Thread: VNT turbo control

So you're running an 18psi actuator now Matt?
You using the bleeder valve thingy - or found it wasn't necessary with the new actuator?

Steve

Originally Posted by steveG

So you're running an 18psi actuator now Matt?
You using the bleeder valve thingy - or found it wasn't necessary with the new actuator?

Steve

Nah, still with the leak off valve and 6psi can, working fine, won't change anything till I get the time to Dyno run it

Thanks - be interesting to know what boost it starts moving at, and when its fully open.

At this stage it looks like mine will go back on the road without an intercooler. Will check out the T25 actuator I've got and see what pressure it is. If its above 10psi will probably just throw it on and see what its like.

Steve

Originally Posted by steveG

Thanks - be interesting to know what boost it starts moving at, and when its fully open.

At this stage it looks like mine will go back on the road without an intercooler. Will check out the T25 actuator I've got and see what pressure it is. If its above 10psi will probably just throw it on and see what its like.

Steve

It wouldn't make more than around 18-20psi in the closed position, wo't make anything open, so now I've just adjusted the leak off valve and it makes 30+, I've backed the fuelling and it'll flicker 30psi, but steady around 27, rough enough for now

With regards to the boost, much to Dougal's disgust, when I removed the fuel to get the boost below 30psi, it also removed lots of torque, still plenty, but now I know what it can have

Anyhow, that'll be about it, till I get down to Mornington and have a play with Joel on the rolling road.......then I'll even have a pretty little graph to post

Originally Posted by rovercare

With regards to the boost, much to Dougal's disgust, when I removed the fuel to get the boost below 30psi, it also removed lots of torque, still plenty, but now I know what it can have

Of course dropping fuel is going to drop torque. You need to find a way to drop boost alone. Shouldn't need more than 25psi with a good intercooler to burn all the diesel your pump can poke out. It takes a lot of power to pump extra boost, you'll gain power and torque when you get the boost levels right.

Does this turbo have adjustable stops for the vane arm? Some do, some don't. Are the vanes wide open at 30psi?

Originally Posted by Dougal

Of course dropping fuel is going to drop torque. You need to find a way to drop boost alone. Shouldn't need more than 25psi with a good intercooler to burn all the diesel your pump can poke out. It takes a lot of power to pump extra boost, you'll gain power and torque when you get the boost levels right.

Does this turbo have adjustable stops for the vane arm? Some do, some don't. Are the vanes wide open at 30psi?

Yea, but without an external wastegate, it may be a little difficult, anyhow, dynotime will tell the tale

Has a stop

I am a time served heavy diesel mechanic who came across this post whilst trying research controlling the boost pressure on a vgt conversion we are thinking of carrying out. Always bear in mind the following, boost will kill an engine on its own- check why race cars have specialised fuel systems to prevent them running lean in corners. What may work today might not in 5000 km's time when you have bits of crank and rods on the floor. The most important part of tuning a diesel is to make sure the correct fuel/air ratio is maintained at all times(not just winding the smoke screw in more). It's why most 100 series cruiser turbo conversions end in misery, nothing to do with heads being different. The only experience of high pressure turbo conversions I have was with Sierra Cosworth motors. The limit of reliable boost on one of them was 26 psi, I would be wary of putting more than 20 psi into a 300 unless you have a rich sugar mummy. I still miss my 300 disco commercial- 11 years, 325,000 MILES on 2 timing belts. What a machine, truly the best 4wd ever