Non Rotor: Tech
Senior Member
Joined: Sep 2002
Posts: 1,030
From: teh frozen nort
The only benefit I'm aware of is that it allows the heads to be very compact and low-profile. Hence how they get such gynormous motors under the hood of a Corvette for example. Helps with centre of gravity height. Also I suppose it must be cheaper to make otherwise GM wouldn't still be doing it.
J
J
Senior Member
Joined: Sep 2002
Posts: 1,030
From: teh frozen nort
erm not exactly, they have overhead valves (as opposed to a flathead setup), and you CAN use four valves per cylinder but it is a real pain to do. You have to have another little set of pushrods going across the heads. Which is why I don't think any factory pushrod engines have had four valves per cylinder.
J
J
Senior Member
Joined: May 2002
Posts: 22,465
From: California
Originally Posted by DJ Rotor' date='Aug 12 2003, 12:55 PM
The only benefit I'm aware of is that it allows the heads to be very compact and low-profile. Hence how they get such gynormous motors under the hood of a Corvette for example. Helps with centre of gravity height. Also I suppose it must be cheaper to make otherwise GM wouldn't still be doing it.
J
J
mike
Administrator
Joined: Jul 2001
Posts: 24,416
From: Stuart, FL
This is a fairly arguable point, many would claim that the engergy lost from the cam to the lifter, through the pushrod to the valve is more then any disadvantage of the having the cams overhead.
And the fact is less moving parts is less room for something to break, that's the general theory behind the overhead cam as far as I know. Not to mention the potential of multiple valve heads and cams. This is very hard to do with a pushrod engine as you would have to increase the width of an already larger block.
And the fact is less moving parts is less room for something to break, that's the general theory behind the overhead cam as far as I know. Not to mention the potential of multiple valve heads and cams. This is very hard to do with a pushrod engine as you would have to increase the width of an already larger block.
Senior Member
Joined: May 2002
Posts: 22,465
From: California
Originally Posted by phinsup' date='Aug 12 2003, 01:50 PM
This is a fairly arguable point, many would claim that the engergy lost from the cam to the lifter, through the pushrod to the valve is more then any disadvantage of the having the cams overhead.
And the fact is less moving parts is less room for something to break, that's the general theory behind the overhead cam as far as I know. Not to mention the potential of multiple valve heads and cams. This is very hard to do with a pushrod engine as you would have to increase the width of an already larger block.
And the fact is less moving parts is less room for something to break, that's the general theory behind the overhead cam as far as I know. Not to mention the potential of multiple valve heads and cams. This is very hard to do with a pushrod engine as you would have to increase the width of an already larger block.
mike
Senior Member
Joined: Jan 2003
Posts: 983
From: redondo beach
Originally Posted by j9fd3s' date='Aug 12 2003, 02:12 PM
[quote name='phinsup' date='Aug 12 2003, 01:50 PM'] This is a fairly arguable point, many would claim that the engergy lost from the cam to the lifter, through the pushrod to the valve is more then any disadvantage of the having the cams overhead.
And the fact is less moving parts is less room for something to break, that's the general theory behind the overhead cam as far as I know. Not to mention the potential of multiple valve heads and cams. This is very hard to do with a pushrod engine as you would have to increase the width of an already larger block.
And the fact is less moving parts is less room for something to break, that's the general theory behind the overhead cam as far as I know. Not to mention the potential of multiple valve heads and cams. This is very hard to do with a pushrod engine as you would have to increase the width of an already larger block.
mike [/quote]
well all pushrod engines are overhead valve.
