source they can give you any tech support as these guys did in TX did for me. I was kind of clueless on the heat shields - they new exactly what I was talking about and what to do. Some suggest pushing the ABS aside for better access. I did it without touching the abs - I did losen its heat shield - this requires some nimble fingers from underneath the car. This is how the lift helps as you can adjust it to get the right height for the ratchet and socket. You will have some extra heat shields - do not remove those near the turbos - just those attached to the lower precat. Some fun facts, you just put your car on a diet, the nuclear reactor pre cat weight is like 40 pounds. You will hear you turbos spool - you will not listen to the radio for days. Your HP will go up, not sure by how much but at list a little bit. My gas mileage improved by a bit as well. good luck

 

Thanks so much for the info guys.

I did call a local rotary shop here to ask about installing it, and the guy actually got pretty angry with me when I asked if he could install a downpipe. He said it was illegal for him to do so, but I'm not sure if he actually understood I just meant removing the pre-cat and not the whole assembly. He was too busy yelling to hear me out. Anyway - I'd prefer to learn to do it myself, I just don't want to mess up my car as part of the learning curve.

Regarding the oil leak - it's been doing that for a while now. I've asked a couple of different "mechanics" to look at it and they all claim they can't find it. I'm not getting any unusual amount of smoke out of the engine (none really once it's warm) and it boosts fine.

I looked around when I took the picture of the pre-cat, and it looks like the oil is coming from the bolts around the oil pan (or somewhere in that area). About 3 of the bolts had fresh drops of oil sitting on the tips waiting to drip. I tightened them up a bit to see if that would help, if not I'll try some of the processes described in the FAQ.

 

Get the HKS. Great fitment and quality for like $200 bucks. You WILL have fitment issues with cheap downpipes, i.e. E-bay. I had a Mazda dealer do mine a few years back. As expected, one or two of the studs broke off, but they took care of everything.

If you do it yourself, be prepared for broken studs, scraped knuckles, and cussing.

 

It took my tech all of an hour to do it on a lift. We used Kroil not PB Blaster or WD40.

When I replaced the JDM downpipe with an HKS Swain-coated one, it took me 2-hours on my back and with jackstands.

:-) neil

 

my car also passed smog without the pre-cat. I have a hks down pipe, air pump and stock cat. like everybody else said soak it with wd40 or some penatrating oil, it helps. It was pretty easy to take but 2 studs came off along with the nut still on it, so you might need new studs and bolts. don't forget the gasket. get it from mazdatrix. good luck.

 

The oil pans leak at least partially due to the stress put on the pan and gasket by the engine mounts. Pan braces also help keep the area from flexing and may help prevent a recurrence. However, I did not use a pan brace, and the repair has lasted over 2 years without any sign of leakage. As the link I referenced says, repair it w/o a gasket, using HondaBond, "The Right Stuff" or some similar high-performance sealant. I used something similar called Mega-Gray.

Dave

 

He could possibly get in trouble - it's technically illegal to remove ANY required emissions component, even if the car will pass all the required tests with it removed - so that's probably why he wouldn't do it. Why he had to yell at you to tell you that is another matter...

Dave

 

12hours!?!?!?!?!?!?! i dropped my downpipe in 20minutes!

patience IS key to this procedure if you have never performed this task before. first time i did it, it took me an hour


i do recommend that you have a swivvel head ratchet (3/8" drive), there's the topmost bolt that's a PITA to get to.

IMO, use new bolts and use anti-sieze on the new bolts.