gearbox,CR questions
Turbo Mini Forums

Hi yet again all.

This is my first turbo conversion so please be patient will all the questions :).

On an A+ 1275, will i need straight drop gears at 12 psi?

I've already clarified i need a cross pin diff.

I've been studying compression ratios all night and i still cant come to terms with it.

am i right i thinking if i get the head re bored say 0.020" i need pistons that are 0.020?

what does cc mean when it comes to the piston dish?

how does V+C divided by C give me 8.5-1?

thanks for all the help its really appeciated !

drop gears is a tricky one, I have destroyed std drops at only 80 hp, however robert on here is using std drops at circa 200hp reliably.

you dont rebore heads, I guess you mean block? anyway, if you rebore the block +20 then yes you will need +20 pistons.

coompresion ratio is the ratio of how much the volume of a cylinder

drop gears is a tricky one, I have destroyed std drops at only 80 hp, however robert on here is using std drops at circa 200hp reliably.

you dont rebore heads, I guess you mean block? anyway, if you rebore the block +20 then yes you will need +20 pistons.

coompresion ratio is the ratio of how much the volume of a cylinder changes to the gap above the piston at TDC,

say your bore is 73.5mm you work out the area (pi R squared ) then mutiply by the stroke (normally 81.3mm) that gives the chane in volume,

then you add up the gap above the piston, ( piston dish +head chamber + gasket volume + deck volume.

then you divilde the change in volume bu the gap above the pston

Edited by Joe C on 30th Jan, 2011.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

I run 12psi on STD drops and gearset and has been fine for 3years+

"Tuning should be a compromise between what is possible and what is necessary"

10)Thou shalt always quest for more power