Cam question for the group

[TIMINATOR]

I looked at the lifter PDF, and, in one instance it says more preload makes less top end HP, later it says less lash (mechanical) and more pre load makes the cam seem bigger. The second starement is correct.
With a mechanical cam, opening the lash definatly makes the cam effectively smaller, just as hydraulic lifter bleed down does. This results in less lift and effective duration, as the lash must be "taken up" before lift starts,(remember to multiply the extra lash by the rocker ratio before you subtract it from advertised lift).
More lash means less effective duration, and its easy to visualize. Advertised duration is measured at .006" tappet rise, duration at .050" is just that, it is duration at .050" tappet rise. I.E. A 280 duration Comp hydraulic cam is 280 degrees at .006 tappet lift, and "duration at .050", IS the duration at .050" lift, and it is 230 degrees. Thats a loss of FIFTY DEGREES DURATION, for .044" difference of lift!
Now, back to what I have been saying:
Standard hydraulic lifters have about .190" travel. At a "half turn down" its about .160" travel. Bleed down occurs from both open and closed spring pressures, and inertial pressure from the weight of the entire valve train: lifter- plunger, pushrod, both ends of the rocker arm, valve, retainer, locks, the upper, moving half of the spring, umbrella type stem seal, and any oil that is inside the pushrod, and any oil all over the valvetrain externally. Inertial loads quadruple with doubling of the RPM also. Bleed down is much worse on blower, nitrous, and turbo engines due to their higher cylinder pressures at exhaust valve opening. Thats one of the reasons why larger, higher RPM hydraulic turbo cams have longer exhaust duration than intake.
Conical and beehive springs reduce the weight of the movable end of the spring, retainer, and locks, and are more efficient if they have enough pressure to control the valvetrain.
Back "in the day" when cam lobe design was out pacing the then current valvespring technology, Rev Kits were popular on roller applications. They were nothing more than springs that set up against the bottom of the head, and pushed against the roller lifter, helping it to better follow the cam lobe and allowing the valvespring to only need to control the upper end of the valvetrain.
Buick V-6s and all of the LS engines have small diameter springs, and are both limited by spring installed height and diameter and can both benefit from these "Rev Kits."
JMHO
TIMINATOR

 

[Haulz A]

I looked at the lifter PDF, and, in one instance it says more preload makes less top end HP, later it says less lash (mechanical) and more pre load makes the cam seem bigger. The second starement is correct.
With a mechanical cam, opening the lash definatly makes the cam effectively smaller, just as hydraulic lifter bleed down does. This results in less lift and effective duration, as the lash must be "taken up" before lift starts,(remember to multiply the extra lash by the rocker ratio before you subtract it from advertised lift).
More lash means less effective duration, and its easy to visualize. Advertised duration is measured at .006" tappet rise, duration at .050" is just that, it is duration at .050" tappet rise. I.E. A 280 duration Comp hydraulic cam is 280 degrees at .006 tappet lift, and "duration at .050", IS the duration at .050" lift, and it is 230 degrees. Thats a loss of FIFTY DEGREES DURATION, for .044" difference of lift!
Now, back to what I have been saying:
Standard hydraulic lifters have about .190" travel. At a "half turn down" its about .160" travel. Bleed down occurs from both open and closed spring pressures, and inertial pressure from the weight of the entire valve train: lifter- plunger, pushrod, both ends of the rocker arm, valve, retainer, locks, the upper, moving half of the spring, umbrella type stem seal, and any oil that is inside the pushrod, and any oil all over the valvetrain externally. Inertial loads quadruple with doubling of the RPM also. Bleed down is much worse on blower, nitrous, and turbo engines due to their higher cylinder pressures at exhaust valve opening. Thats one of the reasons why larger, higher RPM hydraulic turbo cams have longer exhaust duration than intake.
Conical and beehive springs reduce the weight of the movable end of the spring, retainer, and locks, and are more efficient if they have enough pressure to control the valvetrain.
Back "in the day" when cam lobe design was out pacing the then current valvespring technology, Rev Kits were popular on roller applications. They were nothing more than springs that set up against the bottom of the head, and pushed against the roller lifter, helping it to better follow the cam lobe and allowing the valvespring to only need to control the upper end of the valvetrain.
Buick V-6s and all of the LS engines have small diameter springs, and are both limited by spring installed height and diameter and can both benefit from these "Rev Kits."
JMHO
TIMINATOR

JMHO,
I can see your point of view concerning the PDF file wording between the first and the second statement- it is a little confusing the way its worded but I understand what your are saying about the valve train mechanical lash/ preload vs bleed down. I'm no valve train expert - I just enjoy testing, repairing and researching electro-mechanical engine operations of the Grand National.

Timinator- you seem very knowledgeable in mechanical/ kinetic energy valve train operations. As you stated before- there is alot of hidden power to gain in valve train set-up; degreeing camshaft, valve train adjustment, type of components use in valve train, weight of material used etc.

Its a very interesting subject which a lot of mechanical engineering concepts has made cars of today more efficient and faster. Its been my pleasure chatting with you my friend- keep passing that knowledge on so the legend of these cars will continue on long after we are gone.


Haulz A

 

[TIMINATOR]

It AMAZES me how little the "jap crap" kids know about the engines in their cars! "Bolt on NOS" (as they call it), bolt on someones pre engineered turbo kit(rarely), fart pipe exhaust tips, lowering, "whacked out" paint, and butt ugly wheels, are about as far as they go mechanically. What a shame, they are missing out on SO MUCH!
Take a few of these kids for a ride, and see the reaction! YOU did that to the motor? Suspension? How did you do THAT?
Dazzle a few of 'em!
I have given more than a few of them rides on my high 10 second Harley, Pro street Nova ( mid 9s), GN, and I don't think they will look at a rice rocket bike or cars the same way again!
I like to stir their pot once in a while!
TIMINATOR

 

[GNVYUS 1]

This came up earlier but...

What torque converter?
What rear gear?
They're not in your engine build sheet.

Here's your slippage with these rear gears..

6400rpm
133.5mph
28"
Trans gear 1:1 ratio
3.42
Slippage = 16.8%

Change to a 3.73 gear and you're
Slippage = 7.0%
Pretty good here if that's the case.

If you have a 3.42 gear, look at swapping converters, check out what 7% slippage on a 3.42 gear is..

Rpm = 5870
133.5
28"
Trans 1
3.42
Slippage 7%

 

[Mr.Spool]

7% slip may not be better than 13%.
Everybody assuming tighter is better doesnt mean it will et faster for certain distances

 

[GNVYUS 1]

True, combo matters and 60ft but...
from the years of selling converters, going from 16+% slippage to anything 7 or under on a combo that wasn't over turbo'd was a better ET. The issue is really the turbo and launch, some need the slippage because their turbo is way too big and they are quick but not fast. Slippage feels good at first, then it's pissing away tons of power.

7% still slips out of the hole but the extra and wasted 9% slippage (16%+) through each gear adds up to slower in the end, just too much slippage over 1320ft. Now 10% vs 7% etc now we'd have to see, combo again, you're correct.

Personally, I'd rather run WOT at 5900rpm than 6400 in a 109 regardless of it's faster or slower though.

Enjoy, not destroy is my new moto. LOL

 

[Pronto]

Does rpm drop on shifts too? What would a good drop be for 7% vs 12% or 16%?

 

[Mr.Spool]

True, combo matters and 60ft but...
from the years of selling converters, going from 16+% slippage to anything 7 or under on a combo that wasn't over turbo'd was a better ET. The issue is really the turbo and launch, some need the slippage because their turbo is way too big and they are quick but not fast. Slippage feels good at first, then it's pissing away tons of power.

7% still slips out of the hole but the extra and wasted 9% slippage (16%+) through each gear adds up to slower in the end, just too much slippage over 1320ft. Now 10% vs 7% etc now we'd have to see, combo again, you're correct.

Personally, I'd rather run WOT at 5900rpm than 6400 in a 109 regardless of it's faster or slower though.

Enjoy, not destroy is my new moto. LOL

Its distance past the 60ft
1320 is old news
1/8 is where it is and that's a whole new ball game where paying attention to slip and power and suspension takes on a whole new meaning.
I've seen cars slip big time and et their asses off.
I've also seen cars that dont target a great 60ft but 1/8 real hard.
Its distance and surface racing is what guys need to understand.
No substitute for testing and seeing.

 

[Mr.Spool]

Does rpm drop on shifts too? What would a good drop be for 7% vs 12% or 16%?

Depends on the combo and target distances and surface.
When I say combo I dont mean just engine

 

[Mr.Spool]

from the years of selling converters, going from 16+% slippage to anything 7 or under on a combo that wasn't over turbo'd was a better ET. The issue is really the turbo and launch, some need the slippage because their turbo is way too big and they are quick but not fast. Slippage feels good at first, then it's pissing away tons of power.

Depends on distance and surface and target power range with weight balance.
Well, without going into too much detail
I will throw out say it is possible for a turbo buick to leave soft and run a turbo that is much smaller than the motor car handle with percentages above 10% and hammer down a 1/4 mile.
Now take another turbuick that hammers the 60ft and 330 with a properly sized turbo for the motor(
I have undersized and oversized them) to see and I will say it
Really Requires 2 different slippages.