thinking about custom making new pipes from the bottom of the stock headers going into my UUC exhaust. doing so will delete my cats and resonator. what size piping should i use. Last i have heard people having power loss when running test pipes. should i just delete the resonator and leave the cats to not have this power loss. I have a e36 328is auto. i also understand that i will not pass emissions and have a check engine light on.
I've never seen a loss on a BMW. If cats made more power racecars would use them...
I like small engines, so what!
i have heard that you can loss low end power/torque but mid to high is increased.
on my friends G35 we installed a track pipe and the power loss was crazy. it increased 1/4 mile time drastically.
Last edited by pearbmw325is; 07-29-2009 at 01:31 AM. Reason: Automerged Doublepost
I heard the price of tea in china is cheaper....
http://************/kn6wv5
I like small engines, so what!
Modern engines are tuned/optimized based on the existance of OE cats. A properly functioning modern cat will have very little restiction on the engine flow/power. In some cases removing them will yield positive results, but it usually isn't until other things have been modified (cams, headers, etc) that you'll see an appreciable difference in performance.
Removing cats with no other changes may not yield any benefits unless the tune can accommodate the removal. They are an obstruction, so if they are removed and the engine is tuned for the removal, the engine will make more power.
I saw a small increase in top end,but if you have no other mods(cams,airmeter,injectors) it wont make that much difference, and you will not pass emmisions ,it will also be a nosie magnet for cops, all that for a few HP up top? why? ????? is it a race car? or deticated track car? then ok
i also run a 328. why you would want to mod an auto i don't understand but anyway, i have been told by a reputable firm in VA that cat removal will cause a decrease in power in that motor.
"Sell the damn thing quickly, Leedham, before somebody mistakes you for a commoner."
From what I gathered online most E46 M3s dyno 275/235-ish stock
My car is stock aside from no cats; it did 288/229 so I guess it adds some power, but you do loose a tiny bit of torque.
Errr should've read the thread. I get too excited talking about my car If I were in your pants I'd leave the exhaust alone and do a manual swap + M50 manifold.
Last edited by Kaiv; 07-29-2009 at 10:35 PM. Reason: Automerged Doublepost
Current:
Alpine White E46 325i Touring S54 6MT
Titanium Silver E39 540i Touring M-Sport S62 6MT
Past:
Alpine White E46 330i ZHP Sedan S54 6MT
Interlagos Blue E85 Z4 M Roadster 6MT
Le Mans Blue E92 M3 6MT
Japan Red E46 325i Touring S54 6MT
Estoril Blue Individual E46 M3 Coupe 6MT
Cosmos Black E36 M3 Coupe S54 6MT
Alpine White E92 M3 6MT
Alpine White E90 M3 6MT
Laguna Seca Blue E46 M3 Coupe 6MT
Jet Black E36 325is S52 5MT
Lagoon Green E36 325is 5MT
spend that money on a chip and intake. I had my 325is dyno tuned and made something like 15rwhp on a completely stock motor minus an intake (MILLER PERFORMANCE)
KnudsonM3 when you did your cat delete did you run a larger pipe. People have been saying if you run the stock pipe size from the headers back to the UUC you will not have a power loss and gain some mid to high power
i dont think i am going to mess with it. dont want the tq loss. Just going to go with the E46 m 6 speed swap then later do the motor
I actually have the Schrick Cams, 3.5 HFM/intake, machined cyl head, and retune, etc (see sig). with the cams and such will there still be a tq loss?
was thinkin of replacing the cats with the stock 1.75" pipe and getting some long tube headers. thoughts?
Last edited by xear0; 08-07-2009 at 01:57 PM.
-'08 135i JB4 - New Toy!
-'95 ///M3 - For Sale!
i replaced the pipe from the headers back to my uuc system U with 2 2.25in pipe. no torque loss and car sounds great. it improved 1/4 mile slightly. i also did the 5 speed swap, light weight flywheel, short shifter, selector rod, and m50 manifold
Last edited by pearbmw325is; 10-22-2010 at 02:07 PM.
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