Higher ratio rockers?
11-11-2006, 02:24 PM
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Staging Lane
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Higher ratio rockers? What would higher ratio rockers do?
I've heard its like adding 20 degrees of duration, but what would it do in the lower rpm region (1500-3000)? Would it affect this also?
I've heard its like adding 20 degrees of duration, but what would it do in the lower rpm region (1500-3000)? Would it affect this also?
11-11-2006, 03:02 PM
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i dont know about 20 degrees of duration. usally duration is only affected slightly. The lift is what is affected the most. I cant remember the formula but i think its on harlands web page. The formula will tell you what your lift will be with a different ratio rocker. Just to let you know the lift advertised for a cam is valve lift not lobe lift so its the lift with the ratio of the rocker factored in
11-11-2006, 03:11 PM
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FWIW:
new valve lft = current valve lift * new rocker ratio / current rocker ratio
For example, if your current valve lift is 0.55" with rockers (1.75 ratio), and you install rockers of ratio 1.85, the valve lift is going to be = 0.581".....
new valve lft = current valve lift * new rocker ratio / current rocker ratio
For example, if your current valve lift is 0.55" with rockers (1.75 ratio), and you install rockers of ratio 1.85, the valve lift is going to be = 0.581".....
11-11-2006, 03:22 PM
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Originally Posted by N4cer
So you'd just take your lift, divide it by the stock 1.7, then multiply that number by the new ratio. Usually it's 1.8.
I also know it doesn't actually add any duration. The 20 degrees duration comment was an equavalent effect that Crane claims.
What I'm asking is what higher ratio rockers will do to your low end torque(1500-3000)?
Will it soften it, or not? My guess is no, because the duration hasn't changed, but I would some real world experience to back this up.
11-11-2006, 07:13 PM
#6
The Cranes will change the valve duration that it spends at each lift point, but not seat to seat. For instance they will get to 0.200" lift faster than stock rockers due to the off the seat ratio that is higher. Not sure how to figure an "equivalent" number such as they advertise stating its like "having a cam of more duration".
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11-11-2006, 08:45 PM
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you could as the higher ratio speeds up the ramp rates. Basically the higher ratio gets you more useable duration of the listed by getting it open faster and closed faster
11-10-2007, 10:53 PM
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