I’m looking for technical help or recommendations on: __aftermarket exhaust fitment problems
So I’ve bought a decat exhaust system from gravity motorsport and had my local garage fit it for me they had to cut a bracket off that was in the way and not needed and replace the rubber hangers at the rear for longer ones, generally speaking it fits ok and ice nicely tucked up the tail pipe protrudes a little too much for my liking but that’s an easy fix my mane issue is the tail pipe exits the bumper too close to the offside so much so it has melted the bumper. This is the problem I need to fix I have thought of maybe applying a little heat and trying just to put a degree or two of a bend so that the tail exits in the middle not sure how tricky this could be. Suggestions welcome
I I will point out that the exhaust was for a 1.6 but I actually thought the 1.6 and 1.8 shared the same exhaust, clearly I was wrong
Apologies for the many typo’s, written in a hurry on my phone
Early 1.8 Catbacks are the same. Later (late 1995+) are not. Later cars has a missing exhaust bracket. Have they tried to fit basically a 1.6 downpipe to a 1.8 manifold, or have they left the existing downpipe, and basically bolted the cat replacement pipe. Late cars had a different downpipe. Trying to fit an earlier exhaust ends up in poor fitment and burnt exhausts. The exhaust shouldn’t need different hangers.
Late cars can be easily identified through looking at the engine cam cover bolts and breather pipe. If the bolts are plain steel and the breather pipe is all rubber, then you have a later engine.
No I changed the manifold for a new IL Motorsport one, from the manifold back it’s a 95 1.6 decat system, I had to put in my own o2 sensor as it was missing from the down pipe no extra hanging bars needed but one about half way down wasn’t needed I’ll try and add a link to the one I bought and you can all have a good laugh
Oddly I only paid £265 about a month ago?
Because that has a O2 sensor port (albeit the wiring will need extending.
1.8 and 1.6 manifolds are different, and not interchangeable (the 1.8 block is longer). You have somehow married up a 1.6 downpipe to a 1.8, with the result your bumper is melting. You should have fitted a 1.8 downpipe (though the full header is better);
Note O2 sensor port.
Come MOT time, you will need to fit a 440mm cat. From experience, aftermarket new cats are pretty marginal, you really need the genuine Mazda item. My car is a 1996, with a 1994 engine, MX5parts header, scrapyard Mazda cat and cheapo ILM twin exit cat back which I hate with a vengance. It still has to pass as a 1996 engine.
A 1.6 375mm cat will fit to your present set up, but you will end of with a burnt bumper, and over time, those aftermarket longer hangers will give a bit, and cause the exhaust to rattle a bit. A 375mm cat can be fitted to a 1.8 set up if you either have the downpipe off a late (N-reg +) Roadster import OR fit one of those German made adapters that MX5parts were selling at one time (and which were a terrible fit).
I bought the IL Motorsport 1.8 manifold and the garage said fitting the down pipe part was easy with no issues I had already put in my own O2 sensor it’s really when you get to the back box the problems started because of course the hangers are different, I modify Porsche chassis as a living and I’m a good fabricator I have modified the hangers and tig’d them on I also had to re cut the exit pipe at the back box take 15mm off and tig that back on to get it to line up in the centre of the bumper exit, all a bit of a ball ache but it’s done it fits and it sounds fine.
As for the inevitable “Oh where’s your cat sir?” Next MOT (not for ages) I’ll simply fab in the old one and put new flanges or buy a new one mines 440.
Like I say thanks for all your comments, I was a dumb ■■■ for buying the exhaust system but it’s all groovy now✌🏻
I was aware of all of those parts you listed I needed it cheaper my manifold to back box was only £265