VX at higher speeds

[siray13]

I have a 95 vx, I have been into hypermiling for sometime now, and have always figured stick to lower speeds, 5 miles below speed limit, have tried many techniques to improve mileage, have had it as high as 68 MPG but usually it's around 60. I thought I would take a break for my last tank and just drive at higher speeds just to see how much worse it got, I still used many basic techniques, but I mainly stuck to keeping the throttle position as constant as possible. I averaged around 80mph on more then 3/4 of this tank and achieved 63mpg. I don't think you would normally see an improvement on most cars by increasing speeds but perhaps the higher speeds with motors that have lean burn activation preform better? Has anyone ever looked into this?

[Vince-HX]

What rpm is your engine running @ doing 80 mph?

Leanburn will not activate if the engine is above the vtec-e engagement point, with both valves opening there isnt enough swirl inside to support uber lean mixtures. When driven above the vtec point the engine will return FE like a normal civic.

My hx has a EX tranny and I can only use leanburn to about 65 mph because of my shorter gearing.

One thing about leanburn is that is dislikes any rapid increase in throttle. In fact I read an article about someone who made a circuit to smooth the tps voltages the ecu was seeing and on the Insight it worked pretty well.

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[Raysp30]

Originally Posted by Vince-HX

What rpm is your engine running @ doing 80 mph?

Leanburn will not activate if the engine is above the vtec-e engagement point, with both valves opening there isnt enough swirl inside to support uber lean mixtures. When driven above the vtec point the engine will return FE like a normal civic.

My hx has a EX tranny and I can only use leanburn to about 65 mph because of my shorter gearing.

One thing about leanburn is that is dislikes any rapid increase in throttle. In fact I read an article about someone who made a circuit to smooth the tps voltages the ecu was seeing and on the Insight it worked pretty well.

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I think that 95 VX has a 5th gear tranny swap from the CRX HF, which means it is VERY tall gearing. If I remember from my HF, the RPM for 80 mph is roughly 2400. So, If you're still in lean burn, it would make sense that the lean burn would continue to increase, up until the engagement point you described above.

I think what siray13 needs to do is get himself a MPGuino and run some tests...

[MazdaMatt]

Holy crap. At 2400rpm in 5th I'm only doing about 95km/h, approx 57mph (?)... HF is TALL!

[SVOboy]

I doubt you're benefitting from driving faster. My MPGuino on the d15z1 shows a pretty clear drop off with increased speeds. Lots of other factor could be in play.

[siray13]

what are the constraints for lean burn? This transmission does not have the hf 5th gear, I am around 3k RPM at 80. I don't think the tps filter does much for a honda insight in regards to keeping it in lean burn, atleast if you're driving it right, I can manage well above 90mpg at 60 mph and over 120 in the city holding tps constant on an insight. My throttle position was almost constant on this last test, I am trying it again on this next tank.