Diesel and petrol engines

[t_marat]

What are the advantages and disadvantages of both of those engines? Apart from the fuel economy of the diesel one.

I notice that nearly everybody here has a petrol engine, very few diesels. Not many diesel E34s?

Which engine has a longer lifetime, diesel or petrol?

[joshua43214]

As a general rule, deisals last longer for several reasons. They rev lower, so less extreme running wear. They tend to run a bit cooler. The fuel itself is a lubricant. They have far simpler engine management. Until recent breakthroughs in deisal construction, they had far less power.In the past deisals had higher emisions as well.

the main reason for a predominance of gas engines is supply and demand. MB easily cornered the market for high line Euro car diesals. The low power of diesals make them less popular for buyers, and most of the people willing to deal with diesals buy MB.

Modern diesals have far more power, but I don't know if that has come at the expense of longevity. They also require imressive catylitic convertors to meet fleet emision standards.

Diesal fumes stink like holy hell, they sound like they are self destructing when they run, Only model cars and planes should have glow plugs, and the oil stains you hands badly. torquing the head bolts on a diesal will make you feel like a real man. I saw a MB diesal with almost 900k mi, and when I worked on MB, we had quite a few knocking right along with over 400k.

I hate diesals.

[BillionPa]

Diesel works by injecting the fuel and air at very different ratios depending on engine load.

A gasoline engine will always try to maintain a 14.7:1 air fuel mass ratio, with a slightly "richer" ratio during acceleration.

A diesel engine idling can have a ratio of 100:1 using almost no fuel in the process, and during acceleration, 2:1.

Diesel fuel is easier to ingite and slower to burn, and it gells at low temperatures. Adding acetone increases the burn speed a bit, allowes higher efficiency of the fuel burn with lower emissions, and keeps the fuel slightly more fluid at pre gel temps.

since diesel engines use more air and fuel during acceleration, they produce more exhaust, and adding a turbo gives a significant kick to the engine power.

If you are looking at a diesel car, get dual turbo (big and small) and add acetone to the fuel. Also stay out of freezing weather with it!

[BillionPa]

well i really didnt explain the diff between a gas engine so here it is.

gas engines have much better acceleration because of the fast burn speed of the gas vapors, but poorer economy during low rpm low load situations since it needs to maintain a fairly constant ratio of fuel to keep the engine within emmisions standards

if there is too much fuel it produces carbon monoxide, and too little fuel and it produces nitrogen oxides.

most gas you buy at a pump doesnt contain much lubrication, but you can add it to your gas fairly cheeply, increasing the lifespan of the fuel pump and injectors.

in a "high performance" situation like racing, gas engines consume much less fuel than a diesel engine and produce much more horse power (although usually less torque) than diesel, which is why you normally see diesel in vehicles that travel for longer distances with fairly constant velocities.

[kyleN20]

i think bmw put a deisel car into some lemans thing and took the win because they dident have to stop for fuel as much.

[BillionPa]

the only recent win is the McLaren BMW GTR in 99.

you might be thinking of the Mazda quad rotor car which was BANNED from lemans for being too good after it won by a very large margin.

[kyleN20]

maybe not lemans, but i am sure that i saw something on tv where bme put a deisel car in some race, maybe nurinberg and won the thing

[BillionPa]

LMR sorry, the GTR was in 97.

The only fast diesel BMW has is the Z9 concept which uses a 3.9L V8 turbodiesel (less than 300HP but lots of torque)

[rob101]

its not the catalytic converters that have made the biggest difference with new diesels but the "particulate filters" which trap the soot particles and when these meet with some diesel they burn the particles thus reducing their size and ensuring new diesel do not produce the black smoke of their predessors. also now that their is a common rail direct injection there is a pre and post-combustion injection event, the pre-injection ensures pressure increase in the cylinder is more gradual than before which reduces the rattle of the engine and the post delivers diesel to the particulate filter to burn off the soot.
i don't think diesels in the past have had throttle for the air, the only way they controlled power was by injecting more or less fuel.... not sure about the new ones though.

We recently got a 400 kW Liebherr Diesel, very quiet and smooth you can't feel vibration from the engine unless you are standing on top of it. its actually quieter than a new isuzu diesel with one quarter of the power!

[BillionPa]

NB 24 hour race yes, that was like, 9 years ago or something though in a 3 series.