ratio rockers for fuel economy?
 

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.

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?

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.

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.

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.

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.

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.

^^^^^
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.)

What axle ratio are you running?

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

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

Something like 3.73.

Sixto
87 300D

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.

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?

Not crazy-low for a pickup, and I assume that your transmission has an OD 4th gear...

Pet turtle is an obvious Obama supporter as the turtle is a net "taker"; not a provider/ entrepreneur. ( How was that? OK?)

Not fair - you're more intellectually adept than he is.

Yes, it has the E4OD transmission.

Speaking of pet turtles - Colin Kaepernick has a huge pet tortoise | Yardbarker.com

I don't know which way Collin votes... or the turtle. I wish I could hoist 100+ lb and keep a smile on my face.

Sixto
87 300D

Roller rockers will lower friction and give you the effect of a higher lift cam.

Keep in mind though, that you have to have the heads machined for screw in studs, guide plates and use hardened push rods.

Oh yeah, you'll need a set of poly locks too.

All of this just to convert to roller fulcrum/tip rockers...

Even at $4 a gallon, gas is likely cheaper than any of these mods.

While slowing down may be the cheapest way to improve mileage, I don't agree that it's the best. For example, watch the Top Gear episode where Jeremy drives a diesel Audi from London to Edinburgh and back without refueling. Yes he got great mileage, but it was sheer torture. Switching to a more efficient vehicle is the best way to improve mileage. I can drive my 300D like Lewis Hamilton in qualifying and still get 25 mpg. It's probably possible to extract that mpg from an E150, but the driving style required to do that would drive many people insane.

Some truth in that. However, if you NEED the E150 --to carry tools, or materials, or whatever--then switching to a 300D or a Prius is not a viable answer, either. Sometimes the most fuel-efficient vehicle is the one that gets only 8 mpg, but gets it all done in a single trip, with a single vehicle.

No problem. I can think of a couple options.

One would be falling off of a cliff.

The easier option would be to just lie, say it is so.

It's a passenger E150 and we take it when we're more than the 7 that'll fit in the minivan. Right there its 15 mpg is more fuel efficient than a pair of '87 300Ds. The 'burb will seat 9 and get 20 mpg but some of the older folk have great difficulty getting in and out. We can take the most efficient vehicle for a given trip but we're saddled with the inefficiency of multiple vehicles. Oh, for a 9-seat Vito or Viano CDI.

Sixto
87 300D

Many years ago I had to pull the heads off of my 1984 Z-28 and was amazed at how small the intake ports on the head were by comparison to the intake manifold; in some places it was almost 3/16" difference. The gaskets matched the intake very well, so I used them as a template and marked up the heads and went to work. I think I spent about twenty hours match-porting those heads (the exhaust was fine). The results were amazing across the board and I even saw 26+ on the highway after that. Curiously, the exhaust ports were fine.

I cannot imagine how porting the head would increase fuel economy. Power yes, but better economy? I don't see how without changing gear ratios or aerodynamics.

Well, I think someone could do it getting a lot better than 8mpg, even if they couldn't use a Prius or a compact car w/ an efficient driveline. In general, weight matters, but not as much as aero and drivetrain efficiency. Rocker ratio don't much worth you know what. A large ~4-6k lb truck could average 25-35mpg in normal driving, but most people don't care enough bother with the mods needed for something like that.

I think that is a dream at this point. Don't know and won't be able to tell because people lie so much about mileage it is not worth the time to pursue. I believe that you would waste a lot of time and money and never save a lot of gas. If you want to say you get great mileage just lie like the rest of them.

My big dodge gets 22 running about 65. I suspect I could get that to the high twenties with aero mods and a taller gear....really easily. I think if I could get a 355 in there in place of the 373 I would jump 3 mpg immediately. Then if I put on a belly pan, front spoiler and an aero bed cover I could get to 29 or 30 wo too much trouble.

How much are you willing to spend, that is the question?

Lake style wheel covers with narrow (215 or 225 )LT highway tires at max pressure would gain as much MPG as the roller rockers.
A good intake system, good mandrel bent exhaust, synthetic rear diff lube and ATF, plus stay away from ethanol fuels.

I have a friend who installed a 6.9 International diesel (IDI) in a Ford bronco, and another one in an F150 for his son. Both get 30 mpg on the highway. But it wasn't cheap, nor easy.

I think that's your solution right there-just make everybody chip in for gas and you're all set.

For several months earlier this year I had a paying passenger for my commute. His car was sufficiently decrepit that he didn't trust it to drive to work, and he lived about 100 yards out of my way, so I ended up getting paid ten bucks a week for going someplace I needed to go anyway.

It's not a dream, so much as work most people aren't willing to do. It's hard enough to get people off their own couch, much less get them to drop in taller gearing via changes in the rear-end/trans, fabricate an aerodynamic bed cover, do some other aero mods, etc, etc... Well, that and the way a lot of guys think about their truck, you'd think it was their purse. :rolleyes:

A lot of the conventional wisdom simply doesn't work in practice. Great in theory, makes perfect sense, until you throw mother nature into the mix.

I got an increase (slight) in mileage by going to lower gearing in my camper van. The 4.10 gears make cruising up hills in third gear easy work for the engine and it stays near the peak of the torque curve when torque is needed. Still cruises in OD nicely.

Throw a big box like a van into the wind and efficiency left about a quarter 'til three yesterday.

A lot of people lie (some innocently) about their mileage. Some of those are selling you something. Over the years I have seen a few vehicles that perform beyond reason for what they are. They are rare.

Car MPG Efficiency Modifications Main - EcoModder

It's fun to check this stuff out but good luck getting any of it to pay off. Big vehicles need big brakes and tires to stop and lots of gas to go. If you can reduce the amount of gas to make it go you should be able to reduce the amount of brakes to make it stop, no?

#1 gas saving modification: Live close to where you work. Don't give your money to scumbag oil companies or scumbag real estate developers.

#2 Don't drive within ten miles of a Wal-Mart.

I see how #1 works, but what about #2?

You wouldn't swap in lighter duty brakes, you'd swap for a lighter duty vehicle.

One of many counterpoints is when work is driving the van.

It's getting more difficult to not live within ten mile of Walmart. Even if you don't move, Walmart closes in.

Sixto
87 300D

I would have to drive about nine miles to be ten miles from the nearest Wal Mart, and that only works if I head east. Headed north, by the time I'm ten miles from the north Carson store, I'm getting close to one of several in Reno. Heading south, I go five miles toward the south Carson store before I start getting farther away, and you have to go down almost to that Wal Mart to take U.S. 50 over the hill to go west.

It does depend on the population density. I have 3 Wally Marts within 10 miles.

I suspect the poster who said less brakes meant coast more brake less, as a driving style.;)

Possibly, but here's more of the quotation -

Sixto
87 300D

Not equivalent, I think.
Slow acceleration reduces gas consumption.
Slow braking WOULD reduce the amount of energy turned into heat (waste), but do you really want to be in a vehicle that cannot stop as quickly as you want it to?
Reducing the weight of the vehicle helps acceleration, economy AND braking. But we are talking about a specific vehicle--difficult to reduce the weight very much.

the point is not to reduce the size of the brakes.