Camshaft Tech
Registered User
Joined: Feb 2003
Posts: 2,639
From: Mooresville, NC
Re: Camshaft Tech
Originally Posted by jimlab
I asked, if that's the case, why you can turn an engine over with a standard 1/2" ratchet on the crankshaft snout with very little effort.
What was his reply to that?
Registered User
Joined: May 2000
Posts: 799
From: Redmond, WA
Re: Camshaft Tech
His latest diatribe...
Valid points, accept the part where the valves are not opened at once. No kidding, but opening each one once every two crank revolutions takes a lot of power. Those spring pressures are from Isky info. The highest they list works out to 430lb/in springs. So the cam has to push against 532 lbs through the rocker arm to lift the valve .750" Lets say the cam has .500" lift for easy math (that would give us .825 valve lift, thats a lot) And no figuring for cam profile. To lift a cam follower .5 " with a .5" lever would take 22.16 lbft of torque. (Check my math, 1 ft=24 half inches, so divide 532 by 24 right? Do that sixteen times in two revs and you get 354.56 lbft of torque used. HP=torque x rpm / 5252. So we have 354.56 x 8500rpm / 5252. That gets us 573.83 but thats crank rpm but our cam is spinning half that so we get 286 hp drag on the crank. This could be figured as 8 valve events per revolution(177.28 lbft) with the same answer. I'm sure there are many variables that I didn't address but I think the math tells the story.
Registered User
Joined: Oct 2002
Posts: 2,931
From: Upstate NY
Re: Camshaft Tech
Jim,
Springs store energy. Ask your "buddy" if he accounted for the energy or power the spring puts back into the system after the lifter goes over the nose of the cam. Most of the effort used to compress the springs is given back by the spring. The amount lost is due to friction in the valvetrain system and heat generated.
FWIW, the typical timing chain and sprockets or gears couldn't transmit the hp he is claiming; they would self destruct.
Ask him to check out the size of the electric motor which drives just the valvetrain on a SpinTron. The base 10,000 rpm model uses a 25 hp motor. There are 50 and 75 hp models available which can test to 20,000. I couldn't find a 286 hp model for 8500 or a 673 hp model for 20,000 rpm.
Common sense is not a given in all individuals. Unfortunately, sometimes it is especially lacking in those who use higher sciences to try to explain how they think the world works.
A couple of quotes:
"Math is a tool, and it's a poor workman who blames his tools."
"Figures don't lie, but liars figure."
PLEASE don't invite him to Advanced Tech, Jim.
Springs store energy. Ask your "buddy" if he accounted for the energy or power the spring puts back into the system after the lifter goes over the nose of the cam. Most of the effort used to compress the springs is given back by the spring. The amount lost is due to friction in the valvetrain system and heat generated.
FWIW, the typical timing chain and sprockets or gears couldn't transmit the hp he is claiming; they would self destruct.
Ask him to check out the size of the electric motor which drives just the valvetrain on a SpinTron. The base 10,000 rpm model uses a 25 hp motor. There are 50 and 75 hp models available which can test to 20,000. I couldn't find a 286 hp model for 8500 or a 673 hp model for 20,000 rpm.
Common sense is not a given in all individuals. Unfortunately, sometimes it is especially lacking in those who use higher sciences to try to explain how they think the world works.
A couple of quotes:
"Math is a tool, and it's a poor workman who blames his tools."
"Figures don't lie, but liars figure."
PLEASE don't invite him to Advanced Tech, Jim.
Thread Starter
Registered User
Joined: Sep 2002
Posts: 655
Re: Camshaft Tech
How about kinetic energy, mass and velocity?
A lifter, pushrod, valve, retainer, rocker, etc. all have mass and balance
out the spring pressure as they reciprocate.
Ask him why it's so easy to float a valve which weighs xx.x grams (insert weight here) if the spring pressure is so damn high.
A lifter, pushrod, valve, retainer, rocker, etc. all have mass and balance
out the spring pressure as they reciprocate.
Ask him why it's so easy to float a valve which weighs xx.x grams (insert weight here) if the spring pressure is so damn high.
Registered User
Joined: Oct 2001
Posts: 1,462
From: smog zone adjacent to a great lake
Re: Camshaft Tech
Originally Posted by OldSStroker
Common sense is not a given in all individuals. Unfortunately, sometimes it is especially lacking in those who use higher sciences to try to explain how they think the world works.
A couple of quotes:
"Math is a tool, and it's a poor workman who blames his tools."
"Figures don't lie, but liars figure."
A couple of quotes:
"Math is a tool, and it's a poor workman who blames his tools."
"Figures don't lie, but liars figure."
Originally Posted by OldSStroker
PLEASE don't invite him to Advanced Tech, Jim.
Registered User
Joined: May 2000
Posts: 799
From: Redmond, WA
Re: Camshaft Tech
Originally Posted by OldSStroker
Jim,
Springs store energy. Ask your "buddy" if he accounted for the energy or power the spring puts back into the system after the lifter goes over the nose of the cam. Most of the effort used to compress the springs is given back by the spring. The amount lost is due to friction in the valvetrain system and heat generated.
Springs store energy. Ask your "buddy" if he accounted for the energy or power the spring puts back into the system after the lifter goes over the nose of the cam. Most of the effort used to compress the springs is given back by the spring. The amount lost is due to friction in the valvetrain system and heat generated.
Ask him to check out the size of the electric motor which drives just the valvetrain on a SpinTron. The base 10,000 rpm model uses a 25 hp motor. There are 50 and 75 hp models available which can test to 20,000. I couldn't find a 286 hp model for 8500 or a 673 hp model for 20,000 rpm.
PLEASE don't invite him to Advanced Tech, Jim.
Banned
Joined: Oct 2002
Posts: 6,518
Re: Camshaft Tech
Lol, poor Rotary saps.... I can tell he's a math guy and not a actual engineer... If 200hp is the case then a Acura RSX ONLY needs a Cloyes V8 timing chain to connect the engine to the drive shafts.. lol
Why don't you ask him to figure out if a 750hp 358 Cup Motor or a 750hp Rotary motor... which one eats more gas. He would have to know something about BSFC numbers but I'm sure he could "invent" that himself.
And people wonder why I HATE Rotary motors? You can pick up a Harley motor and carry it around too, but does that mean it belongs in a sportscar?
Bret
Why don't you ask him to figure out if a 750hp 358 Cup Motor or a 750hp Rotary motor... which one eats more gas. He would have to know something about BSFC numbers but I'm sure he could "invent" that himself.
And people wonder why I HATE Rotary motors? You can pick up a Harley motor and carry it around too, but does that mean it belongs in a sportscar?
Bret
Registered User
Joined: Nov 2001
Posts: 2,985
From: In a house by the bay
Re: Camshaft Tech
Originally Posted by jimlab
I mentioned that and someone else did as well, and he then "figured" that it gave back about 86 horsepower, so his 200 horsepower estimate is still right...
Oh yeah... "frictional losses", so 0-1+.999
-Mindgame
Registered User
Joined: Apr 2003
Posts: 1,591
From: PA
Re: Camshaft Tech
Originally Posted by Jimlab
I mentioned that and someone else did as well, and he then "figured" that it gave back about 86 horsepower, so his 200 horsepower estimate is still right...
Originally Posted by SStrokerAce
You can pick up a Harley motor and carry it around too, but does that mean it belongs in a sportscar?
Here's a good simple rebuttal:
http://dictionary.reference.com/search?q=spring
Spring (n.) An elastic device, such as a coil of wire, that regains its original shape after being compressed or extended.
It would be perfect to post over there if it referenced 'stored energy'....
Or here is a good high school level reference:
http://www.glenbrook.k12.il.us/gbssc...rgy/u5l1b.html
-brent
Registered User
Joined: May 2000
Posts: 799
From: Redmond, WA
Re: Camshaft Tech
Originally Posted by SStrokerAce
Why don't you ask him to figure out if a 750hp 358 Cup Motor or a 750hp Rotary motor... which one eats more gas. He would have to know something about BSFC numbers but I'm sure he could "invent" that himself.
Registered User
Joined: May 2000
Posts: 799
From: Redmond, WA
Re: Camshaft Tech
Originally Posted by 94formulabz
Please tell me he included calculations for that 86 hp.
However, after being confronted with the Spintron information, he said he searched the net and found estimates from 5% to 15% and settled on 10% (75 horsepower for a 750 horsepower engine) as the correct figure.
Banned
Joined: Oct 2002
Posts: 6,518
Re: Camshaft Tech
Nothing wrong with Harley motors....
I just have a thing against 2-Strokes and Rotaries.... It's kind of like that Coats valveless engine... WHY CHANGE SOMETHING THAT WORKS SO WELL WITH SO MUCH R&D INTO IT!
Bret
I just have a thing against 2-Strokes and Rotaries.... It's kind of like that Coats valveless engine... WHY CHANGE SOMETHING THAT WORKS SO WELL WITH SO MUCH R&D INTO IT!
Bret
Registered User
Joined: Apr 2003
Posts: 1,591
From: PA
Re: Camshaft Tech
No-way, 2 stokes rule. If someone would master a direct injection 2 stoke for emissions it will open up a lot of possibilities. I don’t know how realistic this is since i'm in no way involved with that. 2 stokes still have their place on snowmobiles, atvs, chainsaws, and leaf blowers where limited use and wieght can be a bigger factor.
I’m with you on the rotaries though, my crystal ball doesn’t show any signs of significant evolution there.
-brent
If someone would master a direct injection 2 stoke for emissions it will open up a lot of possibilities. I don’t know how realistic this is since i'm in no way involved with that. 2 stokes still have their place on snowmobiles, atvs, chainsaws, and leaf blowers where limited use and wieght can be a bigger factor. I’m with you on the rotaries though, my crystal ball doesn’t show any signs of significant evolution there.
-brent