4speedfunk
Well-Known Member
- Messages
- 4,250
- Location
- Tardville
True...not on a stock H3. But I'm already SA with Warn lock-outs. I just need the t-case to complete the package.
-
Welcome to H4O! For a reduced ad experience, please login or register with the forum.
Making the H3 more efficient!
- Thread starter n8rfastback
- Start date
True...not on a stock H3. But I'm already SA with Warn lock-outs. I just need the t-case to complete the package.
MaxPF
AGNTSA
- Messages
- 1,394
- Location
- The dark side of the globe
Left hand drop 241's and 261's are readily available. The 241 is a better case and has a slip yoke eliminator kit available, but the 261 is more commonly found in parts yards. If you want electric shift for some reason (can't imagine why), then it would be a 243 or 263. 241's are available in right hand drop for the GM pattern as well, but they are much harder to find since they were only used for a few years.
If you choose a 261 or 263, make sure the pump hasn't rubbed through the case. Then take it apart and install a pump rub kit/case saver kit. This failure is not a matter of "if", but of "when". Replacing the slip yoke bushing is a good idea, since it will likely be worn. If you have the money you're better off with a 241, SYE kit, and a slip-type driveshaft. Much more durable.
Of course, 205's and Atlases are options as well. 205 is the strongest, but the Atlas has better gearing options and you'll break a D44 or 10b long before you break the t-case. Only downside is cost. Meh, it's only money, right?
If you choose a 261 or 263, make sure the pump hasn't rubbed through the case. Then take it apart and install a pump rub kit/case saver kit. This failure is not a matter of "if", but of "when". Replacing the slip yoke bushing is a good idea, since it will likely be worn. If you have the money you're better off with a 241, SYE kit, and a slip-type driveshaft. Much more durable.
Of course, 205's and Atlases are options as well. 205 is the strongest, but the Atlas has better gearing options and you'll break a D44 or 10b long before you break the t-case. Only downside is cost. Meh, it's only money, right?
n8rfastback
Well-Known Member
- Messages
- 89
- Location
- Omaha, NE
Just filled up and averaged 16.1
Half of the tank had the intake tube on it, hopefully that's a good sign, we'll see with the next full tank.
Sent from Nates phone...
Half of the tank had the intake tube on it, hopefully that's a good sign, we'll see with the next full tank.
Sent from Nates phone...
backcountryislife
Well-Known Member
- Messages
- 858
- Location
- Dumont, CO
If you're running aluminum rims, an 18 with a tire keeping the same heights & width will be lighter than a 16 of the same. The rubber is the heavier part in truck tires.
Not true. Take a goodyear duratrac in a 35" tall tire. 315/75r16 vs 325/65r18. Both are 34.6" tall. Both are about 10.5" wide at the tread. Both weigh 64#.
The wheel is the difference.
http://www.tirerack.com/tires/tires.jsp?tireMake=Goodyear&tireModel=Wrangler+DuraTrac
Another example. BFG AT. 285/75r16 vs 275/70r18. Both 33" tall and 9.2" wide. The tire for the 16" wheel is 56#. The 18 is 57#.
More wheel is more weight.
http://www.tirerack.com/tires/tires.jsp?tireMake=BFGoodrich&tireModel=All-Terrain+T/A+KO
Last edited:
- Messages
- 10,677
- Location
- Scottsdale
Building on that logic, then more weight moves outwards, requiring more torque to turn those wheels and tires and likely more fuel as a result
n8rfastback
Well-Known Member
- Messages
- 89
- Location
- Omaha, NE
You gotta remember smaller overall tire size will equate to higher rpm in the motor to turn the same speed on the highway..
The best bet is a larger overall tire size, but very lightweight, which makes for lower rpm and less spinning mass... Unfortunately wagon wheels won't work on an H3
Sent from Nates phone...
The best bet is a larger overall tire size, but very lightweight, which makes for lower rpm and less spinning mass... Unfortunately wagon wheels won't work on an H3
Sent from Nates phone...
4speedfunk
Well-Known Member
- Messages
- 4,250
- Location
- Tardville
Even if you do all of these things...the H3 is basically shaped like a concrete block. I don't see anyway to decrease the drag at high-way speeds. I has to be tremendous. If you really want to see some efficiency...limit your speed to 30mph.
MaxPF
AGNTSA
- Messages
- 1,394
- Location
- The dark side of the globe
I find their listed weights questionable. How does a load range E tire weigh less than a .8" SHORTER load range D tire?
This ^^^. It's also heavy with a capital "H". Not exactly a good combo for a fuel sipper. I have the same problem with my truck. I simply acknowledge the fact, enjoy all the positive attributes, and quit worrying
Ah... No.
The larger the tires diameter the more resistance to rolling it has. The further away from axle centerline the tread is the harder the motor has to work to overcome. Basic physics. Look up moment of inertia.
The motor may be revving higher but that doesn't translate directly into more consumption.
As for the tire weights. Remember, a 16" tire and an 18" tire are the same except for the 1" thick strip of rubber in the sidewall that's 'eliminated'.
Last edited:
n8rfastback
Well-Known Member
- Messages
- 89
- Location
- Omaha, NE
Yea, that's why I stated it would have to be a very lightweight setup... The main resistance is only during acceleration, once it's rolling it takes relatively little power to keep the speed up.
Sent from Nates phone...
MaxPF
AGNTSA
- Messages
- 1,394
- Location
- The dark side of the globe
In nearly all cases it does.That's why newer transmissions have really tall OD gears, like the .667 OD in the 6L80E. With gas engines, the lower the RPM and higher the throttle angle, the better.
Unfortunately it's not that easy. Back to the moment of inertia equation.... Plus just because the engine is at a lower rev doesn't mean it's getting less fuel. Think about lugging an engine uphill in 5th gear vs down shifting. You wind up putting your foot in it less because the engine is in a more efficient range. Now with all that said, a reasonable tire size change on an h3 might be from a 315 to a 265. That's a net change of 200 rpm. Barely noticeable on paper. Until you try and drive.
Now I agree that on flat pavement with no breeze the lowest possible rpm will yield the best economy. But utilizing a taller tire to yield a lower rpm isn't going to improve efficiency. It require more power to turn no matter what. Basic physics. Particularly when you're talking about an rpm change in the 200ish range.
Here's a good article from car and driver about the increase in wheel size at a constant tire size. Using a 15 instead of a 19 with the same od tire yielded more than 2 mpg increase and saved 14# per corner.
http://www.caranddriver.com/features/effects-of-upsized-wheels-and-tires-tested
Now I agree that on flat pavement with no breeze the lowest possible rpm will yield the best economy. But utilizing a taller tire to yield a lower rpm isn't going to improve efficiency. It require more power to turn no matter what. Basic physics. Particularly when you're talking about an rpm change in the 200ish range.
Here's a good article from car and driver about the increase in wheel size at a constant tire size. Using a 15 instead of a 19 with the same od tire yielded more than 2 mpg increase and saved 14# per corner.
http://www.caranddriver.com/features/effects-of-upsized-wheels-and-tires-tested
Last edited:
For the sake of clarity, if we're going to play in the realm of reasonable....
A smaller OD tire and wheel ie... A 32 on a 16" aluminum wheel will be more efficient than a 35 on an equivalent 18" wheel... Even if you can get that 35 combo to weigh the same. It still has a higher moment of inertia to over come. Inertia= mass x radius squared.
A smaller OD tire and wheel ie... A 32 on a 16" aluminum wheel will be more efficient than a 35 on an equivalent 18" wheel... Even if you can get that 35 combo to weigh the same. It still has a higher moment of inertia to over come. Inertia= mass x radius squared.
Happy Hummer
Well-Known Member
- Messages
- 1,465
- Location
- Wisconsin
Ya know I studied allot of this exact discussion back last year when we were going to switch out Happy's wheels and tires to achieve absolute gas savings per mile. I studied allot about Low R tires and there combined effect with the rim weight. The pricing of the tires was a bit high and the life cycle was a bit (tad) short compared to other brands.
But with that said there was a savings.
Conti cross contact were rated high! As were a couple others. The savings translated to about 10% gallon/s per tank.
Chris
But with that said there was a savings.
Conti cross contact were rated high! As were a couple others. The savings translated to about 10% gallon/s per tank.
Chris
MaxPF
AGNTSA
- Messages
- 1,394
- Location
- The dark side of the globe
When you are lugging a gas engine, you downshift for more power, not for improved efficiency. The single biggest efficiency loss of a gas engine over a diesel is pumping loss. This is a direct result of throttling the airflow. Diesels have no air throttle, they only throttle fuel, so their pumping losses are very minimal even with no boost. Gas engines operate under a partial vacuum at everything short of WOT. The lower the throttle angle (throttle opening), the higher the vacuum, the lower the volumetric efficiency (which is the actual measure of pumping loss), and the lower the efficiency. For a given power output, a lower engine speed and larger throttle opening will give better efficiency vs a higher RPM and lower throttle opening, FOR A GIVEN CONSTANT POWER OUTPUT. It sounds counter-intuitive, but it works. If you are on a dyno and monitoring the calculated fuel consumption with a scanner, it's very easy to measure the difference.
MaxPF
AGNTSA
- Messages
- 1,394
- Location
- The dark side of the globe
Just to be slightly picky, that is only valid for a constant cross section and density. Tires are far from either. However, the concept is reasonably valid since the bulk of a tires mass is in the tread and tread plies. For that same reason, a difference in rotational mass between, say, a 16" rim and 18" rim on a 35" tire is going to be much less than the difference in rotational mass between a 35" tire and 32" tire, regardless of rim size.
In simple terms, dinky donut-size pizza cutters will give the best mileage. They're gonna suck off-road though
ABNTROOP
HIPPO
- Messages
- 1,985
- Location
- Vancouver, Wa
ZZZZzzzzzzzzz............ Sorry, nodded off there
guess you havent seen this yet?
http://www.google.com/imgres?q=humm...bnh=181&tbnw=251&start=0&ndsp=15&tx=83&ty=108
MaxPF
AGNTSA
- Messages
- 1,394
- Location
- The dark side of the globe
Those wheels are awesome! Shipping to 85204?
Shipping is cheap. They're light and efficient.
n8rfastback
Well-Known Member
- Messages
- 89
- Location
- Omaha, NE
Yeah, but breaking distances might be a tad longer than stock... :whaa: