Valve spring pressures
09-28-2015, 08:14 PM
#31
Gold Member
Gold Member
"flood the valve covers with oil" How can that have a positive effect for us? Wont that just cause more problems? Plus, cup cars are runnind a 2000++ RPM higher than we ever see.
09-28-2015, 08:44 PM
#32
I like what Reher says here.... "In my experience, an extremely smooth profile is unlikely to win drag races. It might be suitable for a NASCAR stock car engine or an endurance racing application...."
We're certainly not drag racing here and not stock car racing or endurance racing----but obviously the engines need to live/survive in everyday normal wear and tear......and I know I am not saying anything profound here, but what I have observed over the years is that aggressive valve opening/closings will hardly make any noticeable difference in a hi-perf offshore boat engine.
We're certainly not drag racing here and not stock car racing or endurance racing----but obviously the engines need to live/survive in everyday normal wear and tear......and I know I am not saying anything profound here, but what I have observed over the years is that aggressive valve opening/closings will hardly make any noticeable difference in a hi-perf offshore boat engine.
Last edited by KAAMA; 09-28-2015 at 08:58 PM.
09-28-2015, 09:08 PM
#33
I'm guessing that having a lifter out of adjustment (i.e. too loose) or collapsing would also hammer the valvetrain the same way that valve float would, since the clearance ramps can't do their jobs. Am I on the right track with my thinking?
09-28-2015, 09:16 PM
#34
We can talk about high or low spring pressures all day, but whats high? Whats low? Whats high? For example, a GM truck big block, might have 90lbs of seat pressure. Merc 525's, had what like 120lbs of seat pressure? Crane/comp/howards/lunati, etc, normally seem to recommend anywhere from 140-160lbs of seat pressure on a bbc hyd roller off the shelf cam. Then all of a sudden, we are talking 225lbs of seat pressure, and nearly 600 over the nose on a hyd roller. At one time, that was serious solid roller spring territory.
I guess its simply a guess, unless you take you engine combo to a spintron, and see what it really needs for adequate valvetrain control with your combination of parts. Or, take a chance, and tear it down after couple hundred hours, and see what things look like. Like seats, lobes, lifters, etc.
I think most cam companies, do the majority of the testing for us, and hence why they may recommend xxx part number springs, with xxx cams. I am sure they arent pulling those numbers out of thin air. I certainly don't know more than the guys at crane, crower, or comp cams. I can only take their word for it.
My guess is when you really start getting into stuff like 55mm+ cam cores, big body lifters, custom designed lobes, higher lifts, larger pushrod diameters, big valves, different valve materials, untraditional style springs, and so on, a trip to the spintron, is worth the money.
My gut feeling, is a basic traditional, mild lobe, off the shelf hydraulic roller from crane, designed for marine applications, isn't requiring 600lbs of spring over the nose, at 6,000 RPMs, to keep the valve train under control. But, thats just a guess, and I certainly dont know that for sure. I do know, there are lots of guys who've ran those cams, with much less spring here on oso, for lots of hours without issue since the late 90's.
09-28-2015, 09:26 PM
#35
Registered
iTrader: (1)
Was not suggesting the Cup Car deal.
09-28-2015, 09:33 PM
#36
Registered
iTrader: (1)
Read Grumpy's response to the first question:
http://garage.grumpysperformance.com...gine-oil.6491/
Chris Osborn from PAC springs:
http://speedtalk.com/forum/viewtopic.php?f=1&t=4595
http://garage.grumpysperformance.com...gine-oil.6491/
Chris Osborn from PAC springs:
http://speedtalk.com/forum/viewtopic.php?f=1&t=4595
Last edited by SB; 09-28-2015 at 09:37 PM.
09-28-2015, 10:02 PM
#37
Platinum Member
Platinum Member
iTrader: (1)
Abones, theres a little more to it than that though, 2.300 intake, minus .343 for dia of stem lets say 2.0 " for discussion , 2x 3.14 =6.25" area x 14 psi boost = 85 roughly, so to help control intake valve under boost it would take a extra 85 lbs give or take so really my 490 is more like 405 on intake, take away 5% for springs going away before rebuild interval and even though 490 sounds sorta big it gets small quick, in my opinion. Does a NA motor need 490, no but it better have at least 400 to turn 6k+, Smitty
09-28-2015, 10:05 PM
#38
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Platinum Member
iTrader: (1)
Mine are 165 at the seat. Maybe this winter we will tear mine down, and see what things look like in there. But you're right on about the temps, that certain can change the pressures as the spring heats up. One of the reasons I cringe when i see guys saying "my oil temps are 260, but its ok, my 12 dollar a quart oil can take it". I dont care about the oil, I care about the engine parts!
We can talk about high or low spring pressures all day, but whats high? Whats low? Whats high? For example, a GM truck big block, might have 90lbs of seat pressure. Merc 525's, had what like 120lbs of seat pressure? Crane/comp/howards/lunati, etc, normally seem to recommend anywhere from 140-160lbs of seat pressure on a bbc hyd roller off the shelf cam. Then all of a sudden, we are talking 225lbs of seat pressure, and nearly 600 over the nose on a hyd roller. At one time, that was serious solid roller spring territory.
I guess its simply a guess, unless you take you engine combo to a spintron, and see what it really needs for adequate valvetrain control with your combination of parts. Or, take a chance, and tear it down after couple hundred hours, and see what things look like. Like seats, lobes, lifters, etc.
I think most cam companies, do the majority of the testing for us, and hence why they may recommend xxx part number springs, with xxx cams. I am sure they arent pulling those numbers out of thin air. I certainly don't know more than the guys at crane, crower, or comp cams. I can only take their word for it.
My guess is when you really start getting into stuff like 55mm+ cam cores, big body lifters, custom designed lobes, higher lifts, larger pushrod diameters, big valves, different valve materials, untraditional style springs, and so on, a trip to the spintron, is worth the money.
My gut feeling, is a basic traditional, mild lobe, off the shelf hydraulic roller from crane, designed for marine applications, isn't requiring 600lbs of spring over the nose, at 6,000 RPMs, to keep the valve train under control. But, thats just a guess, and I certainly dont know that for sure. I do know, there are lots of guys who've ran those cams, with much less spring here on oso, for lots of hours without issue since the late 90's.
We can talk about high or low spring pressures all day, but whats high? Whats low? Whats high? For example, a GM truck big block, might have 90lbs of seat pressure. Merc 525's, had what like 120lbs of seat pressure? Crane/comp/howards/lunati, etc, normally seem to recommend anywhere from 140-160lbs of seat pressure on a bbc hyd roller off the shelf cam. Then all of a sudden, we are talking 225lbs of seat pressure, and nearly 600 over the nose on a hyd roller. At one time, that was serious solid roller spring territory.
I guess its simply a guess, unless you take you engine combo to a spintron, and see what it really needs for adequate valvetrain control with your combination of parts. Or, take a chance, and tear it down after couple hundred hours, and see what things look like. Like seats, lobes, lifters, etc.
I think most cam companies, do the majority of the testing for us, and hence why they may recommend xxx part number springs, with xxx cams. I am sure they arent pulling those numbers out of thin air. I certainly don't know more than the guys at crane, crower, or comp cams. I can only take their word for it.
My guess is when you really start getting into stuff like 55mm+ cam cores, big body lifters, custom designed lobes, higher lifts, larger pushrod diameters, big valves, different valve materials, untraditional style springs, and so on, a trip to the spintron, is worth the money.
My gut feeling, is a basic traditional, mild lobe, off the shelf hydraulic roller from crane, designed for marine applications, isn't requiring 600lbs of spring over the nose, at 6,000 RPMs, to keep the valve train under control. But, thats just a guess, and I certainly dont know that for sure. I do know, there are lots of guys who've ran those cams, with much less spring here on oso, for lots of hours without issue since the late 90's.
09-28-2015, 10:08 PM
#39
Platinum Member
Platinum Member
iTrader: (1)
I like what Reher says here.... "In my experience, an extremely smooth profile is unlikely to win drag races. It might be suitable for a NASCAR stock car engine or an endurance racing application...."
We're certainly not drag racing here and not stock car racing or endurance racing----but obviously the engines need to live/survive in everyday normal wear and tear......and I know I am not saying anything profound here, but what I have observed over the years is that aggressive valve opening/closings will hardly make any noticeable difference in a hi-perf offshore boat engine.
We're certainly not drag racing here and not stock car racing or endurance racing----but obviously the engines need to live/survive in everyday normal wear and tear......and I know I am not saying anything profound here, but what I have observed over the years is that aggressive valve opening/closings will hardly make any noticeable difference in a hi-perf offshore boat engine.
