Reving the hell out of a diesel

Hmmm
He must have been jealous of your nice fourby......
Actually all modern cars (fuel injected) have rev limiting.. that doesn't mean they want to be flogged to the the limit all the time.
Don't let him work on your car!

Cheers

Why don't you ask him if you can try it on his by holding the gas pedal to the floor for twenty minutes. Bet he is not so keen then. Did he have one hand on his appedage when he came out with this wisdom.

I ain't no mechanic but lets look at the scenario.

Dictionary quote:
A mechanic (n) - definition " someone whose job is repairing the engines of vehicles and other machines:"

suggests to you that: He recons you cant ruin a diesel from thrashing the hell out of it.

and that: reving a diesel and prolonging it's life that

I would suggest the answer to your own question may reside right there. :-))

PS
Don't use him :-)

PPS
He didnt 'just by chance' also give you his business card and say "If anything SHOULD go wrong give me a call...I will 'see you right'....

i am sure you know how it is when you meet some nice bloke out 4x4ing. He seemed quite honest about this revving thing but did not drive a diesel. He was in a sierra with double diff locks all that goes with em. Basicly I do go with logic but also wanted to know if there was something to this whole diesel rev limiting thing. It came accross as though it was some special diesel trait. I have long been of the opinion that diesels did not need to be revved high cause they generate torque down low.

One engine this is the case is with 471 detroit and similar blown engines. Basically they wouldn't pull the skin of a rice pudding unless it is revving it's ring out, this is one case where you should drive it like you hate it. Just wish it had lockers though then it would be unstoppable (commercial front end loader)
By the way, it does like fuel, 20-25 litres per hour at full noise!!!
NickR

my Diesel has a red line at 4500 rpm and the rev limiter cuts in at 5000 rpm - the way I see things is that the red line is the max safe revs for the engine and for the dummies who stuff things up in emergencies or with revs changes the cut out is there to protect the engine - ie do not go above the red line!! - it is there for a reason

I would think that a big characteristic of a diesel engine is the fact that maximum torque (pulling power) is available at quite low revs when compared with petrol engines where the torque peak occurs quite high in the rev band 5000-6000). This of course varies a bit with displacement (3 litre 4 cylinder versus 7.2 litre V8!).

Several magazine reviews that I have read recently indicate that revving diesels above about 5000rpm is pretty pointless. All the torque is produced in the 2500 to 3500 rpm band. All you get past 5000rpm is smoke and noise!

This is particularly true of the new generation passenger cars hi-tech common rail diesels coming out of Europe (Puegot and co).

My Prado 1KZ-TE Turbo Diesel certainly gets breathless after about 4000rpm and redlines at 5000 I think. performs best at around 3500rpm.

I think your Diesel Mechanic "friend" is having a bit of a go - or is seriously misguided!

Cheers
Muddy

Phantom,

I'm not a mechanic, but have operated, and worked on Caterpillar machinery, since mid -70's. The governor in Cat engines is probably a little different to tojo/nissans, and you can rev them at the max, all day, and they love it! In fact, a few engine tests are done at "High Idle"(max revs-no load) Drove a Cat elevating scraper for 6 years, and it was all pedal to metal work.

My idea of thrashing an engine invariably means thrashing the whole vehicle, not steadying up for bumps, purging through mud at over 4,500rpm, slipping the clutch, and negotiating terrain in high range, when transfer case should be in low.

Diesels do like to loaded, otherwise they glaze the bores, and use heaps of oil.

Hooroo...

I find that friends who drive my car after driving their own petrol cars tend to over rev the diesel. This occurs even when gently accelerating through the gears. Using the extra torque at lower revs seems to be counter-intuitive. It is rare that I go above 2500 rpm.

Lower engine speed means less friction which means less wear on metal to metal (actually metal/oil/metal) surfaces, and better fuel economy.

The other factor is exhaust gas temperature. At higher revs you are pumping more air and diesel through the same engine. So the mount of energy lost as heat that needs to be dissipated is increased. The extra heat has an adverse effect on lubrication and oil life.

So I wouldn't rev the head off my engine all day.

No-one seems to have mentioned the "glazing" factor,caused,I am told by our mechanic customers, (almost everything is diesel around here) by allowing a diesel to run at low speeds for longer periods of time..Working stationary engines (including plowing tractor engines that run at consistant revs all day/nite) don't have the problem because they are under load,which is what they are built for..Pehaps the new laws that may discourage us softies,from leaving a motor/air-con running while in the shopping centre,are actually doing us ,the motor and the envior a favour..At work we sell to mechanics de-glazers,which are a number of slightly abrasive balls on the ends of wires of "cylinder" brushes..They are spun by a power tool to de-glaze the cylinders that have suffered this condition possibily due to in-correct engine management by the operator..You could almost think I knew what I am talking about..Don't be fooled.! Helps RockyOne!MPG:3!

A red line on a rev counter does not mean never exceed, it just means max normal operating. You should be able to operate up to the red line any time you want and not do any damage. Above the red line the engine is operating out of its 'comfort zone' and all sorts of combinations of temp, lubrication, load etc. may push the engine into a danger zone where a manufacturer does not want you to go or they may have to pay out on an warranty !

I was told by my diesel mechanic to give mine a 'bit of herbs' every now and then to blow out the cobwebs. He then went onto explain that when doing a lot of city driving the motor starts to glaze up - as explained in an earlier post. He said that by sticking the boot in every now then it can loosen up the glazing and blow it out.

So every now and then I give it a bit of stick through the gears. So far so good.

The detroit must be same as v8 190hp cummins short stroke , so it needs to be flat rev`s to get max power. Would not flat strap my own triton`s or toyota`s any more than needed.
Cheers
Charlie

What an absolute spanker!

Diesel's don't particulary like reving at the best of times. Ever notice your diesel's Tacho, how it only goes to 4 instead of 6 or 7 like your average petrol powered vehicle??

Conventional diesels are running at around 21:1 compression ratio, the new euro diesels are running at about 17:1, your petrols would be lucky to see 10:1.

Think of it like this:
It's good for you to go for a fadt paced walk or even a jog for 20minutes a day. It's not good for you to have a rope tied around your waste and told to keep up while you mate drives from Perth to Adelaide!

It's not so much rev's that diesels like, it's having some load. That means being able to put your foot down 3/4 on the pedal at 2000 or 3000 rpms. Towing is a good exaple, beach dirving, going up long hills, or even just cruising on the highway with all ya camping gear. Thrashing any engine will kill it eventually.

As for rev limiters, what is this guy? a total knob licker? Any car with an ECU petrol or diesel has a rev limiter. Mechanically controlled diesels would not have rev limiters and would keep reving until you see bit of the engine protuding through the bonnet.
My work car (a small 4cyl petrol) hit's the rev limiter every day... Why? Cos it's a work car and it's a POS. ;-)

Look after your diesel, baby it till it's warmed up then drive it normally, don't thrash it and don't drive like grandma and you will be fine.

I lived out western NSW at Tibooburra for a few years and the locals said flog the diesels - a comparison between 2 vehicles I drove both 78 series cruisers 4.2 diesels - one was run in slowly and not reved much, the other was - the one that was reved harder was quicker - did 12Km faster flat out approx if I remember. they said it was all to do with glazing aswell. Top speed was around 135Km - that is above the speed limit I know - but out at Tibooburra it takes you 3 & half hours to get to the nearest major town Broken Hill.

I think I was born on a diesel engine... :)

Old injection pump type diesels, slow reving and low revving could go all day at full revs - redline might be 2700 rpm or even 1500 rpm for the big Gardners. So redlineing all day would never harm it.

Modern *light* diesels are high revving 4000+ rpm. This is due to things like high pressure common rail injection, electronic timing, variable valve timing, pulsed injection etc. Sure they produce heaps of power (eg. Nissan 3.0 diesel), but do so at high revs, with often a loss of low down torque - and the jury is still out on engine longevity. In balance, a petrol may even be cheaper in the long term than some diesels on the market at the moment, if one includes service and a rebuild.

I have a Mercedes diesel, 2150 cc in s Sprinter van. Once the revs are up (4000 redline) it pulls like a schoolboy. Power to weight ratio is amazing and even loaded will easily keep up with the traffic (check out the ambos in NSW - all diesels and they are not slow...). However one of the reasons one might buy a diesel is a little lost on the Mercedes - it is a *very* expensive motor to maintain - e.g. injectors are $1200 each (non servicable) and I look like replacing a second set in the very near future (under warranty).

/viz

I used to drive a few game boats with twin diesels, standard procedure was to go to full noise then drop the slowest engine to about 100revs below full noise then slow the other to match and synchronise.
Newer boats have auto sync and can have single control for both engines, Same procedure for setting cruise speed.

Here ya go guys a diesel revving it's ring out, mine in fact.

the Disco is mine.

A trip to the Watagans

Baz.

Hi all,

I am a diesel driver and tend to keep my revs lower than most but I have a brother that screams his diesel to the redline in every gear and has done so for as long as I can remember.
My other brother and I cringe whenever we are in the car when he is driving. It sounds horribly destructive and I am waiting for a piston to shoot out through the bonnet.
The thing that is amazing though is that this same brother brought a 60 series cruiser in 1982 from the showroom and sold it in 1993 with 650,000 km on the clock and the motor had never been touched.
Then in 1993 he brought an 80 series diesel GXL cruiser and he still has it. It now has 680,000 on the clock and it is still going strong.
I am still not convinced and could never bring myself to drive like this but who knows? There may be some merit in what this mechanic was saying.

Cheers,
Brett

T/D 75 Series Ute

i think i have a solution to give your diesel everything it needs, give your car an easy ride onroad & service it properly, then off road give it hell.