Hi All
This is what you call a really big camshaft, it's out of a top fuel dragster producing around 8000hp on nitro, it has .500tho on the lobe and uses 2.2 rocker ratio which give it 1.100" lift at the valve
Graham Russell
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| Author: | GR [ Sun Oct 25, 2009 2:28 pm ] |
| Post subject: | Camshafts |
Hi All This is what you call a really big camshaft, it's out of a top fuel dragster producing around 8000hp on nitro, it has .500tho on the lobe and uses 2.2 rocker ratio which give it 1.100" lift at the valve
Graham Russell
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| Author: | sports850 [ Sun Oct 25, 2009 2:32 pm ] |
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Cool , can you grind me one like that for the sports850 
Those things never cease to amaze me , I remember reading magazines in the late 70's where they thought they had pretty much reached the peak performance of the engine at 1500 hp , 8000 is almost unbelievable . The stresses involved must be phenominal . |
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| Author: | TheMiniMan [ Sun Oct 25, 2009 2:33 pm ] |
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that big mongrel gives me a big mongrel
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| Author: | gafmo [ Sun Oct 25, 2009 2:48 pm ] |
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Thats what the RE83 is modeled on rite 
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| Author: | 74snail [ Sun Oct 25, 2009 2:59 pm ] |
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gafmo wrote: Thats what the RE83 is modeled on rite
Well if thats true just how many ppm does he have to get to before it comes on cam
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| Author: | sgc [ Sun Oct 25, 2009 3:17 pm ] |
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Can anyone say "duration" and "overlap"
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| Author: | drmini in aust [ Sun Oct 25, 2009 5:50 pm ] |
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Bear in mind these cams use roller followers, so the cam profile is pretty much just 2 radii blending into each other.
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| Author: | BALLISTIC [ Sun Oct 25, 2009 5:53 pm ] |
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sgc wrote: Can anyone say "duration" and "overlap"
 What overlap  ......the valves dont have time to be closed
 Might fit something like that to one of the 998's i have lying around here just for a bit of fun, the std rockers will take it
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| Author: | GR [ Sun Oct 25, 2009 6:46 pm ] |
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Hi Simon to get that to work you need a cam follower about 1.5 ins in dia other wise it would just sheer it straight off on the first rotation like doc said it was ment for a roller follower. But i'm working on profiles something like that, but i've had a few little problems, but i'm working on that i'll get it to work i won't give up that easily. The RE83 is a long thoes lines thats why it needs good valve springs, and thats part of the problem with the bigger cams getting the springs to keep the follower on the lobe. That dragster cam runs close to 750lb on the seat and 1500lb over the nose Graham Russell |
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| Author: | Asphalt [ Sun Oct 25, 2009 9:25 pm ] |
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So who's the first to develop roller followers for the A-series? 
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| Author: | drmini in aust [ Sun Oct 25, 2009 9:27 pm ] |
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Asphalt wrote: So who's the first to develop roller followers for the A-series?
Been done years ago by a few racers, but do you want to lose power or make it??
Not enough room in there to do it properly. |
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| Author: | mini13 [ Sun Oct 25, 2009 10:19 pm ] |
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any more info on the roller lifters? i'm currently looking into converting a block to take some. |
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| Author: | GR [ Mon Oct 26, 2009 11:54 am ] |
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HI Mini13 Save your money a lot of work for no real gain,you can not get the roller big enough on the lifter so your acceleration rate is slower than a good flat tappet cam. The back to back testing we've done on B series motors and the big 6 cly healies proved it is not worth the effort Graham Russell |
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| Author: | bent65 [ Mon Oct 26, 2009 2:09 pm ] |
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I believe a person in QLD has tried a roller cam in group N but havent seen any QLD times quicker than Greig. Is it also, that to have a heavier roller lifter, with an already struggling valve spring trying to control a now faster lift cam, the problem? There is always a trade off. Grahams blue springs are the best (heaviest) springs that have been made for the A series and to add more weight(lifter) and faster lift would mean it would float at a lot lower revs. Graham, someone told me if you work out the working life of the nitro engines its something like 1000 revolutions. --6 sec pass @ 10k/rpm then it gets rebuilt. Ben. ps. Graham, i only rev it to 7000...honest. |
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| Author: | mini13 [ Tue Oct 27, 2009 4:21 am ] |
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Thanks Graham, that's interesting What would you deem as a roller large enough? I am looking at followers from an american ford V engine. What kind of back to back test did you perform on the B series? Have you been unable to lift the valves faster than with an .87 is diameter flat follower? if so what was limiting the acceleration? side loadings into the block from the roller follower? sorry for all the questions, GR wrote: HI Mini13
Save your money a lot of work for no real gain,you can not get the roller big enough on the lifter so your acceleration rate is slower than a good flat tappet cam. The back to back testing we've done on B series motors and the big 6 cly healies proved it is not worth the effort Graham Russell |
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