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Hello,
I’ve just checked the preconverters and main CAT and on my ‘91 and it looks like the preconverters have disintegrated and all the dust partially clogged the main CAT. Now my plan is to replace the main one with the same type- ceramic core from MagnaFlow and not to install the preconverters anymore. Alternatively I could install metallic core preconverters that I understand can withstand higher temperature in case of incorrect fuel mixture(which I don’t know if it can be totally avoided). What do you think?
thank you
If you no longer require inspection remove them all and install pipe in place of them. Better yet, throw a set of long tube headers on it.
I agree, I had an '85 and a '90. I broke the ceramic inside, and hollowed out the converters. It makes it look like they're still installed, and it sounds great! That's IF you're on a budget, or just cheap like me lol
The exhaust is so much cleaner with the cats and I don’t want to remove all of them.
I wonder if the main CAT alone can withstand the temperatures. Two preconverters at the front would burn most of the gas and I think there would be less chances for the main Cat to melt. On the other hand given the distance from the headers to the main Cat is long, maybe it wouldn’t heat up that bad, but I still think the metallic preconverters could give the system the best reliability so less risk of trouble on long term.
previously the main CAT was clogged then partially cleaned but after it was installed the mechanics used a sealing dough because there were some leaks. that sealing paste turns very hard and some of it ended up clogging the exhaust to the same level it was before cleaning, if not worse, with the engine having overheating problems on the track(I don’t know if the overheating is still present) and that could’ve been a possible cause.
On the front I now have two FIA 100cpi converters, with such a good flow that it now sounds like straight piped (the muffler has one way straight pipe and the other muffled but it doesn’t have a flap).
Instead of the main cat now there is a free tube. and I can easily swap it for a cat whenever I need because it on VBands.
The new CAT with air tube is an MF California grade . anyway it’s much smaller that the stock. the cross section is like 20% smaller with same cpi / wall thickness. Now being shorter it may flow similarly Idk.
here is my DIY flow meter. The clogged CAT gas significantly less flow.
yes, now there is one more problem with the drone
I want to try a db killer for when I use it on street. I’ll simply push it through the 3” outlet of the muffler all the way till the other side of the muffler.
Another solution is to weld a 90deg pipe of about 70cm (it can be calculated) but on would slightly sacrifice the flow on track, and ads a little more weight. anyway, probably would work well.
Catalytic converters
. anyway it’s much smaller that the stock. the cross section is like 20% smaller with same cpi / wall thickness. Now being shorter it may flow similarly Idk.
