There are a few in the General Conversation forum that have Modern gas engines will just retard spark to prevent pinging. Even still, in the hottest weather with heavy loads and with regular the V10 or V8 shouldn't ping (some of them do... but they aren't designed to do that...)

The only time an engine should "overfuel" is if it goes into limp home mode due to overheating - and the only time it should do that is if it has a catastrophic coolant system failure.


The higher RPM's with better gas milage is a bit more complex that that - and is based on the engines efficiency at various rpms (torque output for fuel/air input). Most engines are their most efficient (remember this is not fuel efficient... this is amount of torque output per fuel used) at their peak torque rpm. For the V10 this is around 3000rpms. If you want to have a combination of hauling *** and getting somewhat reasonable gas milage, this is where you should keep the rpms.

 

I was speaking of the cost for the manufacturer to purchase them, not you or I.

You are correct with the variable vane turbo's and newer advanced systems. Much added cost there.

 

The V10 has no WOT fuel enrichment in the factory tunes.
It does cut the spark curve back, up to 4* if needed.


I really like the picture in your sig Adrian.

 

If a turbo charger cost $7,000, than there is no way ford could offer the twin-turbo eco-boost.

You can get a brand new VGT turbo that can support 800 HP for $2400. Something the size that a truck would take would be around $1600 or less brand new. That same turbo would probably cost Ford less than $500.

 

He is the exception, I've never heard of anyone getting a 50% improvement in MPGs, and he had other issues going on at the same time.


I wouldn't say that's true, 100% of the time. The peak torque values usually come from ram-air effect in the intake runners and/or the same effect in the exhaust. I wouldn't say they are "more efficient" at peak torque, they might HAPPEN to be, but it isn't a directly causal relationship.

For diesels that operate without any throttle and have a huge amount of air in the cylinder at any one time (which is quite necessary actually, to achieve ignition temp), RPM is modulated with a combination of fuel amount, and injection timing. To make it even more complicated, add the turbo, and put extra fuel in the cylinder (resulting in more exhaust to drive the turbo, while also raising compression).

On a diesel, without the turbo, there might be a direct relationship between amount of fuel burned (needed) and RPM. And even with it, there might still be an almost direct relationship between RPM and fuel usage.

Not so on a gasser.

And no, that doesn't mean I'm saying the gasser is "better" - just that there is a difference in how they function.

 

If I recall that bit about being most efficient at peak torque only applies at full load. I remember something about it working with performance curves for choosing engines for pumps at work.

 

Great.

Peak torque=Peak cylinder pressures=Greatest amount of fuel/air in cylinder. Intake runner volume, bore, stroke, cam timing/duration/overlap, and RPM all affect intake velocity and how much air each cylinder will end up holding for the combustion event. An engine running under peak torque is making less relative power because the valves are open too long for it's slow intake velocity, and low exhaust velocity has less of a scavenging effect which dilutes the intake charge. At peak torque, the cylinders have the greatest air density of their operating range. This has the potential to generate the most amount of power relative to displacement, making it the most efficient spot of the RPM range, as VE is at it's peak.

A diesel running no boost has no larger amount of air available than a N/A gas motor with the same displacement(although diesels are generally undersquare). It's more likely less because diesel cams have short lift and duration specs. The heat generated by compression is the ignition source, and a large amount of air is not necessary for the combustion event to occur. A high compression ratio is. Stoichiometry is not as relevant with diesel fuel, as it can efficiently ignite with a broader range of AFR's. Fuel is added to make more power, and the air follows as cylinder pressures increase, driving up RPM, and intake charge velocity/cylinder O2 density increases. The same concept of intake charge density in the cylinders still applies. Turbos simply create a higher O2 density in the cylinders, so more fuel can be added, to make more power, until the cam and intake tract start to have a diminishing effect.

They're the same, only different.

 

This one's just gettin started.

 

No kidding. In the last 4 weeks it has gained just over 40 pages. At that rate it won't take long.

 

You seem to be assuming the gasser has the throttle plates wide open.

 

You mean there is another position???

 

You are correct. Throttle plates are a bit of a restriction on gas motors, and some diesels.

Can't we assume anything in this thread?

 

But I thought the discussion wasn't about 100% WOT operation, but REAL WORLD use?

 

This is all good and true information.
Too many people think of a turbo as an engine, rather it is simply an air pump powered by exhaust.

Efficiency depends on loading... for EG and engine that has peak TQ at 2000 RPM's, doesn't mean that speed is the most fuel efficient, although it will be at a certain load - close to what the loaded truck will weigh, so that the truck can operate down the highway at that RPM.
Slap that same engine in a smaller vehicle, and 2000 RPM will no longer be a fuel efficient speed, it will be spinning too fast for the load on it.

To a point, the lower RPM, the better. If theres not enough fuel being burned per stroke, lots of energy is being wasted spinning parts around that aren't doing much. An example of this would be an empty truck cruising down the highway at 4000 RPM's. (Not that they do)
Vice versa, if an engine is loaded too hard, efficiency drops off as well.
This is the benefit of a diesel, as the harder you load it, the more air gets pushed into it.

 

Wouldn't that be making whst I was saying right? If you bought a truck new with 285 tires w/ a 430 rearend then pulled those tires of and put 35s or 325 should be same sizes you just shorten the reargear in relation to the final drive. So now rearend has to spin faster to turn those tires in a linear travel time. "Mph". So now he lost milage. Its as if he fell back to 3:55 or so. I don't know the formula to figure that one out. Now when he went to 4:88 he put his relation back in spec. So in reality he recoverd 50% not gained 50% mpg. That's not programming that's old fashion gear mechanics. If he would have left tires stock then jumped his gears to 4:88 he wost lose mpg. The engine will have to turn more rpms to turn the tires at same speed. More fuel. I will go along w/ some fuel saving w/ the taller gears around the farm cause your putting more tq to ground w/ less rpms. But when your hitting hiway speeds it'll cost you more. You might actually see some improved milage in the hills cause here again your putting more tq to ground needing less rpm to make power. This is just what a diesel does. Nothing else. I don't if you seen the pictures I post of friend of mines 350 with the " willis pkg". He's has 8" lift. [I think that's what he said] with 325 toyo A/T. Door sticker says it has 3:73s. He's getting 14-15 mpg. I'm sure if he went with 4:30s he'd get better milage. But if he jumped to 4:88 I believe his milage is gonna suffer.
If we could just throw taller gears in and program the pcm to run the higher rpms but don't use anymore fuel that's how ford would be building these trucks. I can see the ford commerical big powerstroke power w/ 50% better mpg than duramax and cummins. Wooo they would sell fast.