chaffe

iTrader: (1)

Anyone done a "back to back" power run with and without the cats in place? what is the real difference in power on an engine with stock turbo, say runing around the 260-270 mark?
The reason i ask is ive just put the cat back on mine, and it doesnt feel any slower by the *** dyno.

Tidgy

has it been mapped for the decat?

chaffe

iTrader: (1)

Yes, why?

Tidgy

not a good idea to put the cat back on without mapping to compensate

chaffe

iTrader: (1)

why not?

Tidgy

can cause the cat to overheat, also adds a pressure restriction into the system that wasn't there during the map. remaps are alot tighter on tollerance than the standard map so readding the cat can push it outside the safe limits

chaffe

iTrader: (1)

I see, ill not be savage enough on it to cook the cat, as for the decrease in volumetric effeciency i think it would only make it richer on boost, and the ecu is knock sensing right? Ill check it with my wideband later.
Any way, we digress, has anyone done a back to back dyno with the same boost? If so what power differences are shown, thanks

Tidgy

it will porb struggle to compensate enough. but its up to you if you want to risk it.

chaffe

iTrader: (1)

I spoke to a tuner at my local rolling road, unfortunatly he is too busy to slot it in for a run, but he did say the cat will make little odds. This is why i am asking if anyone has the RR graphs to back it up? thanks

MrNoisy

iTrader: (28)

I had my original car mapped about 4 years ago, a bog standard WRX.
Before the map it was running a Green panel filter, nothing else and made 212bhp on the dyno.
The backbox and resonator sections were then replaced for 3" stainless items and it was mapped, making 248bhp.

This year, I had a prodrive sports cat downpipe, prodrive decat centre section, and STI up pipe fitted, and after another remap the car made 281bhp.
Other than a couple of intercooler silicon hoses, the same Green panel filter (albeit cleaned several times since the original map!) and a couple of new exhaust gaskets, the rest is still all standard on the original TD04.

Hope that gives you a good indication.

Tidgy

you know what after all that, i have the graph from mine mapped with partial and full decat, downpipe though lol

with downpipe cat



with full decat




both mapped to suit so comparable