SO when I bought my car from Pettit Racing a year ago, I had them install a 3" downpipe. It was all good until I got home with the car and noticed a small exhaust leak. Tightened up the flange a bit and it was fine. After time the leak got worse (4months) so I pulled it apart to check the gasket. I found that pettit had used two gaskets, one 3" and one 2.5". Didnt think too much of it and reinstalled everything. Leak was worse. Motor needed a rebuild shortly after so I sort of forgot about it. Installed new motor along with a Magnaflow midpipe, using only one gasket this time, but noticed the leak was much worse. Tried some exhaust gasket putty which worked for a bit and blew out. Figured gasket was toast so I ordered a nice, double thickness layered gasket. It makes no difference. Im starting to think the flange on the downpipe is warped.

Is it time for a new downpipe??? I think so. This pettit pipe had exhaust wrap on it but the pipe underneath is rusted and very nasty looking. Maybe from the wrap, maybe I got Bamboozled by pettit, who knows.

Has anyone had issues with the RX7store.net downpipes?
Was looking at the HKS DP, but they are only 70 or 75mm as opposed to 80mm.

Sorry for the wall of text but I had to rant a bit

 

A year? Call cam and tell him.

 

Few things to try here.

First, get a Remflex gasket -

http://catalog.remflex.com/COLLECTOR...t_p/rf8006.htm

That's the one I THINK that works on 80mm flanges, measure to make sure. It's super thick, compresses when sealing, really works well.

If your flanges aren't aligned well due to some other exhaust issues you will always have an exhaust leak. For example, some of the cheap Ebay midpipes/downpipes/catbacks don't have correct angles on the flanges. When you tighten them up they don't sit flush, sometimes they misalign the whole system and shove the exhaust tip into the bumper and crap like that.

If the downpipe is rusty, it's due to it being a mild steel downpipe that's been wrapped. Header wrap belongs on your uncle's 57 Chevy, not on a high-tech sports car. Get your downpipe ceramic coated. I had mine done years ago with Jet-Hot's 2000 degree coating, **** is bombproof and makes a HUGE difference. Also keeps the mild steel from getting rusty.

When I first bought my FD I got a Bonez mild steel downpipe for $30 off Ebay. It was all rusty and crappy looking, but that's fine. Jet-Hot sandblasted it, coated it, had it looking better than new, and it stayed that way until I changed to a different downpipe (Knightsports dual tube ). Every downpipe on every FD should be ceramic coated, makes a massive difference in heat under the hood and keeps the downpipe nice forever.

Dale

 

Thanks for the respnoses guys. I never thought about the pipes being misaligned. I tightened the dp to midpipe bolts first before attaching mid to catback so I may have misaligned it all. Time to check.

 

Disagree....sort of. Jet-coating is nice. But wrap works just as well (or better) if done properly. Some years ago I sanded my mild-steel DP (I think it's also a Bonez) with 80 grit, wiped it down with reducer and sprayed it with DEI hi-temp sealer/paint. Good to 1500 F. Wrapped it and then sprayed the wrap. That stuff is also bomb-proof...just not as pretty. And I can pull off the freeway, run the car up on the lift and grab the DP with my bare hands. And I used the left over paint on the nasty looking heat shields on my twins. The paint has great adhesion and those shields still look almost new. I also had left over wrap which I used on the inlet and outlet of the Bonez HF cat, further reducing radiant heat to my transmission and tunnel area.
Total cost ~ $60.

 

Header wrap is ITCHY, that's my big bitch about it. It can cause the pipe underneath to rust or rust faster and it's kind of hokey.

$80 to get a downpipe Jet-Hot coated. And, you can grab it too, works that damn well. And they coat inside and out as well as the flanges, can't do that with header wrap. And, if you have an old rusty pipe they basically refurbish it.

Again, header wrap DOES work it's just that there's better solutions out there.

Dale

 

It will not rust with if you use the sealant/paint on the DP. It does not itch if you use gloves to install it and then use the sealant/paint. And the biggest advantage for many is that you can install it without removing the DP.
It's just as effective, more convenient and cheaper, especially if there isn't a quality source for coating close to you and you have to ship it off and wait.
It is prettier.
But IF if you're going to remove the DP for coating, I'd consider removing the turbos and and having the manifold jet-coated too.

 

I would coat the downpipe and then wrap it with some of the newer DEI titanium wrap. It stretches and doesn't make you itch.

 

I tried realigning the midpipe, no help. I tried adding the old gasket in addition to the new one and it worked a bit but still leaking on the top of the flange.

Anyone used the rx7store dp? It's only 75$ so couldn't hurt to try. Wonder if it comes with gaskets and hardware??

 

easiest way to see if the flange is warped, is to hold the pipeflange against a book, piece of whatever that is flat and has a hard surface, and see if there is gaps anywhere between the flange and the whatever-surface that is flat
A local machine-shop might be able to shave it flat for ya for a few dollars. As long as they arent taking too much off the flange-thickness, you should be fine

 

Also thought about changing to v-band flanges. Do they leak much?
Or welding the damn flange together

 

As Dale mentioned, the flanges probably just don't line up at adequate angles for a good seal. Take it to an exhaust shop and just have them do a little grinding on the flanges so they can make a proper seal. You don't need a new downpipe to fix the issue.

 

edit