ratio rockers for fuel economy?

[sixto]

Can going from 1.6 to 1.7 ratio rockers improve cruising mpg in a '93 351W EFI? I found an article with aircooled VW dyno tests comparing 1.1 to 1.4 ratio rockers. The 1.4s made more power from 3500 and allowed the engine to rev higher. No torque charts. If the same results apply to a 351W, will that help mpg?

Sixto
87 300D

[MS Fowler]

Originally Posted by sixto

Can going from 1.6 to 1.7 ratio rockers improve cruising mpg in a '93 351W EFI? I found an article with aircooled VW dyno tests comparing 1.1 to 1.4 ratio rockers. The 1.4s made more power from 3500 and allowed the engine to rev higher. No torque charts. If the same results apply to a 351W, will that help mpg?

Sixto
87 300D

My first thought--and it is only that--is that if all other parameters stay the same (vehicle weight, gearing, driving habits, speed) you are unlikely to see a measurable impact on economy. The engine might require a little less throttle opening, but driving at a certain speed will still require the same power--and that means the same amount of fuel burned.
Matching the ports to the intake and exhaust manifold on those small block Fords yields nearly as much as a full porting job, according to something I read years ago.

[t walgamuth]

I agree with MS's conclusion and will add that increased rocker ratios will open the valves further. This is normally to increase the cylinder fill hence more power. I cannot see how it will increase fuel economy. I would think it will decrease it.

does the seller of the parts tout fuel economy gains?

[Air&Road]

Originally Posted by sixto

Can going from 1.6 to 1.7 ratio rockers improve cruising mpg in a '93 351W EFI? I found an article with aircooled VW dyno tests comparing 1.1 to 1.4 ratio rockers. The 1.4s made more power from 3500 and allowed the engine to rev higher. No torque charts. If the same results apply to a 351W, will that help mpg?

Sixto
87 300D

A change of 1.1 to 1.4 is a MUCH bigger change than 1.6 to 1.7. The first is about a 22% change and the second is only about a 6% change.

That aside, there are MANY variables involved. I personally wouldn't bother with such a modification unless I were in the midst of an engine build and buying parts anyway.

On the American V8's, it has been shown numerous times that going to full roller rockers will have almost as much effect as the ratio change due to friction loss. The REAL benefit of full roller rockers is lowered oil temperature.

Another benefit if high lift rockers, is in a situation where you are reaching some valve train geometry stumbling blocks that are putting you in a situation where an increase would make for a short lived cam and lifter combination which made me think of something:

Isn't that a roller cam version of the 351W? If so, already being set up for a roller cam opens up some possibilities. Even so, IF you could wangle any fuel economy improvement, it would be fractional and would take a LONG time to recoup the modification cost.

The biggest factors in fuel economy are weight and aerodynamics. In you vehicle it won't be easy to address either of these situations. Those are good trucks, but they've NEVER been known as economy vehicles.

[Simpler=Better]

Originally Posted by Air&Road

The biggest factors in fuel economy are weight and aerodynamics. In you vehicle it won't be easy to address either of these situations. Those are good trucks, but they've NEVER been known as economy vehicles.

A low rubber front lip is ugly but will give you the most bang for buck mileage wise on a truck. When properly setup you can still go offroad (the rubber bends) but deflects a good amount of air.

[Air&Road]

Yeah Simpler, I had forgotten about that one. They started doing that in the seventies and it cut down significantly by preventing the air underneath from dragging on all those ragged components underneath.

[panZZer]

When the wife tries telling you -"we can save money--By SPENDING money" do you buy it?

hot rod parts vendors have always counted on people lieing to themselves to get what they want--instead of what makes sense.

[TwitchKitty]

I doubt that just changing the rockers would help much.

For mileage I would think that the best valvetrain improvement you could do would be to decrease the drag. I was amazed at how much power you lose to open and close valves. It is obvious when you try to turn a camshaft.

The rocker ratio has to match the cam lift and valve angles and such. It's not a simple shadetree parts swap.

I have that engine in my camper van and it seems to breath really well. It loves to rev and howls like a demon climbing hills. More revs get power better than more throttle. I would love to get better mileage. If you figure it out I would like to hear of improvements.

[MS Fowler]

^^^^^
Best mileage improvement is simple--slow down. The power required to overcome wind resistance is exponential. i.e doubling the speed requires 4 times the power; triple the speed and you need nine times the power. Works the other way too, cut your speed in half and you reduce the power required by 4. That doesn't mean 1/4 the gas will be used--there are other factors, but speed is the big one.
In reading gas mileage threads--here and on other forums--I am amused when someone posts something like this----"Manufacturer claimed 40 mpg highway--I drive all highway miles and I'm only getting 31.03455 mpg. I drive 80 miles each way from home to work, and it takes me almost an hour for the trip"....( Yes, its a made-up quote--but it illustrates how people complain of poor mileage while driving at extremely high speeds. You can't have it both ways.)

[Benz Fan]

What axle ratio are you running?

[Palangi]

Originally Posted by panZZer

When the wife tries telling you -"we can save money--By SPENDING money" do you buy it?

hot rod parts vendors have always counted on people lieing to themselves to get what they want--instead of what makes sense.

A lot of people believe that when 0bama says it.

I guess those people just aren't too bright, are they?

[sixto]

Something like 3.73.

Sixto
87 300D

[sixto]

Originally Posted by panZZer

When the wife tries telling you -"we can save money--By SPENDING money" do you buy it?

hot rod parts vendors have always counted on people lieing to themselves to get what they want--instead of what makes sense.

My wife is far more honest with herself than that. She spends money to spend money, period

It's a '93 E150. I don't know what rockers are in there now but I imagine they're stamped. The oil filler provides no view of the valvetrain so I can't confirm. The 1.7s I saw have a roller pivot and a roller tip. I can't imagine there'll be any more notable drop in oil temp than rise in mpg.

Someone with a similar van in Europe asked about engine mods to increase mpg and someone else suggested higher ratio rockers in his litany of mods. All the suggestions and marketing fall under the umbrella of efficiency but efficiency doesn't always translate to increased mpg.

Ideally the van would have a 4.9, 5.0 or 7.3 but the right van at the right price had a 5.8. And with 185K miles on the clock, it's not worth more than a set of new plugs and wires when needed. If my criteria were towing up Pike's Peak I'm sure higher ratio rockers would make the cut for cost and ease of installation.

Neither the E150 nor the Suburban have a rubber lip. The air dam molded into the E150 bumper hangs pretty low as it is and we tend to park as far into a slot as possible so the back end doesn't stick out. A rubber lip might not last too long. I'll have to check how low they usually hang. Ugly? We're talking about a van

Sixto
87 300D

[Simpler=Better]

Originally Posted by sixto

My wife is far more honest with herself than that. She spends money to spend money, period

It's a '93 E150. I don't know what rockers are in there now but I imagine they're stamped. The oil filler provides no view of the valvetrain so I can't confirm. The 1.7s I saw have a roller pivot and a roller tip. I can't imagine there'll be any more notable drop in oil temp than rise in mpg.

Someone with a similar van in Europe asked about engine mods to increase mpg and someone else suggested higher ratio rockers in his litany of mods. All the suggestions and marketing fall under the umbrella of efficiency but efficiency doesn't always translate to increased mpg.

Ideally the van would have a 4.9, 5.0 or 7.3 but the right van at the right price had a 5.8. And with 185K miles on the clock, it's not worth more than a set of new plugs and wires when needed. If my criteria were towing up Pike's Peak I'm sure higher ratio rockers would make the cut for cost and ease of installation.

Neither the E150 nor the Suburban have a rubber lip. The air dam molded into the E150 bumper hangs pretty low as it is and we tend to park as far into a slot as possible so the back end doesn't stick out. A rubber lip might not last too long. I'll have to check how low they usually hang. Ugly? We're talking about a van

Sixto
87 300D

I once bolted a piece of conveyor belt to my bumper,wrapping around the edges. It was around 1.5" off the ground. Bumped my truck up like 4mpg, but it did get scraped up quite a bit. I finally ripped it off (accidentally) when I was running around in a field.

[Benz Fan]

Originally Posted by Palangi

A lot of people believe that when 0bama says it.

I guess those people just aren't too bright, are they?

Later, I'm going to start a thread about my pet turtle. See if you can try to segue it into a political discussion, ok?