Lugging the engine

What's the consensus on lugging the engine in these cars? (That is cruising at extremely low RPMs.)
A great deal of my driving is on secondary roads at 40-50 mph. If I follow the demands of the upshift light, I can easily be turning 1000-1200 rpm in 6th gear. Is that bad for the engine? Or should I leave it in 5th and run at 1700-2000 rpm?

As long as you dont go below 45 mph in 6th your ok .

Lugging the motor is probably the worst thing you can do to a motor. You're putting a very heavy load on an engine that isn't high enough in the torque curve to handle it. You're right on the edge of detonation at all the times; a slight amount of throttle to much and you get detonation. You might not hear it but it doesn't mean it is not happening. RPM's are your friend. I keep mine above 2k at all times except in 1st gear. Thats means I don't even shift into 6th until about 70. You can't hurt a motor by being in too low of a gear for your speed but you can definitely hurt one by being in too high of a gear.
My wife was always lugging the motor in two of her cars. She was always at least one gear too high for her speed, IMO. She went through 3 engines in two different cars, all with the very same problem, severely burnt valves. On one motor, there was over an 1/8 inch of the valve burned away on two of the four cylinders. She now has an auto and hasn't had any more problems.
This damage happens over time, so being in too high of gear occasionally will not hurt it but over time the damage will eventually add up. You mileage will not be significantly better either, by using the higher gear.
There is a reason that modern cars with auto's immediately downshift on the highway as soon as you touch the gas, even a little.
My old man once told me that if you floor the gas and the car bucks and stutters and doesn't accelerate briskly , then you are in the wrong gear and you are going to damage the engine eventually.

I never used 6th gear when driving under 65 mph. Even when fuel economy might come into play, I would not think you'd be saving any fuel using 6th gear driving 45-50. I would keep to 5th gear under 65. Even 70, as mentioned above, isn't unreasonable.

I use 5th up do about 50-65 mph. 6th for everything above.

Thanks. You all kinda re-enforced my thinking as well. I'd always heard lugging was bad for 4 cylinder engines but wasn't sure about 8s.
I can't belive Ford in it's wisdom put in such a meaningless upshift light. I guess it's only there to avoid a gas-guzzler tax in '03. (according to the book Iron Fist, Lead Foot.)

As far as I can tell, the light will keep lighting up as long as you're at more than 1500rpm and not in 6th gear.

langod said:

Thanks. You all kinda re-enforced my thinking as well. I'd always heard lugging was bad for 4 cylinder engines but wasn't sure about 8s.
I can't belive Ford in it's wisdom put in such a meaningless upshift light. I guess it's only there to avoid a gas-guzzler tax in '03. (according to the book Iron Fist, Lead Foot.)

As far as I can tell, the light will keep lighting up as long as you're at more than 1500rpm and not in 6th gear.

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The upshift light bulb was taken out on mine...makes a world of difference...

I think you can a strike compromise and get better fuel economy.

I use very low operating RPMS for steady state cruise conditions, IE ULTRA LIGHT throttle.

If I need to accelerate, I drop a gear even for medium to light acceleration, but if I'm just going down the road at the same speed, I am often under 2k.

Lugging while attempting to accelerate is where you will hurt stuff.

I also coast a lot when there are lots of lights or stop signs. I look way up the road to see what's going on, If I see brake lights or a traffic signal go yellow or red, I'm coasting.:beer:

^+1

The light will come on in 6th gear too if you have 4.10's!

It gets annoying. Plus passengers get in your car and see it come on and say things like, "Your gas light keeps coming on", or "Is that a check engine light?" I just removed the bulb.

If the engine sounds like it's lugging, it is and thats not good for it.

If it sounds like it's really spinning, it probobly is and your wasting gas.

When it sounds quieter and smoother it's happy and at an efficient rpm. You'll get your best gas mileage there, though if your going over 60 or so you start pushing more air and that decreases mileage.

4V's seem to like to cruise at 2300-2700rpm.

Interesting you mentioned this. I just starting using my 6th gear alot more, and have been getting ALOT better gas mileage. I never let the rpms for any gear drop below 1500. So I usually cruise at 2,000 rpms in 6th which is exactly 70 mph. I don't even check my speedo, I check my tach for speed, lol.

For clarity when I cruised in 5th on the freeway at ~70 mostly I would only get ~225 miles to the tank.

Using 6th as much as possible and never letting it drop below 1,500 rpms I get ~260 miles to the tank.

langod said:

I can't belive Ford in it's wisdom put in such a meaningless upshift light. I guess it's only there to avoid a gas-guzzler tax in '03. (according to the book Iron Fist, Lead Foot.)

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My sticker has over $1k in gas guzzler tax. I guess it didn't work.

divided said:

Interesting you mentioned this. I just starting using my 6th gear alot more, and have been getting ALOT better gas mileage. I never let the rpms for any gear drop below 1500. So I usually cruise at 2,000 rpms in 6th which is exactly 70 mph. I don't even check my speedo, I check my tach for speed, lol.

For clarity when I cruised in 5th on the freeway at ~70 mostly I would only get ~225 miles to the tank.

Using 6th as much as possible and never letting it drop below 1,500 rpms I get ~260 miles to the tank.

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Glad you're getting better mileage. So your mileage calculations were done with freeway driving only? I ask because obviously actual mileage around town depends on how much you get into boost. ;-)

For 6th gear I would want to be atleast aprox 1500rpms , the lower gears its not as critical as long as your under very light loads and throttle.

JedWele said:

For 6th gear I would want to be atleast aprox 1500rpms , the lower gears its not as critical as long as your under very light loads and throttle.

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Why is it ok for lower gears and not higher ones?

CobraBob said:

Glad you're getting better mileage. So your mileage calculations were done with freeway driving only? I ask because obviously actual mileage around town depends on how much you get into boost. ;-)

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No of course not. Its "normal" driving conditions for me. Which means

To and from work/school
highway/city
WOT very few times.

divided said:

Why is it ok for lower gears and not higher ones?

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Shorter the gear , the lower the load on engine

Jimmysidecarr said:

I think you can a strike compromise and get better fuel economy.

I use very low operating RPMS for steady state cruise conditions, IE ULTRA LIGHT throttle.

If I need to accelerate, I drop a gear even for medium to light acceleration, but if I'm just going down the road at the same speed, I am often under 2k.

Lugging while attempting to accelerate is where you will hurt stuff.

I also coast a lot when there are lots of lights or stop signs. I look way up the road to see what's going on, If I see brake lights or a traffic signal go yellow or red, I'm coasting.:beer:

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I concur. I wish a lot of the automatic folks would learn. They haul the mail on take off and then wear their brakes out at the end of the block. Some people just never learn.

Jimmysidecarr said:

I think you can a strike compromise and get better fuel economy.

I use very low operating RPMS for steady state cruise conditions, IE ULTRA LIGHT throttle.

If I need to accelerate, I drop a gear even for medium to light acceleration, but if I'm just going down the road at the same speed, I am often under 2k.

Lugging while attempting to accelerate is where you will hurt stuff.

I also coast a lot when there are lots of lights or stop signs. I look way up the road to see what's going on, If I see brake lights or a traffic signal go yellow or red, I'm coasting.:beer:

Click to expand...

ultra light pedal is key like jimmy said...it's even more dangerous to lug the motor on these cars because they'll start boosting too at the lower RPM's because of all that load put on the motor...

even at 65mph in 6th it's easy to get into too much boost if you're not carefull w/ your throttle...

remember, lugging becomes even more troublesome in a boosted car...