Safe RPM for a ZD30

Hi Guys,

I'm sure this is probably a stupid question. I'm entirely new to Diesels but have finally made the switch from V8's over to Turbo Diesel.

I've purchased a D22 ZD30 which I am loving but I have one concern.

Every evening I travel up a reasonably steep highway at 100km/h for around 10 minutes of which I have 2 options, sit it in 4th at light throttle which revs the engine out to around 3400rpm or sit in 5th at wide open throttle and it slowly labours up the hill at around 95km/h.

I've heard along the grapevine that Diesels don't like to be revved too much on a regular basis (not sure if this is true, once again new to Diesels).

What would be your opinion on which way I should go?

Cheers

the navara zd30 in stock form has a 3000-3500 rpm power band.
3400 rpm is certainly not going to kill it.
going to 5th tends to drop it off the power band.
i would keep it in 4th.

the other way is to mod it. with a better exhaust you will find the power band is a bit wider and you will probably do 5th gear ok.
add in intercooler and especially a chip, i think you will find you will cruise up there in 5th.

Welcome to the forum.

Diesels can safely rev up to about 5000rpm and racing diesels to about 5500rpm. It's nothing to do the governor (which your engine has anyway), it's to do with how long diesel takes to combust (usefully) and push the piston downwards.

Because of the longer burn time, diesels can afford to have longer strokes which means more combustion in the power stroke which means more torque.

As for revving it at 3400rpm - it's not a huge deal. We're accustomed to hearing diesels (trucks particularly) at low rpms - your average truck revs at around 1700rpm at 100km/h (as does the Navara D40 STX550) - it's not really going hard at all!

Here's a vid of a 4.0 litre V6 turbo diesel working hard. It's bloody wonderful - fantastic turbo sounds in it too (limited to just 40psi - 280kPa). Enjoy!

[YT]https://www.youtube.com/watch?v=CzI93pMhaLM[/YT]

Theres a theory of driving by EGT. I would imagine 4th light throttle would be a pretty safe egt while 10 minutes of 5th gear low rpm WOT could be getting pretty toasty.

I just fitted a 3" exhaust from Dandy with the egt probe port in the dump. I have yet to install the gauge but what is considered high end for temps there? I know there is a thread somewhere that says the manifold is the best place but the dump is where I will be reading from for the moment

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The old rule of thumb used to be 550c post turbo. I still work by that now, but stock they can get hotter than that...

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Awesome thanks bods. I kinda wish I had it fitted before I put in the remapped ecu to see what difference there might be. Will probably try and install the gauge this weekend

Tacho's on the ZD30 over read by 10% too, 3400 rpm will be 3060 according to ecutalk which has 2 different rpm inputs.

Thanks guys, that puts my mind at rest