Diesel engine testing

Gilly · 1 Jun 2007 at 10:20

Vertigo1 said:
We're all assuming it was actually running on diesel. Is it possible they were using some alternative fuel in it, which could burn fast enough to make 7500rpm possible?

Why bother testing it on fuel it isn't going to be run on?

merlin · 1 Jun 2007 at 10:21

I think Simon might be on holiday as I've not seen him post for a while.

Jonnycoupe · 1 Jun 2007 at 10:22

Its probably a fatigue test for some components like the valves, conrods *tensile force from the accelerating piston which relates to a tensile stress in the material fibres* also shear stress on the piston gudgeon pin? With the engine powered externally to perform the revs. The revs is a fundamental part of the loasing case.

You increase the peak stress in the components by revving it harder to check you can do x hours which relates to y load cycles. If you get to 1200 hrs thats enough cycles at the higher stress values.

By factoring the stress down and using an S-N curve (stress against number of cycles to failure) for the component material you can predict how long the parts are likely the last under the normal operating conditions without actually having to run the test that long. Helps speed up R&D/testing obviously. As a off shoot of this some parts (steel) may be so lowly stressed they experience a stress lower than the endurance limit, meaning they will last for ever with no fatigue failure.

merlin · 1 Jun 2007 at 10:24

Jonnycoupe said:
Its probably a fatigue test for some components like the valves and conrods?

I just couldn't possibly comment.

/reading rest of your post now

Stonedofmoo · 1 Jun 2007 at 10:28

merlin said:
I think Simon might be on holiday as I've not seen him post for a while.

Sure I saw a post of his yesterday!

I gotta agree with Fox, seems to be to get that far at those revs is amazing. Surely even the modern diesels don't go much beyond 5500rpm.

I wonder if they use special engine oil for such a test, must run a big fuel tank!

merlin · 1 Jun 2007 at 10:30

Stonedofmoo said:
Sure I saw a post of his yesterday!

I gotta agree with Fox, seems to be to get that far at those revs is amazing. Surely even the modern diesels don't go much beyond 5500rpm.

I wonder if they use special engine oil for such a test, must run a big fuel tank!

I think we're swaying towards the engine not actually "running" at 7,500 rpm.

In other words - it's being powered externally to run at that speed.

The engine probably wasn't been fuelled, just turned, if that makes sense.

Jonnycoupe · 1 Jun 2007 at 10:36

Is it a full engine test or a single cylinder prototype.

merlin · 1 Jun 2007 at 10:41

Jonnycoupe said:
Is it a full engine test or a single cylinder prototype.

It's the full engine test, fully built engine in production spec.

Bear · 1 Jun 2007 at 10:43

Vertigo1 said:
We're all assuming it was actually running on diesel. Is it possible they were using some alternative fuel in it, which could burn fast enough to make 7500rpm possible?

I read some where according to Honda they seemed to think they could get a diesel engine to rev like a petrol engine. :confused:

I thought the same as you though and thought the limiting factor was the burn time of diesel itself.

Stonedofmoo · 1 Jun 2007 at 10:45

Perhaps they'll use a VVT system and using this it will get the revs up to a normal engines level lol

Jonnycoupe · 1 Jun 2007 at 10:46

Probably a final test to ensure the life of the engine then with the reasons above. Higher revs to simulate a design life cycle but in a shorter test period. Just means they can get the product into the market sooner/or find issues out sooner.

First stage of 'lifing' something

Hilly · 1 Jun 2007 at 10:48

merlin said:
I think Simon might be on holiday as I've not seen him post for a while.

Saw him on msn a couple of days ago. Give him a call mate, he's definately the one to speak too.

merlin · 1 Jun 2007 at 10:50

hilly said:
Give him a call mate, he's definately the one to speak too.

His brother is here & talking sense, don't need Simon now.

Jonnycoupe · 1 Jun 2007 at 10:52

Stonedofmoo said:
Perhaps they'll use a VVT system and using this it will get the revs up to a normal engines level lol

VVT isnt really the reason engines can rev higher, its just allows them to rev to the same level as anyother engine without having silly valvetrain impeding town driving, idling and most of all emissions.

Its still the mass and fuel burn of diesel engines that prevent the revs.
Theres no reason you cant use VVT on a normal rev range engine, just the gains are lower + unit cost is higher.

Hilly · 1 Jun 2007 at 10:53

merlin said:
His brother is here & talking sense, don't need Simon now.

You trying to say Simon doesn't talk sense? .... good point. Carry on

alexthecheese · 1 Jun 2007 at 10:55

Well, I'd certainly be peeved if I'd waited nigh on 50 days for a test result and it cocked up in the last couple of days!

Very impressive though.

I remember seeing a program on them testing Ford engines and the exhausts literally glowed orange, they were running them that long.

Jonnycoupe · 1 Jun 2007 at 10:55

hilly said:
You trying to say Simon doesn't talk sense? .... good point. Carry on

He said he beat you on Pro Evo.

Hilly · 1 Jun 2007 at 10:57

Jonnycoupe said:
He said he beat you on Pro Evo.

he never bloody beat me on Pro Evo, I thrashed him by a good couple of goals. He couldn't get near me, then resorted to kicking ten bells of **** out of my team!

You tell him... Any time, any place!

Dogbreath · 1 Jun 2007 at 11:00

Whilst it certainly possible to design a diesel to rev this high (in fact there is a military spec Kawasaki KLR611 with a diesel capable of 7500 RPM), I have my doubts that an unmodified production car diesel engine would even run at 7500RPM. Valve bounce and injection timing limitations would surely have become limiting factors well before that.

If by some miracle they could get it to run at that speed, with the heavy internals I would have expected fatigue failures more quickly than 1200 hours.

alexthecheese · 1 Jun 2007 at 11:05

Dogbreath said:
If by some miracle they could get it to run at that speed, with the heavy internals I would have expected fatigue failures more quickly than 1200 hours.

Yeah, I reckon about 1140 tops.