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Underbody braces, turbos and more!

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PostPosted: Thu Nov 24, 2005 12:03 pm 
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Location: Irvine, Ca
martinq wrote:
"A heavy flywheel requires more energy to move than light one."

No, a heavy flywheel takes more energy to move 'as far' or 'as fast' as a light one. But you can put in the same amount of power in each, and extract the same power from each.

Problem is you don't get all that energy back in the form of forward motion. You spend X amount of energy to get the flywheel spinning, you get Y (<X) back if you coast in gear, but as soon as you get out of gear/clutch the flywheel deaccelerates (loses its angular momentum/potential energy) and you lose. Yes all flywheels will lose their energy when yo put the clutch in, but you put more into the heavier one.

Heavy flywheels are mostly for easy shifting and a smooth ride.

Jay W
505/287 Dakota


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PostPosted: Thu Nov 24, 2005 12:10 pm 
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Location: Irvine, Ca
disrespected3cyl wrote:
What would be adequate flow?

The water connections are 1/2" treads with I think 5/8" barbs, this is just barely enough. I run slightly warmer than usual. The fuel connections are 1/4" treads with 3/8" barbs, which I think is working out okay.

Jay W
505/287 Dakota


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PostPosted: Thu Nov 24, 2005 7:09 pm 
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" but as soon as you get out of gear/clutch the flywheel deaccelerates (loses its angular momentum/potential energy) and you lose."

When it comes to fuel economy, I'm actually not refering to using the clutch at all.

If you had two cars travelling at a steady state, the one with the 'larger' flywheel would make more efficient use of the engines torque and would use less fuel.

===

"Heavy flywheels are mostly for easy shifting and a smooth ride."

Smooth ride, yes, but easy shifting? Most prefer a 'smaller' flywheel to increase throttle response and this can make it easier and faster to shift up and down gears. Unless you're thinking that a slower shift is easier.


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PostPosted: Thu Nov 24, 2005 9:27 pm 
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[quote="martinq"]
If you had two cars travelling at a steady state, the one with the 'larger' flywheel would make more efficient use of the engines torque and would use less fuel.[quote]

Are you enjoying this? :lol:

"Larger" ????? Before you said heavier.

If you add weight to a stock flywheel you will not gain fuel efficiency. Just like the tire example rolling down the drivway. More work will be done, if you add weight to the same wheel.

If your flywheel has a "larger" diameter, it will be easier for your starter to start your car, but it may (or may not) save you gas mileage. Rotational inertia depends on weight and the placement of that weight.

http://hyperphysics.phy-astr.gsu.edu/hbase/mi.html#cmi

Look at the formulas for inertia. Why are they different? Because the weight placement is different. A solid has 1/2 the inertia of the hoop If you add weight to any one formula, inertia increases.

Once again, inertia is the ability to resist movement. If you increase mass, you'll increase inertia and the engine will need to work harder from rest to accelerate the objects.

http://hyperphysics.phy-astr.gsu.edu/hbase/rke.html#rke

Notice Kinetic Energy depends on inertia. So your right. The flywheel will have more energy if you increase weight. But.......

You need to stop considering the energy of a moving car. Consider the energy required to accelerate a car (or flywheel) from rest.Consider the energy required to move a light flywheel (from rest), vurses and heavy one (of the same physical size from rest).

I see what you mean my "pulses." But in that situation, your conserving momentum. The energy has already been spent accelerating the heavy flywheel.

Seriously though....have a happy thanksgiving.


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PostPosted: Thu Nov 24, 2005 9:48 pm 
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I'll admit there are some occasions (pulses) when a flywheel comes in handy..... such as going up a small hill and such.

Motorcycle riders add weight to their flywheel to increase momentum when going up hills, but nobody said it would increase overall fuel efficiency from tank to tank.


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PostPosted: Thu Nov 24, 2005 11:22 pm 
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What I'm saying is that a 'larger' (greater mass) flywheel will allow more efficient use of the torque as it is delivered from the engine.

This has nothing to do with the clutch. It has nothing to do with going up or down hills. It has nothing to do with changing gears. It has to do with the torque pulses that are generated from a reciprocating internal combustion engine.

These engines do not generate a constant torque output, but constant torque is what is most effective at accelerating or maintaining velocity. The flywheel helps to make this transition.

If you get rid of the flywheel (weight = 0), you have no benefit. The engine will run rough, you'll feel more vibrations, and it'll be zippy as hell (if you can keep it running).

If you make the flywheel big (weight = 100), then the engine will accelerate / decelerate very slowly (as energy is being transferred into and out of the flywheel), but the engine will run very smooth, and the output will be very smooth.

Other than the drag of air against the flywheels surface and the load on the bearings, there is little loss in the flywheel.

If two flywheels were the same size, shape, texture, etc. but one weighed twice as much, then the only extra loss you would have would be in the bearings assuming they were both well balanced. The gain would be the extra mass available to absorb more of each and every combustion pulse (torque) that the engine delivers.

This is why I’m quite sure you can gain fuel economy by using a larger/heavier flywheel, and why you can also loose it with a smaller/lighter one.


Any more suggestions?


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PostPosted: Thu Nov 24, 2005 11:45 pm 
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Did you look at the links at all?


Things for you to learn......

Inertia
Work
Energy
Momentum

Then you have to relate it to fuel efficiency.

Its as easy as this........

If you add weight, you will increase work done. Fuel efficiency will suffer.

I should have listed a link for work too, but I don't think you read the links.


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PostPosted: Thu Nov 24, 2005 11:50 pm 
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Yes I fully understand inertia, work, energy and momentum, that's why I say that a flywheel can improve fuel economy.

I didn't read the links, see above. :)


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PostPosted: Fri Nov 25, 2005 12:05 am 
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What about work?


What is work?


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PostPosted: Fri Nov 25, 2005 12:09 am 
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Work is getting out of bed in 7 hrs.


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PostPosted: Fri Nov 25, 2005 12:11 am 
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Yeah that's what I thought 8) .


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PostPosted: Fri Nov 25, 2005 12:13 am 
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Sleep good. Don't let bed bugs bite. :D


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PostPosted: Fri Nov 25, 2005 1:38 am 
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I don't know this man. :oops: :-P

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PostPosted: Fri Nov 25, 2005 2:19 am 
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Uhh.. Unfortunetly everyone's driving involves the clutch, hills and changing gears. None of us live in a bubble where we drive in 5mile circles on a track for the entire 500miles tank. If you were talking about controled lab experiments, then I'm out of the conversation since it doesn't apply to getting better MPG in our cars.

Jay W
505/287 Dakota

martinq wrote:
What I'm saying is that a 'larger' (greater mass) flywheel will allow more efficient use of the torque as it is delivered from the engine.

This has nothing to do with the clutch. It has nothing to do with going up or down hills. It has nothing to do with changing gears.


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PostPosted: Fri Nov 25, 2005 5:38 am 
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I think the easiest way of saying it, to us non-physics guys, is that two equal cars use different weighted flywheels. The lighter flywheel will use less fuel to get the flywheel spinning to say, 3000 rpm (highway cruise in fifth, more or less), whereas the car with the heavier flywheel will use more fuel.
In any situation, to increase the heavier flywheel's rotation, will consume more fuel than it would a light flywheel. Having rotational momentum with a heavier flywheel is good and all for smooth driveability, and it does have very few perks in that regards. At highway speeds, the car is always running into forces (that semi that passed you, drafting, wind), so engine rpm's will always fluctuate. To keep 110 km/hr, your foot is always moving a hair this way and a hair that way. Again, the differences in fuel used to keep the car at 110km/hr apply here.
If it were a perfect world where the car wasn't in a dynamic environment that affected engine rotation, then the heavier flywheel would be the best for fuel efficiency, since it would stay at 3000 rpm indefinitely.

Of course I could be totally wrong. I haven't a clue to how much fuel is actually used to get a car up to 110 km/hr.

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PostPosted: Fri Nov 25, 2005 11:19 am 
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Outside of making the engine run smoother or releasing the clutch on a hill, a flywheel only helps when you do not want to accelerate. If you want to maintain your speed while rolling over hills, it will help some.


But even a really large flywheel is not that large in comparison to a car moving above 30 MPH.


Then you have to look at the costs of a flywheel.

You have to accelerate it as part of the dead weight of the car.
You also have to accelerate it as part of the engine's rotating mass.
You really shouldn't downshift and use the engine for braking (It works but it's bad for the check book - brake pads are cheaper)


I might be able to believe that a larger flywheel could make cruising down the highway slightly more efficient but it's losses in all other types of driving outwegh it's benefits.

ed


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PostPosted: Fri Nov 25, 2005 12:29 pm 
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OK-well, thanks for the big flywheel conversation, but let's say we put that one to bed because i don't think i'm going to change the flywheel. Even if i would go with the 3.59 trans, if the flywheel is not different; i am not changing it. There is a benefit from using it on the highway, but bot from starts-can we agree on that and let it go?
Keep it coming gang. This is building a decent list. Looking for a heater setup now.


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PostPosted: Fri Nov 25, 2005 6:29 pm 
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disrespected3cyl wrote:
Keep it coming gang. This is building a decent list. Looking for a heater setup now.


speaking of heaters, don't forget a block heater (i see you're in PA).

not a sexy mod, but using one will help get you out of rich-mixture mode (is that closed loop or open loop.. i can never remember) faster, and reduce internal drag from increased engine oil viscosity due to cold. synthetic lubricants are a good idea for the same reason (reduced viscosity compared to reg. lubricants) in freezing conditions.

and then there's the bonus of having heat sooner inside the car.

i spent a couple of aggravating hours this week contorting myself around the back of the engine block installing one. (of course now if i had to do it again it would only take 30 minutes, but it's all a learning process)

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Last edited by geometro on Fri Nov 25, 2005 11:33 pm, edited 2 times in total.

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PostPosted: Fri Nov 25, 2005 9:53 pm 
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On another site, many people said that sythentic oil improved their gas mileage. What do you guys?

I swear I'm not an expert on this subject. :-P


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PostPosted: Sat Nov 26, 2005 12:48 am 
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if the car is a 5spd how about using a radiator from an automatic trans car and running the fuel through the trans cooler section to heat it up. I know it is on the wrong side of the radiator to get a lot of heat but it probably would still be over 100 degrees. I don't know what the ideal fuel temp would be but if it isn't to high that would probably be the easiest way to get some heat in the fuel.

I have an auto trans radiator I will probably start using for this purpose whenever i get around to swapping it out with the one in the car now. I figure that and routing the air intake to a hole cut in the exhaust manifold heat shield to make a hot air intake should help some.

My car has had 4 tanks of gas run through it with no mods and I have an average of 51mpg (xfi model :) so I will get those 2 mods done to it and see what happens in the next 4 tanks of gas.

The mods I plan on in the future are to change to synthetic grease in the cv and wheel bearings, synthetic gear oil, already got mobil 1 synthetic motor oil, and 10 deg cam advance when I get some warm days to mess around with the car for a while.

If you want to get extreme you could always put a water injection setup and up the compression on the engine. Then maybe fill the ports in the head to lower the size and do a port job tuning the heads for best flow at 2000-3000 rpm. This would probably also involve tuning the intake manifold a bit. I don't know if that would actually help the mileage though. All that would require a custom tune but since there are no public memory maps of the Metro computer so you could build your own tune. The easiest way to do it would be to change to a GM computer or one of the many aftermarket computers. The GM computer is compatible with a knock sensor so you could get more aggressive with the ignition timing. A lot of aftermarket computers use a wideband O2 so you can tune it much easier. Any computer would work as long as you can tune it easily and it is one you are used to working with. The Metro computer would probably be the easiest to tune for a 3 cyl but not knowing the memory locations would make it a lot of trouble to start with.

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PostPosted: Sat Nov 26, 2005 11:54 am 
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Darrell wrote:
On another site, many people said that sythentic oil improved their gas mileage.


visit mobil1.com, look around, and you won't find any direct reference to better fuel economy. you can bet they'd be promoting it if it applied to the average situation.

if you live in "extreme" (e.g. freezing) conditions it will help - a little. the viscosity of synthetics is more stable than regular mineral oils as temperature drops (regular oil thickens dramatically). so there's less internal drag (and arguably better fuel economy) with synthetics while the engine is warming up.

once at normal operating temp, though, there's likely little difference (just in terms of fuel economy) between synthetics and non-synthetics.

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PostPosted: Sat Nov 26, 2005 3:27 pm 
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Yeah, that trans cooler deal may be an idea. I'd like to know how that works when you get to it. I think i may get a cam tomorrow and an xfi computer, but not sure when i'll install it. Dont know if i want to mess with something that isn't broken-LOL!


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PostPosted: Sun Nov 27, 2005 7:42 pm 
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Coyote X wrote:
if the car is a 5spd how about using a radiator from an automatic trans car and running the fuel through the trans cooler section to heat it up...

You should make sure that it's actually capable of withstanding the pressure of the fuel system. A similar question was brought up in another thread about using the automatic transmission cooler as an oil cooler, but the problem is that it isn't designed for the 70+ PSI peaks that the oil pump generates. I wouldn't trust a tranny cooler to handle fuel pressure, unless it can be safely pressurized to at least 50 PSI.

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PostPosted: Sun Nov 27, 2005 8:58 pm 
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A neat collection of info about fuel economy. They're talking about the possibilities of a 'TT' (Tilting Trike) getting over 200 mpg with a list of examples.

Good stuff.

http://www.jestartech.com/jestar_TTW/Jestar_talk_4.html


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PostPosted: Mon Nov 28, 2005 4:12 am 
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Good link!


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