Engine Sizes

Lashout_UK said:
Tight timings? What are you going on about now?
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Valve timing

There is far too much play in a pushrod setup to accurately control when a valve opens/closes unlike an overhead cam setup.

If you cannot control the timing of the valves then you cannot tune the engine as far as you can with an overhead cam setup.

It has nothing to do with reliability
 
rypt said:
Valve timing

There is far too much play in a pushrod setup to accurately control when a valve opens/closes unlike an overhead cam setup.

If you cannot control the timing of the valves then you cannot tune the engine as far as you can with an overhead cam setup.

It has nothing to do with reliability
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Your posts make no ****ing sense, ever. You never have a point, reading back through the last five posts you've made you just... waffle on about... something, and I'll be damed if I know what it is.

/breathes
 
I'll step in here if I may.

Pushrod tech is flattered by its use of ferrous materials in the crankshaft pullies. The angle of the conrod at TDC is affecting by the spark voltages, but not as much as it is in a jet engine. And then there's the combustability of the smaller fuel droplets in the vacuum chamber. Pushrod setups just make no sense.
 
Muffin` said:
Your posts make no ****ing sense, ever. You never have a point, reading back through the last five posts you've made you just... waffle on about... something, and I'll be damed if I know what it is.

/breathes
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Or maybe you know sweet **** all about how an engine works.

If I wanted to have my valve close at exactly 30degrees before TDC, which setup (pushrod or ohc) would get me the closest to that to that point more consistently with the smallest range of variation?

Remember, if a valve does not close in time then the piston may strike the valve.
 
rypt said:
Valve timing

There is far too much play in a pushrod setup to accurately control when a valve opens/closes unlike an overhead cam setup.

If you cannot control the timing of the valves then you cannot tune the engine as far as you can with an overhead cam setup.
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This is true, to an extent - but like all mechanical systems, it's not difficult to develop it to the standard you need.

For example there were pushrod V8s that could crank out 10,000RPM in the 60s - just like those modern-day Nascar pushrods that regularly run up to 10,000RPM for the entire race, using just pushrods, and make 830bhp and 520ft.lb from 5.8 litres.

They can even run up to 11,000 if needed :)

Let's put this outdated pushrod, two-valve per cylinder, tech into perspective, by comparing it to a McLaren F1. The old pushrod Nascar engine makes a mere 203bhp and 40ft.lb more, and revs 1500RPM higher, than the larger 6.1-litre 32 valve quad-cam V12 from the McLaren.
 
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rypt said:
I wasn't questioning sound and feel, I was questioning liking a technologically inferior setup (ie one that has a lower potential for power / fuel economy)
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Is it really that hard for you to understand? He likes the feel of old-school pushrod V8s. The fact that they are 'technologically inferior' doesn't come in to it, he likes the feel and sound.

But you know that already, you have just decided to use that post as another excuse to shoe-horn your faux knowledge into the thread, this time on the virtues/weaknesses of a pushrod engine. Give it a rest, you really don't do yourself any favours.
 
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rypt said:
Or maybe you know sweet **** all about how an engine works.

If I wanted to have my valve close at exactly 30degrees before TDC, which setup (pushrod or ohc) would get me the closest to that to that point more consistently with the smallest range of variation?

Remember, if a valve does not close in time then the piston may strike the valve.
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I am grasping the technology of what you write about but how did you get to it? Look back yourself, you're having a conversation with yourself. Do you walk into social situations and say 'I like mudkipz'?
 
Nascar V8s were they OHC would be able to easily make more power, we are talking a mean piston pressure of only about 13bar, which is a level that you find in road cars now-a-days.


If you can control exactly when a valve opens or closes you can make more power, you can be more fuel efficient.

Pushrod setups simply do not let you get the same level of control as cams.
 
rypt said:
Pushrod setups simply do not let you get the same level of control as cams.
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This much is obvious. But your original point was:

rypt said:
I was questioning liking a technologically inferior setup (ie one that has a lower potential for power / fuel economy)
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I suppose it's an affection thing, in the same way that people still enjoy flying Spitfires or will choose mechanical watches over quartz.
 
Robbie G said:
This much is obvious. But your original point was:



I suppose it's an affection thing, in the same way that people still enjoy flying Spitfires or will choose mechanical watches over quartz.
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Yeah like those who continue to use the XBOX 360 when the PS3 is miles better.

Rypt, what do you do?
 
Well by feel I assumed he meant the overall feel of the car, the responsiveness of the engine to throttle input.

Both of which would probably benefit from cams
 
rypt said:
Or maybe you know sweet **** all about how an engine works.

If I wanted to have my valve close at exactly 30degrees before TDC, which setup (pushrod or ohc) would get me the closest to that to that point more consistently with the smallest range of variation?

Remember, if a valve does not close in time then the piston may strike the valve.
Click to expand...

Technology is only a replace for displacement on some of the attributes a powertrain has, some, not all.
 
Jonnycoupe said:
Technology is only a replace for displacement on some of the attributes a powertrain has, some, not all.
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No-one is arguing you have to replace displacement, but why not make the best use you can of the displacement that you do have.

If using cams can gain you an extra 15% hp/torque and an extra 10% fuel efficiency ... why not use it?
 
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