bolt ons that help/hurt fuel economy?
 

A few things I've been curious about if they would help FE (fuel economy/effeciency)


Header?

freeflow exhaust/catback exhaust?

converting to an electric fan from a mechanical style?

aluminum flywheel?

underdrive pulleys?

I was also curious if I were to upgrade to a high output alternator, would that hurt things any?
I would have sworn I made this post already, maybe i didnt submit it or something? :confused:

Anywho, thanks in advance.. :thumbup:

Do you know the output of your current alternator?

My tbird has a measly 75 amp alternator stock. I plan to do a "3g swap" sometime in the future, to a 130 amp unit from a 90's Ford.

The shadow has a 90 amp unit stock. It doesn't have nearly the electronics in it the Tbird has, ABS, ride control, that kinda stuff.

I'm gonna say an electric fan would definitely help you. A freer flowing exhaust might too. If you reduce the backpressure too much you will move your power band up a bit in the rpm range. Cure that with a turbo though ;). I don't know about the lighter flywheel and pullies though.

properly sized headers could help as they have smoother curves, but over sized headers will hurt you, study fluid dynamics and you will understand this better, otherwise if you look at the cars that get great gas mileage they all have smaller exhaust systems then their lower mpg brother of the same displacement engine.

An electric fan is going to be lighter, and only run when the coolant coming out of the radiator is still to hot, but converting mechanical to electrical and back to mechanical is not efficient, so it depends on if you have a big engine that is under load alot, or if you never load up your truck, in other words, if the fan is on nearly all the time then it should be mechanical, if it only comes on when you tow a trailer, or go up a mouton, then it should be electrical.

a lighter weight fly wheel gives you less torque, and makes it harder for your engine to run slower, but if your engine speed varies alot, like driving in the city, or racing where you might shift alot and rev the engine higher, then a light weight fly wheel is perfect.

under drive pulleys are designed for racing, where the engine is turning enough faster that you can afford to turn your alternator slower, they are often aluminum so they are lighter, but they are also smaller, v-belts have a minimum size pulley that they can go around, the larger the pulley they go around the looser the belt can be, and the more efficient the whole setup can be, the belt will also last longer as it's not bending as tightly, so instead of going with a smaller engine pulley, I would go with a larger alternator pulley, that is if your engine is going fast enough to keep the alternator spinning, at the minimum rpm needed to produce the voltage needed to keep the battery charged, turn it to slow and your battery will go dead, or your alternator will over heat and die a sad death.

a higher output alternator will have larger winding, and should be over all heavier duty, so it will be a little extra spinning mass, but it shouldn't ever be over worked, I don't think it will be any easier to spin, but it might last longer.

In my experience only a well-designed header will actually do much for modern engines, and even that will make very little difference. On older equipment--predating FI and ECUs--some of that stuff might make be beneficial to FE when coupled with good driving technique; however, I can only speculate on that.

A scangauge is the best bolt-, um, velcro-on accessory for the money, and probably the only one that will surely pay for itself over time.

I saw a thread on another forum where the guy gained ~4 mpg and ~70 mpt after installing a Nismo (made by Nissan) exhaust system. For him it would pay for itself in a little over 1 and a half years. Maybe someone on your tundra forum has experience with a free flowing cat back system that increased MPG for them.

an E-fan got me 2 MPG on my 4.0 v6. Well worth the money. Felt like i had more power, and after i got used to that the fuel economy went up. Quite easy to install most kits. Plus it is so much safer if ever tooling under the hood with the engine on. You are less likely to stick your fingers into and aftermarket fan as the enclosures have smaller spaces, unlike most factory ones that i've seen are more open

electric fan

Is it just large pickups and SUVs that come with belt-driven fans anymore? I'm wondering why this design hasn't been phased out, since the electric just makes more sense. I suppose this can be likened to air-cooled vs. water-cooled motorcycle designs.

In the case your car came with an engine-propelled fan, I do think the electrical replace would help.

I can't imagine mechanical fans working on anything but longitudinally mounted engines, which are really only common to trucks, SUV's, sports cars, and classic cars. They are probably still being used because they are cheap, and with a fluid clutch can still be effective/efficient.

Headers:
Any aftermarket exhaust is going to be interested in high-hp, which is not useful for hypermiling. Headers that are "tuned" to shift the torque band into lower rpm's would be useful, but they would probably have to be custom made and mated to higher gearing to be useful.

Freeflow Exhaust:
I don't see much of a benefit as under hypermiling conditions the exhaust shouldn't be much of a constriction.

Electrical --> Mechanical Fan:
Beneficial, especially if the fan is not clutched (unlikely). I've seen people switch from clutched fans to electric fans and record a mpg/hp improvement, but I bet the improvement is less than moving from an unclutched fan.

Aluminum Flywheel:
I'd like to know. :) I'd assume lowering reciprocating mass would lower friction/energy consumed, but it kills the idle and makes it easier to stall. Some first had testing would be nice...

Underdrive Pulley:
I would expect a marginal improvement in mileage, but I have no idea of the impact on the cooling or oil pump. An underpullied alternator will probably make up the speed difference by increasing field current (i.e. no MPG gain). Removing items from the circuit (alternator delete, electric coolant pump, etc.) will see bigger gains.

High-Output Alternator:
Not too sure on this. I don't know whether a larger alternator could charge a battery faster than one smaller...which is the only area I could see a decrease in engine load.

- LostCause

electric fan only

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