tuned derv ZS update

[petet16]

How about some form of spring loaded valve in the manifold to release the excess pressure into the exhaust further downstream.

The high gas temps are going to be a problem, I'm sort of thinking about how gas turbines release excess compressor pressure, but in that scenario gas temps are around 250 degC.

[p_b82]

yeah, well at the moment we ave got where the EGR valve use to be to play with, but the control is going to be the challenge.

make the path too easy to take and the turbo will not spool properly, dont take enough and the turbo becomes a restriction and the pressure goes up.

One option might be to alter the mapping of the EGR valve coupled with a narrow outlet post valve side. this could either be done via the ECU or by a seperate control method to activate the solnoid in it.

the downsides to this is either design and build a 'mini' ecu for some pre-programmed values, or cost\time to get a remapper to 'muck about' with things. and then istill need to devise a method to read the pressure while all this is being tested.

With the % increases of things i am not really sure i want to risk tapping the exhaust manifold directly at this time, so i need to be able to utilise a blanking plate of some shape still.....

An External wastegate would not cope with the gas temps so it pretty much out the question

It is not going to be easy i dont think....

thanks for the thoughts though

Ps the 'real' solution is a turbo with a bigger hot side - but VNT control has it's own problems and non vnt units are too laggy

[peterzs]

Sounds like you are almost there, hope you can sort the pressure problem out.

Got to give you respect for carrying on and boosting the L series.

Will have to see it in the flesh one day.

[p_b82]

Right have worked out my first port of call method to control this EMP and it is going to try to follow the KISS approach (keep it simple stupid)

going to decide on an external wategate that i might* purchase.
*the word might is there for a reason
Then i am going to get an adpator plate made up that will go from the EGR port, a short section of intermediate pipework and then the end plate will match the possible external wategate i might* buy.

I will get the short section tapped to fit a boost reading device - currently using a compression fit and some brake line, so happy to keep that method for now.

then get a few blanking plates made up for the wastegate end; to start with i will literally just drill a hole and see if we can lower things enough without affecting spool by following this very simple approach.

If i discover a suitable diameter hole that fits the bill i will then either:
a) mate the correct diamter pipework to the downpipe to by pass the turbo
b) feed the pipework under the car to let it vent that way.

If lag is affected too much, or not enough pressure drop occurs, then i will get the wategate that matches the adaptor plate i have had made up, and start the testing again using the pressure to manipulate the actuator\wastegate.

As wastegates are generally quite large things i will need to experiment with a restrictor again to lower the flow either pre or post wastegate or both.

If that fails then i will cry and sulk lots

being serious though if the 2nd attempt fails then i will look at electronic boost controllers - but they are quiet pricey so want to avoid theat outlay if it is not needed.

Now just to work out which wastegate i might want and then get the adaptor made up.

[peterzs]

Hi Pete, is a wastegate the same as the dump valve???

On my Volvo 440 I could hear that sucking and hissing away, I cant say I've noticed the same with the L series, did squirt some WD40 around the adjustment arm to see if it was stuck.

The turbo kicks in OK, just dont get the suck and wooosh noise.

Your one is much too technical for me, just about know how the derv works, but with the torque you are getting I bet it goes.

[p_b82]

Not quite Peter,

On a petrol when the throttle closes and it blocks off the intake in order to dump the air to avoid stalling the turbo you vent it off to atmosphere in a 'psst noise'

Our diesels dont ever get a closed throttle plate, so we dont need a dump valve. you can bodge one up electronically, but it actually looses performance as you need to get the boost pressure back again

the wastegate on our turbo's is actually integral to the hot side of the exhaust itself, they are driven by the actuator. When boost pressure on the cold side is reached they open up and divert the hot gas away from the exhuast turbine therefore restricting the rpms the turbo can spool and therefore hitting you boost limit.

As a combination of the wastegate and hot side of the housing is too small for the volume and flow of gas, we are now seeing the pressure building up.

I have also realised that if my single simple plate method doesn't work, then i am going to also need another actuator to drive the wastegate, unless i get one with summit integrated into it.

I had put in a bit about the run back from the station to the farm, but discretion being the better part of valour and all that i decided to not post it, just suffice to say: it shifts

[peterzs]

Cheers for that, I can stop spraying the WD40 about. Glad its going well.

[p_b82]

Right finally got off my backside and took a few pics of the engine bay... for those randomly interested in the bodgetastic Exhuast manifold pressure reading system then take a quick peak at these






And yes i know i need to clean my air filter

[Jay-ZS+]

Id want to remove that and push it down my stairs

[p_b82]

lol... took me a while to work out what you are on about....

I am afraid it has no spring, as it is brake line... the end result would be to wach it roll down