Engine/Transmission (1998.5 - 2002) I need an engineer that designs diesels!!!

[2-ND TIME]

I need to know why a diesel cylinder pounds when it is compressing fuel / air mixture??? THANKS.

 

[Rattler]

If you are referring to the Diesel rattle, it is just the fuel-air mixture combusting under the compression and heat. Randy. Also the higher the compression ratio ,the louder the bang when it ignites.

 

[raychem]

If you are referring to the Diesel rattle, it is just the fuel-air mixture combusting under the compression and heat. Randy. Also the higher the compression ratio ,the louder the bang when it ignites.

CR ratio has something to do with the "louder bang" but it is the timing that changes the "rattle" or "pitch" that you hear. Also the answer the previous question is that the main injection cycle happens only a few degrees before TDC, hence why we talk about timing as much as we do on the site especialy w/12v. The "bang" that you hear is the simutanious injection and ignition of the fuel.



Richard

 

[n7gxz]

Also a point of clearifaction. A diesel dose not compress air and fuel during the compression cycle, only air is compress. Fuel does not enter until the piston is just about at TDC.



Kevin

 

[JasonCzerak]

Also a point of clearifaction. A diesel dose not compress air and fuel during the compression cycle, only air is compress. Fuel does not enter until the piston is just about at TDC.



Kevin

are direct injection gasser motors the same way? compress air then inject fuel and then spark?

 

[RustyJC]

Under light loads the DI gassers operate unthrottled on the air side and inject during the compression stroke for extremely lean combustion. Under heavy loads, they reactivate the throttle(s) on the air side and inject during the intake stroke to operate on a homogenous mixture.



Rusty

 

[cojhl2]

I did not realize there was such a thing as "Direct Injection" SI engines.



Where can I find more info on them.



I wonder how they keep from predetonating the charge.



This will turn out to be a very interesting thread. .



The question though is what is "diesel Knock".



I have understood for years it is actually a shock wave because the mixture in the cyl fires from many positions simultaneously, unlike a SI engine where the flame wave propagates from the spark across the cylinder.



I provide this knowledge not as any kind of expert but mostly to make sure this thread keeps going.

 

[cojhl2]

Ye Gads,, I was not thinking regarding the above questions. Driving down the road today thinking about how that DI might work I realized there would be no more predetonation problem than a port injection system cause the mixture is charged in any form of SI engine!!!! What a dork

 

[2-ND TIME]

diesel designs

Sorry for not getting back sooner. Why I ask is because mine has always.

The injection cycle has always been irratic by ( this is caused by the bad electrical from some componant ) this I mean on the different cylinders get varing amunts of fuel , this I can tell because of the different thumping in the seat, and the varied shaking of the engine. Some years ago when going up a 10 % grade 2200 rpm the engine shuttered vary violently at the speed of a transistor being turned off on offf and back on , it used to do this at 1700 ,1800 and 1900 rpm vary regularly but has since stopped. The other 50 diesel engines that I have operated, haven't done this , so I can tell that the engine isn't operating the way it should.

In July for awhile it was giving me more power; the tone of it was deeper and a little smoother ( other diesels with power for acceleration have a much deeper tone as well , for mine always sounds very tinnny ) Hence for me thinking that the tone tells of the amount of fuel being injected into the cylinder. With mine the tinny sound goes with not having the piston under the right amount of air/ fuel mixture pressure. Also I get for fuel mileage (KM's) I have read on the over head display 7. 4 liters of fuel per 100 km's this was in Alberta on one trip and the weight was from a Ministry of hiways scales for varifacation. MY usual milage is around 22 to 27 miles to the gallon.



Have you by chance got a fax number that I could send you a couple of sheets on what the signals look like ??? If so PLEASE PM me. For it is toooooo complicated for cryslurr and cumins to understand ! When cumins put the brakeout box on the engine it ran much smoother, but I couldn't get the service manager to go further then that with gained info so another dead end.