Printable View
I think I understand cams fairly well. What I haven't seen is why using two cams is better. Especially because they are usually in 4 and 6 cylinder engines. If it is better why don't we see them in V-8s? What about position? What difference does the cam location make? You would think introducing even more moving parts that have to work together and do wear would add to the headaches. Is obviously isn't done for power in and of itself so why?
Actually your wrong, there are less moving parts "no pushrods or lifters"
and it is done for power mostly on 4 cylinder engines case in point typical 4 cyl. head ya got 4 intake valves & 4 exhaust valves,typical dohc head ya got 8 intakes & 8 exhaust valves, double the valves double the air ya can move, although a bunch of the modern v-8's are of the overhead cam design the engine bay confines dictate a single overhead design because a DOHC v-8 is massive in width even a DOHC v-6 is massive in width just look under the hood of an SHO Tauras,
Smokey Yunik did extensive research on pushrod verse overhead cam engines and the overhead won hands down on reliability,power,rpm's, and effieciancy BUTTTTTTTTT all that being said give me a pushrod V8 motor anyday, unless your gonna go try and whip them boys at Indianapolis, Just look at Nascar most engine failures are valve train in nature cuzz they are trying to run em at 9500 rpm's,but the Indy guys with overhead cam engines turn 12,000 rpms all day long with out failures.
The DOHC also is much easier to configure for heads with 2 or more intake and exhaust valves per cylinder. The design allows the valves to be place where they can work the best.