Whats the most efficient and economical rpm range for driving in a 6th gen accord? I noticed at 2000 rpm its exactly at 55mph. But in newer cars 2000 rpm is at 70mph. I assume anywhere between 2000-2800 rpm?

 

9000rpm

Anything under 3k realistically.

 

To be at 2K at 70 would require a good overdrive top gear, and is more likely to be found in larger displacement motors (v6 v8)

There will be I4 exceptions I'm sure. Maybe one with a 6 speed tranny??

Assuming you have a 4 cyl, the most economical rpm I have ever driven my accord was at 2000 rpm/55mph yielding around 36 mpg. It was ideal conditions, a good road, and possibly with a tail wind

Usually I see around 30 mpg on the highway, and you have to remember that its not only about engine speed, but also aerodynamics. The faster you go, the more drag is working against your cars fuel efficiency...

sohc

 

i find mine works best at 120 km/h with 91 octane. That's just me. I think im running about 3k when im at it.

 

Dont bother with 91 octane. Do your research about octane and you will see it doesnt result in any increase MPG. Generally, keeping it under 3k RPM is efficient. The Accord have pretty tall gear ratios compared to other Hondas. I seen Preludes rev somwhere around 4k RPM going about 70MPH, (I think).

 

Yep, use what's recommended, the higher the octane, the more it compresses before it explodes so you really don't want to run it in your 87 recommended car.

 

my CL type S is 1500 rpm for 55mph 2K gets you 75mph. 4.2K and you have hit the fuel cutoff at approximately 150mph

my old 98 accord it was 1700 for 55 and 2K for 70

my 94 was 2800 for 70 and 2400 for 55 that car was great of gas 80 mph at 34mpg

 

To be clear about high octane fuels, as muffinman said, a high octane fuel will be able to burn with out detonating from either too high compression or excess heat. Neither of which are present on a stock engine that reccomends 87 octane.

Using 91 will not hurt your engine, only your wallet. If you are racing or other wise abusing your engine, excess heat could build up, and in that case a high octane fuel WILL prevent premature ignition (knocking/detonation/etc) and prevent resulting engine damage.

So if you're taking it to the track, go for it, otherwise, highway driving is very easy on engines and wont require excessive octane.

sohc