Engine rumble

[Cleartec]

When ever I drive I try to follow the computer for best fuel economy possible. The point is even on hills the computer recomends shifting into 5th gear while driving 60 km/h arounnd 2000 rpms but if I do that the engine will do a lot of rumble noise. Isn't this rumble bad for the engine?

[Daox]

Yes, I would say rumbling or lugging here as we call it is bad. It creates very strong vibrations in the engine and that can't be good. I would downshift.

[Cleartec]

Yes, I would say rumbling or lugging here as we call it is bad. It creates very strong vibrations in the engine and that can't be good. I would downshift.

So you can't drive economiacally then

[Daox]

You certainly can drive efficiently (despite what the eco light tells you). Most engines actually prefer a slightly higher rpm IF the engine is fairly loaded. Here is an example of the Geo Metro's G10 1.0L engine brake specific fuel consumption chart. It shows how fuel is burnt per how much power it puts out (smaller number is better). You'll notice the engine actually produces the most power for least fuel burnt around 3000 rpm. If you look at BSFC charts for other engines generally 2500 - 3000 rpm is where they are the most efficient.

Unfotunately, we don't have a BSFC chat for the 3A90 or 3A92 to 100% verify this, but I'm quite sure it is true based off of the other BSFC charts I've seen.

http://ecomodder.com/wiki/index.php/...on_(BSFC)_Maps

[Cleartec]

wow thank you buddy. I have seen these charts t uni but never knew that it was burnt fuel per kwh, know I get the chart. thank you very much btw if you get another chart for mirage plz keep me updated

[Cleartec]

You certainly can drive efficiently (despite what the eco light tells you). Most engines actually prefer a slightly higher rpm IF the engine is fairly loaded. Here is an example of the Geo Metro's G10 1.0L engine brake specific fuel consumption chart. It shows how fuel is burnt per how much power it puts out (smaller number is better). You'll notice the engine actually produces the most power for least fuel burnt around 3000 rpm. If you look at BSFC charts for other engines generally 2500 - 3000 rpm is where they are the most efficient.

Unfotunately, we don't have a BSFC chat for the 3A90 or 3A92 to 100% verify this, but I'm quite sure it is true based off of the other BSFC charts I've seen.

http://ecomodder.com/wiki/index.php/...on_(BSFC)_Maps

But again I thought driving with the lowest engine speed as possible gave the best fuel consumption, am I wrong?

[Daox]

You are correct, most of the time. However, once you start lugging your engine you can cause damage if its done for extended periods.

[Cleartec]

I will try a different driving style to see how economy goes

[MetroMPG]

Worth repeating:

generally 2500 - 3000 rpm is where they are the most efficient

Note: that's UNDER SIGNIFICANT LOAD (accelerating or climbing). Not when cruising, eg. under light load. When cruising, choose the lowest non-lugging RPM (highest gear possible).

[Cleartec]

Worth repeating:



Note: that's UNDER SIGNIFICANT LOAD (accelerating or climbing). Not when cruising, eg. under light load. When cruising, choose the lowest non-lugging RPM (highest gear possible).

excactly what I thought to do