Japspeed down pipe experiences?

[Sadsaps]

Hi all, been a while since I have posted on here, but I am after some user experiences of the japspeed down pipe from the turbo, has anyone on here fitted one and if so have you had any problems?

The reason for asking is I have recently removed my exhaust manifold to drill out some broken studs and while it was dismantled I decided I’d do away with the cat down pipe and fit a japspeed straight through so that it matches the straight through of the remainder of the exhaust system, however since putting it all back together I’m now building insane amounts of boost really quickly and erratically resulting in fuel cut to activate and I’ve checked all my vacuum/ pressure lines and they are all good ,also I notice when it is boosting it sounds like I have an external wastegate and wondering if the cat down pipe was creating a bit of back pressure that the japspeed exhaust isn’t allowing the turbo to spool up too fast? It’s the only thing left I can think of and plan to put the cat down pipe back on tomorrow to confirm, but just wondered if any one else has had a similar experience or if they are running a different turbo (I’m using a CT26)

Thanks in advance

[Snorkie]

Did you check that the flange that bolts to the turbo wasn't fouling the waste gate?.

[Sadsaps]

This was another thought I had, and currently I’m only going off the fact that it appeared there was enough of a cavity for the waste gate to operate, but yea quite a plausible issue as it is the only thing I have changed since the manifold removal and it was operating fine beforehand, hopefully can give a bit more detail tomorrow

[Sadsaps]

Ok never mind, not being caused by the down pipe back to square one trying to figure out what’s going on with it

[BYRNEY1984]

Check the actuator hose is connected to the turbo housing. Sound like this may have come off. Hence why you can the boost pressure as its escaping from the housing. Also you will have no cut off of boost pressure because the actuator is not opening the waste gate. Hence you hitting the fuel limiter and making massive boost. Don’t drive it until its fixed or you risk blowing the engine with unlimited boost.

[Sadsaps]

Thanks for your thoughts, I have checked that they are fastened, I even replaced the little spring clips with small fuel clamps to ensure that no pressure was slightly creeping out, my next port of call is I’ve ordered some pvc end caps of various sizes and some tyre valves so I can simulate boost pressures through the compressor housing and blank of the inlet manifold end of the boost system and ensure that 1 all boost pipes are holding securely (which I’m pretty sure they are) and 2 that the actuator does respond to the pressure, I’m able to move the actuator manually so I know it’s not seized or contacting anything, it’s an unusual one and I just know it has to be something stupid but just trying to find it is driving me nuts , I can feel straight away whether the fault is fixed and I’ve got a boost gauge so I can trial it and try to hold a steady 5 psi boost and see how it responds and know it’s not right, but appreciate your concerns and any other ideas will be greatly appreciated cos I seem to be banging my head against a wall right now

[BYRNEY1984]

Check the actuator is functioning properly. It opens under boost pressure. The diaphragm may have split so the pressure just escapes that way.

[Sadsaps]

I’m hoping to achieve this by pressuring from the compressor housing with the inlet manifold end blocked off but I’m waiting for the bits to turn up to make a test rig and looking for the wastegate actuator to start moving relative to the pressure I put in, it does point towards wastegate operation given that it’s allowing it to over boost its just trying to understand why atm but as with other messages am grateful of all suggestions