High-MPG Corvette

[Christ]

Originally Posted by theunchosen

I also would avoid juice.

The 08s weren't bad especially the high end.

But Juice is. . .a mistake. Too many variables that can easily go wrong. You nitro dump and your sensors are behind just a tenth of a second and you've lean burned your cylinders about 3 and a half times. Not just a little lean either, very. Also the nitrous oxide is much more flammable than gasoline and much more prone to pre-ignition.

A toasty valve head because your coolant is lagging a little is enough to toast the engine.

Those big hp setups are probably steady state. . .so ALL the components are designed for enormous loads to start with. Yours won't be. Their coolant lines are driven by turbo pumps, they are running specialty coolant and they probably brush their cylinders, pistons and valves every few hundred miles to keep residue out(think glow dust).

I've seen a few juiced engines that are junked just because a little bit of carbon residue was warm when they started purging. The first couple of lean strokes got it glowing and then nitrous ignites and bores a hole through the piston.

The pistons afterward make for good conversation pieces. If its going to drop big power all its systems will need to run as if its going to do it all the time otherwise they go bye bye at the wrong time.

Nitrous oxide is NOT flammable or explosive... it's mostly nitrogen, an inert gas. The Oxygen part of Nitrous Oxide is what actually does the work... the Nitrogen is a stabilizer. Either way, that BS part of the Fast and Furious movie where the car exploded b/c the Nitrous bottles ignited was obvious Hollywood Syndrome.

Yes, you can burn up an engine running Nitrous Oxide... but Diesel engines don't run on a "lean or rich" principle... they're almost constantly lean, unless you really turn up the injectors. If you turn up the injectors too high (advance the pump and get into the throttle enough), you need more air than the engine can suck in, even at 100% VE... so you add nitrous. If you don't want to tune your injectors and pump, so you can maintain OEM efficiency, you can get more fuel by adding propane, and get more "air" by adding nitrous... it's a killer combo.

[theunchosen]

Ah, My bad I didn't catch it was a diesel. disregard all of that then.

[roflwaffle]

Reliability aside, the $/hp ratio favors chebby gas engines, and w/ a taller rear end, the stock six speed, and manual AFM, the $/mile would be pretty close too. Heck, a vette aside, someone could grab a brand spanking new vortec 5300 engine for about a grand less than used 4BTs go for on eh4y, shove it into a mid 80s/early 90s manual Camaro (maybe mess around w/ the rear end/trans ratios), and have a peppy muscle car w/ a brand new engine that can pull ~40+mpg on the freeway for a few grand.

[Frank Lee]

40 with a V8? I'll believe it when I see it.

[jamesqf]

Originally Posted by Christ

Nitrous oxide is NOT flammable or explosive... it's mostly nitrogen, an inert gas. The Oxygen part of Nitrous Oxide is what actually does the work...

Just out of curiousity, if all it does is add oxygen, then why not inject pure oxygen instead?

[Christ]

Stability... if you add pure oxygen, the mixture could lean out excessively with very little pressure in the lines, which could cause a serious problem... that on top of the fact that Oxygen alone isn't specifically stable, and reacts with just about everything it touches.

Adding Nitrogen to Oxygen stabilizes the elemental oxygen so that it doesn't react with other gasses before entering the combustion chamber, and since nitrogen is mostly inert, it actually helps to cool the cylinder during N2O use, to prevent hot spots and detonation.

With a hot enough combustion chamber, you could actually use steam as an oxidizer... but you'd have to get the chamber hot enough to distend the bond between hydrogen and oxygen, and then you'd end up with quite the machine... water for fuel, actually.

[roflwaffle]

Originally Posted by Frank Lee

40 with a V8? I'll believe it when I see it.

Didn't ya see it already? Granted, gas engines are a bit more finicky and need to be run at a higher load to see the same (energy adjusted) BSFC, but it ain't impossible, just unlikely because most people w/ enough money to spend on a muscle car don't give a crap about the $/mile side when they're driving it.

[Frank Lee]

I just know how tough it is to hit 40.

[Big Dave]

There is an enormous amount of experience out there with hopped-up Cummins B-series engines. A 4BT3.9 is nothing but a "12 valve" Cummin 6B5.9 with two cylinders missing, so all that experience is applicable.

A LS2 makes 405 HP. How many minutes of full power do you suppose that a LS2 actually see in its service life You can get some serious tickets by driving 175 MPH.

The diesel is what pushes a 'Vette over 40 MPG. You could put an itty-bitty gas engine in it but I don't think 40 MPG is possible without competition-grade hypermiling. The diesel, with its higher efficiency does it easily.

The propane/nitrous is there for bursts of acceleration. I specify nitrous to avoid having to put a bigger turbo on the engine (and accept more turbo lag) for maybe fifteen minutes of raw power a year. Its simply "turbo logic." With a turbo, a small engine can have a "Jeckyll and Hyde" personality. Economical most of the time, but powerful when needed. How many turbo cars are at full boost much of the time? They'd grenade themselves.

The little Cummins is straight mechanical and I don't have to mess with electronic controls.

[Frank Lee]

This is the sort of thing I wouldn't mind being wrong about.