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What?
You think this would be a greater part of advertising campaigns.
Cam bushings
- Thread starter roachie
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You think this would be a greater part of advertising campaigns.
SPEEDSHIFT
New member
I do...:fish:
Is that a race pressed in the block? I am curious how you get the cam in, and keep the bearings in place. Race in the block, bearings on the cam, and the keeper holds everything in?
edit: Nevermind, the rollers use the cam as a race.
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Hamilton Cams
ignorant
That will help, but it will not solve all of the issues associated with roller lifters with the kind of short duration, high lift cam profiles we use with a small bore roller lifter. Dlc's might keep the lifter from galling and transferring metal to the lifter bore but there will still be elevated oil temps over the use of flat tappets. A major improvement would be to use a larger bore lifter similar to the duramax. Problem is, we do not have enough room in the cummins block. To make rollers a great match, a custom block with large bore lifters, larger journals and larger basecircles would make them more of a logical choice.
This is just my opinion.
This is just my opinion.
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I could see where this might make a noticeable difference in an oval-track car, etc, but what about in a drag car or sled-puller? How large is the temperature difference?
Hamilton Cams
ignorant
I don't remember the exact temperature difference. They were talking about different spintron tests with differing valvetrains. In this way friction can be isolated because there is no combustion to mask temperatures or oil to coolant heat exchangers in operation.
Drag racer or sled puller, if you are talking about a cummins engine, unless you have BIG duration cam and higher ratio rockers, flat tappet cams win.
A lot of people might call B.S. on the fact that the roller side loads and creates more friction but it is the real deal. I have heard the question that why does it work so well in gasoline engines? Why does the Duramax use roller?
On gas engines the lobes are totally different due to the type of fuel and the RPM range. It is not uncommon for a cam in or around the ranges of 270/292 /.320"/.340" where pulling grinds in diesel are around 230-250 and .375" to .390". This large duration to lift ratio found in gasoline profiles creates an easier ramp for the roller lifter to follow without as much side loading so smaller bore lifters can be used. Higher ratio rockers also help to offset the penalty in initial acceleration by amplifying the ramp rate further.
Although the profiles we use with diesel flat tappets work well this kind of profile converted to roller would create more side loading.
People ask why does it work in Duramax engines. For one thing the duramax engine has a very large lifter bore to spread the load more and fight the side loading. The lobes also have modest lift compared to pulling grinds we use in a cummins. In a Cummins B engine there just isn't enough meat to install larger bore lifters to give more surface area for the oil film between the lifter and the bore. If all of the advantages of a roller profile are to be used, A custom block that can accept a larger bore lifter and higher ratio rockers that can amplify the ramp rates, will make a Roller profile much more of an advantage than adapting a stock block.
Zach
zstroken
For $$$ your name here
Big advantage to rollers is you don't have to worry about spring pressures nearly as much. But there are costs associated with the rollers.
Yes and no.......
Cup engines use high lift, short duration cams quite often. They also use ROLLER cam bearings and FLAT tappet lifters that are of a smaller diameter that a stock SBC. The reason for the flat tappet lifter with the small diameter is light weight. All lifters and rods are DLC coated. Here.... Read this. Ever hear of Reher-Morrison??
#43- Trouble with Flat Tappets Reher-Morrison Official Blog
Cup engines use high lift, short duration cams quite often. They also use ROLLER cam bearings and FLAT tappet lifters that are of a smaller diameter that a stock SBC. The reason for the flat tappet lifter with the small diameter is light weight. All lifters and rods are DLC coated. Here.... Read this. Ever hear of Reher-Morrison??
#43- Trouble with Flat Tappets Reher-Morrison Official Blog
Hamilton Cams
ignorant
The flat tappets we use are almost twice the size of the ones in the article. This allows ramp rates much greater than that of a .842 flat tappet. This article is written about small flat vs roller. I think you might have your facts a little mixed up. I welcome you to come up with a roller street cam for the 5.9L. My little old flat tappet will go head to head with anything you can come up with, stock ratio rockers, stock cam bore size. Without changing rocker ratios, we can isolate cam vs. cam. Looking at valve lift vs. crank angle will tell the whole story.
Flat tappet cam- $599
Flat tappets $99
Roller cam - $1300-$1800
Roller lifters $199+
Machine work $300+
Looks very expensive to make less power on a street truck. Now on Puller with duration over 250 @.050" and higher ratio rockers, I can see some benefits.
Zach
Flat tappet cam- $599
Flat tappets $99
Roller cam - $1300-$1800
Roller lifters $199+
Machine work $300+
Looks very expensive to make less power on a street truck. Now on Puller with duration over 250 @.050" and higher ratio rockers, I can see some benefits.
Zach
Read this......
I think maybe your facts are a little off, sir. Read paragraph 7-8 again. See where it says, "even the fattest flat tappets cant..." Keep reading. You can accelerate a valve MUCH faster with a roller than a flat tappet. You can hold it open longer if you wish, and then close it much faster in a controlled fashion. All the while keeping the roller on the profile of the cam, not lofting it over the nose and bringing it back down on the back side of the lobe like almost ALL aggressive flat tappets do. Trying to use large flat tappets is a band-aid at best. Yes, it allows faster ramps than small flat tappets, BUT not nearly as fast as roller lifters, AND AT A EXTREME WEIGHT PENALTY. How much you think those big azz flat tappets weigh. Guess what, our cams have more aggressive lift numbers and higher ramp rates than anything you make, we run SMALLER diameter flat tappets that are lite weight and casidium coated, and I would give my left nut to be allowed to run rollers. FYI, our lifters cost almost $1000 a set. I can show you a pic of a cam for a top fuel Harley that is actually nearly over square. The lobe is almost as wide as the base circle and is opened with rollers. Talk about side loading!! If you tried to open that valve with a flat tappet.... KABOOM is what you would hear. That cam has OVER 1 inch lift. Also, this thread was started about roller CAM bearings, not lifters.
I think maybe your facts are a little off, sir. Read paragraph 7-8 again. See where it says, "even the fattest flat tappets cant..." Keep reading. You can accelerate a valve MUCH faster with a roller than a flat tappet. You can hold it open longer if you wish, and then close it much faster in a controlled fashion. All the while keeping the roller on the profile of the cam, not lofting it over the nose and bringing it back down on the back side of the lobe like almost ALL aggressive flat tappets do. Trying to use large flat tappets is a band-aid at best. Yes, it allows faster ramps than small flat tappets, BUT not nearly as fast as roller lifters, AND AT A EXTREME WEIGHT PENALTY. How much you think those big azz flat tappets weigh. Guess what, our cams have more aggressive lift numbers and higher ramp rates than anything you make, we run SMALLER diameter flat tappets that are lite weight and casidium coated, and I would give my left nut to be allowed to run rollers. FYI, our lifters cost almost $1000 a set. I can show you a pic of a cam for a top fuel Harley that is actually nearly over square. The lobe is almost as wide as the base circle and is opened with rollers. Talk about side loading!! If you tried to open that valve with a flat tappet.... KABOOM is what you would hear. That cam has OVER 1 inch lift. Also, this thread was started about roller CAM bearings, not lifters.
See if you can follow this.......
If you think that flat tappets are the answer on the street, can you explain why almost all current design engines use roller tappets? GM, Ford, Chrysler, all use roller lifters in there pushrod motors. WHY you ask. Well, because they free up horse power, get better mileage and last longer, especially as they keep taking the good additives out of the oil. And who do you know who spends alot of time over 6k rpm on the street. If it didnt work the manufacturers wouldnt use it. I am pretty sure they spend more than you on testing and R&D.
If you think that flat tappets are the answer on the street, can you explain why almost all current design engines use roller tappets? GM, Ford, Chrysler, all use roller lifters in there pushrod motors. WHY you ask. Well, because they free up horse power, get better mileage and last longer, especially as they keep taking the good additives out of the oil. And who do you know who spends alot of time over 6k rpm on the street. If it didnt work the manufacturers wouldnt use it. I am pretty sure they spend more than you on testing and R&D.
M_Thomas07
CompDEX
op:
KILLER 'B'
Pro Wrench Turner
holyfuchingchit.......... op:
op:
XLR8R
Crew Chief
Many grinds promote loft - just need the spring to complement it... how else are we supposed to skirt a lift rule class? :rules:
OK, just to finish derailing this Cam Bushing thread - 3rd exponent septic polynomial 4th order lobe lift coefficient B-spline Guass/Siedel iteration Landis-generated pulsed CV ramp 4stHEAD code... LOL
OK, just to finish derailing this Cam Bushing thread - 3rd exponent septic polynomial 4th order lobe lift coefficient B-spline Guass/Siedel iteration Landis-generated pulsed CV ramp 4stHEAD code... LOL
kazairl
New member
X2. I'd like to see where this goes.
Hamilton Cams
ignorant
Large flat tappets in the gas world are .9xx" Once again apples and oranges to what we have at 1.300" of 1.500". Rollers were needed in large part to the flat tappet wear issues associated with low zinc oils. They work very well for their intended purpose. In most stock cams they have much lower lift and much higher duration than that of a cummins performance street cam. I can appreciate your opinion but I am going to have to ask you to start naming application, lift duration, rocker ratio and roller diameter. I think you will see a major difference than our performance cummins cams. Also you keep saying the lobe is shaped like a square or an apple or whatever. That really doesn not mean much to me. Plotting valve motion as a function of crank angle factoring for rocker ratio is the only way to adequately compare any two designs. Initial aceleration......flat tappets win. In large racing profiles, with high ratio rockers, rollers do have obvious advantages. I think continuing to spout off partial information in something your cousin's uncle's brother's sister ran is much different than plotting valve motion and having an intelligent conversation about advantages in differing designs. Opinions are useless, lets get some data out here. I have a 207/220@.050" profile I would like to compare to something you might have in a roller profile. Lets compare their valve motion in terms of lift at varying crank angles from .001 to .500. The trouble you will find is the same thing I have found. It is very hard to find a roller 207@ .050" .360" lobe lift.
I am not going to ignorantly throw insults back and forth and say x or y is better. You get your apples out and I will get mine.Do you have any data on a similar profile with a 1.7 to 1 rocker ratio?
XLR8R yes but most of the profiles that promote loft are much larger in terms of duration @.050" than our cummins street cams.
Zach
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Hamilton Cams
ignorant
We can talk about it in this thread or that thread. All we need to do is get someone with a similar profile that is roller to plot valve motion so that we can have an inteligent conversation. Posting an opinion from a blog about an application far different from the one at hand and using a tappet almost half the size of the ones we use is far from proof of superiority. By the way, I have a pretty good Idea what we will find without having that data.
Zach
Zach