live2themaxuk

iTrader: (2)

Hey all


Ive had my car for about 10 months now and really enjoying it, but recently i have noticed until now, but assumed i was imagining it, is now starting to intrigue me.

My car has Test Pipes, Fujitsubo Legalis-R Stainless Exhaust with Stock OEM Y-Pipe and a JWT Pop Charger, and i have never driven the car without them. The car came with all of the mods.

While on the whole i am happy with the performance, it seems that there is a certain characteristic that seems to occur. Basically, some times it will seem to accelerate strongly and more importantly smoothly and responsively under WOT @ about 2.5k , but other times, it will seemto be , how can i put it, 'breathless' when i go WOT from 2.5k, with more 'noise', from the exhaust but no responsive 'go' that it has at other times. This 'roar/rasp' is more noticable because i have 'test pipes or decats', and it will really rasp/roar around 2.5 to about 3.5k under hard acceleration, The times though that it does accelerate by my book 'as smoothly and strongly', it does'nt seem Rasp/road quite as much, weird.

I have had 2 occasions when, after a spiriited drive, i have come to a stop and the car has developed a misfire for about 10-15 seconds, and then clears with no engine lights etc, but since changing fuel supplier, it has not re-occured, but i was prepared to start swapping plugs, etc but i assume it is not related to the performance issue above.


I am SURE im an not imagining this, and i trust my butt dyno, but more importantly my ears. There are times when it Rasp/roar's at WOT and on those occasions, it does'nt seem to be as torquey/responsive as it seems to be when its not roaring/rasping. Seems to sound more 'exhausty' and less 'inductiony'.

Its so hard to explain. Anyone have any ideas? Testpipes causing backpressure issues? Remap needed with the mods? anyone else experienced this?


cheers in advance

Jamie

black06z

iTrader: (1)

Does the system have a resonator?

live2themaxuk

iTrader: (2)

In the test-pipes? I really couldnt tell you. I looked under the car a few months ago and the test pipes just looked like that. . pipes. . with thread for the emissions sensors. Whats on the 'inside' of the pipes i dont know, but from the outside, they just looked. .normal (?)

Stock Y-Pipe too


Jamie

black06z

iTrader: (1)

I mean a resonator on the mid pipe, right after the y-pipe. It looks a little like another muffler, sort of. Im getting that mean rasp as well, on hard acceleration and I was told that w/o a resonator expect a rasp.

live2themaxuk

iTrader: (2)

AFAIK its just a standard Fujitsubo Legalis-R system, 'cat back' as such, leaving the stock Y-Pipe in situe, replacing all the pipework back from that. I dont know if Fujtisubo have one in there or not. Why, what were your thoughts on this?

Im not bothered by the rasp as such, i understand that its a characteristic of test-pipes, and theres not alot one can do about it, i was using the noise of an indicator as to when i seem to see a change in performance, and how when its MORE raspy/roary/exhausty noise sound, the performance seems to seem slightly asthmatic

thx

Jamie

black06z

iTrader: (1)

Well, it seems like it does have a resonator right there. Its a single pipe exhaust, so an x-pipe won't work. Im strongly thinking its the test pipes. Seems like there's too much exhaust gas velocity. I would get rid of the test-pipes for either resonated test-pipes or high-flow cats. I would exactly prefer the highflow cats, since there's a higher chance of little to no rasp whatsoever and you'll get some of the low-end torque back.

live2themaxuk

iTrader: (2)

There were large discussions on back-pressure etc on our cars with a contravertial outcome. My own impression was that its never good to loose Cats on an N/A car, but on a turbo car then it certainly helps performance. I have seen people decat other cars with more noise, and less go. I just dont have the experience with Z's to know if they react the same way. All i know is , my setup and. . .my symptoms.

Jamie