Honda Civic VX?...better MPG by NOT clutchless coasting?

[NachtRitter]

If you are bump starting (clutch starting) in such a way that you are putting more stresses on the engine than you would using the electric starter, then you are not bump starting correctly. Likewise with the wear on the clutch, input shaft, etc compared to down shifting (unless of course you don't ever down shift, or you double-declutch & rev match on every downshift). Bump starting can be done in a way that the engine would not know the difference if it is the key starting the car or the clutch.

[ksa8907]

Originally Posted by jeffcat

I don't like clutch induced starting an engine as it puts a tremendous amount of stress on the clutch, input shaft, and especially the engine itself, before the oil pump can keep back up with the pressure of immediately starting the engine. If it had a built in racing style oil accumulator, then perhaps I would consider it, but I just find it to be less practical to save $500 doing that then spending $800 on a new engine, but that's just me. To each their own.

Bump starting isn't going to hurt anything. Its no different that using the starter.

[jeffcat]

Originally Posted by NachtRitter

If you are bump starting (clutch starting) in such a way that you are putting more stresses on the engine than you would using the electric starter, then you are not bump starting correctly. Likewise with the wear on the clutch, input shaft, etc compared to down shifting (unless of course you don't ever down shift, or you double-declutch & rev match on every downshift). Bump starting can be done in a way that the engine would not know the difference if it is the key starting the car or the clutch.

This is true, but the starter turns the flywheel at a much slower rate than bumpstarting. Also, oil accumulators are designed for engines when they are starting, because that is where you are doing the most damage to the engine...also why on the Civic, you don't get instantaneous start and the engine will cycle before it starts...partially to establish some degree of oil pressure.

You might say it doesn't do more damage than starting an engine, and that might be true, but if you are doing this on a CONSTANT basis on your daily commute, it adds up over time and you are having more metal to metal interaction due to the lack of oil pressure via the oil pump not already pumping(engine off). That fractional time difference between the engine running and the oil pressure resustaining itself adds up over time which is why oil accumulators were developed. I'm actually considering putting an oil accumulator on this VX if I can get around to it just to increase the life of the engine.

[slownugly]

With True bump starting after it starts you push the clutch back in and then rev match to speed then let the clutch out. After practic it can be done extremely quickly and it won't even be physically notable.

Oil changes are worse than bump starting. I've seen some vehicles take 2-4 seconds til they get oil pressure after putting a new filter on.

To each his own I guess. Like I said I don't eoc in my vx because it can't instantly engage lean burn after restart and I don't like that. I really need to get the Mpguino then I could do better testing with it.

[NachtRitter]

Originally Posted by jeffcat

This is true, but the starter turns the flywheel at a much slower rate than bumpstarting. Also, oil accumulators are designed for engines when they are starting, because that is where you are doing the most damage to the engine...also why on the Civic, you don't get instantaneous start and the engine will cycle before it starts...partially to establish some degree of oil pressure.

You might say it doesn't do more damage than starting an engine, and that might be true, but if you are doing this on a CONSTANT basis on your daily commute, it adds up over time and you are having more metal to metal interaction due to the lack of oil pressure via the oil pump not already pumping(engine off). That fractional time difference between the engine running and the oil pressure resustaining itself adds up over time which is why oil accumulators were developed. I'm actually considering putting an oil accumulator on this VX if I can get around to it just to increase the life of the engine.

Fair enough. Would be interesting to see what you come up with.

[basjoos]

Originally Posted by slownugly

Basjoos- my afr gauge shows a richer ratio when I coast in neutral as compared to dfco in 5th. Maybe your aerodynamics play a role. Are you still runnin the p07-g01 ecu? If so do you run 87 octane with it? I picked one up on eBay from Europe but I haven't tried it yet.

When idling, the engine runs at normal fuel:air ratios, but it uses so little fuel when idling that the mileage shows 150+ mpg while coasting at any speed over 15mph. Still running the p07-g01 ecu. I run 87 octane with it.

[slownugly]

Originally Posted by basjoos

When idling, the engine runs at normal fuel:air ratios, but it uses so little fuel when idling that the mileage shows 150+ mpg while coasting at any speed over 15mph. Still running the p07-g01 ecu. I run 87 octane with it.

Oh ok. I really have to get a Mpguino hooked up. My afr gauge is the only instrumentation I have. When I dfco it pegs out at 21.9 which is the lean limit on my gauge. If I pop it in neutral on the same hill it will go to 21.5 then slowly get richer and richer the longer it stays in neutral. Sorry hope I'm not thread jacking.

[basjoos]

In dfco, the afr gauge would of course be showing lean since the injectors are off and the air fuel ratio would be at ultimate leaness. Idle is at the normal 15:1 ratio, so if you dropped off a lean burn cruise into idle, the afr would drop from the lean burn 21 to the idle 15.