All Big Six MPG thread

Relates to all big sixes
The 1989 F150 4.9 federal emissions engine had an air tube also right at the cat. My understanding is air was put in the cat and the engine was set up to run slightly rich to help light the cat off.
Where was the other end of this tube connected, adding air only to the cat would cool it? The diesel trucks with the soot catchers have to add fuel to burn off the soot, diesels always have excess air in the exhaust, but thats another story.
 
In my opinion, the best place to start when trying to increase MPG is by focusing on the nut behind the steering wheel. I can honestly say that I improved the MPG in my 2006 Infinity G35 (it now has 105,000 miles) by about 25% by changing driving habits.

The Ecomodder website has some good and easy to implement ideas. It also has some really interesting and drastic measures people have taken to increase MPG. If nothing else, it is a fun website to read (although I've not been there for 3 or 4 years).
 
195 degrees= richer mixture, less timing
160 degrees = leaner mixture, more timing
If my premise is correct, why is a 195 degree thermostat preferred for max mpg?
 
195 degrees= richer mixture, less timing
160 degrees = leaner mixture, more timing
If my premise is correct, why is a 195 degree thermostat preferred for max mpg?
The claim is at 195 the cylinder pressures will be higher which is good for low end torque. Low end torque is good for fuel economy.
 
I’m sure that I am not an expert in these matters but, if mixture and timing adjustments are needed to bring down the combustion chamber temps, with the goal of staying below the detonation threshold with a 195 thermostat, and a leaner mix and more timing with a 160 thermostat bring the combustion chamber temp up to the detonation threshold, what is the difference in the combustion chamber temperatures?
( sorry for the long run on sentence)
 
The claim is at 195 the cylinder pressures will be higher which is good for low end torque. Low end torque is good for fuel economy.
Dave, that's just not it. The 195* t stat was an emissions-based change. The high temps reduce unburned HC. Most unburned HC's are caused by the fuel/air that is up against the cylinder walls. High coolant temp significantly reduces unburned HC, but works against the other emissions, especially NO. For low emissions on gasoline, the physical parts need to be hot, the combustion temp/pressure "cool".
On these old engines, the most economical burn is a richer than stoichiometric (+/- 13.7:1), and maximum ignition timing, just avoiding detonation. A lower coolant temp works in favor of this ideal tune. A cool chamber that won't detonate the max spark advance will yield higher effective cylinder pressure than a hot cylinder requiring less timing advance to avoid detonation. A fuel efficient 300 is a high-emissions tune.
 
Dave, that's just not it. The 195* t stat was an emissions-based change. The high temps reduce unburned HC. Most unburned HC's are caused by the fuel/air that is up against the cylinder walls. High coolant temp significantly reduces unburned HC, but works against the other emissions, especially NO. For low emissions on gasoline, the physical parts need to be hot, the combustion temp/pressure "cool".
On these old engines, the most economical burn is a richer than stoichiometric (+/- 13.7:1), and maximum ignition timing, just avoiding detonation. A lower coolant temp works in favor of this ideal tune. A cool chamber that won't detonate the max spark advance will yield higher effective cylinder pressure than a hot cylinder requiring less timing advance to avoid detonation. A fuel efficient 300 is a high-emissions tune.
Ok yea that makes sense. I think i remember something like that when i went thru my “MOS” (air force afsc) training. I was sharing what i have heard richard holdner say before.
 
Ok yea that makes sense. I think i remember something like that when i went thru my “MOS” (air force afsc) training. I was sharing what i have heard richard holdner say before.
Holdener, whilst a knowledgable guys is NOT as far as I know an engineer. He does some interesting work and does from time to time get away from strictly US stuff.
 
Another aspect of putting a vehicle together for fuel mileage is to make the engine (a 240/300 six) as dynamically small as possible.

One way that is very familiar to everyone, is to gear the engine to reduce the amount of piston travel per mile but still have enough torque to move the vehicle down the highway at cruising speed.
Since the piston rings represent the highest source of friction in the engine this also reduces the total power lost to friction per mile driven.
If you need more power for a steeper grade or extra load, you shift the transmission into a lower gear.
Thats why the transmission has multiple gears.

The second way is not so obvious and may get some comments.
A later closing intake valve will allow the piston to push some of the cylinder fill back into the intake manifold at low rpm which makes the engine dynamically smaller.
A later closing intake valve also allows a higher static compression ratio which increases the thermal efficiency of the engine.
The previous two statements relate to the Atkinson-cycle.
In this case the peak engine torque is at a relatively high rpm and the object is to operate as far below the torque peak and still have sufficient torque to to move the vehicle down the highway at cruising speed.
This is contrary to the to the "operating at or near the torque peak for best gas mileage" theory.

Some examples;
My 283 hp V6 makes its peak torque at 4400 rpm but I get 27 MPG at 1500 rpm (60mph) on the highway in a 4500 lb van.
1977 Ford pickup, 300 six, very big cam, 9.75 compression ratio, peak torque at 3600 rpm gets almost 18 mpg at 2400 rpm (70 mph).
Goldie's mustang, 200 six, 10:1 compression, 221 degree (.050") duration cam, automatic trans with 2500 stall converter gets 23 mpg mixed driving.
 
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I’m starting to understand this much more. Thanks for posting this. This is exactly what I’m hoping for with the modifications of the 240. And, being able to use lower octane fuel.
 
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Motor Oil Engineering Test Data

Just spent an hour and half reading about motor oil’s.

It goes though oil with high zinc and modern oils with lower zinc. It goes through the additive packages.

It was very interesting, especially when I read that Quaker State Full Synthetic 5W30 was rated #1 in shear strength when compared to 268 different oils.

The test says that todays modern additive packages in some modern oil’s exceed the popular high zinc oils by a fair amount.

I’m posting the link here so others can read and comment about the study.

 
I started using QSFS 5-30 in my 2cycle chain saw and weed whipper when I ran out of store bought 2 cycle oil. Was busy cutting up a tree and thought that Gramp mixed motor oil and gas. That was four years ago and running good. The bad is when out of fuel in the tank, I was done with weed whipping for the day, now it seems to run forever before running out of fuel.
 
That was four years ago . . The bad is when out of fuel in the tank, I was done with weed whipping for the day, now it seems to run forever before running out of fuel.
That's you aging my friend! LOL- I know. . I now make my living using one of those awful machines, and with each passing year the fuel tank "gets bigger"!! :)
 
That's you aging my friend! LOL- I know. . I now make my living using one of those awful machines, and with each passing year the fuel tank "gets bigger"!! :)
I knew that was coming:). I am stronger now than I have ever been, but I run out of give a .... a lot sooner.
But I think that there is something to it, seams to run smother and cleaner. Try it in one of your most hated tools.
 
I knew that was coming:). I am stronger now than I have ever been, but I run out of give a .... a lot sooner.
But I think that there is something to it, seams to run smother and cleaner. Try it in one of your most hated tools.
10-4 on the staying motivated.
Thanks for the oil tip but no, will stay with what is working superbly. All the small equipment is Stihl 4-mix. 4 cycle engines but use oil/gas mix. Stihl synthetic oil+ premium non-E gas. This is the piston as it came out of the trimmer, not cleaned up. 8 years and couple thousand hours. Lapped the valves, put same piston/rings back in, still going strong daily.
 

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Thinking about it now. Could he have achieved the same results just by adding a metering plate? I know in old school fire truck foam systems we metered the foam injection with meter plates and poppet valves. Ill be honest, im not an expert on carbs so i dont know if a plate with holes centered on the bore would work or if other holes would be needed in the plate for the carb to function properly. Or would it be better to have a whole adaptor that would act as a funnel? Ooor a meter plate on a throttle body, megasquirt to tune the injectors to give the right fuel ratio. Well thats enough rambling from me tonight. I look forward to responses in the morning
 
Motor Oil Engineering Test Data

Just spent an hour and half reading about motor oil’s.

It goes though oil with high zinc and modern oils with lower zinc. It goes through the additive packages.

It was very interesting, especially when I read that Quaker State Full Synthetic 5W30 was rated #1 in shear strength when compared to 268 different oils.

The test says that todays modern additive packages in some modern oil’s exceed the popular high zinc oils by a fair amount.

I’m posting the link here so others can read and comment about the study.

It’s a very interesting read!
If I am understanding correctly, peak cylinder pressures are around 1,500 psi and the rod bearing pressures are around 6,000 psi so why is a 100,000 psi motor oil important?
I‘m sure that I am missing something.
 
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