S2 De Cat pipe - can I buy one???

[bodders]

Have standard exhaust on the S2. her can i buy a de cat pipe (second Cat only) and before i buy a full stainless when this exhaust goes will the De Cat offer up the 10 bhp lost to the SE Turbo? And is De Cat worth having just fitted to standard exhaust?
Thanks All
mark

[ailwyn]

Go for a PECO, it's stainless, has a larger bore, has a nice deep sound (more in-keeping with the rest of the car), and it replaces the main (2nd) cat. Cost is around £300.

[nickb]

I'd second what Ailwyn has said being a fellow peco user on an S2.

Prior to fitting the peco my CAT was getting blocked and reducing the boost, simple solution, a local Exaust firm cut out the Cat and welded in a straight piece of tube, boost returned to normal and the car was alot quicker, This maybe be down to the fact I was only getting 0.3 boots???

The car pass's the MOT no prob as the pre cat is still in place in either case.

£50 for the tube and fitting
Nick

[nitroman]

If your MOT is an annual event have you considered using the SE "non"-precat (same exact casting as your S2 but with no restrictive converter-honeycomb inside)? I used to play the "put the cats on for emmissions" game back when Florida had annual testing. The cats stayed on the car for only 2-hours a year! If the government employee didn't run a mirror under the car it passed without them! I one time asked "If I bolt it to the top of the boot will you pass me then?"... since the car actually passed the sniffer test. Somehow he failed to see the humor in that.

About 4-years ago I sold a "non" precat to a fellow LEC-member which I had payed a machine-shop $60/£30 to port the outlet to 2 1/4", the same diameter as the PECO system. At the time this was just a curiosity project for me to see what could be done to the stock piece. As well as removing the restriction of the converter-material this also eliminated the most restrictive part of the exhaust, the 2" pre-cat outlet. At the time I simply sold it for cost, £25 for me to buy and £30 to port.

I have a spare pre-cat in storage (an American one with studs that actually screw-out!). If you'd like I can have Johnson & Brown (machine-shop) port it after I remove the converter-material.

Just a simple way to complement your PECO investment, and even valuable if you just have an SE as you'll still be eliminating the 2" restriction.

[ailwyn]

The UK MOT test is annual, the problem with doing the CAT swap is unless you have the time/patience/ability to swap the CAT it's a no-go. Swapping the main cat would be easier, than the pre-cat, but that would mean getting a large bore exhaust made, with the main cat included, and a de-cat pipe to use for the majority of the time. As far as I can see, swapping the pre-cat in and out would be a right pain in the a*se.

I did try and generate enough demand for a sportcat peco system, and generated a little interest, but it was not enough to get peco interested in developing the sportcat version, if it had proceeded they would have had a different design to the back two sections of the system, because the non-cat version does not have enough clearance at any point to accomodate a cat of the required size.

My personal preference now would be for a downpipe (that someone might design as part of a turbo upgrade kit) to include a sportcat, so that the PECO can remain as-is.

The other option is to again try and generate enough interest for PECO to develop a sportcat version, which would then allow the removal of the pre-cat. Based on my previous attempts, I can't see PECO being bothered unless there are 20 or more definite orders, which is acheiveable only IF there is interest outside of the S2 owners (i.e. US and any other country where CATs are required for the SE).

Ailwyn

[nitroman]

Ailwyn,

I don't think that will ever happen simply because far less than 50% of the USA has emmision testing. Only counties (from 0 to over 100 in some states) which don't meet the EPA's air-quality standards are required to test for emissions. Certain 'nanny' states like California, New York & New Jersey require testing statewide, but they are in the minority. And, since USA Elans are only OBD1 (on board diagnostics 1st-generation) compliant the ECU has no idea if the cat has been removed. I personally had a Euro-version sport-exhaust shipped from SJS and the carriage was almost equal to the part price! Long-story-short is that the USA will not provide sufficient demand for a european sourced "catty" exhaust because the cost is prohibitive. It is far cheaper just to have a custom-cat exaust custom fabricated "on-car" locally.

As for a downpipe/converter combination, it's hard enough just to fit a decently flowing downpipe beside the engine, hence the current "stiffy" not being compatible with A/C. Besides, the last place you'd want a heat-oven (which cats certainly are!) is under your engine & right beside your oil-supply/pan.

For your specific dilemma the best/easiest/cheapest/permanent solution would be to port the outlet of the existing pre-cat to 2 1/4". It would still mate to the PECO system and would then be a downpipe/sportcat as the exhaust gasses would have a much easier time getting to your new PECO exhaust. The area of a 2" pipe is 3.14" vs 3.98" for a 2.25" pipe. That is a 27% larger opening. Putting that into perspective, imagine if you could spin your turbo 27% faster!

As concerns a continued (and cheap) supply of these downpipe/converters, there are both the ones currently on S2s and those from colonists who've removed theirs. As noted, I currently have one which is still complete, was removed at low-mileage, and is not a rust-encased codger.

Anyway, I leave you to consider my engineering solution, my math, and my economics.

Assisting my fellow LECers, Matt