CosRush

Ive recently run my Sapph 4x4 engine on the road for the first time.
I started off with no preload on the actuator, so that once i got to a good stretch of road i could check and then slowly increase the boost to normal.

With the engine running im getting about -14psi, However even with little or no preload, i expected this to rise once running but it doesn't.

First few people i spoke to said they thought the gauge was knackered so i started plans to get anoter gauge.
I took mine out and tested it with a pump and another gauge and it worked fine.
Pipework was fine (all new).

So i guess my question is, is it likely that im currently running with no boost hence the constant -14psi with no rise at all................

Should i try upping the boost to see if it'll rise on the gauge?
or is there anything i should look at or try first?

This is my first turbo engine so im still learning........

foreigneRS

even with a non turbo engine, when you got to Wide Open Throttle you are effective opening up the inlet manifold to atmospheric pressure (essentially 0 bar or psi or whatever on a gauge).

you should get about -14 psi with a closed throttle (with the engine running it is effectively sucking against the throttle to get the air in hence a negative or vacuum pressure) but this should rise to close to 0 as you open the throttle. a turbo gives you what is termed positive boost, i.e. above atmospheric pressure. so 15 psi boost pressure is 1 bar above atmospheric, or 2 bar absolute. hence the '2 bar Manifold Atmospheric Pressure' sensors you might have heard of that were standard for a cosworth. if you want more than 1 bar boost, you need to go up to a 3 bar MAP sensor or higher if you're really mental.

CosRush

ForeignRS,

Thanks for the reply.
So just to clarify -14psi is ok at idle? only ask as somebody else has said that this is wrong and that i should have around -5 to -7psi, and that as ive got -14 i have a massive air leak...
Although i cant seem to find one.

CosRush

Ok, does this help?

Ive just been out for a drive and here's what ive got...

Starts of at -17psi at idle.
Once driving this goes upto 0.
Once boost comes in (about 3000rpm) it goes to +3psi.
I turned the actuator (shortened) it 2 turns but it stayed at 3psi.

Any idea's???

Guinnless

How hard is it to pull the actuator eye over the rod? If you need a bit of ooomph the the actuator should be fine.
Where have you got the boost gauge plumbed in?

CosRush

The actuator requires a bit of pull to get it over the rod, but not loads.

Ive got the gauge plumbed into the plenum on its own connector so cant be affected by anyhting else.

Should 2 turns make a difference?
Should i just try some more???

Guinnless

No mate. Providing the actuator has enough preload you should be fine. Is the Amal valve working? How much boost do you want to run?

CosRush

How can i check the amal valve's working?

Its in standard form so im looking for 12psi.

swerv

take the plug off the amal valve and plug it back in with the ignition on if it clicks a couple off times its working!

foreigneRS

all sounds ok to me. just need to wind in the actuator to get more boost. 2 turns from zero pre load will more than likely make no difference. just be patient and keep turning 2 turns at a time and rechecking your boost.

i assume from your username that you're running this engine in a DAX Rush? in that case, i think you'll find 12 psi sufficient for a while.

the amal valve clicking will not happen if you have a Level 2 ECU from a 3 door engine, but as you have a 4x4 engine I presume you are running the 4x4 Level 8 ECU.

CosRush

Thanks Fellas.

I do indeed have a Dax Rush and i already have a 330 conversion for when its run in

You're right too that i have the Level 8 ECU with my 4x4 engine.

So based on what you've said, when i next get a chance to go out in it i'll just go 2 turns at a time and see what happens.....

Thanks again for you help, its much appreciated

I'll post again if i run into any more problems.

Mark_w

an easier way to check but you have to be very careful, but i set mine up like this and it works for me....set the actuator a 1/4 hole short and then fit.....remove hose from actuator to amal valve completely and then take car for a run carefully taking it on boost and recording results,if it doesnt hold what you need decrease length until it holds the boost you need.......i found that wastegate will open without hose connected as the pressure builds up and forces it open so you have to set preload knowing it will cope with the max you want......once you know that the actuator will hold the required boost,reconnect hose to amal valve and run again,if your maximum boost drops now you have to adjust the amal valve outlet to actuator....to do this i made up some nylon inserts the same size as original and drilled a 1mm hole through middle and then super glue it in place of original...run again and adjust as nessasary....smaller hole =more boost and vise versa......just be careful when setting up for obvious reasons

mark