PDA

View Full Version : Some interal combustion tech questions



Lexstang
11-29-2008, 11:19 PM
I have several questions I came up with while driving. What is the RPM of an engine either diesel or gas limited by? The combustion speed? Like I know some motorcycles can turn almost 20,000 rpm. I think indy carts turn like 13, 14,000 rpm and nascar is around 10,000. So if you make the rotating assembly and valvetrain light enough and the intake short enough how fast the fuel burns limits it?

Are the super high RPM's to get the horsepower to a certain level? Why not build the engine to have a peak hp at lower rpm? Peak torque has to be lower than 5250 rpm right? Would the max efficiency of an engine be right between the torque and hp peaks?

If that is correct how do the multi sparkplug engines work? I know detonation is a problem because the flame front from the pre ignition crashes into the sparked front. The damage comes from the explosion hitting the still rising piston right? I am just wondering how the 2 or more sparks improve the combustion.

So where is this going. I was trying to think about making a diesel street legal drag racing car, presumably mustang. How fast can you make a diesel turn? In the diesel drag vehicles like the gale banks dodge pickup how many rpm do they turn? Can you make it have good times with hp peak at low RPM's since the torque peaks lower? If one was to throw a diesel engine into something how would you make it have good times? Weight transfer and traction, but what else? Could you make it into a remote turbo like the sts Squires Turbo Systems turbo for gas engines? From what I've read it had a lot of benefit. I am thinking primarily to move as much weight to the rear since they are so heavy. I thought moving the engine back as much as possible, using an electric water pump. Maybe rig up a electric air conditioner compressor in the rear might help a little. Make the k member tubular. Could you make the engine mounts support the engine from furthur back like the frame under the firewall? Would that transfer weight furthur back? Is there anything other than strength and convenience for coming off the k member?

Must you use the heavy transmission from the diesel it came from in the car? Would there be any way to lighten it other than not having a transfer case?
Is there any other way to make it into a good drag racer?

I am just thinking and wondering. I appreciate any help understanding the truth of things.

Rick93coupe
11-30-2008, 12:05 AM
Have you ever seen a diesel crankshaft, or rotating assembly for that matter? When I saw the components of one, I was surprised they turn the rpms that they do. They take a lot of abuse considering they're designed to detonate. Looks to me that weight is probably one of the biggest factors.
When you get a chance, look on youtube, there's a grand national with a turbo diesel. Pretty neat if your into that sort of thing.

Rick93coupe
11-30-2008, 12:16 AM
I was on the right track, check this out.

http://www.hotrod.com/techarticles/engine/hrdp_0609_banks_performance_duramax_diesel/index.html