Dawes fitment check please...

[scotty83]

That make sense of the canister. Sorry I hadn't seen one that age before. Glad you got it sorted. My Dawes is up as tight as it can go and I get 10-12psi max which is what I wanted.

[Chaz]

mudski,

Those figures that I quoted are generally conservative safe levels for setting up. You can go a bit higher if you like, but then you may have limp mode issues and need to go back a bit.

I normally start by setting up the needle valve first and do this by closing it all the way (clockwise) and start the engine. Watch the turbo actuator as you begin to open the needle valve and when you see the actuator begin to drop away from it's stop screw, leave it there for the time being. Then go for a drive and see how high your boost goes. Ideally it should spike to around 16 or 17 and settle at 15 with a bit of throttle and load. Drive it normally as you would taking off at the traffic lights. Then just stop and make adjustments until you get it right. Even at full throttle, the Dawes should hold your boost at it's set point until you go over about 3500rpm, where the turbo will overcome the Dawes and your boost should continue to rise up to 18psi at 4000rpm. If you can't get enough boost with the Dawes adjusted all the way in, then you may need to stretch the internal spring slightly until you can. Quite often we need to stretch them about 5mm to get the 15psi setting.

After that, you may be able to increase or decrease boost slightly on the run with the needle valve. I use to close it sometimes going up hills to help EGT's and could get 3psi adjustment with about one turn.

If your car is a GUII, you'll have the vacuum canister. Nissan wisely omitted them on the GUIII and later. I've found quite a few that caused problems when they cracked from heat. If you have any low vacuum issues, just remove the canister and bypass it. You won't notice any difference.

[mudski]

I normally start by setting up the needle valve first and do this by closing it all the way (clockwise) and start the engine.

O.k So I have the needle valve in my dash the same as in your pics. So if i adjust the needle valve first, and the dawes is fitted. What position or setting should the dawes be in?

Watch the turbo actuator as you begin to open the needle valve and when you see the actuator begin to drop away from it's stop screw, leave it there for the time being. Then go for a drive and see how high your boost goes. Ideally it should spike to around 16 or 17 and settle at 15 with a bit of throttle and load. Drive it normally as you would taking off at the traffic lights. Then just stop and make adjustments until you get it right. Even at full throttle, the Dawes should hold your boost at it's set point until you go over about 3500rpm, where the turbo will overcome the Dawes and your boost should continue to rise up to 18psi at 4000rpm. If you can't get enough boost with the Dawes adjusted all the way in, then you may need to stretch the internal spring slightly until you can. Quite often we need to stretch them about 5mm to get the 15psi setting.

After that, you may be able to increase or decrease boost slightly on the run with the needle valve. I use to close it sometimes going up hills to help EGT's and could get 3psi adjustment with about one turn.

On my needle valve mate. Is there an in and out on the valve? I didn't see anything on it so I just plumbed it up.

If your car is a GUII, you'll have the vacuum canister. Nissan wisely omitted them on the GUIII and later. I've found quite a few that caused problems when they cracked from heat. If you have any low vacuum issues, just remove the canister and bypass it. You won't notice any difference.

Yeh mines the GUII. I was actually trying to work out the purpose of the canister, and I nearly did just remove it too. As one of the barbs had broken off, so I glued it back in with some 406. Good gear that. I might just take it off anyhow.
Driving around town and out on the freeway it maxes out now at just a smidge over 12psi. I can't bear to rev the engine to 3500rpm, let alone 4000.
I was playing around with the needle valve today whilst driving and from opened right up to fully closed I didn't noticed anything. Nada.

[Chaz]

O.k So I have the needle valve in my dash the same as in your pics. So if i adjust the needle valve first, and the dawes is fitted. What position or setting should the dawes be in?

The Dawes needs to be adjusted so that it will allow the boost to hold at 15psi. This is usually a safe limit below 3000rpm because if you go above that for more than a few seconds, it'll most likely go into limp mode unless you can modify the MAF voltage to the ECU. The best way is to drive the car and see where it holds boost and make small adjustments until it holds 15psi.

On my needle valve mate. Is there an in and out on the valve? I didn't see anything on it so I just plumbed it up.

There shouldn't be unless your valve is a needle valve with an inbuilt check valve. I have heard some people say that their valve is directional, but I suspect that they are using a needle with a check check valve built into it. The valves that I use are not directional.

Yeh mines the GUII. I was actually trying to work out the purpose of the canister, and I nearly did just remove it too. As one of the barbs had broken off, so I glued it back in with some 406. Good gear that. I might just take it off anyhow.
Driving around town and out on the freeway it maxes out now at just a smidge over 12psi. I can't bear to rev the engine to 3500rpm, let alone 4000.
I was playing around with the needle valve today whilst driving and from opened right up to fully closed I didn't noticed anything. Nada.

The needle valve can only reduce boost at cruise by opening it. This doesn't work well if you haven't adjusted your VNT grub screw, but should still slow down the spool rate a bit. It's not really an option worth considering anyway, but it's there. I just prefer to set and forget the thing and the best way to have more than one boost setting is to use more than one Dawes valve. It won't do much under power once the Dawes has reached it's limit. Try adjusting the Dawes to hold at 15psi.
Yeh, the canister is ok if it's in good condition, but I've seen a few crack causing problems for the owners. Removing it solves the issue easily.

[mudski]

The Dawes needs to be adjusted so that it will allow the boost to hold at 15psi. This is usually a safe limit below 3000rpm because if you go above that for more than a few seconds, it'll most likely go into limp mode unless you can modify the MAF voltage to the ECU. The best way is to drive the car and see where it holds boost and make small adjustments until it holds 15psi.

The way it is now it won't go over 12PSI. Even over 3000rpm. When I get back home I'm gonna start from scratch as I adjusted the dawes first. So. Should I open the dawes right up to adjust the needle valve first?

There shouldn't be unless your valve is a needle valve with an inbuilt check valve. I have heard some people say that their valve is directional, but I suspect that they are using a needle with a check check valve built into it. The valves that I use are not directional.

I got my valve from Dependable...I had a look on it and I did see an A and B on each port. But no arrows so I think its not directional.

The needle valve can only reduce boost at cruise by opening it. This doesn't work well if you haven't adjusted your VNT grub screw, but should still slow down the spool rate a bit. It's not really an option worth considering anyway, but it's there. I just prefer to set and forget the thing and the best way to have more than one boost setting is to use more than one Dawes valve. It won't do much under power once the Dawes has reached it's limit. Try adjusting the Dawes to hold at 15psi.
Yeh, the canister is ok if it's in good condition, but I've seen a few crack causing problems for the owners. Removing it solves the issue easily.

Great. I haven't touched the VNT screw at all, I'm considering buying another dawes and fit two inline with a solenoid switch and I think i will just remove the canister, I can't really see the point of it and if nissan don't fit it to the later GU3 & 4's with the exact same engine, I see no point in having it...

Thanks for you help

[Chaz]

The way it is now it won't go over 12PSI. Even over 3000rpm. When I get back home I'm gonna start from scratch as I adjusted the dawes first. So. Should I open the dawes right up to adjust the needle valve first?


I got my valve from Dependable...I had a look on it and I did see an A and B on each port. But no arrows so I think its not directional.


Great. I haven't touched the VNT screw at all, I'm considering buying another dawes and fit two inline with a solenoid switch and I think i will just remove the canister, I can't really see the point of it and if nissan don't fit it to the later GU3 & 4's with the exact same engine, I see no point in having it...

Thanks for you help

The Dawes and Needle valves are two separate items and one shouldn’t affect the other. The Dawes will limit maximum boost and the Needle valve will control the spool rate or how quickly the boost will rise, so the needle valve should have no influence on maximum boost under load and the Dawes valve shouldn’t have any influence on how fast the turbo spools. It shouldn’t matter if the needle valve is open or closed to set up the Dawes, but if it’s too far open, it will take longer to get to the maximum boost level. I just setup the spool first because it’s done with the engine idling and then go for a drive to set the maximum boost level.

If you’re not sure if the needle valve is directional, try blowing through it open and you shouldn’t feel any restriction blowing in either direction.

[mudski]

Thanks for all your help.

[BOWZER]

Hey mudski, my GU has that black canister as well, i want to install my needle valve but i am confused on how to do this because of the canister. Can you please help me out? and the needle valve that im using will be in the engine bay not the cabin.

Cheers chris

[mudski]

Hey mudski, my GU has that black canister as well, i want to install my needle valve but i am confused on how to do this because of the canister. Can you please help me out? and the needle valve that im using will be in the engine bay not the cabin.

Cheers chris

Hey Chris that black canister is a vacuum canister, you can bypass it if you want as many of them snap the ends off where the vac hose goes on. I have just left mine on.
This is the diagram you need to go by if installing the needle valve.


So basically you will only have one line coming from the air resonator, next to the air filter housing, going into one side of the needle valve and the other side tee's into the vacuum side of the Dawes. Then you need to block off all three vac ports on the solenoid.
Hope this helps.

Edit : I bought my needle valve from Dependable distributors in Adelaide too. Mine leaks though, with the radio off and the car at idle you can hear a hissing sound coming from it. All the fittings are tight, the leak is coming from the centre section on the valve. I pressure tested it in water and does not leak, but under vacuum, it leaks. So I'm am wondering if this valve is designed for vacuum. My guess that it's not. Plus, I can wind my valve all the way in or out and it make sweet f.a difference. Because of the leak I believe. Jut one of the many things on my list to get around fixing.

[BOWZER]

Cheers mate I ended up doing mine on Saturday, I removed the vacuum tank, was working good but now When the car is under load it's getting a high pitch hiss noise.