P&G freeway tested ABAB +14% FE

[d0sitmatr]

Originally Posted by toc

I was trying pulse and glide today on the freeway, I'd accelerate to 105kM/hr, and stick it in neutral leaving the engine on (at those speeds I think engine off coasting is disturbing), it doesn't take long for it to drop to 90kM/hr, and then I need to get back up to 105.

That's what I thought a Pulse and glide cycle was - if so, what am I doing wrong as surely, you aren't sitting there on the clutch every 15 seconds engaging gears (or in EOC, starting the engine)?

its how I PnG, run it up to speed then coast with the car in neutral until Im 5-7 under, rinse repeat.
I did this behind a fairly large truck that was running 5 under, and I think I averaged close to 50% increase, but I did it only because I was in a bad spot when my fuel light came on with no recourse but PnG or run out of fuel

[California98Civic]

Originally Posted by d0sitmatr

I did this behind a fairly large truck that was running 5 under, and I think I averaged close to 50% increase, but I did it only because I was in a bad spot when my fuel light came on with no recourse but PnG or run out of fuel

Impress your friends and family by saving them from standing on the shoulder! Thanks for all the responses and questions guys. I went through and tried to respond to each below:

“Is the whole course uphill?”

No. It is mostly uphill. Possibly 1.5 of the 5.7 miles are flat with a slightly descending grade. Two are flat/mild and one is a pretty good but short favorable hill. There are three sections of steep hills. In general I am climbing from near sea level to several hundred feet during this 5.7 mile run.

“What is a typical glide time between pulses?”

Sorry, but I have never tried to track that. But it is definitely shorter running uphill than down.

“Just to clarify, engine is on the whole time, right? Also how did you measure engine load, is it a scangauge function?”

The engine is on the whole time because that is safer for me, the car, and everyone at highway speeds. I use an Ultra Gauge, which offers a load reading, but I hear Scangauge does too.

“Ahh: Found this: Introducing "LOG"”



“Still, how does that work on hills exactly?”

I will accelerate uphill and see 25mpg numbers on the Instant MPG readout but even gliding uphill with the engine on in neutral the instant MPG reading shows numbers like 234mpg at 65mph. So, gliding uphill my average trip FE starts to climb again. But don't be fooled. My average between accelerating uphill and gliding uphill goes down still, just not as fast or as far. The gains on the shorter flat and slightly descending sections are high enough to fully compensate--even though the flat sections are shorter than the uphills.

“P&G is currently defined as accelerating at higher engine loads, followed by coasting with the engine turned off. Restart and repeat.”

I did not know only engine off was considered P&G here. Thanks.

“The only difference is he is leaving the engine running instead of shutting it off during the glide.”

Yup.

“You could use PNG-on and PNG-off to differentiate.”

Sounds good to me. GLEN was just my mnemonic device, and it carries one piece of info P&G lacks. I wanted a name that carried a reference to DWL in it. Doing a P&G, as you know, without high load, will not accomplish much other than wear-out your foot.

[Fat Charlie]

California98Civic, I don't think you're giving P&G enough credit. I don't think you can get a legitimate "A" run anymore when the mod you're deleting is your driving style.

My first hypermiling tank was 20% better than my last non-hypermiling tank, and I didn't start hypermiling until 1/4 way into that tank. The last bad tank read 22.8 on the car's display, a good tank for me back then. The tank with P&G added read 27.5 and I wasn't even good at it yet.

[euromodder]

Originally Posted by toc

I was trying pulse and glide today on the freeway, I'd accelerate to 105kM/hr, and stick it in neutral leaving the engine on (at those speeds I think engine off coasting is disturbing)

So I thought as well.
But you quickly get used to it

it doesn't take long for it to drop to 90kM/hr, and then I need to get back up to 105.

That's where low rolling resistance tyres, pumped up to high pressure, and aerodynamic modifications come into play.
They'll greatly increase the glide portion.

surely, you aren't sitting there on the clutch every 15 seconds engaging gears (or in EOC, starting the engine)?

That's exactly what quite a few folks on ecomodder are actually doing

Restarting the engine is often done by briefly letting out the clutch again in high gear (5th), then shift into the appropriate gear for the speed.
(Saves wear on the ignition keyhole.)

[Fat Charlie]

Originally Posted by euromodder

That's exactly what quite a few folks on ecomodder are actually doing

Yep. The more performance you want out of your car, the more effort you've got to put into driving it.

toc- What's wrong with having to change gears? What's so disturbing about EOC at higher speeds? I feel safer then because the car is easier to steer and bump starts don't need the brief mental pause to pick the right gear.

[toc]

toc- What's wrong with having to change gears? What's so disturbing about EOC at higher speeds? I feel safer then because the car is easier to steer and bump starts don't need the brief mental pause to pick the right gear.

You'll lose brake booster function (which is from the vacuum of the engine).

The increased wear on the clutch and engine from many restart cycles (and at every 15 seconds or so, that's a lot of cycling on / off of the engine). I remember reading somewhere also the electrics can be sensitive to the rapid voltage changes that can occur by bump starting (because the voltage can bounce around a bit when starting whilst moving).

That might damage the ECU for example?

[Daox]

Plenty of us here have been using P&G for years on our vehicles. Most cars get a good 3 pumps on the brake before you run out of vacuum. Enlarging the vacuum reservoir is also quite easy to do with some PVC pipe. Most people don't bother though since 3 pumps is normally plenty. The wear on the clutch is quite minimal if you learn the proper technique. The electronics stuff isn't an issue. I've never heard of anyone having any problems with it. If it is an issue, delete the alternator!

[Fat Charlie]

The first time I lost power brakes when I needed them, I learned everything I needed to know about the problem. Power brakes or no, you want a healthy buffer in front of you so that you don't have to use the brakes period. That alone makes it safer, and once you've learned how much power assist your car stores then the problem is solved.

Increased wear on the clutch is only a factor if you should really be driving an automatic. The only clutch I've ever needed to replace was the one that got drenched with oil when the rear main seal went. The voltage problem with starting while moving makes so little sense that it doesn't even count as wrong. The engine doesn't know or care where the force that starts its crankshaft spinning comes from, and a good bump start is more gentle on the engine than using the starter motor: watch the tach the next time you start it with the key and note how high it jumps before it drops down to idle. A bump start is more of a nudge- it gets things moving and the engine climbs up to idle speed.

Most of my glides are with the engine on, but on the long ones I shut it off. Long downhills, stretches with tollbooths or almost certain stops at the end and the like. I'm not constantly bump starting, but I am constantly in and out of gears.

[deathtrain]

I dont mind if i lose brake vacuum. I just sold my 65 olds delta 98. it had all wheel drums breaks. was a good car and it floated at 60mph

[PaleMelanesian]

I did a cross-country trip last month, from LA to Savannah GA. Pulse and Glide the whole way. There were two of us driving. We checked one segment and we were doing about 2 cycles per mile, so the 2,500 mile trip took about 5,000 P&G cycles. Yeah, that's a lot. We also got 63 mpg crossing the country in a brand new Fiesta. P&G works.