ZD30 DI boost with nads

[june]

have been in archives [zd30 di turbo egt] and was wondering wether I have set nads up correct. dawes/needle valve have been in for several months now and seems to work how it should. [it was set up by chaz link] I notice in some of the posts that hwy driving[100klms] a lot of you are running boost around 10 psi. my boost doing 100klms is 12psi . this boost will stay at this reading cruising down the hwy. is this what it should do. I thought it might vent off down to 5psi and start climbing again. maximum boost is 14psi. egt are between 250/280 degrees c. I am happy with the set up but just want to check.

[threedogs]

That's sounds fine ,my is 10psi @ 100kph, My max is 15psi and temps re the same.
I'm happy as with the way mine performs atm.
Very crisp and perky might be the term

[Sir Roofy]

Hi june what you have there is pretty good each moter has its own charcteristrics so woudnt worry to much
if you want to fiddle with it just turn the dawes down a hair width to get what you want

[threedogs]

If you feel 12psi is a tad high for 100 kph back off
the Dawes one full turn only and see how that goes.

[mudski]

No need to back the Dawes off, just back off the needle valve. Backing the dawes off will alter the maximum boost level. Opening the Needle valve will correct the cruise boost level.

[june]

thanks guys this is very interesting. you guys have been around for some time now and your advice is valuable. so I got roofy and 3D saying back off the dawes and mudski saying open needle valve to correct cruise boost. please note I am mech minded but average so explain in simple terms. so mudski what does setting the cruise boost do? as I said in first post boost stays at 12 psi does this change it. and 3d and roofy how do I know if boost is too high when cruising. all I know is doing the nads has stopped the high boost spikes and dropped egt down.

[mudski]

O.k The all the dawes valve is for is to take away the ECU's control of the boost limit. So say for instance, you set it to 15PSI, which is what most people set it too. The needle valve controls how fast the turbo spools up. Wind it up too much and you will see your boost quickly go up and past your 15PSI, usually around 2psi higher it will go, and then settle at your maximum 15psi level. Don't wind it up enough and you will see how long it takes for your turbo to create the desired amount of boost. And you will feel it too, the car will go like a slug.
Whilst cruising at 100k's it is best to have the boost sitting around 10psi, too low and your EGT's will go up, too high and your just wasting the turbo's effort for no gain at that speed.
So think about it. If you back off the Dawes valve all you are going to do is change your maximum boost level and still probably get 12psi at 100k's.
I, only last week, had my boost at 12psi at 100k's. Its been that way for ages and I just got lazy and didn't do anything about it. Even though it takes a whole 2 minutes to do. I backed off the needle valve, took it for a spin and now it sits spot on 10spi, my "boost bounce" has gone too. I can floor it and it stops dead on at 15psi.
Before I did this actually, I will say that I was hitting "limp mode". ONLY, whilst dragging out 3rd gear up to hills in my area. I could drive it any other way, floor it hard or drive like like Roofy and it would hit limp mode. After opening up the needle valve this has gone too.
So take note. If you ARE getting limp mode and your boost is set at 14-15psi, try opening up the needle valve a little too.

[june]

now that's what I like! someone that can put it into plain English. when driving normal on road that is! going through gears on my troll boost goes to maximum set boost of 14 psi and settle back to 12psi on hwy. so if I tweak with needle valve to 10 psi will it help with egt.[reminder that I am only average] and no I don't get any limp mode since fitting nads

[threedogs]

I've been playing with my boost for a while now, not to go against Mudski
but I set my boost of 10psi at 100k via the Dawes and Chazs' rule of thumb
Then with needle valve closed and idling open the needle valve till arm on turbo moved,
I then locked it off, and to be honest my patrol has never run this crisp or hard since I've had it
3yrs. Won't be fiddling any more, seems Like a dyno may be a waste at this stage as happy as.

[mudski]

@ June, your EGT's a good now. Don't worry too much. But remember, Higher boost = lower EGT's but there is a point where the higher boost becomes useless. Like cruising at 100k's. Your over working the turbo for nothing.

I've been playing with my boost for a while now, not to go against Mudski
but I set my boost of 10psi at 100k via the Dawes and Chazs' rule of thumb
Then with needle valve closed and idling open the needle valve till arm on turbo moved,
I then locked it off, and to be honest my patrol has never run this crisp or hard since I've had it
3yrs. Won't be fiddling any more, seems Like a dyno may be a waste at this stage as happy as.

Not to go against TD the almighty. But if you set the boost at 10psi, it will be 10psi period. With the dawes there is only one point you can set it at. Thats why the needle valve comes into play. Kinda.