DP to MP gasket?
 

Ok so i've used Vibrant, Remflex, and the cheap ones you can get at any parts store, but not of them are holding up. I'm running a 3" RX7store DP into a 3" Greddy MP and i keep literally burning/blowing through the gaskets. I'll start to get a small exhaust leak after just about 500-700 miles and then a couple trips down the track and the whole top or bottom of my gasket will be just completely fried. Anybody have any ideas on what to use?

Have you used a flat bar to make sure the flanges aren't warped? If its warped bad enough I bet no matter what gasket you use it would blow out.

Try adding some RTV to both sides of the gasket?

The flanges need to be clean, smooth, and true. Also, the flanges should be flat to each other when bolted up. Cheap Ebay downpipes/midpipes have big problems with this, they don't get the angle of the flange right.

Also, the gasket needs to be run with NO RTV or sealant of any kind. This just creates a weak point, that stuff blows out then the gasket follows. You should NEVER run any sort of RTV on an exhaust gasket. At best it's a temporary fix.

Dale

Interesting, on my turbo KL the Y-pipe gasket leaks almost right after I install them. I took them back off and put lots of RTV on both side, no more leaks. Had it for 2 years before I turn it back to N/A for daily.

+1

You may be able to hit it with a belt sander to make it more even. Otherwise, a local machine shop will level that baby out.

I have the same issue with my downpipe flange. It's slightly bowed causing a leak. I ran 2 gaskets to remedy it, though I haven't tried Remflex yet. It will likely get a trip to the ship to make it right.

I'll look into it, but it appears to be mating flush. If its warped it would be slight.

OEM gaskets are the only ones I've used that stand up for any length of time.

I too have gone through numerous gaskets with little success. I have a Pettit DP, stock cat, and RB muffler. I've check the flatness and even hand ground the faces to be sure. I've tried and toasted numerous high temp RTV's. I've cut my own from supposedly the best materials. If you search for my handle and "gasket" you'll see the sad tale.

SCE gaskets make an embossed copper gasket that fits this application pretty well. Being embossed, they handle misalignment well. They're expensive ($25 / ea) but I've got a set in for four years now and so far no major issues. I don't have the part number handy but I think they're cataloged under the subaru exhaust gaskets.

Dave

I'll have to look into them. Went for some "spirited" interstate driving with some "fast" cars today and noticed my exhaust leak got a LOT bigger on a new gasket.

As others have said your flanges warped. Rather than machine my flanges I used a sanding machine to make my gaskets tapered.fatter in the middle and skinny on the edges. Has held up for many miles on my dp to MP gasket. Its about making the sealing pressure even

rx7.com sells some nice aftermarket exhaust gaskets sized for typical aftermarket units that are suitable for the FD's monster EGTs :)

This may be a little off the original question but still on the exhaust gasket topic. Could you use a standard FD exhaust gasket for a 3" HKS DP that mates to the stock main cat? What's the diameter of the stock main cat? The standard exhaust gasket if somewhere around 2.8" so will that create issues if you mate a 3" DP to a 2.8" gasket?

It might cause minor flow issues, but shouldnt really cause any other issues that i could think of.

^I was thinking about the same thing since there will be a "lip" that the exhaust gases will run into when going from a 3" DP to a narrower main cat. I was also thinking that since there will be less contact surfaces between the gasket and the DP ( because the smaller inner diameter of the gasket), it may be easier to have exhaust leak.

Does anyone have a 3" DP going to the stock main cat? Any leaks or problems?

Most people I know that start upgrading their exhaust they either run no cat or get a high performance cat because the stock cat will restrict flow bad enough that there's really no reason to run a bigger exhaust

True. Unless you don't want to get a boost controller or upgrade ur ecu yet and just want to get the heat out of ur engine bay

I have full exhaust and no boost controller, but at the same time i do have the powerfc which i rely on to control my boost.