Loss of boost

[PSH]

Hi guys, before I get my hands dirty, or should I say ask one of my boys to get their hands dirty I have a problem that I thought best to put to the collective first.
When I say, loss of boost, I mean 'zero' boost, nothing whatsoever. The scenario was this, drove to the club this morning as I do every Thursday with nothing unusual about the drive except just before I got to my destination. I was in 4th coming up behind a lorry and when accelerating a little more to pass there was a loud pop, just like a backfire. I didn't think anything of it at the time as my car often pops/bangs and since I backed off immediately afterwards to approach a junction I didn't think anything of it and drove the last mile or so to the club as normal.
A few hours later it was time to leave, the car started immediately as it always does and I headed for home, it was as I got onto an A road that I realised that I had no boost, the car felt fine, that is normal when off boost? There are no strange noises, there is no smoke and all of the instruments are reading normally.
So I now need to track down what is wrong and thus am putting it to you guys for suggestions. I first thought the turbo, but if so I would have expected some smoke and if it had seized I'd expect to feel some form of restriction in the engine. Stuck wastegate perhaps but again, surely I would see some form of boost on the gauge that never reached above zero on the gauge, the vacuum seems as per normal, perhaps a little down?

What do you guys think that I should be looking at first?

Cheers

Pete

 

[robwright]

The only time I ever experienced this was when the turbo compressor wheel was shredded Pete.

 

[PSH]

The only time I ever experienced this was when the turbo compressor wheel was shredded Pete.

Something like that I would expect other symptoms...smoke being one of them. I'm leaning towards stuck wastegate but won't know until the car is looked at. A shredded wheel would cause a lot of internal damage which I would have expected to show itself during the 15 mile drive home.

 

[blade7]

On my mates Escort RS turbo it was a split in the turbo to intercooler rubber hose, on my Capri 2.8 injection turbo it was the intercooler to throttle body hose. That will be £75 to you.

 

[robwright]

Happened to me from a stray bolt Pete. Basically turned the wheel into dust that simply passed through the engine. Only the vanes need to go then it can't make air. Just lost all boost and had NA only. Other than that no other symptoms. Really hope it isn't the turbo with your set up. Fingers crossed mate.

 

[PSH]

I have checked the hoses Paul, I've had leaks or pipes blown off in the past but I have never had a total loss of boost and no strange sounds. The car is driving just like an N/A car, no sign or sound of any engine problems.

It's a new one for me...all gauges read normal, temp, oil pressure are all as they were last time I drove tge car. I wasn't even driving hard at the time either.

Pete

 

[blade7]

Sounds like a wastegate or EBC fault then?

 

[PSH]

I had thought about the EBC but surely there would be some boost? There's no sound from the solenoif but then with zero boost the solenoid wouldn't operate anyway? Wastegate stuck wide open makes sence but again, I would expect some sign of low boost? Needless to say I won't use the car until the problem is found.
Rob once one of my boys can pop over the first job will be to remove the intake hose and check the turbo. However, there are no bolts anywhere in the setup on my car that could enter the intake. I guess it's possible that the compressor shaft has snapped cleanly giving no spool up, unlikely but possible.

Petr

 

[Eldavo]

EBC failure would still allow you to boost to wastegate spring pressure so unlikely to be that.


Fingers crossed that it is something simple like a hose or vac line popped off or split. Next best would be wastegate or BOV and after that Turbo!

 

[944Turbo]

Intercooler piping split or detached either before or after ic or wastegate failure / stuck open you have a Lindsey if I remember correctly? (Old parts compared to a tial)
Stuck or failed dump valve. Compressor or exhaust turbine failure or came off shaft.
Hope it's just a pipe!
Tony

 

[PSH]

Thanks for the suggestions guys.. diagnosis will have to wait until one of my boys can take a look, my days of doing these things are in the past, fingers too painful now to undo clamps/bolts etc.... I've carried out a visual and can't see anything split or loose, so must be wastegate or turbo itself? The engine is running fine, no strange sounds, no smoke and nothing to suggest leaking boost. It revs just like an N/A, has a vacuum on idle but try to hit boost and the vacuum gauge won't build into positive territory, it gets very close to boosting but just drops off at say -900+.

I tell you one thing, boy are N/A engines boring...

Pete

 

[PSH]

Morning all A question for the collective who are using the Tial wastegates as mentioned by Tony above. If my wastegate has failed, I don't know yet as no one has taken a look, but if it has then I'll take the opportunity to change for a Tial. My question is I note two sizes most commonly used by 951 owners, the 38 and 46mm sizes. I found that Augment do a kit for the 38mm but think that with my mods I most likely need the bigger 46mm gate. So far I have only found these available in the US, does anyone know of a UK-based supplier.
A second question is I note that the 38mm needs an adapter plate, Augment supply a kit with theirs, is the same true for the larger 46mm and if so where can I get it to fit our cars?

Over to you guys...

Pete

 

[Eldavo]

I’ll take this one then as I have a 46mm Tial WG. It was actually made for a Porsche race car so one side bolts straight up. The other is a case of welding a cone between the original pipe and the Tial Flange and that’s it. Picture tells a 1000 words:

 

[Eldavo]

You can get them here: https://rivalmotorsport.co.uk/products/tial-sport-f46-external-wastegate-46mm

 

[PSH]

Morning David....so a 46mm needs some welding, yes?....

 

[PSH]

I note the BAR choices.....I wonder what I would choose....I have no idea what mine is as I fitted a spacer to increase spring pressure which I'm sure is one of the many things that made a substantial improvement on performance?

 

[Eldavo]

Yes, bracket needs cutting off the pipe as shown in my first pic and then a cone welded to meet the Tial flange. Although I seem to recall that the WG doesn’t come with the flange and I had to order it separately from Rival Who had to order it from the states.

American guy on FB who goes by the moniker "Frank Zappa” sells the Tial flanges for the 38mm WG at a very reasonable price too.

IIRC Hass Mustafa ("Hesketh” on here) fitted a Tial 38mm not that long before his car got driven into and written off - I can message him and see if he still has it as he’s been selling parts off the car?

 

[Eldavo]

I note the BAR choices.....I wonder what I would choose....I have no idea what mine is as I fitted a spacer to increase spring pressure which I'm sure is one of the many things that made a substantial improvement on performance?

General rule of thumb is half your target boost.

 

[PSH]

From what I've read the 38mm would be too small for my setup...if I do need a new WG, it will be the 46mm that I go for.

 

[blade7]

From what I've read the 38mm would be too small for my setup...if I do need a new WG, it will be the 46mm that I go for.

Seem to remember reading something that stated the 46mm was designed for larger engines, and didn't respond as quickly as the 38mm on a 944. Some Yanks always think bigger is better though. Haven't you rebuilt the Lindsey WG before?