ZD30 Turbo.

On the way home the other day from Coffs I noticed a different note in the turbo around 2500rpm, didn't think much of it. As the turbo had been working hard all day.

Had a look at the wastegate actuator and its stiff. The ute has lost 30km's off the tank of diesel. Gauge usually hits the top line on the gauge at 450km's, hit it at 420km's yesterday.

Gonna have a better look today and get a local turbo joint to check the turbo.

Anyone else had a issue with the wastegate ?

The turbo sounds like a D4D Prado vvt turbo above 2500rpm.

Dave.

the wastegate should be reasonably stiff. it takes about 20psi to push it.
easy way to check is rev it past 3000 rpm at idle and check if the waste gate rod moves.

if its noisy check air filter and oil. i usually find turbo is quieter with fresh oil.

Cheers Tweake, maybe I jumped the gun. I will find out when I have it checked.

Id prefer to know that things are right rather then having a turbo blow down the track.

The turbo changing pitch is not something that happens everyday.

Dave.

niether of mine changed pitch before they went

Cheers Josh, thats good to know.

Down the track when this one is known to be on its way out, I am gonna go a ballbearing turbo.

I found a place that will supply parts for these turbo's.

Dave.

hey does anyone know if ZD30 patrol turbo will bolt onto the ZD30 navara ?

i know of one patrol owner who fitted a navara turbo to his patrol. afaik it bolts up to the exhaust manifold.
fitting the patrol turbo might be a back would step. if your going to fit a variable have a look at he latest generation ones they are more efficient. you will also need to make some sort of control system.

I would be surprised if the VNT jobs would not be able to be controlled directly by boost pressure like a normal wastegated job. About the only issue I could see is that it could well be delivering high boost at low load.

I have wondered if just a nice water cooled BB core job might be a worthwhile benefit on the old ZD. Oil cooling is pretty basic and I was surprised to find that is all they have, good thing I habitually drive it quietly for the last couple of KM after any hard work like towing a trailer and then usually idle it down for a couple of minutes as well.

Knowing how basic the factory turbos usually are an aftermarket job might be better both at low revs AND in the top end, I replaced a stock Nissan turbo from a bigger engine with a Garrett for my engine size and gainied all three, throttle response, lower boost threshold and better power at high revs. It would be nice to do the same in the Nav.

you can get VNT's set up to be controlled by boost. only concern i have is excess back pressure when your trying to get boost up very early. don't forget they are less efficient than normal style turbo's but they trade that for wider operating range.

I would not be too concerned about low rpm back pressure. I do not think it is that significant. It can not be much more of a restriction Than a fixed nozzle that a ten cent piece would not fit through in a conventional turbo.

so if i were to bolt on a patrol turbo it would be a straight swap over ? or is there quite a bit of stuffing around to do with the electrical and control side of things

the_bluester said:

I would not be too concerned about low rpm back pressure. I do not think it is that significant. It can not be much more of a restriction Than a fixed nozzle that a ten cent piece would not fit through in a conventional turbo.

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yes it can. thats kinda the whole point of variable turbo, being able to decrease nozzle size lower than a normal turbo. it may not be producing much gas flow but its shoving it though one tiny hole to increase gas speed.

matty said:

so if i were to bolt on a patrol turbo it would be a straight swap over ? or is there quite a bit of stuffing around to do with the electrical and control side of things

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plenty of stuffing around required to get a turbo control system to work. either convert to boost control or use dawes valve and run off system vacuum.

Actually they do not work quite that way and it is not as simple as making a smaller nozzle. They have vanes around the turbine housing that direct the flow more sharply inwards at the centre of the turbine wheel and at higher boost and gas flow levels they are aligned more at a tangent to the turbine so gas flow is more like a conventional turbo. If anything the AR of the housing is probably larger.

It would effectively be slightly more restrictive at low boost and engine speeds than a fixed geometry turbo with the same AR but given that at the engine speeds we are talking about, gas velocity is low and the engine is a complete torque black hole I reckon any slight increase in back pressure would be a good trade off for some useful boost pressure.

probably the only things stopping me from looking at one seriously for mine is cost (I doubt I would just drop a Patrol VNT on it, I would hunt around as the factory turbos are a real compromise for cost reasons as per my above post about a replacement turbo for my RB20 that is literally better in every way than the stock one) and my second worry would be finding that Nissan expected them to produce no boost pressure down that low and have not programmed the ECU with any useful fuelling under boost at really low RPM.

It would be costly but I wonder if a better fix for towing would be a ball bearing turbo with a larger AR exhaust housing (To promote top end power at the cost of a little low end boost) along with the five speed auto from a Patrol so that the initial stall speed of the torque converter would allow you to overcome the lack of boost and torque at low RPM.

the_bluester said:

Actually they do not work quite that way and it is not as simple as making a smaller nozzle. They have vanes around the turbine housing that direct the flow more sharply inwards at the centre of the turbine wheel and at higher boost and gas flow levels they are aligned more at a tangent to the turbine so gas flow is more like a conventional turbo. If anything the AR of the housing is probably larger.
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actually other way around. vanes open up to let gas by pass turbine. closes to choke it to increase gas velocity to spin turbine faster.

a bit more back pressure for a bit of boost is what they normally do. however if not setup properly they will make big boost at low rpm with even bigger back pressure to match.
several problems with that. you can get vibration problems when running large boost at very low rpm. no problem IF the engine is built for it and i the nav ZD30 isn't.
turbo efficiency is often not good so they could make far greater back pressure than boost.
lastly you tend to waste fuel making boost which is not really used for anything. there is a point where increasing boost doesn't increase combustion efficiency. ie fuel economy goes poor as boost goes up.

its a problem some of the patrol guys get, huge boost at low revs.....then motor goes bang

unfortunately i havn't heard of anyone testing the back pressure and see what it actually does. it may not actually increase to much. won;t know till you put a gauge on it.

All a bit academic really. I can not ever see myself being the guinea pig for a VNT transplant to a Nav ZD30. If and when the hair dryer gives trouble I will look for what should amont to simply a better design conventional turbo where there is less compromise for the sake of money.

thats probably a wise move. the VNT's are know for the vanes to stick and overboost/overrev.
tho i do like the idea of the latest generation VNT. something like 10% more boost and 30% less back pressure !