Gasoline VS Diesel Engines....
You want as much fuel that the motor can burn while staying in the design parameters of the short block and with the exhaust gas temperature remaining in check (1300 for most stock motors it seems). I've got a 2002 7.3L powerstroke that apparently doesn't like above 400rwhp because of the pink rods this motor has. The cummins and dodge and newer 6.0 power stroke (if you can keep the rod bearings in the new 6.0 power stroke which may be a problem even stock) don't seem to have this problem. The duramax seems to be the one if you plan on just adding bolt ons and the cummins is a good choice if you want to get stupid power out of a diesel from the research i've done.
Staging Lane
Joined: Jun 2004
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Wouldn't the direct-injection engines be plauged with the same problem as diesels as far as a limited time to spray the fuel? Unless they spray before TDC, but then that would create atomization problems, right? And if it dosen't, why don't diesels employ this feature?
Thread Starter
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Joined: Nov 2001
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From: Raleigh, NC
Originally Posted by moyam01
Wouldn't the direct-injection engines be plauged with the same problem as diesels as far as a limited time to spray the fuel? Unless they spray before TDC, but then that would create atomization problems, right? And if it dosen't, why don't diesels employ this feature?
I think the Gas and Diesel setups are different due to the differences in the chemical properties of the two fuels (I have very limited knowledge of this).
Staging Lane
Joined: Jun 2004
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So why do diesels not employ the same technique with the direct injection engines (inject on the intake stroke)? My guess is that you wouldnt be able to run the compression levels diesels would normally run (it would ignite at abot 15:1). Also, why are direct-injected engines more effective if they don't atomize the air-fuel mixture as well as intake injected engines (or maybe they do. I don't know).
Off topic: What exactly limits the RPM of a diesel? And why do they put down so much torque?
Off topic: What exactly limits the RPM of a diesel? And why do they put down so much torque?
Originally Posted by moyam01
Off topic: What exactly limits the RPM of a diesel? And why do they put down so much torque?
Rpm wise, I think it's a combination of things. For one diesel parts are very very heavy to deal with the extreme cylinder pressures they generate so that's one reason rpm would be limited i'd think. Second, because the diesel motor is a compression motor there is no spark before top dead center; therefore, once the rpms rise the piston may start to outrun the flame front hence generating no power in the high rpms.
A diesel makes so much torque cause it can generate such high cylinder pressures in the low rpm band. My 7.3 is 17.5 to 1 compresssion and in stock form was generating around 20 pounds of boost and it's now modified form generates around 30. It's pretty simple really, think of a 444" gas motor with 17.5 to 1 compression and 30 pounds of boost, and the ability to live andn not detonate, and that's essentially what a diesel is. The reason the torque is always higher in production diesels is the rpms in which they run consisting of 3500rpm and lower.
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TECH Fanatic
Joined: Nov 2001
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From: Raleigh, NC
Here is some good info from an inside GM source on the design of the new solstice/sky DI 2.0L turbo:
Posted over on solstice forum
link:
http://img480.imageshack.us/my.php?i...erpage21jb.jpg
Good info on the camshaft overlap afforded when going the direct injection route.
Posted over on solstice forum
link:
http://img480.imageshack.us/my.php?i...erpage21jb.jpg
Good info on the camshaft overlap afforded when going the direct injection route.
