Shift Timing.

[Erik86]

Good day forum users.

So since I'm fairly new to this forum I have some feedback regarding shift timing and would also like some input on this subject.

So on my first tank of gas I managed 479 miles (12 gallon tank). This was done with shifting at 2000 rpm.

Second tank I managed 500 miles. This was obtained by shifting at 2500 rpm.

I will next shift at 3000 rpm to see what happens. Seems like shifting too early or too short has a negative effect of fuel consumption.

My questions are:

1) Can shifting at 500 rpm higher make such a huge different in distance traveled?

2) Maximum torque for my vehicle is 4000 rpm. Is there any benefit at shifting at max torque rpm (higher rev range) or shifting at lower rev range but having less torque to propel the vehicle forward?

Regards.
Erik.

[iamnotahippee]

If you shift at even 2500 rpm, you are never getting near your part curve. Peak hp is be at even higher rpm. Let that baby rev and get the most of it. While accelerating, let it rev, but shift up at cruising.

[ksa8907]

I have noticed that of the bsfc charts i have seen, peak bsfc is typically tucked just below (200-500 rpm) the peak torque of the engine.

But this is just a trend, not definite. If you have a way of watching injector pulse width that would help you a lot.

[Erik86]

Thanks guys. Will be experimenting a bit more and keep you guys posted.

[Xist]

Baltothewolf has said at least once:

when I went from shifting at 2250 to shifting at 2750-3k I gained 3mpg.

http://ecomodder.com/forum/showthrea...tml#post446061

[UFO]

Your torque peak is 4000 rpm? That sounds strange, most engines I've looked at peak around 2600-3300 rpm. Is it because I'm in the US and used to large displacements? My Toyota 22RE peaks at 2700....

Edit: Just looked at Honda engines, looks like torque peaks around 4000 rpm, little more. Ok, never mind.

[ninetynineSC2]

My torque peak is even higher, around 4800. HP peaks at around 5600.

[user removed]

Generally I find that moving with the flow of other accelerating traffic is good with staying in your lowest gear while moving with traffic flow is best. Faster and you invite attention, slower and you suffer the "proctologist tailgater" syndrome.

regards
mech

[Erik86]

Originally Posted by UFO

Your torque peak is 4000 rpm? That sounds strange, most engines I've looked at peak around 2600-3300 rpm. Is it because I'm in the US and used to large displacements? My Toyota 22RE peaks at 2700....

Edit: Just looked at Honda engines, looks like torque peaks around 4000 rpm, little more. Ok, never mind.

I guess that could be the case. SA is quite littered with small cc 4 cylinder cars, mostly naturally aspirated so torque peaks are high. Other issue we have living in Johannesburg is that we are situated about a mile above sea level which leads to N/A cars losing some power compared to forced induction engines.

[superrick]

I am sure there is a optimal shifting rpm range for every car. find it and add that technique to your overall fuel economy methods.