Noice, Like how he doesn't need to know how fast he is going, what gear box is in that??

_________________
Nick

http://www.ausmini.com/forums/viewtopic.php?f=3&t=86675

Like the web site, it's very crisp.

You reference the fast off base circle acceleration of the cam, are you at any limits in this? And what's limiting it?

HI Besser
The acceleration rate of a std cooper S cam can be to much if you don't have the right springs my road cams are now raising the bar as far as road cams are, I am using low lifts fast rate of lift and a bigger nose radius to hold it open longer with short duration, that's why I use MINI SPARES springs on my road cams.
The sort of acceleration and velocity rates I am using on some of my cams is getting up to the rates used on roller cams and I am the first to admit that I have gone to far on some of my cams, I remember one cam I made we stuck it in a motor on the dyno and it would not go past 4000 RPM the lifters were flying of the top of the lobe, the cam I used in the video racing with Andrew in the wet was a very aggressive cam, quick runs up on the dyno showed it should be fine,but the long runs down the straight told a different story above 7000 RPM the valves were not following the cam profile the springs were to light and I ended up braking a piece out of the inlet valve.
At Phillip Island last year I run a good cam an used a set of vary special beehive springs that the spring manufacture said with the cams I was running they would more than cope because of the design of the spring, well they got through the first session in the wet then snapped a rocker in the next and bent valves, I run these springs twice and broke rockers twice they don't under stand Mini harmonics.
When Keith Calver took on selling my cams he got Piper cams to grind them they were not happy because they were not scatter cams as I don't like them,and they and the said my cams were to radical, (well the 284 is on the limit it tends to get off the edge of the lifter) so they did a test using my 284 cam up against their top race cams a MD310 and got Richard Longman to do the testing not telling him what the cams were, the also ground the 284 of mine as a scatter cam as well, then Richard Longman added two of this cams as well, the end result was the 284 came out on top producing more torque and HP and a much better spread of torque, the thing that I was happy about was that my straight grind beat all the scatter cams.
To answer your question have I reached the limit with cams the answer is NO I will keep doing R and D work with the mini cams and motors because I LOVE IT and the challenge, but I also do cams for other engines like BDA / twin Cam fords push rod fords dato's love the dato's , does this answer your question?
Graham Russell

_________________
"It's better to be not informed than ill-informed"

Graham,
interesting real world evidence about the beehives in a bmc a series - thanks for sharing - as you mentioned on paper or in theory the relatively low spring pressure of the a series and the light weight of the beehives would be ideal - but not in real life.

given a low lift long opening duration, would 'increasing' the base circle assist keeping the lifter on the back of the lobe..... not trying to get proprietary secrets here, just trying to see if that is a way to step further away from the lifter velocity edge- seeing if my understanding is correct?

and in a more general sense, in a CNC world , are master cams still used

The lift plots for your 284 md 310 etc would be interesting to see - again i am thinking the extra 20percent volume available earlier on your 284 is more than a match for the longer duration - area under the curve earlier seems to be highly advantageous


enjoying the technical aspects this is raising Cheers Darryl

Maximum lifter velocity and minimum lifter radii are mathematical certainties.

Simple to calculate in either direction:

[b]To calculate max velocity for a given lifter diam[/b].
Allow for any edge chamfer or design minimum/none.
If there is chamfer designed or already supplied this is deducted from usable/available lifter radius.
Formula surmises perfectly aligned lifters/bores and no edge chamfer.

Formula: (Py/180) * lifter radius = max velocity,
assuming perfectly aligned lifters/bores and no chamfer.


[b]To calculate min. lifter diameter for given velocity[/b].
The velocity (actual, smoothed or designed) will determine the required usable/available lifter diameter/radius.
Either allow for any edge chamfer by adding to required minimum radius or have no chamfer.
Formula: velocity / (Py/180) * 2 = min available lifter diam.

cheers Ben

_________________
The formula for the length of a piece of string is simple: Twice as long as from one end to the centre!

Hi Darryl
The 284 @.050 lift is only around 254 dur where as the 310 is around 260 because of the short duration you can not get a lot @.050 because of the base circle but once you get above .050 lift you can lay into it and that's what I did with this cam.
In saying that you can cheat a little with bigger durations after getting of the base circle you can lay into it and then hold back as you approach the top of the lobe, I have some really aggressive cams that you can run on the std lifter.
If you can remember back to the MINI 50th at Wakefield in the second race my motor died going up the hill every one thought it was fuel but it was not, the cam I was running at the time which made really big torque had .385 tho lift on the lobe which is massive for a mini but this cam was 276 @.050 running on a big lifter so to tame it down I run 1.3 rockers and very big springs 155lb on the seat and 360lb over the nose to try and control it, but the valve caps were very very close to the under side of the rockers and they decided to get caught on the rocker and hold the valve open on two cylinders, but on the way back to the pits they cleared them selves so I took of after the field and the rest is history.
Then in the last race it burst a radiator hose but that was just another learning curve, sure I don't always finish races but that does not worry me at all after all some one has to be the test pilot better me than one of my customers and if it brakes I can fix it and not have an unhappy customer I just love the R and D with these things.
Graham Russell

_________________
"It's better to be not informed than ill-informed"

thanks to bent65 and GR for great responses...

still distilling the info...

ben or others, as i understand it the ramp angle of the cam/lobe/back lobe etc determines the rates of lift and velocity.. if the ramp is too steep then the lifters' limits are reached and the cam profile/valve follows scenario gets compromised.... so my thoughts are if someone does not need to use super high lifts ( say as an example.322 at lobe for 1.5 x.322 at valve =.483) then could that be achieved on a slightly less aggressive ramp by adding to the baseline- (which reduces overall lift but reduces the angle)?

if anyone had suggested that the mini coming from the back of the pack in that race was running 1.3 rockers i wouldn't have believed it..... keep those ideas running , there must be still a few cats around unskinned yet...

Hi Darryl
It is not the lift that determines the dia of the lifter but the rate of acceleration of the lobe I have cams that have .380 tho lift that run on a std lifter, then the 286i with only .300 tho lift is getting out near the edge.
Now if you compare the 286i and the 282 cam of mine both make the same type of HP but are two totally different cams, the 282 has .327 tho lift on the lobe and the 286i only has .300 tho made for small bore motors but works really well n the 1275's
the 286i is a pig to drive on the road imo but then i'm getting old but young guys like it, the 286i has a much larger nose radius than the 282 to make up for the lack of lift so once it's open I holds it open for much longer across the top of the lobe, now I have a 282 in in my LS 1275 running a 1 3/4 SU and it's like a pussy cat to drive,but it makes really good HP.
It was funny I ground a 286i for a guy that has a sprite 1098 and runs it in supa sprints and hill climbs, at Eastern Creek he was 1 3/4 seconds quicker than with his old cam and 400 RPM quicker down the straight, but he wanted to take it out because it was a lot more lumpier than his old cam to drive around the pits and put it on the trailer, after about 20 minutes I got through to him that we don't race in the pits.
So he still has the cam in his car and winning trophies so he is happy for now

_________________
"It's better to be not informed than ill-informed"

Hi graham, with this big Hp do you run a mechanical or electric fuel pump?

_________________
67 Deluxe under going full resto

What are you talking about old man, my 286i drives perfectly on the street! (provided you keep it above 4000rpm hehehehe)

_________________
1968 Mini-matic - 1340cc, 45 weber - 92hpatw, 14.5 @91mph, GrandmaSpec

i am picturing the freddy flinstone take off technique whilst skilfully slipping the clutch

Just checking in.
Any updates

Hi Kiwiinwgtn
Yes it is coming just need to catch on some work before I can play, and Aaron's been working hard so he can not do much either, but it wont be long and we will be back in to it i'm keen to see the results with the new cam, had a few phone calls about the new 274 wanting to know how it is going as other people are keen to try it also, we'll get there soon.
Graham Russell

_________________
"It's better to be not informed than ill-informed"

Plus there might be some smaller motor stuff happening... maybe....just maybe....

_________________

Thanks for the update.
Looking forward to the next episode.