Exactly.I agree.

the only correction is that I know for a fact that the compression ratio in my 85SD is 21.5:1.

If I understand you correctly, you're referring to the fact that a gas engine at idle will eventually overheat on a hot summer day, where a diesel will just plug along happily.

I think it has much to do with two things:

1: Diesels run hotter to begin with, they like heat, and therefore have to get "hotter" before they are technically "overheated"

2: Diesels have way more air going in at an idle than needed, hence, internal cooling. It's like having a box fan blowing down your throat when your gasping for breath!

Correct me if I'm wrong or misunderstanding the question.

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-Matt

EPA Section 609 Certified MVAC Technician
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Oil Burner Kartel Member #10

Ahh the smell of Diesel Fuel, it's like coffee in the morning!

My Car:

1982 300SD Turbo Diesel (231,500 miles!) RIP

1984 300SD Turbo Diesel Custom (235,500 mi on driveline.) - On Road!!

www.icsrepair.com

the main reason a diesel runs so much cooler than a gas engine is that it is so much more effecient. less wasted energy so less heat to be gotten rid of.

a diesel will run on gasoline. it will rattle a lot more and if you try to accelerate it will kindof die. or try to.

and if you drive it very much it will get too hot and do very bad things to your cyliners, score the cyl, blow head gasket and crack head. at least this is what happened when my lovely #3 daughter filled up with gas in colombus ohio and tried to drive back to lafayette indiana. she made to richmond indiana before the car wouldnt go any more. i brought it home on the trailer. too bad. it was a freshly rebuilt 74 240d, very low miles.

oh yeah it will smoke a lot too. blue.

i could be wrong but i think the diesel will inject some before tdc.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

I think my car's start of fuel delivery is 24 degrees before top dead center.

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1977 300D Lost coolant while someone else was driving
1983 300D Can't run without oil
1985 300SD (gone but not forgotten)
1990 300TE 4matic Sold
1991 Yamaha Venture
1975 Kawsaki 250 triple
1974 Honda 200CL
1951 8N Ford
2008 Wildfire 650C

i thought so.

now admittedly a gas engine can start at up to 40 degrees btdc depending on the other factors, perhaps more.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

MB-Owner, for curiosity's sake, do you still have that old SD I sold you? If so, how is it holding up?

Thanks
David

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_____________________________________________

2000 Honda Accord V6 137k miles

1972 300SEL 4.5 98k miles

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I thought gassers were timed much closer to TDC, like ten degrees or less.

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Seth

1984 300D 225K
1985 300D Donor body
1985 300D Turbo 165K. Totaled. Donor Engine. It runs!!!
1980 300SD 311K My New Baby.
1979 BMW 633csi 62K+++? Dead odo

My jeep is at 9 or 12 degrees TDC. that is also because i did a nutter bypass. this means instead of having the ECM control ingnition i wired the rotor directly to the Ignition module.

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Kaleb, 17 years old. I own a 1988 jeep wrangler. it has a carburated 4.2 liter. it also has an automatic. I bought it all stock from a man that had it for a couple of years and had bought it from the original owner. when the guy dropped it off it was driving some what good but not the way i test drove it. i put alot of new things in it, the list is:Radiator, water pump,fuel lines, fuel filter, plugs and wires, egr valve, pcv valve, jet and seat. i think thats it.

That's at idle. Rev it up with the timing light hooked up. You'll see at least 30 degress BTDC. If not, your engine will idle well, but won't do anything else.

It's amazing to see how many people can spread so much misinformation.

One thing is right, gasoline will not lubricate your injection pump, and will wreck it quickly.

Gasoline will not burn properly in the engine because of it's resistance to burning. That's right, gasoline is designed to be compressed, so it is designed to have a high OCTANE so it resists detonation. Obviously once it self-ignites, it then burns rapidly. Because of it's resistance to self-ignition, it has a LOW CETANE RATING.

Diesel, on the other hand, has very low resistance to self-ignition, and will burn rapidly upon injection like it's designed to do. This is reflected in the cetane number. Biodiesel is even better in this regard. If you put a diesel fuel into a gasoline engine, it will knock and ping like crazy because the fuel will self-ignite before the ignition event near TDC.

There has been much success with mixing gasoline with vegetable oil and using it as a diesel fuel. The running speculation is the vegetable will flash over first, as it has a moderate cetane rating, then the gasoline will enable the slow-burning vegetable oil to burn quicker, more like a thinner diesel fuel by itself.

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'83 240D with 617.952 and 2.88
'01 VW Beetle TDI
'05 Jeep Liberty CRD
'89 Toyota 4x4, needs 2L-T
'78 280Z with L28ET - 12.86@110
Oil Burner Kartel #35

http://i16.photobucket.com/albums/b1...oD/bioclip.jpg

You better check again, eh?

i was talking of total advance at high rpm on a non emission controlled engine designed 50 years ago.

static advance will be much much less from 0 to maybe 10 btdc. that is tested at cranking or idle.

i dont really know what a modern engine does. it may retard or advance or retard then advance then retard, whatever is required to meet emission standards and give reasonable drivability.

things were a lot simpler in the sixties.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Back in November I let a 1984 300SD W124 chassis go by me in an auction. This car was absolutely MINT. Must have been garage kept since new. There was not a single flaw that I could find. Only problem was that it's last owner put gasoline in the tank. When started it seemed like the motor was running on 3 out of 5 cylinders. Would a motor that this happened to be saved?

P.S. The car sold for $600.00. Kick myself in the butt everyday for not getting it.

From what I've seen gas in a diesel will not only kill the pump and injectors VERY quick, it burns so fast the combustion pressure will max before the piston is at TDC. Compressing gasses already at 1500psi is not easy, that's why you will bend rods, crack pistons, blow head gaskets, and blow the head clean off the engine (there will still be diesel in the lines/IP, so if you rev it up or load it down it could inject enough gas to make an amazing show).

It could have went either way. It may have just killed the ip and you could have picked up a spare one at a pick-n-pull, or had it rebuilt. It may have also completely destroyed something major, requiring a complete rebuild. Either way I would have bought it because I just spent $500 today on a W123 body that is trashed inside and half of the motor is gone in hopes of doing an engine and whatever else is required swap to keep at least some part of my wrecked car alive.

__________________
Seth

1984 300D 225K
1985 300D Donor body
1985 300D Turbo 165K. Totaled. Donor Engine. It runs!!!
1980 300SD 311K My New Baby.
1979 BMW 633csi 62K+++? Dead odo