Yeah I understand that Dave, I know I'm expecting too much from the ZD30 to rev that low, I just tend to let the clutch out most of the time before I even touch the accelerator, probably explains why my clutches last forever. :18:

I've just had a read of the service manual for the ZD30 and I'm unsure opening the swirl control valve will improve things, according to the manual it is only ever closed when the coolant temp is above 50 degrees C, and engine speed is below 1250 rpm. Opening the valve below this engine speed to my thinking could actually be detrimental due to the lower intake velocity, while there is more air with the valve open, the lower intake velocity means less swirl in the bore, and therefore a less efficient burn.

Here's what the manual says regarding the swirl control system.
I'll try it out anyway to see whether it improves things or not since it's super easy to try, all that is needed is to unplug the solenoid that controls the vacuum to the actuator.

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Former 2003 D22 Nissan Navara STR ZD30 Driver - Now driving 80 series Cruiser

yes/no. i'm told that many DI motors are 18:1 even with atmo motors across different manufactures. IDI NEEDS the higher compression because it looses so much heat in the flame port. ie its inefficient and requires the extra compression to get enough heat to ignite the fuel.

the smoke is unburnt fuel, but its unburnt because the EGR puts the flame out.

couple of things they don't tell you.... egr slows down the burn so they need to swirl it to raise it back up to normal. imho its more about how the egr gas mixes with air. if egr is mixed poorly with air you will get inconsistent burn ie good burn in one part of the chamber but lossy burn in another. that not good for emissions.

also that closing the swirl valve INCREASES egr. because egr is only on one runner you normally get 2 part air and 1 part egr. close the swirl valve (blocking one runner) you only get 1 part air and 1 part egr. effectively decreasing the amount of air (read nitrogen) as well as increasing the amount of egr.
this is done because at low rpm there is very little backpressure to push egr into the motor.

with egr blocked the swirl valve simply restricts the amount of air going in. which i why there is a bit more performance at low rpm with it disabled.

When blocking the egr what sort of plate did you use? I have some 2mm ally lying around that I could use would that do the trick or something a bit more substantial?

The thinner the better Jon, if you go too thick it could deform the shape of the EGR tube, if you were to do it on the EGR valve side, rather than at the exhaust manifold you could get away with cutting up a coke can in the shape of the gasket. If you go on the exhaust manifold side you will need to go to something heavier due to the amount of heat it will have to deal with there.

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Former 2003 D22 Nissan Navara STR ZD30 Driver - Now driving 80 series Cruiser

i don't think so.

exhuat side a couple mm STEEL plate is fine. who cares about the shape of the egr tube, there won't be any gas in it to worry about.

inlet side thin alloy sheet is fine. coke can is NOT thick enough. something about the same thickness of the gasket or bigger is ok. stainless steel might be better.
2mm alloy should be fine.

the pictures are a little bit confusing for me.

i'd like to do this mod on my new d22, but there doesnt seem to be hectic wiring like in the original pictures. also i'm running the stock air to air intercooler so i dont know if that will affect it or not.

anyone with a turbo/intercooled car done this mod yet?

you have the 2.5 intercooled variable turbo D22 ??

if so...... blocking the EGR is a whole different ball game. its nothing like the old ZD30. the turbo plays a big role in EGR operation and you need to adjust the turbo to suit the blocked EGR.
not sure if anyone has a write up on doing it on the D40. otherwise have a look through Patrol 4x4 - Nissan Patrol Forum and about the dawes valve.

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D22 ZD30 egr+butterfly mod, 2" lift extra leaf springs, enk-tek dump pipe, 2.5" exhaust.
single cab workhorse, to muddy to clean

Hi tweak'e can i just unplug the red swirl solenoid plug?

as i cant get on the uk site and i can't remember what you told me last time

thanks i will see if this helps mine from bogging on take off

thanks mike

yeah, i've been running mune upluged for the last 6 months or so.

don't forget you can ONLY do it if EGR is blocked off.

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D22 ZD30 egr+butterfly mod, 2" lift extra leaf springs, enk-tek dump pipe, 2.5" exhaust.
single cab workhorse, to muddy to clean

Thanks i'll give it a go