39 replies to this topic

[mini.cooper998]

fitted the standard metro turbo setup, put a decomp plate in and tried running it up today. runs ok but doesnt seem to come on boost. have a boost gauge fitted at tickover pulling -20 psi when it gets to 5000rpm it shows 0 psi so no idea


any idea

cheers

ps im running a converted N/A carb if that helps

[Turbo Nick]

is this at standstill or actually when driving along?

[glyn]

as above you don't get boost unless your driving.

[wardyxxx]

is this at standstill or actually when driving along?

Just about to say that too!

[mini.cooper998]

while driving

sounds like its spooling but theres no kick

and no boost on the gauge

[Turbo Nick]

have you got the right amount of preload on the actuator? usually needs about 6mm ish preload from memory.

[mini.cooper998]

how do you mean by preload.

i must admit when its sat on the drive and revved (not driving) the actuator never moves even at full revs

[Turbo Nick]

you need to adjust the actuator rod so that it's about 6mm shorter than it needs to be to drop onto the wastegate, you'll have to pull on the rod to get it over the wastegate. this way it holds the wastegate firmly closed so no gas is diverted from the turbine untill your actuator moves the arm and opens it.

if you don't have enough preload or the arm is too long then it will hold the wastegate open and you'll struggle to make boost.

[Wil_h]

The actuator won't move until you make boost, and it's been established that revving it on the drive won't do this.

Deffo sounds wastegate related.

[Carlzilla]

this may sound a daft question, but if the turbo is driven off exhaust gasses, why wont it produce boost when not moving? i dont see how its affected, except for the load on the engine when moving

[Turbo Phil]

Simply revving it on the spot won't create enough gases to make any measureable boost, the engine needs to be worked & under load to properly spool the Turbo.

[Ethel]

A carb works "on demand", if it takes no power to accelerate the engine because there's no work to do in pushing a car along the piston will barely rise in the dash pot and airflow will be restricted to what the engine needs - even with a wide open throttle, as the engine will rev up so quickly. The cylinders will be almost empty so there won't be enough exhaust gas to spin up the turbo.

[mini.cooper998]

so how do i preload the actuator to close the wastegate

cheers

Andy

[Ethel]

You could use any pressure source, foot pump, or just do some maths - area of actuator piston/diaphragm x boost pressure.

[mini.cooper998]

do i not mechanically preload it ie wind the shaft out or stick washers in it