Full Throttle at low RPM, or High RPM and low throttle

[theholycow]

There's a link about lugging in my sig. Technically it is when you have severe predetonation, such that you hear explosions under your hood.

With the disappearance of manual transmissions, and doubly so with the appearance of knock sensors, its meaning has shifted to be as you describe, or to be when the engine is giving you the vibrations you described, or when it's making a growling sound.

I imagine that it will go rich with the TPS measuring WOT, but then why does it have a WOT switch if it can do that?

[thecheese429]

Originally Posted by theholycow

...but then why does it have a WOT switch if it can do that?

I don't know, actually. I wish I had the documentation on my ECU, or could take it apart and tweak some settings.

I would imagine that it stays in closed loop operation (according to the speed sensor and MAP sensor, among everything else)(no, it has no MAF sensor) until the WOT switch (just a little micro switch) is closed, in which case it goes rich.


Would it be odd if I said that sometimes it seems to have more power around 60-75% throttle instead of 100%?

[JanGeo]

Just remember that those BSFC maps are good for a proper running engine. If you have bad rings poor sealing knocking faulty timing all bets are off. In the case of worn out engine heavy loading is a no no you generate more blowby increase loading on rod bearings and crank etc better to use light acceleration and rev gently if it will rev with light throttle then shift.

[machworx]

I was once told (30+ yrs) ago by a thermo teacher that in general the best mileage is obtained, all other things held constant, is low RPM & WOT providing you aren't detonating! This only makes sense because an engine is basically an air pump & the less friction getting the air thru the engine (blockage in the carb/air butterfly valve for injected engines) & low RPM for minimum mechanical friction in the engine helps maximize MPG. Think of other things that also help are low restriction air filt (K/N), 4 valves/cyl/bigger valves & low restriction exhaust system. High rpm is generally a destroyer of both mileage & engine life (diesels last 500000 miles because of their slow rpm) even though high rpm is where the HP is & the fun. Remember the HP equation has RPM in the top of the equation! Using these methods I have gotten as high as 71 mpg in my 95 civic VX & 20 in my old 97 powerstroke.

[intropiles]

Originally Posted by theholycow

Knock sensors are in every modern car.

You definitely want to avoid knocking.

Hell yeah! definitely!

[Ilikebmx999]

Originally Posted by machworx

I was once told (30+ yrs) ago by a thermo teacher that in general the best mileage is obtained, all other things held constant, is low RPM & WOT providing you aren't detonating! This only makes sense because an engine is basically an air pump & the less friction getting the air thru the engine (blockage in the carb/air butterfly valve for injected engines) & low RPM for minimum mechanical friction in the engine helps maximize MPG. Think of other things that also help are low restriction air filt (K/N), 4 valves/cyl/bigger valves & low restriction exhaust system. High rpm is generally a destroyer of both mileage & engine life (diesels last 500000 miles because of their slow rpm) even though high rpm is where the HP is & the fun. Remember the HP equation has RPM in the top of the equation! Using these methods I have gotten as high as 71 mpg in my 95 civic VX & 20 in my old 97 powerstroke.

Diesels last because they cannot incur pre-ignition(detonation). That coupled with their heavy duty build qualities makes for a very stout, long lasting engine. If they could physically rev higher there's no doubt they would from the factory but the fuel power isn't there on large diesels and the sheer piston speeds they see due to long rod stroke is why they're rpms run so low.

The main killers of engines is pre ignition and oil starvation. Lugging an engine even equipped with knock sensors is silly. Remember; knock sensors work by reading pre ignition and retarding timing to deal with it. That means the engine is still seeing knock which could still damage a bearing.