2000 GMC FastBack AeroCap Project

[Bicycle Bob]

"Does that mean that on a bike the gear ratio is listed in the opposite?

Car - drive:driven
Bike - Driven:drive

?? That's confusing, if it's true.."

If in doubt, you can do a visual check to see which end has more teeth.

[KamperBob]

Originally Posted by Fubeca

I think it is hard to compare trucks from different manufactures - especially from different eras. Your truck has lower gears - but I think it has a 5 or 6 speed transmission vs. our 4-speeed autos and may have a more efficient final drive ratio.

I agree that comparing apples and oranges is risky. I offered my case not for brand comparison but I think ~30% improvement over sticker demonstrates upside. I am using a glass t-cover which no doubt helps but I attribute more of my gains to smarter driving than better aero. I'm sure most of this crowd doesn't need lectures on optimal driving habits so in case someone was planning to read that into my message I'll nip that in the bud now.

I wish my Tundra had the new 6-speed automatic. I understand its torque converter locks in the top 3 gears! Not only good for MPGs but helps keep the tranny cool, epecially when towing. No, my '02 has a 4 speed. Compared to the '00 Jimmy they have similarities actually. That said, the danger of comparing apples and oranges stands.

I think I've bent this thread enough. My apologies for that...

Cheers
KB

[KamperBob]

Originally Posted by Bicycle Bob

"Does that mean that on a bike the gear ratio is listed in the opposite?

Car - drive:driven
Bike - Driven:drive

?? That's confusing, if it's true.."

If in doubt, you can do a visual check to see which end has more teeth.

Car/truck engines peak torque is usually above 3000 rpm.
Where is peak torque on your bicycle engine?

Cheers
KB

[Christ]

Originally Posted by KamperBob

Car/truck engines peak torque is usually above 3000 rpm.
Where is peak torque on your bicycle engine?

Cheers
KB

I think mine peaks out any place I'm going downhill, where gravity*weight is comparable to acceleration by horsepower.

The confusing part is remembering that they're stated in opposite directions, not the actual implementation.

[Big Dave]

Nice job, Chaz. You may know all the blemishes, but it looks a lot better than mine.

3.42 would give better MPG than 3.73. 3.08 would be better yet, but those are getting to be hard to find these days.

[MetroMPG]

Originally Posted by ChazInMT

I dunno if I'll take the time to A B A, but I'm very curious about how tuft testing will look so expect that within a week.

Charlie, any news? Suspense is killing me.

[MetroMPG]

Originally Posted by ChazInMT

Although I intend to start on my new cap in May when I finish up at the Nuc plants, I'll probably just scrap my current cap...

If you do that, I'm sure you could find someone here who'd take the old one.

[Christ]

Originally Posted by MetroMPG

If you do that, I'm sure you could find someone here who'd take the old one.

:raise hand:

MEMEMEMEMEME....

If only you were closer... I'd love it. It might help the 5MPG I'm getting right now! (Fuel system issues. )

[ChazInMT]

I have run 2 tanks of gas through my truck, the results are not groundbreaking. I'd expect to have gotten 14-15 mpg, and was hoping for 17 or better going 70 with the aerocap instead of 78-80 w/o. I'm only averaging 16 so far. Going through 3 more tanks in the coming days and will update as soon as I have more.

Driving from Bozeman, MT to NYC, in Fargo now. Weather wasn't too cold, 25F winds were either cross or tail 5-15, usually only 8mph, until mid ND terrain was hilly.

At this point I'll rename the 2000 GMC Sierra the "AeroPig" and unless things change, the AeroCap will be code named "LipStick".

Back to the road, update soon.

[bondo]

I'd hate to see you take your LipStick off too soon. I have run an aerocap for almost three years now. My fuel efficiency numbers always tank in cold temperatures. The air is just denser and any aero modification is not as effective. Terrain and, as you note, wind speed and direction effect fuel efficieny too.

So don't give up on you aerocap yet, which you have done a very fine job of constructing. Let the air temps warm up this spring and summer and then start seeing those 20 mpg+ runs. In a years average, you should see around a 15% increase in your fuel efficiency. Just be patient.

Bondo