Reading KM to MPH and when to shift

[Anonymous]

So I've made a little picture that kinda explains what gear to be in and converts the Km to mph on the speedo of a skyline. Does it look correct? Im using this as future reference. (If i manage to buy an r32)

[Anonymous]

Oops just realized the 70mph is off. its on 10 instead of 15.

[GTofuS-T]

sure, this might be an appropriate granny shifting guide...but i wouldn't buy a skyline to granny shift it unless it's snowing

[GTSBoy]

Don't worry about the shifting guide. You can change up at any speed between idle and redline. The only question after that is whether it will have enough torque to swallow much throttle opening in the next gear> RB20s have little torque, so the answer to that question will be "no" unless you're above about 3k rpm. And just to the right of the speedo is the gauge that will tell you about that.

The km to mile conversions are correct enough. Everyone since forever has treated the conversion as 40=60, 50=80, 60=100 and 70=110, to within the accuracy that matters.

[Murray_Calavera]

Great excuse to by a sexy aftermarket dash and set it to MPH.

[BK]

When to shift. The threads keep getting better and better around here....

[Ben C34]

I normally just count to 3 then shift, seems to work.

[GTSBoy]

I wait until the wheelspin stops.

[joshuaho96]

For efficiency shift based on the peak efficiency RPM, shift just past the peak efficiency point while maximizing load without encountering high load enrichment so you sweep through the efficiency sweet spot. Looking at the gearing of the GTRs it looks like you want to be shifting at 3000 RPM so you drop down to ~2000 RPM when accelerating. Hold the engine right around 50-60% throttle if this is an NA engine or right at atmospheric pressure for turbo engines for best results.

For cruising pick the highest gear that doesn't have you exceeding the accelerating throttle condition. As for the best speed to cruise at, something high enough that you aren't running below 2000 RPM and something low enough that you don't exceed 3000 RPM.

[Ben C34]

Hahahaaha

[Murray_Calavera]

7 hours ago, joshuaho96 said:

accelerating throttle condition

please explain this condition of accelerating throttles. 

[r32-25t]

Why are we talking about trying to be fuel efficient with a skyline, if you want to be fuel efficient buy a Hyundai i30!!

[GTofuS-T]

especially considering petrol is dirt cheap thanks to corona

[niZmO_Man]

On 22/03/2020 at 9:15 AM, r32-25t said:

Why are we talking about trying to be fuel efficient with a skyline, if you want to be fuel efficient buy a Hyundai i30!!

no, you want a Kona or Ioniq electric/hybrid

[r32-25t]

Then you can be an arrogant flamin mongrel on top of saving fuel lol

[joshuaho96]

On 3/21/2020 at 3:01 AM, Murray_Calavera said:

please explain this condition of accelerating throttles. 

It's simple, it's the condition where you are accelerating with the throttle.

[Piggaz]

3 minutes ago, joshuaho96 said:

It's simple, it's the condition where you are accelerating with the throttle.

How do you accelerate without using the throttle... unless rolling down a hill? ?

[joshuaho96]

3 minutes ago, Piggaz said:

How do you accelerate without using the throttle... unless rolling down a hill? ?

Very carefully?

Jokes aside the point is that lugging the engine at 1500 RPM and WOT to cruise is going to actually be quite inefficient even if the pumping loss is minimized. It's better to cruise at 2500 RPM with less throttle. The exact numbers are going to vary by engine but the principle is the same.

[GTSBoy]

I have decided to not participate in this discussion any further. Please consider this an act of social distancing, to prevent the risk of infection.

[Murray_Calavera]

1 hour ago, joshuaho96 said:

Very carefully?

Jokes aside the point is that lugging the engine at 1500 RPM and WOT to cruise is going to actually be quite inefficient even if the pumping loss is minimized. It's better to cruise at 2500 RPM with less throttle. The exact numbers are going to vary by engine but the principle is the same.

Can you explain how you came to this conclusion? 

I am interested in the math and any other data you are relying on to make this statement.