Little or No Boost
Turbo Mini Forums

Hi All,

looking for some help!!!!!! I have just had my Metro turbo engine and gearbox rebuilt, I have fitted it back into the car and it fired up okay. The engine builder who specialises in race engines has a rolling road and offerd to set it up for me as part of the build.

When we first ran it up on the rollers it was running lean at the top end and we found the problem with the carb and sorted that, We ran it up again and there appeared to be no or little boost. The gauge showed -20 on idle and 0 at 4500 rpm at around 5500 the actuator stared to operate.

I had the pipe from the turbo directly to the actuator..... so I expected 0.2bar (4psi) as the standard actuator would operate at that but it only went to 0. We removed the pipe of the actuator and the boost went to 0.9 bar (13.5psi) and blew the safety valve in the plenum. so the turbo is creating boost.

So i checked the Preload on the actuator and the hole was about 3mm from the pin so I adjusted it to 6mm and refitted the actuator, I also fitted a pressure control valve which is made up of a T piece and a aluminium valve with an adust know on it.

The T Piece has a tail with a 1mm hole and the other 2 have 3mm holes so i have fitted it with the 1mm hole to the feed pipe (turbo side) and the other side to the actuator side and the last to the valve. we ran it up on the rolling road again and it was worse than before 0.4 bar (5psi) at full chat.

we pulled the pipe off the actuator again and it was still 0.4 bar (5psi) at full chat, with the wastegate closed. the turbo is new, the engine is fully rebuilt along with the gearbox. there are now air on the pressure side or vacuum side. its a bit frustrating.

I have put the actuator back to the original setting of 3mm, but cant run it up on the rolling road till Tuesday next week as the guy is at a race meeting this weekend..... I am going on Monday to finish tinkering till we can run it up on Tuesday but any one has any ideas for me to try that would be great!!!

Pete

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Is the actual wastegate free to move? With the actuator disconnected it should just flap about freely. I think it is either a sticking wastegate, or actuator.

No I have tested the actuator with a pump and it moves at 4psi ish. And if I disconnect the rod I can move the leaver freely and I can hear it clank in the closed position when the flap meets the manifold.

all sorted now!!!!!!!

So what was it? For folks futue reference?

After much head scratching and tyre kicking, I think we have sorted it....... Not quite sure what it was but....We tinkered with the actuator a little more and ran it up on the rolling road and it worked. The BDD was running to lean at the top end
and the BCA was running to rich so we fitted the BCF and this was running about right till about 4000RPM and leaned off to much so we modified the needle so at 5500+ rpm it was about 12.

we adjusted the boost control valve so we got 0.6 bar (8.4psi ish) at 5500rpm but the valve is blowing in the plenum at around 0.5 so I might blank it off? It is producing 103BHP 122ftbl of torque at 5500 rpm bearing in mind the engine is brand new although they have ran it in on the rollers it probably could do with a few road miles now.

So it was a combination of the wrong gasket between the carb and plenum and the actuator adjustment , fuelling and **** happens...... but it is all up and running now!!!!

thanks for the advise and thanks to Turbo Phil for the input on facebook as well.... Taking it back in a couple of weeks to roller it again.

Ok so fuel pressure not rising on boost due to the gasket blocking the hole from plenum to carb. You are not the first and no doubt won't be the last to suffer that fault.
Blow off valve, you used to be able to get a stronger spring to sit behind the plastic spool. Or you can pack it out with washers etc to increase the blow off pressure. Or as you say block it off somehow.

Yes, I have ordered a new HD spring from Avonbar....I taxed it yesterday and went for a blast.... After a few miles I could smell a strong smell of Petrol.... On investigation I found the boot had a couple of gallon of fuel in the wheel well and it was leaking onto the road. I have a left and right had fuel tank fitted and they are linked together with a pipe one to out let.i have the fuel return going to one tank. I fitted a new hi pressure fuel pump and it is taking fuel from both tanks and retuning it to one, so it was filling up and coming out of the overflow into the boot.....so I need to fit a second return to the new right hand tank as well.....thought I would share just I case Anyone else has the same set up..

Pete

Yes i moved to the darkside

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