Graham's bmw 2002 race car.

[jimmy2006]

Re: Graham's bmw 2002 race car.

when you back out ?

[Graham]

Re: Graham's bmw 2002 race car.

wont be for ages yet im afraid, simply cant afford it

[jimmy2006]

Re: Graham's bmw 2002 race car.

i see you was over brands in October when the tin tops were on

[Graham]

Re: Graham's bmw 2002 race car.

ive been trying really hard to make the big valve flow, at ultra high lift i have achived it with some style, ive got it upto over 137cfm@10", however, its at huge cost flow throught most of the lift range is well down, and it will need a cam lifting to 600 thou which is nearly 100 thou more than any off the shelf cam!



im going to have another look at filling the bottom of the port in next

[Group4_Mark2]

Re: Graham's bmw 2002 race car.

Hi Graham,
Is the problem with the flow on the red and the blue curve is at 115 / 120 cfm, the air cannot go around the short side. If you continue the graphs at higher lift will the curves continue to rise but at a slower rate. If that is the case then I found that widening the width of the port at the short side radius helped get the flow around the corner without effecting the high lift flow. If you could keep the lines increasing at the same rate then you could see nearly 140cfm at around 12mm lift.

This is kind of what I tried to do



I dont know anything about your cylinder head so this may not work at all for you.

[Graham]

Re: Graham's bmw 2002 race car.

Hi Graham,
Is the problem with the flow on the red and the blue curve is at 115 / 120 cfm, the air cannot go around the short side.

.

absolutely, the blue tops out at 115cfm red at 120, the problem with the bmw port is its rectangular and already as wide as the valve, so widening it further may not work, but its something i will have to try

when i was using daves superflow i found airflow on the blue line stalled dead @115cfm, but with my bench running @28" (i convert the results to 10") i do get a slight increase if i lift the valve further but not much, i can see this is going to end up with a custom cam and welded up port

[Graham]

Re: Graham's bmw 2002 race car.

didnt get a picture, but i tried widening the port at the sides like works on a pinto, clearly doesnt work on an M10!



i think the problem with going wider is the bmw port is already very wide

[rwd2ltrfiesta]

Re: Graham's bmw 2002 race car.

All seams very technical to me but I get and understand what and why, be good to see ya back on track again

[stevec33]

Re: Graham's bmw 2002 race car.

Huge arches on that, never seen one done like that

[Graham]

Re: Graham's bmw 2002 race car.

oh yes there certainly are, 7 inch wheels on inch spacers are lost in those arches

[Jarno]

Re: Graham's bmw 2002 race car.

Thought I'd share.. I bought a set of Wössner pistons for my M10. 575€ a set. 13:1 ratio after machining the domes (5mm narrower) and combustion chambers. With a practically stock head and block height. They come with deep valve cutouts big enough for 48/40mm valves I think. Piston height is 1mm higher than stock Tii pistons.

[Graham]

Re: Graham's bmw 2002 race car.

right been at it again with the flow bench, if you have been following you will know ive hit a wall flow wise, essentially what ever ive tried i cant increase the average airflow over the valve lift range,

my instincts are screaming the short turn is all wrong and needs raising to give a longer radius, but that doesnt work, only lowering it more, which increase high lift flow at great expense to low lift, raising the port between the guide and manifold face works at high lift, big valve was fantastic and megga valve lift, like way more than ever practical,

the one part of the port i had ignored all along was the long turn, its quite concave, but i figured the air would ignore it like on a pinto, i was wrong! i filled that section and gain a whole heap of air flow both with standard and big valve, my guess is the air was following the concave section of port and simply crashing into the back of the valve rather than going round it. i wont know for sure until i get home and put the numbers in a spread sheet, but i think i have made progress, even if in an ideal world i still need a cam that lifts to 600 thou

[Graham]

Re: Graham's bmw 2002 race car.



boy did filling the long side of the port work the big valve previously lost out massively everywhere but the very top end, what i did was also put back a bit of material on the short side which picked up lower lift flow, there is still work to be done, but clearly with welding the big valve now becomes viable

[Graham]

Re: Graham's bmw 2002 race car.

blue line is best conventional port, green line is big valve with long turn filled, im sure with work it can be better still, infact i dont thinki used the best set of flow figs for the big valve

[Graham]

Re: Graham's bmw 2002 race car.




same valve same port, just with long turn filling, the filler is worth 10cfm through most of the lift range