Bleed valve on T5 850

[Godzilla]

I bought an 850 T5 1996 earlier this evening. Excellent condition inside and out. Only thing that has given me concern is she has a bleed valve fitted, manual screw thing. I remember these being a crude way to add a few extra horses on some of the old Turbo'd cars in the mid 90's, cars like the Escort RS Turbo, Renault 5 GT Turbo etc...... I really was not expecting to find one on an 850 T5!!? Shall I remove this thing or leave it be?

[Sun Dodger]

Is it a bleed valve or is it a manual boost controller?

Manual boost controllers are okay as long as they are not set too high and need setting up properly with a boost gauge.

Bleed valves (small hole in the body) are not as good.

I have used manual boost controllers on my last few turbos with no ill effects.

[Godzilla]

Originally Posted by Sun Dodger

Is it a bleed valve or is it a manual boost controller?

Manual boost controllers are okay as long as they are not set too high and need setting up properly with a boost gauge.

Bleed valves (small hole in the body) are not as good.

I have used manual boost controllers on my last few turbos with no ill effects.

Did'nt know that mate..... thought all these screw turning things that sit next to the actuator were bleed valves. This one does not look like it has a little hole, will have a good look in the morning. So you have not had any trouble with them? I always thought they would put more stress on the Turbo?

[Sun Dodger]

I've tended to use these on Turbo'd Rovers.

The only snag I have heard about is going through gearboxes a bit quick - the Rover boost modulation valve uses a low boost (about 5psi) in the first couple of gears and 11.7psi in the top gears.

The manual boost controller set at 12psi means you are getting full boost through all the gears - great fun but heavy on the gearboxes (Rover use chocolate bearings in the PG-1).

Most turbos are not generally running to their maximum capabilities, but you need to be aware of things like boost cut and the maximum amount of boost your pistons and rods can handle!

[John_C]

As SD says a properly set up MBC is not necessarily a bad thing on a T5, it should certainly give some extra shove.

The problems come if they are fitted to try and "fix" an underlying boost problem or if they are set too high - too much boost too low down causes bent rods and more than a few T5's have met their end that way

Post some pics of what you have got fitted, someone will probably be able to identify what's there.

Cheers,
John

[Sun Dodger]

There is another issue I thought of as well, if you already have a problem with the turbo and run the boost too high it probably will kill the seals in the turbo.

[don kalmar union]

They were not a damaging addition to the earlier T5s with their Motronic 4.3 ECUs, just delaying the opening of the wastegate if adjusted properly and giving a bit more output low down.

If you have £285 to spare I can install MTE's software upgrade which will give you very progressive delivery of higher outputs throughout the rev. range....that is after I have taken that valve off! I am not too far away in Mill Hill, London NW7.....

Regards, Don.

[Godzilla]

Originally Posted by don kalmar union

If you have £285 to spare I can install MTE's software upgrade which will give you very progressive delivery of higher outputs throughout the rev. range....that is after I have taken that valve off! I am not too far away in Mill Hill, London NW7.....

Regards, Don.

Thanks Don

What kind of power gains as in bhp and torque can I expect with the MTE upgrade? I'm sure mine is 225bhp as standard?

Regards,

Paul.

[don kalmar union]

A stage 1 MTE software upgrade will gain you 270bhp/405nm of torque provided that your engine is generally in good order.

Don.

[Godzilla]

Originally Posted by don kalmar union

A stage 1 MTE software upgrade will gain you 270bhp/405nm of torque provided that your engine is generally in good order.

Don.

Thats a fantastic power increase for not that much money! Will def' be in touch Dom.