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October 28, 2013

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Alfista

What tracks are you expecting to race? At any danish racetrack you would want acceleration rather than topspeed. Only at the end of the straight at JyllandsRingen can you dream of reaching the topspeed, and I expect it to be too short for the Giu ;) On the other hand; are you going to Spa? Well, just change the diff :)

Ultimostile

Hey Alfista, as always your comments are spot on! But my Giulietta is not a RACE car; it's a Gran Turismo. And I intend to drive to and (hopefully) from races. And I will probably drive Ring Knutstorp as the only 'danish' track ... but it's really built for Nurby and Spa. And on those tracks it will be too tiresome not being able to stretch out ...
But who knows?! It all depends on the torque characteristics of the engine ... I may be proven wrong in the end

Kosmopolitten

i think your have made a miss calculation, unless you are mounting 13" wheels your topspeed will be a rather bit bigger. try making the calc. of the crown pinion first saying it gives you 5,3 then start all over again. also secure the correct diameter of your wheel, (there´s a list at Vintage tyres if i remember correct).
i guess your v max is around 170/180 at 7000rpm with the 8/41 stick to that one.

damn early for english spelling, sry for mishits.

yours Frank #23

Ultimostile

Thanks Frank
Lets recalculate:
7000 revs pr minute engine speed equals 7000 revs pr minute propshaft speed in 4th gear. And this is also the speed of the pinionwheel.
With 8 teeth on the pinionwheel and 41 teeth on the crownwheel the crownwheel will rotate at 1366 revs pr minute. This is also the rotation speed of the rear wheels.
The roll diameter for the 15-165 wheels is 61 cm and that means 1,92 meter for each revolution. 1366 revs times 1,92 meter equals 2623 meter pr minute. That is 2,623 km/ minute. And that is 157,4 km/h.

With a 5th gear 1:0,79 it gives 199 km/h at 7000 rpm

This is the same as I calculated. I hope to get enough torque to drive 6500 in 4th gear ... I suppose 7500-8000 rpm is possible in 1-2-3 gear. How is your gearing in the Giulia TI Super?

Kosmopolitten

my gearing is exsactly 8/41 . and it gives me just a bit over 200km/h.
and that is too much i´d rather have the 8/43 (but that is no go´within FIA regulations) i do not use 5th gear on danish racetracks.

my new upgrade is a Baggi GTA gearbox, with looong 1th and 0,89 5th gear . that should keep me ahead of some green cars ;-)

/Frank #23

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