A new page under construction as of 2011, will add more asap.
As with the other pages, all figures are in 50 thou increments of lift, tested on a Superflow 110 machine at 10inchs draw.
The Good old A SERIES 'Mini', Standard flow, Inlet- std 33.2mm Valve
11.5 22.6 33.3 42.8 49.3 53.1 56.6 60.3 61
As modified by Sabre using all std parts as above, still to come
As modified by Sabre using the Factory Cooper Tam 1059 Inlet- 35.6mm- MPI casting.
12.4 25.8 39.3 49.1 58.3 64.1 67.1 67.5 67.5
As modified by Sabre using REC Stainless performance valves of 36.7mm as used in 1460cc Racer, offset guides. Car has around 150hp with phenominal torq
13.3 27.4 39.7 46.9 60.15 65.8 69.4 72.3 72.3 73.6
As a note on the above figures, do not be fooled by what looks like limited increases with the larger valves- the std Inlet ports are VERY Efficient, even the chamber is not obstructive to a great degree. Plus with the small bore/longer stroke of the A series, the larger the 'valves' get, the more Shrouding occurs, BUT when your looking for power, every Cfm counts. There is a limit and that is 37.5mm Inlet size. Larger valves have been tried- up to 38.6mm but they were discarded due to the reasons of shrouding etc as mentioned. They gave no more than the smaller valve in flow or power & took greater effort to jam into the small chamber space.
Finally, while the Inlet is quite efficient, much of the gains are actually derived from the exhaust port, it is more the improved removal of the waste gases that leaves more area for the inlet flow to fill. It is the removal of a particularly large Guide 'Boss' that blocks off around two thirds of the port area under the valveseat tied to other important changes that achieves this.
As mentioned in the text about Inlet valve sizes, the larger inlet valves also restrict the exhaust valve size, too many people think only the Inlet flow to be the most important, while the opposite is true. So the 38.6mm Inlets as talked of would be reducing your output by restricting the exhaust size as well as its own dia & proximity to the chamber wall causing shrouding.
All the following figures are on unleaded heads using Unleaded seat inserts, these also cause difficulty with fitting larger Inlet valves- an exh 'Valveseat' insert should preferably be 1mm larger in dia than the exh valve for strength, thus this interferes with the larger inlet valve fitment. I have to offset the guides(space them further apart) to fit all those big valves in, this is all a great deal of time & money
Exhaust flow, standard head & valve as factory produced, 29.4mm dia
9.8 19.7 26.7 31.5 34.9 37.4 40.1 41.5 42.9
Fully modified using the standard 29.4mm factory valve
10.1 19.7 30.3 38 4 44.9 46.8 48.9 50.5
Fully modified utilising R.E.C's Stainless performance 30.4mm valve
10.3 21.9 32.5 38.8 44.2 48.5 51.7 54.7 57.4
Full on Race head for a 1460cc engine using R.E.C's 32mm valve
10.8 22.8 33 40.6 46.7 52.6 56.7 62.3 64.4 65.7
FORD PINTO, 2 litre, Std Inlet. 42mm valve
13.1 28.8 40.9 55.1 69.2 75.4 79.9 83.9 87.2
As above, modded, std valve reshaped
14.3 31.7 48.3 63.8 76.7 83.6 87.3 92.4 95
Here is a 1600 pinto fully modded with performance 44.4mm Inlet valves. The 1600 casting is often chosen because of its smaller combustion chamber to aid compression volumes. The port floor turns are beneficially deeper which aids porting/flow.
15.5 33.2 50.5 68.99 82.6 91.3 97.1 100.2 102.9
FORD PINTO, 2 litre, std exhaust. 35.7mm valve.
11.8 23.2 34.6 44.1 51.8 55.4 56.3 56.6 56.9
As with the Inlets, here is the 1600 again, with larger performance valves & porting, 36.7mm
12.6 28.2 48.8 55.9 65.7 66.9 66.9 66.9 67.9