Tractionlimit

iTrader: (12)

Hi, I'm currently running a High Flow Cat on gasoline (guilty conscience & was afraid of the smell). It's only 6 months old and cost me $300 from Ultimate Racing (metal subrate). I later realized that even this was an illegal mod, because it has a dummy O2 sensor. I'm now thinking this might be an impedence when running high boost & E85, so I'm considering a resonated test pipe ($300... gotta keep it quiet) to replace it.

My questions are: will I see any gain from doing this at the 450whp level? With E85 will it smell worse with the cat gone (wife has super nose)? Has anyone passed/failed a sniff test without a cat on E85? We have emissions testing, but it's generally just an OBDII affair, and maybe a visual.

Car setup after tune next week (I welcome any other comments, too):
2008 Evo X
AMS tune 30psi E85 / 25psi 93oct
ported FPRed
Kelford stage 2 cams
1000cc DW drop-ins
Walbro HP + inline Walbro HP
AMS Fuel Rail
UR FMIC / pipes
UR Downpipe & HFC
Buschur "quiet" exhaust
HKS WGA

Jim in Tucson

iTrader: (3)

I suggest a test pipe, of the non-resonated variety. That will yield the best performance.

Drive it like that for at least four weeks. If the exhaust note is too loud for your tastes, then take the car to a muffler shop and have them add a 3" resonator, or have Dave send you a second muffler to add to your BR system. But, don't put it in place of the test pipe, leave the test pipe in place so you can easily swap in your cat if/when needed for future emissions testing, or selling the car, or racing in some class that requires a cat, who knows.

tmiller

I can comment on the smell and sound levels, as I have run a test pipe on e85 and 91. I, like you, could not deal with the smell, or guilt, of always keeping the test pipe on when I was only using 91. When I swiched to e85, I got it tuned with the test pipe and a new HKS exhaust with a resonator in the intermediate pipe plus the muffler. It proved to be quieter (lower tone as well) and the smell was less intense. I, at least, can live with the sound and the smell when I am running e 85 and no cat. Don't know about smog yet, as Denver has quirky test procedures that don't require yearly testing unless you fail a "fastpass" drive by test.

Tractionlimit

iTrader: (12)

So does it still have the 'no-cat' smell, or is it more like a catted car on 93?

tmiller

Sorry, I wasn't very clear. It still does have an unpleasant smell, but not nearly as bad as with 91. I usually do not notice it unless I have been in the boost, then slow quickly and the exhaust fumes "catch up" to the car.

I also figure that e85 produces much fewer tailpipe emissions, so I can be guilt free for running catless...right?!

scumrat

iTrader: (1)

its all up to you,if you get a mil-spec 100 cell cat,they only lose like 8 whp to a test pipe.Also, if you plan on spending $300 on a test pipe you are crazy!! They can EASILY be found used for $60-100 on a regular basis.

Tractionlimit

iTrader: (12)

Yeah, I think the UR cat I have may be similar. I can handle 8WHP but if that's just at a stock power level, and it's really like 20+hp at 450whp, than that's a bigger deal.

Also, this is an Evo X, so that's why the prices are still high. not much used stuff around yet.

Tractionlimit

iTrader: (12)

I would think E85 would prevent some of the ill effects of no cat. I appreciate your clarification on the smell though, that might make it a tough sell with the wife. She got 'headaches' from the exhaust stock .