Dawes valve, egr block for a dummy with a crd

[rottodiver]

I know I know.... This topic has been done to death , I have read and read all about it.... Just about every topic about Dawes valve and egr blocking gets answers from almost all engine types and it confuses the hell out of me.
So a simple question for those with the knowledge on crd,s
If I install a Dawes valve and block the egr( both of which I have sitting there ready to do) do I need a boost control needle(or alike) or is it still controlled by the ecu ( which is my preference) as I understand once egr is blocked the ecu doesn't control the boost or is that on the di, and not the crd?
I know about the need for a hole in the egr( have scan gauge )but might tempt fate without it, do I need gasket or some sort of sealant for both sides of the egr plate if not which side do I place the original gasket( engine side or exhaust side?)
And if anyone has any photos of the Dawes valve done a crd it would be much appreciated.
For the record.. The boost I am currently getting on my scan gauge is 16psi tops but see the needle on my pod guage quickly spike to 18 ish for milliseconds so not sure which is correct and once I block the egr I expect things to rise.

So basically I am after dedicated info for the crd,s as this is really starting to confuse me.

Thanks Scotty

[Fry]

With regards to the scangauge boost readings I would only use it as a guide and trust your pod gauges more. I have never seen my scangauge go above 16.2PSI but I dare say that my CRD has boosted over that but I Don't know as I don't have a normal boost gauge yet.

After the reading I have done it sounds like if you do one may aswell do the others. (have to do?)

[mudski]

All the dawes valve does is limited your maximum boost. Using a needle valve in conjunction with the dawes will let you control how fast the turbo will spool up. Its not really needed to use the needle valve but you may find acceleration a bit sluggish. Using a needle valve will improve your acceleration.

[rottodiver]

Ok Dawes valve installed... 15 1/2 is the max it seems to reach now.. 2000rpm around 10-11 psi ... Do these numbers look right or do I need to wind it out more...
What damage can be done if not wound out enough?
Still got to do the egr but might get used to these numbers first..
Scotty

[threedogs]

sounds about right they are not big boosting motors, it may spike over to 20 now and again.
At 100Ks you'll need 10 psi boost as a rule of thumb which is roughly 2000rpm

[Rumcajs]

When EGR opens the ECU reduces the boost so if you are planning to "shim" it there is no point/makes no sense to retain factory solenoid control.
So the pictures are worth thousands of words look at the following pics bellow.
They show what happens when you retain factory boost control. BTW fitting just Dawes valve on CrD makes absolutely no sense.
First pic shows factory boost control (pay attention to EGTs when boost drops off) the boost is all over the place
Second pic is the same scenario (driving) but this time with needle valve and factory control bypassed. Boost is much smoother, linear and with much better torque and power delivery.
These graphs are from Di but CrD boost control solenoid principle is the same.
Cheers

These pics were kindly pilfered from this location --> P4x4.com Boost drop, EGTs rise help

[rottodiver]

Ok so this is what I have noticed today after doing a bit of driving around and hwy driving(100km/h) with my Dawes valve installed( still not sure if I should have installed it) yes my egt was up a little bit but settled down at hwy speed, yes the boost does still jump around a bit and hard to get an exact reading of what boost I am getting at what speed but it is now not going over 15 1/2 psi which I believe was the whole point.... I was getting 18,s( if the gauge was reading correctly).
Does anyone know what happens if my boost is too low? Is it just the rise in egt...
Now the question is to shim the egr or not, is all this just a waste of time because it is crd?
I do appreciate the gragphs but I would like to see one for crd as it is my understanding crd ecu controls boost better that di,s

Scotty

[Jimbo4x4]

I have just fitted a egr block to my crd about 3 weeks ago, So far the boost hasn't changed max boost of about 16psi on pod gauge and the fuel economy seems to be about the same around town, haven't had a chance to do a motorway test yet. But i have noticed egt are a little lower at 100kph , just under 350" I did drill a 10mm hole in the blank plate before fitting ! and so far no error code :-)

[rottodiver]

I have just fitted a egr block to my crd about 3 weeks ago, So far the boost hasn't changed max boost of about 16psi on pod gauge and the fuel economy seems to be about the same around town, haven't had a chance to do a motorway test yet. But i have noticed egt are a little lower at 100kph , just under 350" I did drill a 10mm hole in the blank plate before fitting ! and so far no error code :-)

Thanks jimbo,
Do have have a chip and exhaust upgrade( I run a 3 inch exhaust and tunit chip) or Dawes
Scotty

[Rumcajs]

Ok so this is what I have noticed today after doing a bit of driving around and hwy driving(100km/h) with my Dawes valve installed( still not sure if I should have installed it) yes my egt was up a little bit but settled down at hwy speed, yes the boost does still jump around a bit and hard to get an exact reading of what boost I am getting at what speed but it is now not going over 15 1/2 psi which I believe was the whole point.... I was getting 18,s( if the gauge was reading correctly).
Does anyone know what happens if my boost is too low? Is it just the rise in egt...
Now the question is to shim the egr or not, is all this just a waste of time because it is crd?
I do appreciate the gragphs but I would like to see one for crd as it is my understanding crd ecu controls boost better that di,s

Scotty

Look, laws of physics apply, you'll need to lower the boost to be able to feed exhaust gases back in to intake. Low boost equals high EGTs = bad news for diesel engine. Yes, ZD30 CrD engines are much better at handling higher EGTs than Di but that doesn't mean that it is good for them in the long term.
CrD control system is much more sophisticated than primitive/rudimentary Di control. Boost of 18 psi is normal on CrDs.
CrD not only uses MAF but also MAP and MAT to correctly calculate optimal AFR. (not really doing a great job there though)
Again that doesn't mean Jack if you are feeding crap down your intake mixing it with oil vapor from crankcase ventilation layering the intake manifold and restricting the airflow.
This has consequences in reduced engine life and increased maintenance costs including fuel consumption. So if you are planning to keep Patrol for 4 years (or while under warranty) max on lease like plan than don't bother fiddling EGR, Dawes, boost control EGTs what not.

Current emission control tech punishes you the consumer with higher costs and reduced reliability. Basically car makers are making it your problem while handsomely profiting from it by selling you crap cheap technology which makes you to fork out more and more often. Its a win for them and oil companies because these techs also increase fuel consumption.

You want to effectively reduce emissions you need to reduce fuel consumption. You will reduce it by making the engines more efficient and powerful at the same time while reducing their size.
So variable camshaft timings or even camless engines, variable hybrid turbo compound chargers, cylinder switching off technologies, water injection etc.
Instead of outdated technology which costs users fortune like DPF, SCR, EGR, AHI and whatever these assholes would do anything but making better efficient engines.
Did you know that common rail diesel injection patent was applied for in 1911. It took 80+ years before we started using that technology, for Nissan even longer they started putting that tech in their ZD30s in 2007

Its your choice. There is no point for Dawes valve alone on CrD. ECU has the boost under control quite well. There is a point for Dawes and needle valve if you want better torque down low, improve power delivery and tractability.
Would I do it on mine if it was CrD, hell yeah. The difference is phenomenal on Di so it will be even better on CrD me thinks I'd at least try for the cost of it. ($150)
Have you ever wondered why CrD has the same power and torque output as Di. It makes no sense when D40 2.5L (Navara) has more power and torque than 3.0L.