Decat or Hi Flow Cat complications

[Jovic82]

I have just had a rebuild done on the car and she is all back up and running beautiful but i am having a little dilemna ........:2Confused

At the moment the car is running with a decat silenced mid pipe on the car - no other mods, stock ecu etc. only looking to keep it relatively standard too.

Now i know that when you start playing with the exhaust system you really should be looking at aftermarket ecu\'s etc.

I recently bought a Bonez Sports Cat off Charlie P off here and planned on fitting it to the car to replace the silenced mid pipe.

my questions to you guys are - will i still have to port/ change the waste gate as the flow rate will have increased from the standard to the new sports cat? I know just by having a power fc will not address boost creep / spike issues.

Is it safe to run a hi flow exhaust in the car without a Power fc?

one reason of course is cost and once you start adding, power fc 500, + Mapping 350, wastegate ?? - starts racking up just to put a decat on!

cheers
Nick

[damehyndman]

Carl Hayward has just transformed my car. I have decat pipe and an Apexi PFC. He fitted a boost controller also (Apexi AVC-R) and that  should address most of your concerns, but obviously get the PFC mapped at the same time.

[neil_jdmr]

Me personally, without a pfc wouldnt run anything other than a stock cat

[damehyndman]

I should have also mentioned that all the advise I ever been given about de-cat pipes is do not run them on a stock ecu...hope that helps

[Jovic82]

cheers for tips guys - one of the reasons i wanted to remove the decat and replace with the hi flow cat is because i dont have a pfc, potentially dangerous. New stock Cat from Mazda is something like 1300 QUID!!!!!                


on the rx7club there is a hell of a lot of talk of porting wastegates and boost creep / spike etc but there doesnt seem to be much reference to any of it on uk sites particularly. any reasons for this? are our jap engines different?

meant to say on my first thread - is it safe to run a HI FLOW CAT with a stock Ecu?

[CharlieP]

Hi Jovic
 
 I dont think boost creep should be too much of a problem...that happens more when you put a decat on as far as I know....but to be safe, I\'d look into getting a PFC sooner rather than later....you can often get secand hand ones for around 3-400 then 250 for a mapping, then you should be safe in the knowledge that the cars running the best it can!
 
Did you get a picture of your de-cat pipe? Still interested!

[BlitzBoy]

So let me get this Correct Jovic you have been running a silenced DECAT pipe with no problems?

By putting the a Sports CAT on you are introducing more restriction anyway so in fact making the car safer and less prone to spikes then it has been running.

Personally I think you do not need an aftermarket ECU if your only mod is a sports cat.

[CharlieP]

So let me get this Correct Jovic you have been running a silenced DECAT pipe with no problems?
 
quote]
 
He had a rebuild remember!:Hammer

[BlitzBoy]

yes I read that :Hammer, I am asking has he been driving it since the rebuild on the decat pipe and if yes then by putting a sports cat he will be making the exhaust system more restrictive thereby safer and therefore no need for an Apexi ECU

[neil_jdmr]

The stock ecu retards the timing anyway if it senses excess boost so give it a try and if you feel it start to pull then flatten out your ecu is saving your engine,
 
Wouldnt advise doing this for long though!!

[nuki]

what do you meen by flattening out??

[Jovic82]

okay well i understand the part about getting a pfc to manage the fuelling etc but from what i have read the pfc has no control against boost spike / creep anyway. is this the case? I always used to be under the impression that 2  or more of the following 3 mods -
Intake
Decat
Downpipe

and you will need a PFC mapped for the fueling.

Blitzboy - yes your right the car has been running fine with the decat but i also assumed would be safer putting the sports cat back on. It is called a hi flow cat so an increase in flow over the standard cat unit is obvious in my mind but didnt think it would warrant spending huge amounts on pfc and all other bits!
seems a lot of people run decats and dont really know the effects it has and supporting mods needed. well not like the yanks anyway!

[CharlieP]

Can you get a picture of the mid pipe pls!!

[Jovic82]

sorry charlie, missed that bit of your post! mid pipe still not off car yet but ill stick my head under tomoz and get a shot under the car. that okay?

[Jovic82]

charlie , only pic i could get today (dont really show you a lot TBH) as dont have time to jack up the car etc .

if i have time tomoz ill get a better one.