Just an update

Hello,

Just thought I'd let you know that I am thoroughly impressed with the 200TDi transplant - it's totally transformed the thing I do have a few questions to ask now though

First of all, where abouts does the temperature needle sit on your 200TDi? Mines been just over the 1/4 mark, so I made a rad muff today which has taken it up to the 1/2 way mark which seems warm enough and I can certainly feel a difference in the cab. I've got an adapter in the thermostat housing which takes my old 2.5 N/A temp sender - mated with my 2.5 N/A gauge.

Secondly, I've noticed that the turbo kicks in and helps me accelerate away after about 2 seconds. It then accelerates and pulls away very well until it flattens off (doesn't pull as hard) after about 5 seconds of constant acceleration - just as if the turbo has given up boosting. Is this normal? I take it that it's just the turbo boosting upto the maximum pressure established by the waste gate adjuster? Or should it keep boosting and pulling like **** until I come off the gas?

Cheers
-Pos

Glad the transplant went well , The turbo will only boost up to the set pressure when it reaches that pressure the waste gate opens and dumps the pressure . Hense the flatening out or power ( time to change gear just before that happens ) .

Best way to check is to get a boost guage and pipe it into the system to see what shes boosting at , you might .. have a badly adjusted waste gate actuator or a weak spring in it .
Just a thought or it ould be just the way it is

Do you know what the pressure is ment to be when the gate opens?

Cheers for the heads up It sounds perfectly logical really. I expect then, that the turbo will maintain the final (set) boost pressure, but allows any excess exhaust gasses that are generating that boost to escape back into the exhaust system via the waste gate? Or does it in fact totally dump all the exhaust gas so that the turbo isn't boosting? That said, where abouts in a turbo system would you "bolt on" a dump valve? I don't want to put one on, but a dump valve serves the purpose of releasing the exhaust gasses that would usually exit through the waste gate does it not?

-Pos

pos said:

Cheers for the heads up It sounds perfectly logical really. I expect then, that the turbo will maintain the final (set) boost pressure, but allows any excess exhaust gasses that are generating that boost to escape back into the exhaust system via the waste gate? Or does it in fact totally dump all the exhaust gas so that the turbo isn't boosting? That said, where abouts in a turbo system would you "bolt on" a dump valve? I don't want to put one on, but a dump valve serves the purpose of releasing the exhaust gasses that would usually exit through the waste gate does it not?

-Pos

Click to expand...

A wastegate should maintain the set pressure.
A dump valve is a device that allows the excess boost that builds up between the compressor and throttle butterfly on a closed throttle to be dumped to atmosphere. The logic being that this reduces the pressure difference between either side of the compressor turbine. This means that the turbo can continue to spool, and retain inertia as it faces less resistance. When you get on the gas again the turbo doesnt have to spool up from such a low speed, thus reducing turbo lag.

Chur said:

A wastegate should maintain the set pressure.
A dump valve is a device that allows the excess boost that builds up between the compressor and throttle butterfly on a closed throttle to be dumped to atmosphere. The logic being that this reduces the pressure difference between either side of the compressor turbine. This means that the turbo can continue to spool, and retain inertia as it faces less resistance. When you get on the gas again the turbo doesnt have to spool up from such a low speed, thus reducing turbo lag.

Click to expand...

Thanks for that Very informative! I'll assume that it's running as it should be then, but theres no harm in checking the waste gate is working properly.

Cheers
-Pos

Dump valves are what all the sissy boy racers in their 1.0 Corsas use to scare little old ladies as they drive down the high street at 20mph. Great idea on a high spec race car but a complete waste of money on any thing else.
The waste gate is a constantly variable valve that diverts some of the exhaust gas around the turbo vanes once max boost is reached. The boost is set by adjusting the length of the wastegate actuator rod. A small change in length (normally shorter) can result in large changes in boost pressures so be careful if you play with it. A half turn on mine was equal to just under 3 psi change. Dont forget even a small turbo is more than capable of boosting beyond 60 psi if you disconnect the wastegate and will likely blow your hoses or intercooler, and very possibly your head gasket if you turn it up too much.