1991 Turbo 2 3" decat and cat back - Any issues to worry about ?

[Koose]

Hi guys

I have a bog standard 1991 Turbo II , the exhaust is shot pretty much from tip to toe. I won a 3" decat and cat back system for a good price and wanted to try and get it on tomorrow. Will it cause any issues ? Either on the fuelling or boost fronts ?

Or can i literally just fit and forget?

Mark

[TiddlesRX7]

You will almost cirtainly hit fuel cut if you put on an free-er flowing exhaust (not a good thing). A FCD (fuel cut defencer) will be needed to eliminate this. L1am is selling a good one cheap if you go this route. You may also end up with boost creep too. Porting the watsegate on the turbo helps with this. Although I only just did this recently and my car has had a full decat system on for years.
Your new one is only a cat back system so you might get away with out doing either of the above though. TBH though its better be safe than sorry.

Ade

[dthebuk]

uk or jap spec?

tiddles is right, you\'ll need something to stop the fuel cut due to extra boost. You could always go for a piggy backed ecu instead of the FCD.

doubt you\'ll get bad boost creep, maybe enough to hit the fuel cut though

[dthebuk]

just read your earlier thread. I\'d suggest going for a piggy back ecu over the fcd as you plan to get a full exhaust and fmic and run more boost

http://cgi.ebay.co.uk/OWorks-Stage-1-ECU-Mazda-N374-13BT-Rx7-Fc3S-Fc-89-91-/390228868625?pt=UK_CarsParts_Vehicles_CarParts_SM#ht_4406wt_1140

[L18M]

as above.
fcd will do for £35 delivered, knightsport job.

prob better to think how far you want to tune your fc. more so to save you buying twice.

either:
1) fcd for now to make the most out of intake and exhaust (£35)
2) aftermarket ecu, will see just under 300bhp with supporting mods (£110)

if you thinking of getting lots more out and a change in tub then think about which ecu route you want to go with.
3) aftermarket ecu + piggyback ecu (greddy emanage / hks f-con) (£300+)
4) complete standalone, apexi pfc, microtech etc (£450+)

so can go either 1 and 4 or 2 and 3. bit silly to go 2 then 4 as 2 is not used for long so saves you a bit of money.

hope this makes sense.

[m1tch]

You need to port the turbo wastegate as it will boost creap, which is baaaad lol you got a mechanical boost gauge installed?

[dthebuk]

You need to port the turbo wastegate as it will boost creap, which is baaaad lol you got a mechanical boost gauge installed?

i struggle how he will need to port the wastegate just for a de cat and back

[m1tch]

i struggle how he will need to port the wastegate just for a de cat and back

Yeah, but im just thinking ahead as im sure that they will bolt on an air filter soon lol

[dthebuk]

still no need. Even with a full system etc you could still get away with running a leaky bov instead.

[TiddlesRX7]

I ran a HKS induction kit and a straight through exhaust without a ported wastegat for at least 2 1/2 years. Im not saying its the right way to go about it. But I can\'t see it being a major issue for Koose with only a cat back.

[L18M]

i had 3" throughout de-cat and induction cone. did hit fuel cut when no fcd plugged in.
otherwise didnt really notice boost creep on the stock gauge or spike. though i was driving 3/4 throttle rather than wot.

[festa]

Got hold of a realy nice mandrel bent 3 inch down pipe from speedline imports a few weeks ago very light weight as well, after install and a few broken bolts later it when\'t well no boost creep the biggest difference is the the turbo spools a lot easyer and faster