Jap V Borgy ratios

[balemo]

Hi Guys im new here.
I have been searching here for hours and cant find this info.
Been racing a sigma on speedway for years and about to do engine upgrade fron 2lt astron to a 2.6 wide astron

What im after is the ratios of the 2 gearboxs so i can work out total gearing.
Really only need 2nd gear ratios as we only run in 2nd ..Also is the Jap box as strong as the BW??

[Superscan811]

Hi balemo,

The jap box's are stronger than the BW.

If you are making a fair bit of torque, a gearbox out of a 4g54 triton (2wd), 4g54 pajero (2wd) or a Starion would be a good option as the gears are physically wider AND they run tapered roller bearings on the bottom lay-shaft rather than a double row ball bearing and needle roller.

Of the ones below, the KM132 out of the triton/pajero/starion are the strongest.


BW 4 speed
1st - 3.65
2nd - 1.97
3rd - 1.37
4th - 1.000
5th - na
rev - 3.66

Jap 4 Speed (KM110)
1st - 3.525
2nd - 2.112
3rd - 1.442
4th - 1.000
5th - na
rev - 3.867

BW 5 speed
1st - 3.65
2nd - 1.97
3rd - 1.37
4th - 1.00
5th - 0.86
rev - 3.66


Sigma/Scorp (KM132)
1st - 3.369
2nd - 2.035
3rd - 1.360
4th - 1.000
5th - 0.856
rev - 3.635

Starion/Triton/Pajero. (KM132)
1st - 3.369
2nd - 2.035
3rd - 1.360
4th - 1.000
5th - 0.856
rev - 3.578


Cheers.

[balemo]

Thanks for that.

Thats great info.
Yeah im putting in a high comp methanol holley 2.6 so im hoping to have 150+rwhp and plenty of torque.
As a side note that is important in this discussion i suppose.

We have been spinning the 2ltr to 7500+ for years..Is the 2.6 going to take those sort of revs.??

[Superscan811]

My last engine build was making 133 rwhp on E10 fuel and around 9.6:1 comp. Stock internals, just a Magna M7 head (they flow a lot better than the others), a set of genie headders and a set of 4x38mm carbs off a 750cc motorbike. It worked well.

cheaterparts has a 2.6 astron making 160rwhp and spinning above 7000rpm. He uses twin 45's with custom choke tubes.

Hope this info helps.

Cheers.

[balemo]

Yeah thanks mate..Been running the same thing so long and everyone else is getting faster except me..time to kick some ass again.Sigma Style.

[cheaterparts]

Hi Guys im new here.
I have been searching here for hours and cant find this info.
Been racing a sigma on speedway for years and about to do engine upgrade fron 2lt astron to a 2.6 wide astron

for any form of racing I would use the narrow pattern 2.6 - it lets you get away with a smaller dia flywheel ( lighter ) and the 2.6 works a shit load better if you can get some weight out of the crank/flywheel

there is a lot of weight in a 2.6 flywheel + they are a 12" dia where as a 2 lt flywheel is 10 1/2 " there is a lot if a reduction in moments of inertia by just using the smaller flywheel and clutch
I use my own billet steel flywheels and they weigh very little under 5 kg

just some food for thought