De-cat question..

[m1tch]

The top power is gained at about 6,800rpm anyhow, so you don\'t need to ever hear the buzzer lol

[L18M]

The top power is gained at about 6,800rpm anyhow, so you don\'t need to ever hear the buzzer lol

thats a bit random.. or am i missing sth..?
so i can boost it to say 6,500rpm n still be safe with no boost creep etc..?
i heard the buzzer go off a couple of times b4 i modded my fc.. nasty sound.. i want a ding dong noise like in initial d ae86 =p

[Prof]

thats a bit random.. or am i missing sth..?
so i can boost it to say 6,500rpm n still be safe with no boost creep etc..?
i heard the buzzer go off a couple of times b4 i modded my fc.. nasty sound.. i want a ding dong noise like in initial d ae86 =p

err - no
 
Boost creep will happen more at higher revs, and potentially at lower RPM\'s.
 
You\'ll know if you are getting it - boost rising slowly - not under control and increasing in each higher gear.  It\'s usually down to a mods made to the car without sorting out the wastegate on the turbo.  If the wastegate isn\'t big enough you\'ll get creep.

[Jimi_Hendrix]

Just read through this whole thread and its making my head hurt! I almost wish i\'d bought a fecking N/A FC! Simple case of straight through spout and air filter. Fit and forget! Lol!
 
So now with my Turbo II - as i understand it - if i want to upgrade the exhaust system to a 3" system straight through from the downpipe to the back box with nothing between I\'m going to need to......
 
(A) first fit somekind of upgraded and mapped ECU?.... Well how do i get an ECU mapped for an exhaust i dont have and how do i safeley run an exhaust without the ECU and map?:Hammer
 
(B) Get a boost controler to limit the amount of boost produced (is that boost creep?) and cut the fuell suply before the fuel mixture runs lean and knock occours?? What the hell IS a boost controler!? In what instance would you use one? What does it do?
 
Also what about a BOV? Do i need one of them too? I dont even know the diff between a dumpvalve a BOV and a wastegate!
 
I\'ve ALWAYS had Hondas! Lol! So i know NOTHING about turbos! I\'m also a total novice with Rotarys! I\'m quite good with regular Honda 4 bangers like the B series VTEC engines, but i\'m WAAAAAYYYY out of my depth here!
 
If ANYONE can explain this to me in some kind of an "exhaust tuning turbo cars for morons 101" sence making way! I\'d be forever greatfull!:Thumbs-up

[m1tch]

Boost creap is when the wastegate can no longer get rid of enough of the exhuast gasses, meaning that the turbo keeps boosting past a set point, this can be sorted by porting and enlarging the wastegate flapper assembly, when you de-cat the exhuast has an easy path to get out, it just gets stuck getting out lol remember:



Just remember that the above diagram will happen if the boost isn\'t controlled properly

[L18M]

from my experience:
you can run the car de-cat fine.. but the turbo spools up lots quicker n ur more likely gonna hit the boost limit so the fuel cut will kick in. when this happens the car kinda stutters.
so i drive 1/2 throttle.
 
best to get boost controller which can limit the amount of boost the turbo produces.
check this link for good info
http://www.turbobygarrett.com/turbobygarrett/tech_center/faqs.html
 
you can remap the stock ecu but dont kno anyone in uk who has the equip to do this. otherwise can go for standalone fuel management systems like apexi pfc (hard to find!! but i got one on its way from japan as we speak =D ) microtech or few others.. think maybe hks f-con pro?? (pls correct me if im wrong)
or even a piggyback system which works alongside the stock ecu (they similar to standalone ecu but limited to what they can do)
 
if you do de-cat then u can get rid of the air pump. if you de-cat then you need some form fuel controller else the car will run too rich on idle n fail mot.
(which remindes me my mot is due soon n i think im gona fail the emmissions due to the exhaust stinking of fuel on idle!!)
 
u should have a stock bov (same as dumpvalve) (not sure what a stock bov looks like on fc\'s) u can change to aftermarket one.
 
this is some ppls bible to tuning their fc
http://fc3spro.com/TECH/FM2W/power.htm
its a good rough guide
 
best advice i can giv is to follow that guide roughly and not do what i did n start from stage 4 working my way back lol

[m1tch]

The stock \'BOV\' is a recirculation valve and yes you need some sort of pressure release in a turbocharged system else the turbo won\'t last long. When looking in the engine bay its on the left hand side just behind the big black air box, there should be a black metal pipe leading from the turbo to the intercooler, there should be a rubber pipe leading off that to a round black recirc valve, which then plugs into the back of the air box.

The options for BOVs/Dump valves are either:

Recic: Reciculates the presurised air back into the intake, these are usually quite quiet and are good if you don\'t want to get noticed

Atmospheric: These are the sort that you always see everyone with as they make the SHHH should when you lift of the throttle, they do improve throttle response...plus they sound good lol

The BOV I have is a Blitz dual drive, which is quiet on low boost and sounds CRAZY when on high boost lol



The boost controler limits boost by controlling the wastegate, to increase boost the wastegate is held closed for longer which increases the exhaust flow though the turbine on the turbo and increases boost, once a certain boost level has been reached the controller then opens the wastegate and controls it so that its kept at that level

[Jimi_Hendrix]

Right then i just bought a 3" exhaust system and downpipe for my TII with no cat and no mid silencers all it is is a pipe from the turbo back to the rear can!
 
I also have an HKS F-con piggyback ECU which i think is mapped to run with a FMIC (which i dont have, just a standard top mount) and big exhaust. I DON\'T however have a boost controler or an upgraded BOV. I will however have both very soon (funds permitting! Lol!)
 
So could i fit the exhaust system and plug in the F-con and safely run the car just NEVER full throttling it? (Which i cant do anyway because the roads are always sooooooo wet in the West of Scotland i\'ll just spin the damn thing! Lol!)
 
Or should i just wait, get the BOV and boost cont, fit EVERYTHING and THEN run the car safe in the knowlidge that all will be well?
 
REALLY dont want to spit apex seals out the exhaust ports! Ha ha!

[grinder]

were you still running with cats in the exhaust ??

and dont use the exhaust until you can stop it spiking - its not worth it - you suddenly get boost crazy and bang - its all gone and a empty wallet

[Jimi_Hendrix]

were you still running with cats in the exhaust ??
 
and dont use the exhaust until you can stop it spiking - its not worth it - you suddenly get boost crazy and bang - its all gone and a empty wallet

I havn\'t got anything fitted to the car yet Grinder, just i have an HKS F-con and this 3" exhaust and downpipe.
 
I think i will just wait and get a boost controler and BOV then fit everything in 1! The only thing i\'m panicking about is getting it done before my MOT is due in the 9th of March! Because it will DEFO fail on the exhaust thats on it now! More holes than metal! Lol!

[Prof]

You can normally do the exhaust mod without hitting too many issues except the possibility of rear rotor fuel cut when you hit 8.8 psi boost.
 
There are 2 cheapish solutions to that problem:
 
1) Get an FCD - which just lies to the stock ecu and prevents the fuel cut - the car runs progressively more lean as the boost increases - which is bad
 
2) Get a chipped ECU - this will have the FCD built in and usually has timing and fuel maps changed so that it can run higher boost levels safely.  The downside of these is knowing exactly what the ECU\'s are chipped for in terms of mods - as they are usually ex Japan and have no documentation with them.
 
A better solution is to go with a piggy back or Standalone ECU as that will allow you to map in more fuel and change timing safely.
 
I only hit real problems when I had the air intake done as well, as then the Turbo spooled far too easily past 11 psi and needed a chipped ECU to reign it back in.
 
Porting the wastegate is a good thing to do if you run the stock turbo - it will help with controlling boost.  A boost controller will not lower the boost that\'s made if you do intake / exhaust - it will only allow control of the higher point.
 
In short - if you mod the airflow and improve it the stock turbo will boost higher and will be far more likely to result in boost creep - a boost controller won\'t stop that happening - only a larger wastegate / ported wastegate / weaker actuator spring / clipped turbine wheel / restricted intake / restricted exhaust will do that.
 
Only removing the air pump will make it potentially fail MOT - a well tuned engine with a decatted exhaust will still pass.

[Jimi_Hendrix]

Thanks Prof. Love this place! Replys are always soooo speedy! ha ha ha!
 
I have an HKS F-con piggyback maped to run with a bigger exhaust and FMIC plus other bits and bobs its good up to 300BHPish. Thats not fitted to the car yet though
 
I\'m going to be buying a Blitz dual something or other BOV very soon so maybe that will help out. I just have the standard Turbo II BOV and also standard air intake system with an HKS panel filter instaled.
 
I think i\'m going to wait and get this Blitz BOV, fit that then plug in the F-con which should make the car fuel properly, then fit a boost controler to control the high boost? and then fit the exhaust system. And finaly take it to Dasteck or something to get it all mapped up properly. Would that be a good course of action?

[grinder]

do you have a centre cat pipe on the car - or is it already decatted at that point ?

and i ran with a fully decatted system , air cone , bov etc.. and the MOT was fine - no probs ( although i still had the air pump )

[Jimi_Hendrix]

It just has the standard mazda exhaust system on it. But fitting a full exhaust system and downpipe will remove all cats anyway.
 
I still have the air pump fitted so hope it will be ok.

[pdtaylor18]

Jimi I do have the HKS GCC which when paired with a F-Con can adjust fuel at 6 points and by 12% each way. It will only pair with a HKS item but you will need to find  out how to wire it in. There is only 5 or 6 wires anyway. Few pics on the net which might give it away if not just put a thread on here, i did but then wanted to use it with a non HKS item which will not work. I am going to use an Apexi instead when i can get one cheap enough.
This will be good to get the idle right for the MOT and is easily tweaked at all 6 points from the front of the unit. I\'ll let you know a price if you are interested.

My white FC is fully decat, chipped ECU, and better intake but still retains the AFM and my MOT\'s are always very good.