Cadwell Lap

[Ade 517]

I felt much the same about the shorter final drive after comparing mine to Dans Harrop with the shorter FD. Some corners you were in a nicer gear, others the stock was better. Felt a bit like swings and roundabouts. 

Theoretically in a straight line with instant gear changes a short FD will keep the average power to the wheels higher and therefore accelerate faster but sacrifice top speed (A supercharged car can hit the red line in 6th). 

I do think Kevin has a very good point though, gear changes do cost time so you have to factor that into the equation. 

 

 

[DanJ 374]

The best thing about the shorter FD for me is less downshifts to second required, but otherwise its definitely a horses for courses thing and where it gains in some situations/scenarios it loses in others.

[KevinA 695]

54 minutes ago, Foulsmell said:

Found this which may be of interest. It relates to the 4.88 FD but give a better indication than a bar chart I think.

 

 

4.88 would be well short and lively 

[Foulsmell 120]

54 minutes ago, Foulsmell said: Found this which may be of interest. It relates to the 4.88 FD but give a better indication than a bar chart I think.

 

 

4.88 would be well short and lively 

 

Yeah I have 4.67 on N/A car. That’s plenty. 4.88 would be too much.

[KevinA 695]

On 10/5/2017 at 9:31 AM, Foulsmell said:

 

 

 

 

 

 

Was it this?

 

 

 

 

I was interested in this, so I did a few calculations of acceleration over various speed ranges for the different final drives. There are a couple of simplifying assumptons: no wheel slip, all tractive effort is used to accelerate the car, car mass of 1240 kg, shift times are 0.5s.

 

 

 

 

58b47f66de282_GT86Acceleration.thumb.png.280e3bf7cfc1f3ff381a6a925f30c634.png

 

 

 

 

There's a lot less in it than I expected, across a variety of acceleration scenarios. Something I didn't graph that's interesting is that the fastest setup for a 40-80 pull is 4.1 final drive as you can do it in third. It;s very slightly faster than a 5.1 FD in fourth over those speeds.

Very interesting, too many variables to really say what is best. Think it will be circuit orientated and driver choice, thanks for the info.

[KevinA 695]

Roll on Snetterton, probably be wet again 

[Cerastes 204]

1 hour ago, KevinA said:

Roll on Snetterton, probably be wet again 

If it is, I will be having fun with stock Primacys sliding about all over the place. 

[GraemeI 41]

6 hours ago, KevinA said:

Roll on Snetterton, probably be wet again 

Gutted, can't make this one - will have to be next year now   

Have fun everyone!