Diesotto engine - any details ?

[rev-erend]

I've seen the recent release from Merecedes about the diesotto
petrol engine.

It's supported to be the next big thing (according to their own PR)..

Offering benefits of petrol and diesel but I cannot find many details.

Such as CR - it says variable displacement - so I'm presuming the CR changes based on hydraulic rams - I presume.

Other stuff like ignition is either convetional spark plug or diesel compression
- I guess based on load / engine speed.

Anyone know more details.

[stevieturbo]

Bit risky Mercedes adding more technology to their cars. You'd think they would try and make the current ones reliable first, before adding more crap !!!!

[rev-erend]

stevieturbo said:

Bit risky Mercedes adding more technology to their cars. You'd think they would try and make the current ones reliable first, before adding more crap !!!!

Yes - I thought it strange.

The generally seem to have quiet old tech engines .. big V8 loads of bhp and torque.. poor mpg etc..

I'm sure they probably paid someone like Ricaro pretty handsomly for the R & D..

[Sam_68]

rev-erend said:

Such as CR - it says variable displacement - so I'm presuming the CR changes based on hydraulic rams - I presume.

:scracthchin: Unless I'm missing something, here, changing the compression ratio does not change the displacement (swept volume).

The tilting block mechanism that Saab showed a few years ago could change the compression ratio by changing the relationship of the cylinder head to the crank centreline and hence the TDC position of the pistons, but to change the displacement, you'd need to alter either the bore or the stroke?

[rev-erend]

Well - I would think they would need to change the CR and not the displacement anyway..

Running at 11:0 in poor area's and 15 ~ 18 : 1 if you want to be a diesel..

[GreenV8S]

I remember reading about an engine with an epicyclic gear around the crank controlling the stroke, which also (as a side effect) controls where the piston stops at TDC and hence the CR. Is that the system used by Diesotto, or am I thinking of something else?

[annodomini2]

The easiest way from an engineering perspective would be to move the cylinder head up and down as you would end up with fewer moving parts.

[buggalugs]

http://en.wikipedia.org/wiki/DiesOtto

Looks like HCCI, variable compression, direct injection, VVT and a variable geo turbo! My god that's a hell of a shopping list they've got there.

I imagine it cruises along at 11-12:1 running in hcci, getting crazy economy - then you plant your foot and it simultaneously drops the compression, switches to spark ignition and changes the turbo vanes to wallop some boost in there.. awesome

Edited by buggalugs on Monday 10th December 14:32

[rev-erend]

buggalugs said:

http://en.wikipedia.org/wiki/DiesOtto

Looks like HCCI, variable compression, direct injection, VVT and a variable geo turbo! My god that's a hell of a shopping list they've got there.

I imagine it cruises along at 11-12:1 running in hcci, getting crazy economy - then you plant your foot and it simultaneously drops the compression, switches to spark ignition and changes the turbo vanes to wallop some boost in there.. awesome

Edited by buggalugs on Monday 10th December 14:32

Thanks - did not think of wicks pedia..

I would think the cruise cr would be a lot higher . more like 15 to 1 or even 18 to 1 like a diesel..

Hope they put it in a A class to really show us what it can do.

[NightDriver]

buggalugs said:

http://en.wikipedia.org/wiki/DiesOtto

Looks like HCCI, variable compression, direct injection, VVT and a variable geo turbo! My god that's a hell of a shopping list they've got there.

I imagine it cruises along at 11-12:1 running in hcci, getting crazy economy - then you plant your foot and it simultaneously drops the compression, switches to spark ignition and changes the turbo vanes to wallop some boost in there.. awesome

Edited by buggalugs on Monday 10th December 14:32

I beleive the HCCI C/R is more like 15/16:1. The idea is pretty much what you have said. Trouble is its VERY tricky to get all the systems calibrated and as far as I'm aware mercedes havent really got the calibration right yet. There are a few other company's trying it but I beleive only GM have a running car, with a less than perfect calibration.
When someone can get an engine switching smoothly between spark and compression ign this idea will be the way forward.

[buggalugs]

NightDriver said:

buggalugs said:

http://en.wikipedia.org/wiki/DiesOtto

Looks like HCCI, variable compression, direct injection, VVT and a variable geo turbo! My god that's a hell of a shopping list they've got there.

I imagine it cruises along at 11-12:1 running in hcci, getting crazy economy - then you plant your foot and it simultaneously drops the compression, switches to spark ignition and changes the turbo vanes to wallop some boost in there.. awesome

Edited by buggalugs on Monday 10th December 14:32

I beleive the HCCI C/R is more like 15/16:1. The idea is pretty much what you have said. Trouble is its VERY tricky to get all the systems calibrated and as far as I'm aware mercedes havent really got the calibration right yet. There are a few other company's trying it but I beleive only GM have a running car, with a less than perfect calibration.
When someone can get an engine switching smoothly between spark and compression ign this idea will be the way forward.

Yes I think you're right. Its amazing really that they can get it to work at all, to have such good control over when it auto-ignites but without being directly in control of the ignition - from reading a few bits and bobs don't they vary EGR to help tune it? Maybe compression ratio too but I wonder if that reacts quick enough? All great stuff.

[renrut]

I'd imagine this engine will have the mother of all 'turbo' lags as it switches over. But I could put up with that if it returns super economy. The first generation of cars will be plagued with problems thanks to the masses of new technology all in one go, most manufacturers havent got variable turbos sorted yet.

Another thought - isnt the main reason diesels are heavy is to stop the very large pressure pulse caused by dieseling from wrecking them? And if so won't these engines have to be similarly strengthened (i.e. heavier). Plus the addition of all the variable CR gear these could weigh a lot.

But I would love for this idea to work for many reasons - for a start it could get rid of the old petrol vs diesel arguement that crops up every few weeks on a lot of car forums

[buggalugs]

renrut said:

I'd imagine this engine will have the mother of all 'turbo' lags as it switches over. But I could put up with that if it returns super economy. The first generation of cars will be plagued with problems thanks to the masses of new technology all in one go, most manufacturers havent got variable turbos sorted yet.

Another thought - isnt the main reason diesels are heavy is to stop the very large pressure pulse caused by dieseling from wrecking them? And if so won't these engines have to be similarly strengthened (i.e. heavier). Plus the addition of all the variable CR gear these could weigh a lot.

But I would love for this idea to work for many reasons - for a start it could get rid of the old petrol vs diesel arguement that crops up every few weeks on a lot of car forums

I don't think it would need to be as heavy as a diesel for the same reasons, as HCCI is not the same as diesel combustion. As I understand it, it's a controlled burn, if it pings or knocks then there's something wrong. At least thats what wikipedia says anyway