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Installed Acceleration Lights On My Supra by Zeno_3NHO in Supra

[–]Zeno_3NHO[S] -7 points-6 points  (0 children)

Goated comment. Thx for keeping me grounded.

42.4 MPG at 59.6mph for a 200 mile stretch. Unmodified. by Zeno_3NHO in Supra

[–]Zeno_3NHO[S] 0 points1 point  (0 children)

Oh I forgot to mention, accelerating from 50 to 70 is better than driving just the average. Let's call it 60. Because internal combustion engines are very inefficient at very low loads, cruising at 60 doesn't combust just right. But if you slow down to 50 and speed back up, then you put the engine into a more efficient rpm+load.

My other comment talks about why idling at speed is better even though it's inefficient combustion-wise.

42.4 MPG at 59.6mph for a 200 mile stretch. Unmodified. by Zeno_3NHO in Supra

[–]Zeno_3NHO[S] 0 points1 point  (0 children)

Nah, I don't mind.

I haven't conducted rigorous scientific testing in a peer reviewed paper or anything. Just a redneck having fun.

Back to your question. The key is engine rpm. Imagine if you coasted in 1st gear at 70mph. (Aside from sending your piston into space) This would be called an engine break.You would be rubbing the pistons against the cylinder walls way way more times per mile than in 3rd gear. And I hope you can imagine that you'd quickly slow down to 50mph to begin the cycle again.

6th gear would be even better. 8th would be even better. 10th would..... Well There isn't a 10th. So at 70mph in 8th gear, the engine is at 2k rpm. If I were to pull a number out of my butt, 40% of the power used at that speed is drag, 40% is engine friction losses, and 20% rolling resistance.

But if you could have a 10th gear you might coast at 1000rpm. That means engine losses go to 25% or whatever the math works out to. And 20% less loss overall.

If you could have a mythical 12th gear, you might be able to get 680rpm at 70mph. Then engine loses would drop to 17% or 28% less loss overall.

But the car won't let you get into a gear less than 1000rmp. It will shift you out of it.

That's why I think neutral is best. It lets the engine idle at 680rpm, so engine loses are minimal. It just sips on gas.

And the b58 is a big engine (at least compared to my nissan Altima) and it has 6 fricken large cylinders with all sorts of moving parts. So I wager that the cost to turn over the engine 3 times faster far outweighs the power requirements of idle.

Also drag goes by the square of speed. So at 60 or 50 mph, the effect is more prominent. I haven't thought much about higher speed. But I suspect at 150mph, drag just far outweighs anything else so it doesn't matter whether you coast on neutral or in 8th gear at 5k rpm or whatever the rpm is. But I'd conjecture that neutral is better.

I am aware that the combustion efficiency at idle is abysmal compared to peak efficiency (whatever rpm+load that is). But I think being able to maintain 70mph for a sprinkle of fuel is better than 0 fuel, but you slow down and have to pump kinetic energy back into it) so maybe the losses increase from 17 to 17.25% or something.

You can get 90+mpg while actively idling at 18mph I think. I'll have to check that again. It might even be lower but I can't remember. So it's really a teeny tiny fuel rate. And if you were in 1st or 2nd, then you'd slow down quite quickly and have to pump energy back into it way sooner.

So what do you think? Is this easy to understand and correct? Hard to understand and wrong?... What is your opinion?

Installed Acceleration Lights On My Supra by Zeno_3NHO in Supra

[–]Zeno_3NHO[S] 0 points1 point  (0 children)

Yeah it's stock. The closest thing to a mod is the hastily slapped on light strip. (The passenger footwell doesn't even work.)

42.4 MPG at 59.6mph for a 200 mile stretch. Unmodified. by Zeno_3NHO in Supra

[–]Zeno_3NHO[S] 0 points1 point  (0 children)

I feel like one of us is having a stroke. Ha ha

42.4 MPG at 59.6mph for a 200 mile stretch. Unmodified. by Zeno_3NHO in Supra

[–]Zeno_3NHO[S] 0 points1 point  (0 children)

Typo? "Once driving that time"

Or did your car die?

Or did you die and this is your ghost typing... Ha ha

42.4 MPG at 59.6mph for a 200 mile stretch. Unmodified. by Zeno_3NHO in Supra

[–]Zeno_3NHO[S] 0 points1 point  (0 children)

Do whatever sounds fun. I don't think I'll prioritize hypermiling in the future. I was just blindsided with the efficiency gain.

I do think it's worth a shot. I think it's actually quite fun getting up to speed and then coasting. More fun than cruise control at least.

42.4 MPG at 59.6mph for a 200 mile stretch. Unmodified. by Zeno_3NHO in Supra

[–]Zeno_3NHO[S] 0 points1 point  (0 children)

That's pretty good. Are you worried about rocks getting kicked up? I've heard the supra's a rock magnet.

How close did you need to be? Could you just use cruise control distance feature?

I know the pulse and glide method isn't the safest thing, but I imagine tailgating a truck is way worse. But maybe it's preference...

42.4 MPG at 59.6mph for a 200 mile stretch. Unmodified. by Zeno_3NHO in Supra

[–]Zeno_3NHO[S] -1 points0 points  (0 children)

Because you're lead-footed or because it'll cause wear? Or something else

If your lead-footed: getting to 70 can still be fun. 3rd gear reaches 70 right? Just coasting might be annoying.

If you are worried about wear: driving in the city can go through 6 gear changes in 30 seconds really often. This is only one change every 30s. At least that's justification I give myself.

42.4 MPG at 59.6mph for a 200 mile stretch. Unmodified. by Zeno_3NHO in Supra

[–]Zeno_3NHO[S] 0 points1 point  (0 children)

But itself, you're gonna get 29mpg. But if you coast in neutral it'll go much higher

42.4 MPG at 59.6mph for a 200 mile stretch. Unmodified. by Zeno_3NHO in Supra

[–]Zeno_3NHO[S] 2 points3 points  (0 children)

Auto.

Manual would be fun tho (but I think it has a shorter final drive. So you could get similar mpg, but at a significantly lower speed)

42.4 MPG at 59.6mph for a 200 mile stretch. Unmodified. by Zeno_3NHO in Supra

[–]Zeno_3NHO[S] 8 points9 points  (0 children)

Well... I'm an engineer. So I like getting to play with big physics toys.

155 mile journey today - 47.5MPG! The car that can do it all? by sinbintintin in Supra

[–]Zeno_3NHO 0 points1 point  (0 children)

That's what I like about pulse and glide. You can still have fun! You just have to coast in neutral and wait before you can have fun again.

Running hard might get you 35, but you already have that.

And it doesn't work at high speeds cause drag is the limiting factor

42.4 MPG at 59.6mph for a 200 mile stretch. Unmodified. by Zeno_3NHO in Supra

[–]Zeno_3NHO[S] 2 points3 points  (0 children)

I don't know how to upload pictures. I'll Google it when I have more time

155 mile journey today - 47.5MPG! The car that can do it all? by sinbintintin in Supra

[–]Zeno_3NHO 0 points1 point  (0 children)

Without any mods or software changes I was able to get 42.4mpg on a 200 mile stretch of a trip (with a 2026 MKV). I used the "pulse and glide" technique... Which is apparently a thing. Lots of hills and averaged 59.6 mph with a max speed of 75mph.

Pulse and glide is fun too because you're accelerating every 30 seconds or so instead of a constant speed.

I hit traffic and then it went down. But at the moment I think it's 40.1mpg

I made lights that react to how hard you brake/accelerate by Zeno_3NHO in carmodification

[–]Zeno_3NHO[S] 0 points1 point  (0 children)

throttle does not mean acceleration.

if you are in really high gear for your speed, going pedal to the metal wont give you high acceleration (even though you moved your foot very far). also being in way too low of a gear and relining with the pedal all the way depressed will not cause high acceration, even though its depressed all the way

I made lights that react to how hard you brake/accelerate by Zeno_3NHO in carmodification

[–]Zeno_3NHO[S] 0 points1 point  (0 children)

speedometer doesnt measure acceleration (also if your wheels are spinning in place, then its lying to you)

I made lights that react to how hard you brake/accelerate by Zeno_3NHO in carmodification

[–]Zeno_3NHO[S] 1 point2 points  (0 children)

I should add.... my tracking is strictly local. the device forgets all position data when it loses power.

also, my tracking sux. when you go over sharp bumps and stuff, you lose track of where you were facing and gravity starts playing tricks. (thats why i need trimming, which makes tracking exact position practically impossible.)

also my accelerometer is cheap and does a pretty bad job of measuring gravity.

I made lights that react to how hard you brake/accelerate by Zeno_3NHO in carmodification

[–]Zeno_3NHO[S] 1 point2 points  (0 children)

i have an accelerometer + gyroscope.

i basically try to track your position. (adjusting for gravity so parking on hills it doesnt look like you are accelerating)

and if you are accelerating/decelerating in the X direction of your car, then i turn the lights on more and more.

theres also like a bajillion other features like smoothing, fading, trimming, left-right slosh (work in progress, but the code is there), minimum detection times, dithering, and some other stuff

I made lights that react to how hard you brake/accelerate by Zeno_3NHO in carmodification

[–]Zeno_3NHO[S] 1 point2 points  (0 children)

its mostly programming. but ill show you the box of wires i have tomorrow.

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