Pushrod Power vs. High Tec OHC
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Re: Pushrod Power vs. High Tec OHC
Both can go about as fast as you want to go. Really what matters is how much money do you want to spend!
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Re: Pushrod Power vs. High Tec OHC
Here is a good writeup:
generally speaking, overhead cam engines allow higher rev operation, and thus are better for peak power output. They're found in many different exotic car and racing applications (Ferrari, IRL, etc) where high rpms are desirable.
Pushrods are generally cheaper to make for V engines than OHC, OHC is sometimes cheaper for inline engines.
Using two cams instead of one (DOHC vs SOHC) can give you a bit more flexibility when designing lift profiles, as you'll have less contact stress, and you may be able to achieve higher speeds. DOHC is a logical choice if you have a variable cam phasing mechanism, as you can put your intake and exhaust lobes on separate shafts.
Both OHC and pushrod valvetrains can use timing chains or timing belts, but timing chains are more common on pushrod engines, and timing belts are more common on OHC engines. The advantage of a chain is that it lasts longer; belts are quieter, easier to package, and offer better high-rev performance if the drive load requirements aren't too high. OHC and pushrod configurations can both use hydraulic lash adjustment, which almost eliminates the need for periodic manual lash adjustments.
Valvetrain friction can go either way. For reduced valvetrain friction, it is preferable to use a rolling follower, and it is preferable to use manual lash adjustment. Either of those can be done on a pushrod engine, but they seem to be more common on OHC engines. An OHC valvetrain will generally have less mass to control (hence the potential for higher operating speed), which translates to lower spring forces for a given operating speed, and lower friction.
generally speaking, overhead cam engines allow higher rev operation, and thus are better for peak power output. They're found in many different exotic car and racing applications (Ferrari, IRL, etc) where high rpms are desirable.
Pushrods are generally cheaper to make for V engines than OHC, OHC is sometimes cheaper for inline engines.
Using two cams instead of one (DOHC vs SOHC) can give you a bit more flexibility when designing lift profiles, as you'll have less contact stress, and you may be able to achieve higher speeds. DOHC is a logical choice if you have a variable cam phasing mechanism, as you can put your intake and exhaust lobes on separate shafts.
Both OHC and pushrod valvetrains can use timing chains or timing belts, but timing chains are more common on pushrod engines, and timing belts are more common on OHC engines. The advantage of a chain is that it lasts longer; belts are quieter, easier to package, and offer better high-rev performance if the drive load requirements aren't too high. OHC and pushrod configurations can both use hydraulic lash adjustment, which almost eliminates the need for periodic manual lash adjustments.
Valvetrain friction can go either way. For reduced valvetrain friction, it is preferable to use a rolling follower, and it is preferable to use manual lash adjustment. Either of those can be done on a pushrod engine, but they seem to be more common on OHC engines. An OHC valvetrain will generally have less mass to control (hence the potential for higher operating speed), which translates to lower spring forces for a given operating speed, and lower friction.
slayerofall- MACH 1
- Number of posts : 168
Registration date : 2007-12-08
Re: Pushrod Power vs. High Tec OHC
id have to go with OHC just because there more technology advanced. theyve been making pushrod engines since the beginning of time. of course some of the most powerfull engines ever made in america were push rod there is a greater potential for power with a OHC engine
Re: Pushrod Power vs. High Tec OHC
250mav wrote:id have to go with OHC just because there more technology advanced. theyve been making pushrod engines since the beginning of time. of course some of the most powerfull engines ever made in america were push rod there is a greater potential for power with a OHC engine
Umm, DOHC engines have been around since 1912. Pushrod OHV has been around since 1902.
Guest- Guest
Re: Pushrod Power vs. High Tec OHC
That's beside the pointZachW04Stang wrote:250mav wrote:id have to go with OHC just because there more technology advanced. theyve been making pushrod engines since the beginning of time. of course some of the most powerfull engines ever made in america were push rod there is a greater potential for power with a OHC engine
Umm, DOHC engines have been around since 1912. Pushrod OHV has been around since 1902.
slayerofall- MACH 1
- Number of posts : 168
Registration date : 2007-12-08
Re: Pushrod Power vs. High Tec OHC
Honestly I don't think either is better or worse. Each one has its pros and cons. Either motor can be made just as fast. If you go to any naturally aspirated shoot out at the track your not gonna see a single overhead head cam engine but this is mainly due to lack of parts for dual overhead cam engines. Your not gonna find to many 800+ cubic inch engines that are dual overhead cam and intended for automotive use. In drag racing right now pushrods still seems to dominate but classes like outlaw 10.5 are now dominated by modular motors.
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