diesel dragster

[honda_racing101]

Originally Posted by jcurtis3

I ran across this the other day. Banks is building a diesel pro-mod. 2500 horse. Should run pretty quick.

http://www.bankspower.com/mercedes-pro-mod.cfm

that isnt diesel tho....if u actually read it says it runs on alcohol

[cnassiri]

Here's why those new diesel full sized trucks you see on the road are so powerful - one word - BOOST!

Turbo gas engines that run on 91 -92 octane pump gas are practically limited to around 15 psi of boost, beyond that they will detonate and destroy their internals.

Yah Yah Yah, I know somebody out there has a friend of a friend, of a friend that runs 30 psi on pump gas in their Supra, and makes 15 gazillion hp at the rear wheels, but in real life, coming from someone that owns and has built many forced induction motors, 15 psi is the limit, and even then it requires very percise fuel management, timing, and intercooling.

Roughly speaking, 15 psi of boost doubles the atmospheric pressure in the intake manifold, and makes the engine behave like it is twice as big. A 3.0L (182ci) V6 motor behaves like a 6.0L (364ci) V8.

Now here's why diesels make so much power: Diesel fuel is a light, crude distalate of petroleum, (close to kerosene) it is cheap and has less energy per-pound than gas. It does however have one great quality: It won't detonate! This mean two things:

#1 - Diesels can run very high compression, 20:1 - 30:1 without detonating!!! Pump gas cars are limited to around 11:1 High compression makes BIG torque!

#2 The Diesels you see on the full sized trucks these days are all turbo-charged (as are most big rigs). A turbo-charged pump gas car from the factory will run about 8:1 compression and 9 psi of boost max. Diesels run 22:1 compression, and 20 - 30 lbs of boost! People that own them modify them to run up to 45 lbs of Boost! That's 3 times atmospheric pressure!

Now look at that new Diesel Ford, it's got a 6.0L motor running 45 lbs of boost when heavily modified. The engine will behave like it is an 18.0 L or 1092 ci motor!

I don't care how heavy the truck is, a wimpy little 302 ci GT can't compete agains a 1092 ci big block, even if it is a Diesel!!!! You'd have to modify the GT by adding three 5.0L V8's and a 3.0L V6. A bit of an exaggeration, but you get the point.

So that's the story on modern diesels - do remember one thing: Diesels are inherently inferior motor when compared to a gas motor, if they were better, everbody would be running a diesel at the drag strip. They just happen to have certain qualities that make them very desireable for heavy trucks that need a ton of low rpm torque. Diesels opperate completely differently than gas motors, for example, no spark plugs, no throttle body, etc .... they are very different animals.

Cyrus