I have been looking to make subtle mods to my '94 1.8 mk1 to give it a bit of extra oomph without straying into FI territory.
With the K&N filter fitted I’ve started eyeing up the ugly exhaust manfold and constricting cat (no MOT here in Brunei so I have only my concience to struggle with)
MX5 parts warn to measure up the cat before purchasing a thru pipe stating they should be 370mm or 440mm - mine is 395-400mm depending on which flange im measuring from - typical! has anyone else come across this - could be because mines a Jap import?
On the manifold front I’ve seen some beautiful 4-2-1’s but im concerned any gain in smoothing out the exit will be lost in heating up the intake air with the filter directly above - any comments?
Cheers,
Ben
Thanks niggle - will have to see if they deliver!
Or if you know someone local to you with sheet metal working skills then they could probably fashion something suitable for you very cheaply out of a polished stainless steel sheet.
Make a template out of cardboard first and then salvage some thick gauge stainless sheet from some scrapped catering equipment.
Seems a shame to hide a nice stainless manifold but the factory fitted heatshield was there for a purpose I suppose.
You’re measuring something wrong. All Eunos Roadsters, 89-97, used a 370mm cat. MX5 parts manifold, is designed for a European car, with a 440mm cat. Which means you either need to purchase the small adapter to bridge the 70mm gap you’ll have between the downpipe and your catpipe. or buy a 440mm catpipe. Be warned; don’t bother with the adapter pipe. Its just one more bit in the exhaust to leak (and it will eventually rust away, being mild steel), poorly made (I had so much excess weld on mine, I couldn’t fit a nut properly. On top of that, it knocks the rest of your exhaust out of kilter. On mine, it cause the mid bod to gouge a nice groove in the PPF. I ended up fitting a 440mm cat. Also, it has a EGR fitting on the pipe, which Roadsters don’t use. MX5parts supplied me with a blankng cap, but they may not do that anymore.
After 2 years, one of the welds on the cylinder head has burnt through. Not impressivbe quality, and probably no better than a cheapo Chinese made ebay manifold. The solid pipe construction also means you get odd vibrations at certain revs. Japanese manifolds tend to use Goodrich flexible hosing, which I think reduces this, probably leading to increased longevity.
The same fitment issues apply to US manifolds from Racing Beat and Moss (Jackson Racing, Cobalt). If I was looking again, I’d avoid the MX5parts manifold. I can’t got back to the old manifold now, as the adapter pipe mashed the original cat.
Got to be suppliers in Asia who can get you a Japanese manifold for reasonable money; very active MX5 clubs in Thailand,Phillipines and Hong Kong.
Thanks SAZ, ive got the cat on the table in front of me - on the underside it is 400mm btwn flanges and on the top side 435mm (making it the 440mm model I guess) had no idea it was so lopsided. In the end I managed to find a local mechanic keen to tryout for American Chopper and he knocked me up a thru pipe with bracket to secure it in the middle - sounds great not with a lot more poke at the top end - time will tell if it lasts!
I’ve just noticed your car is a LHD, but is referred to as a “Jap import”. I guess it must be a US or Phillipino model.