My Z has now had de-cat pipes and everything backwards done in stainless, straight through. The mid and top range feel noticably faster but the car seems to me as though it is giving much more turbo lag, especially in second from low speeds. Is there a reason why this might be? I am going to get some extra silencers fitted as the car is too noisy, will this rectify the difference?

wonder if its due to less back preassure?

 

im no mechanic mate, just thinking in type

personnally, im not convinced about the back pressure argument. As we are talking about spinning a turbine surly its flow of gas over the turbine that spins up the turbo, so a free flow exhaust system should mean more gas over the turbine therefore as good a spin.

 

It might be that your just not noticing as much of a kick from the turbo as the car is now pulling harder.

 

Also, how much louder is the car? Was thinking of decating my zed, but its already very loud so dont want it to get any louder.

http://www.300zx.co.uk/forums/showthread.php?t=59400

http://www.300zx.co.uk/forums/showthread.php?t=59400

the logic of a free flow exhaust helping the turbos to spool up faster is logical.but if you speak to zed world theyll tell you that de cat pipes have been the downfall of many a turbo!!!

this zed downfall of turbos by decats confuses me (not questioning the authority of guys at zedw, but just asking for more information)

 

surely if the turbos are fine a decat wont hurt them, and the decat downfall is more a case of the problem being highlighted earlier? if im wrong ready to stand corrected... but ive decated previous turbo'd cars and enjoyed the extra BHP with no ill effects and am not really sure why it should be any different on a zed

My Z has now had de-cat pipes and everything backwards done in stainless, straight through. The mid and top range feel noticably faster but the car seems to me as though it is giving much more turbo lag, especially in second from low speeds. Is there a reason why this might be? I am going to get some extra silencers fitted as the car is too noisy, will this rectify the difference?

A Decat will Improve spoolup.

 

The Correct amount of backpressure is ideal for NA cars, but the least amount of backpressure is ideal for TT's. However there is a point at which an excessive exhaust pipe diameter causes cooling of exiting fases, slowing down their travel...increasing backpressure.

 

What diameter piping do you have ? 2.75" is ideal, and anything more than 3" has been proven to have a negative affect. .

this zed downfall of turbos by decats confuses me (not questioning the authority of guys at zedw, but just asking for more information)

 

surely if the turbos are fine a decat wont hurt them, and the decat downfall is more a case of the problem being highlighted earlier? if im wrong ready to stand corrected... but ive decated previous turbo'd cars and enjoyed the extra BHP with no ill effects and am not really sure why it should be any different on a zed

 

Basically, if your Turbo seals are on the way out then a Decat will push them over the edge. The Large majority have ran decats for years on 60k+ tubs, with no problems.

cheers legrath... that does kind of make sence to me now. And totally my experiance of decats on other cars as well regarding the seals ...

fooked seals means new turbos

 

is that such a bad thing? mine is decatted with stright through pipes and sounds loud and awesome

 

too loud? i dont give a fook

reason im worried about the noise is the fact that my zed has stainless exhaust anyways (2xtwin scorpion) and is loud enough for my use. Only reason I would decat is to get the extra 15-20 horses!!

 

Generally, decats offer the best value for BHP IMHO on turbo cars...

reason im worried about the noise is the fact that my zed has stainless exhaust anyways (2xtwin scorpion) and is loud enough for my use. Only reason I would decat is to get the extra 15-20 horses!!

 

Generally, decats offer the best value for BHP IMHO on turbo cars...

yup that is what ive got 2xtwin scorpion it sounds great :hyper:

does sound good, but would be a bit too loud for me with decat... ive got some dynamat waiting to get fitted in my boot... hoping to quiet down the noise just a bit...

does sound good, but would be a bit too loud for me with decat... ive got some dynamat waiting to get fitted in my boot... hoping to quiet down the noise just a bit...

the louder the better IMO

 

but i understand where you are coming from

Mines de catted with a scorpion cat back, not too loud at all, bit droney on a long motorway run.

 

But not half as loud of some ive heard.

Generally, decats offer the best value for BHP IMHO on turbo cars...

 

£75-£150 for zed decat pipes - 10-15hp

 

5p for pair of Boost jets - 40-60hp

 

;)

id not really counted boost jets... but yea 5p for bhp... :hyper:

I was running de-cats with standard piping rearwards for a week and it was only when the silencers just before the backboxes were removed that it got too loud. With just de-cats and standard rears it hardly sounded any different. I am only worried about the noise as some circuits have noise limits and I dont want to turn up to any track days and get turned away. Also it sets off all the car alarms in the underground car park where I keep it and security are getting annoyed, understandably.

 

It is 3 inch piping that was used.

 

Anyways, went to ztech today and any lag problems I had have disapeared with a chip and re-map, so its a happy ending!!!

Thanks for the help, I learned some things as well!

£75-£150 for zed decat pipes - 10-15hp

 

5p for pair of Boost jets - 40-60hp

 

;)

 

 

 

Blowing your engine cos of an undetected boost spike - priceless!!!! :rofl:

Blowing your engine cos of an undetected boost spike - priceless!!!! :rofl:

LMAO :D

my car has been de-catted, has aftermarket exhausts on and doesnt sound loud at all.