The 40MPG Crown Victoria Challenge

[winkosmosis]

Originally Posted by jtbo

2011 :d

edit: Frank, 80's top tech should be available today for consumer market, only thing needed is someone with too much time in their hands:
Pneumatic valve springs - Wikipedia, the free encyclopedia

I googled and it looks like usually the valves are all closed.

Although Cadillac Northstar engines have a limp home mode in case of coolant loss. The engine alternates between banks, and the off bank just pumps air to cool itself.

[jtbo]

Originally Posted by winkosmosis

I googled and it looks like usually the valves are all closed.

Although Cadillac Northstar engines have a limp home mode in case of coolant loss. The engine alternates between banks, and the off bank just pumps air to cool itself.

But with electronic control and little designing you could make valves be open too, if there is clearance. There is also solenoid route too from my memory, really long time since I looked into these, but everything is really old stuff.

I don't know how exactly it is done in 300C SRT8, but there is fuel saver mode that squirts fuel for only some cylinders, it is running then with only 4 cylinders.

There are many possibilities these days, they might be bit too expensive to pay back during lifetime of car, but world needs pioneers, right?

With big motor there is always issue of it needing more fuel than smaller engine, to get better economy motor need to be 'made smaller' to get past that minimum consumption motor has and with such large engine as Crown Vic, minimum might be rather large, getting rpm too low will increase fuel consumption from my understanding as torque curve will drop some point quite fast.

[Christ]

You'd want the valves closed, so there was no pumping loss.

I'm fairly certain that is what Frank was alluding to.

[jtbo]

Originally Posted by Christ

You'd want the valves closed, so there was no pumping loss.

I'm fairly certain that is what Frank was alluding to.

This sounds very logical and that would be perhaps easier to implement too as any design would have closed rest position ?

Bit much of work and engineering for average ecomodder anyway, imo. However very interesting.

[SlideWRX]

Originally Posted by winkosmosis

I don't really understand cylinder shutdown. Why not just reduce engine RPM with a taller overdrive? Or would the cylinder speed be too low?

On a V8 of this size, that can mean going very low in terms of rpm; way below intended operation speeds. My Mustang V8 idles at ~750 rpm. I can accelerate in fifth (top) gear from ~400 rpm, which is about 15 mph. I don't usually do this, as the result is a misfire. I also get the impression that at this speed some 'do not stall' code is written in to add more gas to keep the engine from stalling if it is operator error. The oil pump might not keep pressure at such low speeds.

When I added my underdrive pulley it looked to add ~0.5 mpg, although I haven't accurately done before/after measurements.

[SlideWRX]

Originally Posted by jtbo

I don't know how exactly it is done in 300C SRT8, but there is fuel saver mode that squirts fuel for only some cylinders, it is running then with only 4 cylinders.

With pushrod engines such as this, the hydraulic lash adjuster between the cam and pushrod can compress instead of staying stiff. The cam lobe pushes the adjuster up, but it compresses so it doesn't push on the pushrod hard enough to open the valve. The valve stays closed, both intake and exhaust, and the cylinder just keeps compressing/expanding the same combusted gas it had in there from the last combustion cycle.

[SlideWRX]

Originally Posted by winkosmosis

I don't really understand cylinder shutdown. Why not just reduce engine RPM with a taller overdrive? Or would the cylinder speed be too low?

I should also add that the most efficient range is near the torque peak. reducing engine speed too low and the efficiency will go down, even though the load goes up.

[comptiger5000]

Exactly. With big engines, even though they'll pull at very low RPM, there's a point where going lower is impractical, or won't actually help mileage.

[roflwaffle]

Originally Posted by SlideWRX

I should also add that the most efficient range is near the torque peak. reducing engine speed too low and the efficiency will go down, even though the load goes up.

That depends more on the engine than anything else. This 3L V6 for instance can do ~260g/kWh at ~1k rpm, but if the Ford 4.6L V8 is really crummy then it won't be able to see decent efficiency at low speeds.

[trooper Tdiesel]

the 4.6L was made in many forms
sohc 2 and 3 valve per piston
and a dohc 4 valve per piston.
Ford Modular engine - Wikipedia, the free encyclopedia

mabe a 4.2L V-6 and manual trans from a 2WD f-150? there about 200hp
the super early 2 valve 4.6L engines where 190 to 210 hp so you could in thery have the same power with less LBs
Ford Essex V6 engine (Canadian) - Wikipedia, the free encyclopedia



would get you closer to 40 with a 4.2L V-6 and manual transbut theres still a TON of other stuff that would need to be done to get there.