LSPI ..... I didn't know it was A Thing.....

[3930dave]

Low-speed pre-ignition - Wikipedia

potential for major engine damage.....

'Bright Idea' For Short Detection | MOTOR

..... not that I needed convincing.... already considered "old" school MPFI as Peak Reliability ICE.....

Rgds, D.

 

[rScotty]

Not knowing about "Low Speed pre-ignition" is a generational thing. It was a major problem for hot rodders back in the WWII era. Mostly a problem when gasoline or any of the more volatile vapors are used as fuel. Not really applicable to diesels.

It used to be a common problem because pre-ignition put a low upper limit on compression ratio and therefore hp in gasoline engines. It still does. There are all kinds of remedies, but nothing except the physically impossible theory of instantaneous injection can ever solve the basic problem, which is that compression causes heat.

rScotty

 

[3930dave]

Not knowing about "Low Speed pre-ignition" is a generational thing. It was a major problem for hot rodders back in the WWII era. Mostly a problem when gasoline or any of the more volatile vapors are used as fuel. Not really applicable to diesels.

It used to be a common problem because pre-ignition put a low upper limit on compression ratio and therefore hp in gasoline engines. It still does. There are all kinds of remedies, but nothing except the physically impossible theory of instantaneous injection can ever solve the basic problem, which is that compression causes heat.

rScotty

I'd heard a carb'd gasoline car "dieseling" back when (not WWII, I'm not that old....) but it was fairly rare in unmodified production vehicles.

I wasn't going looking for this (none of my fleet is GDI so far) honest.... was chasing an unrelated oil question I had.... "Hmmm, what's this Spec That I Haven't Seen Before".....

I have a limited sense of humour for Nu TekNology being introduced, with significantly lower reliability than what it's replacing. Not impressed with the fuel-dilution risks with GDI.... my earlier assumption was "Accelerated Engine Wear", and that's bad enough, but these type of catastrophic failures line up with some stream of consciousness (anecdotal) cases that were showing up where I didn't expect (Hyundai for example). That, and de-coking GDI heads (I think it was BMW that wasn't making much more than 30-40 k, and that's kilometers !)...... if I want to spend my time doing that, give me a 2stroke MC - heck, modern MC engines are way better.

Given the high compression, low weight, and turbo-charging in many modern GDI, I'm starting to think they should not be run on 87 octane.

Rgds, D.

 

[cannuck]

Not really applicable to diesels.

rScotty

Which of course IS the simple solution.

If LSPI really was about oil in the cylinder, diesels WOULD suffer as they commonly run extremely high cylinder pressures at very low speeds.

 

[3930dave]

Which of course IS the simple solution.

If LSPI really was about oil in the cylinder, diesels WOULD suffer as they commonly run extremely high cylinder pressures at very low speeds.

Multiple factors at play, that I'm just starting to get my mind around.....

Diesel (at least quality product) oil had been designed to deal with fuel-dilution for some time. Gasoline.... it's a relatively newer game.

Not that I think diluting diesel oil with diesel fuel is a good thing, but relatively speaking, I'd sooner have that issue in the background to deal with, than gasoline (esp. loaded with mandatory ethanol) diluted DI crankcase oil.

So... there is the potential high level volatility issue with DI gasoline engine oil to consider.......

Broken DI gas pistons/ring-lands..... at a glance, the pistons seem pretty light-duty to my old eyes.... but I can't say I've A/B compared them to modern diesel pistons...... Reduce Weight, Reduce Cost, repeat, repeat, repeat - then up the compression and Power Output......

Just ^ kicking some thoughts around...... I use forums on here to help edumucate myself on these New ! Improved ! teknologies.....

Rgds, D.