This may be a dumb question but I can't seem to figure out... How many catalytic converters do F355's have? Two or Four? All this time I thought there were only two. But recently I've heard people saying there are two primary AND two secondary cats!!?? If those secondary cats are the ones that people most referred to when they de-cat (as in putting on a straight pipe) or replacing them with aftermarket units such as hyperflows, then where are the primary cats? Are they located by headers (exhaust manifolds) or by Y-pipe?? Can someone knows this stuff for sure please educate me....Thanks much.
Four total .......... two primary cats ....... two secondary cats ...... secondary cats are utilized when the bypass valve opens, at that point all four cats are in play.
Actually , I believe there are cats in the Y pipes in 1995. The increased horses are due to the less restrictive airflow and the OBD1.
This is correct, the Y-pipe incorporates 2 metallic cats for the bypass, just like the later 5.2 cars.
Oh, I get it. there are 4 cats and one p*ssy. . . . . Seriously, thanks guys for all your info/input.
There are, one for each side. During my major I pulled the Y and cut off the heat shields. Found signs of heat build up just in front of each cat...so I de-catted and ceramic coated. There's no O2 sensor after the bypass so OBDII has no clue... I posted pics in my 355F1 engine out thread
That is what I thought ...... they all have 4 cats from the factory, except the 2.7 has a slightly different shaped y-pipe and different headers to meet up with that different y-pipe.
+1 .......... that missing 5 crank HP is easily regained with 'hi-flow air filter tops' for the 5.2 ......actually at least 5 'wheel' HP ..............
Oh come on now Goth... That is some shameless self promotion. There's no way a new airbox cover can overcome the defecits of the 5.2 v the 2.7
The Y-pipe cats are the bulges on either leg of the (upside down) Y. Looks like a snake swallowing a cat to me. I also wonder why we don't see as many problems with the secondary cats as we do with the primary cats. My guess is that due to the bypass valve being closed most of the time the cats don't heat up as much as the primaries. John
A: exhaust does not flow across them most of the time (car in standard trim) B: they are not in the path where the ECU cares C: If they did go out, who would know--certainly the sniff test does not use this path I do happen to know that they choose metalic converters, here, so that the converter would heat up fast (fraction of a second at full throttle).
