Decat help? *Quite Urgent*

[matthewbellamy]

Hi Guys
 
Very shortly i will be receiving delivery of a Knightsports De-Cat pipe for my FD3S, it will be connected to a standard manifold and a 5" HKS HI Power Exhaust. My ECU is standard. My question is, will i need to buy a boost controller to make this work safely as i have heard that sometimes running a free-er flowing exhaust/decat can cause apex seal failure (im not sure if this is right) if someone can help me or point me in the right direction that would be a great help
 
Thanks

[matthewbellamy]

I meant standard twin turbo\'s as it bolts on to them..

[kev-yorks]

Any other mods done Air filter, intercooler, porting etc?

[matthewbellamy]

Ok i have a XS POWER aftermarket intercooler, HKS twin induction kit and a Blitz dump valve, HKS oil filter, Magnecor competition HT leads

[matthewbellamy]

standard engine non ported

[bmatharu]

my understanding is that it can lead to boost creep without the proper controls to keep it in place (power FC or as you\'ve stated maybe a boost controller). The issue is that the car may run lean causing the failure you described. Definitely not worth taking the chance given that you have aftermarket filters and intercooler. Correct me if I\'m wrong guys

[rx-dave]

I think it\'ll end in tears on a standard ecu Matt, you\'ll almost certainly boost spike = run lean = go bang = rebuild =empty wallet :3Confused
It\'ll be much safer to buy an Apexi first, then fit your mods and drive slowly to someone to re-map it :cheers
Dave.

[B.Martin]

Looking at the advice you\'ve been given, i\'d consider a new ECU before you play around anymore mate. No one wants a blown 13B under the bonnet, its no fun at all!

[matthewbellamy]

Thanks for the advice guys. I didn\'t want to go ahead just in case and I\'m glad I didn\'t go ahead last thing I need is a rebuild lol. Ok so if I get the apex and commander on the car get the decat and the exhaust on the car and drive normally to WGT and get her remapped it should be ok? Will I still need a boost controller? I also have a stock mid section pipe which came with the exhaust which is silenced and sure it\'s not a decat is it safe to run the exhaust with this for the time being? Also how much would a remap set me back guys?

[trotter]

yeah, by all means put it on, but be VERY careful against playing with the loud pedal until it\'s remapped!!

if you\'re remotely interested, the reason you get boost creep with a decat is thus:

The maximum pressure any compressor can produce depends on the backpressure it\'s working against. So the higher the backpressure downstream of the turbo, the harder the turbo has to work. Now, with the decat in place you create a restriction for the exhaust gases to travel through. This has the effect of creating greater backpressure between the cat and the turbine outlet. This limits the speed at which the turbine can spin and thus how much air it can force in the other side. If you remove the cat, you remove the restriction and make it easier for the exhaust gases to leave. This allows the turbine to spin faster and easier which sucks in more air. If the air flow gets too much, you run lean and go bang!

You only really NEED a boost controller if you\'re getting a couple of maps done so you can switch them around. The temptation with a boost controller is to turn it up which can also result in things going bang. I have a Greddy one that i use just for boost gauge, the controller tubes aren\'t plugged in.

HTH

graeme

[neil_jdmr]

The apexi will control your boost just fine and Pip will likely give you two boost settings, one slightly higher than the other.

[m1tch]

Get the ECU first, else you will be back on here in a months time wondering how much an engine rebuild is as you have blown a tip.

[matthewbellamy]

Thank you everybody for your advice i will not run the decat until i get a Apexi ECU and commander. Please see this link http://mazdarotaryclub.com/forums/showthread.php?t=71543 this is the hi-power exhaust will it be ok in the meantime to run my car as it is with the midpipe shown in the pic and the exhaust?

[RobMatthews]

I cant seem to access that post, but
wtf are you not listening aftermarket parts such as airfilters,downpipe, decat etc lead to boost creep.

gather all your aftermarket parts and fit all at the same time, may even get a good price from the tuner you go to for the remap

[B9 KLF]

Matt

The silenced mid pipe in the link is efectively a decat and will increase the flow too much if you already have an aftermarket induction kit.

As a rule of thumb you should only have two mods done before changing the ecu to an Apexi so that it can be remapped.

Once you get it remapped though, with an aftermarket intercooler, aftermarket induction, a decat pipe (or silenced mid pipe) and a cat back rear section you may need to keep an eye on the injection duties so ask for this to be shown permanently on the hand held unit of the Apexi together with max boost, induction air temp and water temp.

Hope that is clear now.

Keith