Efficiency Modifications

[KiwiBacon]

Originally Posted by Stale Trooper

Just my , but If you can't get it out, you can't stuff more in; Any low restriction air intake/filter is useless until & unless you also make changes to the exhaust. Headers, Low restriction mufflers, and oversized pipes are the cheapest mods for power/performance, or economy. I've been tuning both ends of the scale for almost 50 years, depending on the need and expected use of the vehicle. Trust me, I've tried just about everything, and achieving a good air flow through the engine is the whole secret, no matter what your target is.... Power, or ECONOMY.

High flow filters are not going to gain any economy or efficiency.

At cruise your engine is heavily throttled. Reducing the pressure drop at the filter just means you need to increase the pressure drop at the throttle plate.

Exhaust improvements can help if the original one is restrictive. But again at cruise the airflow through your engine is small, very few standard exhausts offer a significant restriction at such low flows.

[Ian Szgatti]

I very much like the idea of making the underside of the vehicle more areodynamic. How about the gaping wind scoops under the tail end of most cars? Wind resistance accounts for a great deal of lost energy.

The major road-block to my experimenting with this is coming up with a suitable material to work with... but you know, I can see it working well, actually, I KNOW it would work well... but where do you get a decent piece of plastic to fit perfectly where you want it too??

[curtis73]

While thats a good idea, it requires a great deal of R&D to get the aerodynamics right. You might end up making things worse or adversely affecting handling, cooling, or other things. Removing turbulence under the car can increase downforce. More downforce means more friction and can show up as lower MPG. I guess what I'm saying is; the right aerodynamics will help MPG, but the same thing won't always work in all situations. I lost measurable MPG when i lowered my car, but others have measured an increase.

[mrgamma]

Originally Posted by GreyGoose006

... and please dont inflate your tires to 100psi

You can also put Nitrogen in your tires. It improves your tire life, keeps them inflated to an optimum pressure longer, and will save you money on gas. Nothing to be worried about as it's commonly practiced by the military, Nascar and alot of service stations will do this for you.

[KiwiBacon]

Originally Posted by mrgamma

You can also put Nitrogen in your tires. It improves your tire life, keeps them inflated to an optimum pressure longer, and will save you money on gas. Nothing to be worried about as it's commonly practiced by the military, Nascar and alot of service stations will do this for you.

Waste of time and money.
Air is already 78% nitrogen.

[2.2 Straight six]

Nitrogen is only used because in the temperature ranges tyres experience, it expands less than air does.

no need on road cars, used more on race cars and high performance aeroplanes.

[mrgamma]

Originally Posted by 2.2 Straight six

Nitrogen is only used because in the temperature ranges tyres experience, it expands less than air does.

Exactly... Nitrogen will keep your optimitum inflation in your tires longer. If you feel that you can maintain the optimum pressure without the assistance of Nitrogen well then I guess your right. There would be no need for it in a road car. From what I can tell it is also a popular modification with truck companies who are concerned about thier milleage.

[KiwiBacon]

Originally Posted by mrgamma

Exactly... Nitrogen will keep your optimitum inflation in your tires longer. If you feel that you can maintain the optimum pressure without the assistance of Nitrogen well then I guess your right. There would be no need for it in a road car. From what I can tell it is also a popular modification with truck companies who are concerned about thier milleage.

No it won't.
Nitrogen will diffuse out of your tyres at damn near exactly the same rate that normal compressed air does.

In addition, people who've paid for Nitrogen won't check their tyre pressure as often and won't want to top up their tyres with normal compressed air. So they'll probably suffer from underinflation and have worse fuel economy than with compressed air.

[mrgamma]

Originally Posted by KiwiBacon

No it won't.
Nitrogen will diffuse out of your tyres at damn near exactly the same rate that normal compressed air does.

Okay... It is really easy to find countless references on a number of websites which will tell you that Nitrogen will escape diffuse from you tires more slowly... I think the popular number is 30% - 40% slower that normal air...

But if you would like a reference from a science guy then here you go...

http://mailer.uwf.edu/listserv/wa.ex...emed-l&P=11555

[KiwiBacon]

Originally Posted by mrgamma

Okay... It is really easy to find countless references on a number of websites which will tell you that Nitrogen will escape diffuse from you tires more slowly... I think the popular number is 30% - 40% slower that normal air...

But if you would like a reference from a science guy then here you go...

http://mailer.uwf.edu/listserv/wa.ex...emed-l&P=11555

You don't understand your own links.

For a start the link inside that link is from Parker.com, it is a sales brochure for a nitrogen generator to inflat car tyres with nitrogen.

Secondly.
They are discussing the diffusion rates of oxygen to nitrogen.

Air isn't 100% oxygen, it's actually 78% nitrogen and about 21% oxygen.

If it were true (but it's probably not) that oxygen travelled through rubber 30-40% faster then 30% of 21 = 6% faster.
Given that I've seen tyres stay pumped up for more than 10 years, that 6% is a pathetically small number.

But again if it were true, I could simply pump my tyres up with air, let the oxygen find it's own way out and pump them up again. By the 3rd or 4th time I'd have more nitrogen in my tyres than was coming out of that nitrogen generator in the first place.

Summary.
It's snake oil.

[mrgamma]

Originally Posted by KiwiBacon

If it were true (but it's probably not)

I understand what I referenced. It is a concerned consumer asking a chemist if there is any benefit to use Nitrogen over Oxygen. The chemist clearly says that Nitrogen will diffuse through rubber at a slower rate than Oxygen.

I am not into physics but I highly doubt that you will end up with a pure nitrogen mix if you let the oxygen diffuse from your tires... That's like saying only oxygen will be left over if you let water diffuse through rubber.

Anyways... here is another reference... to be clear... this one is a message to from a motorcyclist to conservationist asking how to best conserve the considtion of thier bike...

http://palimpsest.stanford.edu/byfor...2006/0485.html

The Conservationist says to put nitrogen in the tires to prevent the rubber from oxydizing...

You can continue to believe that Nitrogen in Tires is snake oil and that the whole world is trying to rip you off or you can do a little research and find the truth...

Hey, for $20.00 you can run your own tests...

[beef_bourito]

ok first of all your references aren't to be taken seriously, where does it say this guy is a chemist? what credentials does this conservationist have? does he have a PhD in chemistry? does he even have a bachelor's in chemistry? we don't know, therefore he can't be taken seriously. he could be some random guy with no university education that ended up conserving motorcycles somehow.

second, i'll address that whole thing you don't get about filling your tires up with air and getting nearly pure nitrogen. air is 78% N2, 21% O2. if the O2 leaks out faster than the N2, the concentration of N2 will increase. let's say, for argument's sake, that after leaking out the contents of the tire are 85% N2 and 14% O2, and that 30% of the volume leaked out. so you see that your tires have deflated by 30% so you top it up, you add air. now the concentration of nitrogen in the tire is higher than it was before because more oxygen has leaked out. over time the conenctration of N2 goes up and the concentration of O2 goes down, you refill, you now have more N2 than the previous refill. you can see how after a few refills you would have nearly pure N2 in your tire.

your example of having only oxygen left after you let water diffuse through rubber is flawed. in the case of air in the tire it's a homogeneous mixture, water is a compound, they are two very different things.

also, the reason they have nitrogen in certain applications (planes, race cars, etc) is because they need to maintain proper pressure when the tire temperature changes, they don't really care about how quickly oxygen difuses through rubber when compared to nitrogen. pressure changes when the temperature changes, and since nitrogen expands slightly (read extremely slightly) less than oxygen with temperature increases, they can more accurately tune the tire pressure. i could go into detail as to how small this difference is, but i don't feel like putting the effort in. you won't see a difference of more than 5% until a few dozen atmospheres (1 atm is about 15 psi). so you won't notice a considerable difference until a few thousand psi.

bottom line: it's a waste of money, you'll end up with just about as high a concentration of nitrogen in your tires after a few refills.

edit: i just looked at the bottom of the message to the motorbike guy, he's an intern, so at the very best he's a university student, but most likely he's got no formal post-secondary education other than restoration or something.

[INF3RN0666]

To make the bottom of your car aerodynamic, you would have to put plates along the entire bottom. HIGHLY NOT RECOMMENDED. If you have a small gap, wind will fill the pocket you create and either slow you down even more or make the car hard to handle. Spoilers supposedly help fuel efficiency, but it would have to be a test one. One that is curved up is much better than those stupid ones you see on riced out cars. It only helps at high speeds though...

If I was you, I would make sure that my breaks were properly adjusted and aren't dragging. Then I would look at bearings.

[beef_bourito]

how would a spoiler help fuel economy? it creates drag and if it creates downforce it's increasing the rolling resistance of the tires.

[mrgamma]

Originally Posted by beef_bourito

ok first of all your references aren't to be taken seriously, where does it say this guy is a chemist?

Look... I tried to keep my references to a strictly non-commerical source... All of the previous sources were from .edu's and if your going to tell me that the person from stanford was making everything up as well as the chemistry professor http://www.stolaf.edu/people/hansonr/ then keep kidding yourself...

http://www.dunntire.com/Services/Nitrogen/

Why not call up Dunn Tires and tell them they are lying?

Why should I take you seriously... Who are you??? Obviously all of these people are lying... It's a big conspiracy... Please tell me more about your in depth knowledge about aerodynamics...

EDIT: I just read your profile... your a 19 year old with a 1992 Honda accord... You must know what your talking about...