Boost/FCD advice with JSpec

Just got car back after turbo system being replumbed/wired as previous owner had screwed installation of boost controller so it was only on 1 turbo! Garage junked boost controller too as it seemed to be knackered anyway.

Car now pulls much better, and the 2nd turbo actually works - a nice kick too!

The thing is while giving it a bit of a sprint I had a sudden loss of power - a real jolt through the car - for a few seconds. This sounds like a fuel cut problem, and the boost was running ~1.0 bar so sounds about right.

The thing is I'm not sure what to do now. The obvious solution is to fit a FCD to allow boost over 1.0bar, but I've still got 1 of the CATs fitted (and surprised I'm hitting 1.0bar actually - cold weather?). I'm worried that if I fit the FCD to allow over 1.0bar I'll just end up overstressing the turbos as they've still got a restrictve CAT to push against.

Just after your advice and options on where to go - I'd rather not remove the current CAT (and therefore have to go full BPU with restrictor ring, FCD, etc) as a bit short of cash currently.

Fit FCD and hope turbos will hold together?

Find someway to bring boost back under 1.0bar?

Go full BPU on the credit card?!

Drive slower (I've got a shift indicator thingy fitted too, so I've just set that lower in the rev range for now to remind me).

Thanks in advance.

Just for clarification but what upgrades do you currently have on your car and which Cat is missing mucka?

Don't go over 1.0 bar with a cat in. Just stick a restrictor ring in for the moment until you want to go full decat.

Performance wise mods are minimal - APEXi induction kit and exhaust. I'm guessing it's the CAT nearer the back, I'll need to have a look under the car tomorrow (I'm not very technical so not 100% sure what to look for!), but think this is the most likely one.

Restrictor ring for 1.0bar....is that a product as such, or something a garage would need to make up? Would fitting that lower the boost/power even further when the weather warms up?

Performance wise mods are minimal - APEXi induction kit and exhaust. I'm guessing it's the CAT nearer the back, I'll need to have a look under the car tomorrow (I'm not very technical so not 100% sure what to look for!), but think this is the most likely one.

 

Restrictor ring for 1.0bar....is that a product as such, or something a garage would need to make up? Would fitting that lower the boost/power even further when the weather warms up?

The basic principle that some people seem to forget very easily is that upgrading any part of the performance output of the engine does place more stress on the engine components, regardless of whether its to BPU level or higher. It's OK saying that a Supe can easily pop up to BPU without affect on the engine but like ying & yang; if you take something then you have to give something.

Also, by you requiring 33% increase in performance from your tubbies (i.e .75bar to 1.0bar), then this inevitably means that other parts of the engine (fuel pump) may be operating at 40% higher performance levels in order to achieve your desired increased. The figures are just set as an example and are therefeore made up, but it gives you an idea of where I'm coming from. The other thing to conisder will be the condition of your fuel pump, side mount intercooler (SMIC) and the general health of your engine.

Personally (and to stay as safe as possible), I would invest in the 2nd cat; a fuel pump; a Greddy BCC and a 1.0 bar restrictor ring. You will need to check the state of your SMIC of course and I would also see what state the engine is in by way of oil and lube checks (and changes where necessary).

Very surprised it's going over 1 bar with a cat still in though I suppose that is also a product of the cold weather. The biggest worry you should have is potentially high EGT's rather than the turbo's, depending on which cat you've still got in.

Most of the traders on here should be able to sort you with a restrictor ring - mine came from Whifbitz if that helps

It's not so much I'm requiring 1.0 bar boost from the turbos, it's just the way it seems to have happened when they were fixed - I expected them to be running at the stock 0.7/0.8 level - but I guess this is down to have a CAT removed (was already removed when I bought the car)? Running at stock levels is fine by me, just need a cheap way (for now at least) to do so.

When you say invest in the 2nd CAT do you mean put one back in, or take the remaining one out? If you mean to put one back in why would I need a restrictor ring and fuel pump, won't putting the CAT back drop the boost anyway? If you mean take it out won't that effectivily be a BPU level car (with fuel pump, and restrictor ring, etc), only limited to 1.0 bar instead of 1.2 bar?

Sorry to be a bit thick, first turbo car - and not overly technical with NA cars either - so getting a bit over my head!

Sorry to be a bit thick, first turbo car - and not overly technical with NA cars either - so getting a bit over my head!

No, you're not thick at all mucka but its great that you have the commen sense to ask the question - unlike some numpties that just blow their engines in to pieces!

I think I failed to put de-cat in the sentence, therefore; fully de-cat and add the BCC (Boost Cut Controller), a pump and Restrictor Ring are you're good to go. Just check that the oil and lubes look good and that the fins on the SMIC don't look totally squished (i.e. it should look as if an 'affective' airflow can get through the fins without restriction)

EDIT: should ne bo more than £250 or much less if you manage to pick the parts up from the 'for sale' section