@TT
You are indeed correct sir
2 mins on google has found me out! 41mm is the figure!
So.....
R32/S3 Front is 57mm compared to 54mm for the Gti
R32/S3 rear is 41mm compared to 38mm for the Gti
Total surface area of all 4 pistons on the GTi = 6850 mm2
Total surface area of all 4 pistons on the R32/S3 = 7745mm2
A 13% increase on the same (23.8mm)??? master cylinder (confidently assuming 23.8mm as the Gti piston sizes are the same as the Mk4)
So 13% is the figure that we can hydraulically upgrade to and keep an OEM Pedal
TT you aware of any proportioning that goes on front to rear?
So just considering MC upgrades from within the VAG group, you could calculate as a percentage the master cylinder surface area against total piston area which works out for the GTi at 6.5% and for the R32/S3 5.75%. Interestingly enough the S4 with the 60/43mm pistons works out at a middlingish 6% dead with the 25.6mm master cylinder.
So assuming you could reduce that OEM 6% by 13% to 5.22% on the S4 or similar Master Cylinder in much the same way that VW did with the S3/R32 against the Gti it would give you a total piston surface area of approx 9850mm2 which would be handy and would
maybe open up the possibility of some 4 pot rear conversions
So im off to scour EKTA for a master cylinder within group that would suit, I normally try to find the servo/MC seal part number from the unit Im trying to replace and search for that as a starting point - anybody else any other ideas or candidates???
With the ESP sensor being downroute of the MC now Im thinking maybe something like a transporter van, we could also do with somebody with a Mk5 track slag that we could experiment with as opposed to a road car.
Its funny how history repeats itself - sticking a Mk2 Gti MC into a Mk1 Gti was a popular upgrade in the eighties
E&OE !!!!!!! Somebody for fecks sake check my maths