Discussion
Anyone know anything about cams?
Just looking over the specs of the standard components in my car and the cams in particular. The figures I am getting for duration are very low. Does anyone else find this odd? E.g. for the Merc 2.3-16 the duration is only 199 degrees (at valve clearance of zero) for both the intake and exhaust cams. There is no overlap, in fact something like minus 18 degrees of overlap. Which is surprising for a performance engine making over 80hp/litre isn't it? Perhaps the data here is wrong I don't know:
102.983 = 190E 2.3-16 185hp valve duration 199/199 (at zero clearance)
102.990 = 190E 2.5-16 200hp, valve duration 209/211
102.992 = 190E 2.5-16 Evo 2 235hp valve duration 219/211
edit: Lift is claimed as 9mm, 10mm, and 11m for the 2.3, 2.5, evo2 respectively.
Looking at the duration for things like M3s, MX5s and Hondas of the same era, from what scant info I can find they're usually in the 250+ degree range with some overlap so I just wondered what's going on and am surprised about the 'cosworth' 190E. Perhaps room to fit bigger cams
. Cheers for any insight.
Just looking over the specs of the standard components in my car and the cams in particular. The figures I am getting for duration are very low. Does anyone else find this odd? E.g. for the Merc 2.3-16 the duration is only 199 degrees (at valve clearance of zero) for both the intake and exhaust cams. There is no overlap, in fact something like minus 18 degrees of overlap. Which is surprising for a performance engine making over 80hp/litre isn't it? Perhaps the data here is wrong I don't know:
102.983 = 190E 2.3-16 185hp valve duration 199/199 (at zero clearance)
102.990 = 190E 2.5-16 200hp, valve duration 209/211
102.992 = 190E 2.5-16 Evo 2 235hp valve duration 219/211
edit: Lift is claimed as 9mm, 10mm, and 11m for the 2.3, 2.5, evo2 respectively.
Looking at the duration for things like M3s, MX5s and Hondas of the same era, from what scant info I can find they're usually in the 250+ degree range with some overlap so I just wondered what's going on and am surprised about the 'cosworth' 190E. Perhaps room to fit bigger cams
. Cheers for any insight. Edited by Pentoman on Monday 17th May 21:46
stevieturbo said:
the timing figures you are using clearly state they are measured at 2mm of valve lift.
Not from a closed valve.
Typical UK cams tend to quote from a closed valve. Yanks tend to quote from 0.050" lift.
Stevieturbo - Correct - the parentheses are not the seat-to-seat values as I had read the chart. Okay so I would like to correct those values. So these are for 2mm (or 0.078") lift.Not from a closed valve.
Typical UK cams tend to quote from a closed valve. Yanks tend to quote from 0.050" lift.
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