Roller rockers useless?

[vxcalais_01]

lol i dont know what trade school you went too because you are totaly wrong about that. The cam effects duration, not the rockers.

Listen, how clear does it have to be that the rockers cannot effect the duration design on a cam ? Yes i agree with you and others on this, but in the overall picture and in relation to the valve, plain and simple. If you were standing on something spinning, the higher you jumped, are you not in the air longer in relation to the item turning below you ? Duration under the curve, whatever people want to call it, duration of how long the valve stays open is increased. If I am wrong so what...... We are also talking in the context of increasing the ratio on the rockers which was the original question. When talking in relation to Cam duration, yes the rockers cannot physically change how the cam has been grinded.

 

[MACE]

It depends on what where you measure duration I guess.

at zero lift their certainly won't be a change in duration, at say 0.050" (which is a good indication of cam ramp rates hence commonly used) it's certainly not by a lot going by the previous graph but it does change. This increases proportional to the increase in ratio. If anything basing valve train characteristics on just the cam isn't really accurate and should ideally just be at the valve IMHO.

 

[GenReaper]

, yes the rockers cannot physically change how the cam has been grinded.

Yep, all it does is make the opening/closing ramp rate faster and increase lift, nothing more.

Gains to be had yes, but minimal at that.

 

[vxcalais_01]

It depends on what where you measure duration I guess.

at zero lift their certainly won't be a change in duration, at say 0.050" (which is a good indication of cam ramp rates hence commonly used) it's certainly not by a lot going by the previous graph but it does change. This increases proportional to the increase in ratio. If anything basing valve train characteristics on just the cam isn't really accurate and should ideally just be at the valve IMHO.

Mace,

Have you have many run the 2.25 ratio rockers on stock heads springs etc ? Or can they only be run with the modded heads ?

By the way, nice to see you now have the better polished aluminium rocker covers for sale grrr.... I have super cheap auto version ones. What gasket to these work with ? Man you have ramped up the site, stroker kits, metal intake gaskets and all.

 

[MACE]

Mace,

Have you have many run the 2.25 ratio rockers on stock heads springs etc ? Or can they only be run with the modded heads?

Hey vxcalais_01, with these rockers heads and springs packages we've probably got around 3 customers running this setup at the moment. Hopefully when we get them up on the site many more will be running them. They really need to be run with modded heads considering how close the pushrod gets to the cylinder head

By the way, nice to see you now have the better polished aluminium rocker covers for sale grrr.... I have super cheap auto version ones. What gasket to these work with ? Man you have ramped up the site, stroker kits, metal intake gaskets and all.

The stock factory supercharged 6 gaskets work with these covers. We can supply these for $30. Yeah the site can certainly come along from since a couple years ago. Still far from finished though

Cheers
Steve

 

[Tsunamix]

It all depends on how you measure duration.

Maybe im weird but in terms of effective duration, thats the time the valve stays open for. I'm not talking in terms of the reference points used by cam grinders, but by the effective performance of the engine. The 0.75" Lift figure is often used because a valve is open by then. At 0 lift, the valve is not open. Depending on engine design, valves may actually open anywhere between the 0 lift and 0.75" lift as measured at the cam.

So - ignoring the 'reference' points, and assuming the point on the cam at which the valve actually loses contact with the valve seat and becomes open remains constant with rocker choice, then whats left is the amount of time the valve is open for. And according to the charts above, the rocker DOES increase valve open time or duration. But It's not by much.

Cam grinders don't speak in terms of effective duration, but in terms of refernce point. "Point X is where we start the ramp up to valve fully open". So the total duration of the valve open circle starts at X. This is not the EFFECTIVE duration, as valves open after being on the ramp up a very short time.

yes I've just said the same thing twice. Hopefully one way will work for you readers.

Sorry MACE, forgot about the difference between axial roller and roller tipped rockers.

 

[MACE]

It all depends on how you measure duration.

Maybe im weird but in terms of effective duration, thats the time the valve stays open for. I'm not talking in terms of the reference points used by cam grinders, but by the effective performance of the engine. The 0.75" Lift figure is often used because a valve is open by then. At 0 lift, the valve is not open. Depending on engine design, valves may actually open anywhere between the 0 lift and 0.75" lift as measured at the cam.

So - ignoring the 'reference' points, and assuming the point on the cam at which the valve actually loses contact with the valve seat and becomes open remains constant with rocker choice, then whats left is the amount of time the valve is open for. And according to the charts above, the rocker DOES increase valve open time or duration. But It's not by much.

Cam grinders don't speak in terms of effective duration, but in terms of refernce point. "Point X is where we start the ramp up to valve fully open". So the total duration of the valve open circle starts at X. This is not the EFFECTIVE duration, as valves open after being on the ramp up a very short time.

yes I've just said the same thing twice. Hopefully one way will work for you readers.

Sorry MACE, forgot about the difference between axial roller and roller tipped rockers.

Well put

 

[nathanVY]

Yeah the site can certainly come along from since a couple years ago. Still far from finished though

Websites are never finished haha.

 

[vxcalais_01]

I wish i could have explained it like Tsunamix.... good stuff.

 

[MACE]

Websites are never finished haha.

You don't need to rub it in LOL

I wish i could have explained it like Tsunamix.... good stuff.

Yeah he certainly did put it well