mopar340dave
Well-Known Member
It just felt a little too much like chain yankin' to me ! LOL
Cam Duration Vs Lift
- Thread starter Petzschler
- Start date
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moper
Well-Known Member
Lol... give him time. This can go somewhere good if we can keep it on course...
Petzschler
→Welcome backâ†
well Mr mopardave340,
89 rangers with the 2.3l had overhead cam engines. gee you just learned another lesson....internet toughguy.....
moper said:
yah its the usual 4" sb. ported stock heads for now. indy's later. going in a 76 Laguna for the street.
yah that KV-6 wild talked about seems to be the cam at the moment.
moper
Well-Known Member
What are the intake lobe center lines? Why 113° LSA? Where did the flow numbers come from? A test, or a wish? What castings?
mopar340dave
Well-Known Member
360Z28, that's great that you actually knew you had a OHC in that Ford of yours, that was my point, apples and oranges.....good luck with your mismatched pile of crap.
mopar340dave
Well-Known Member
As far as I can tell, he pulled all of this out of his ***! Two cams with very different durations that produce identical dynamic compression in the same engine.....:read2:
One question Z28: WHEN DO YOUR IMAGINARY CAM'S INTAKE LOBE'S CLOSE THE INTAKE VALVE IN RELATION TO THE PISTON?
Petzschler
→Welcome backâ†
no kidding. thought in the first post I said hypothetical. well see the answer below and do the conversions
then you can tell me.
first cam somewhere around:
intake 37° btdc 74° abdc
and the exhaust events just becouse..
exaust 77° bbdc 34° atdc
second cam somewhere around:
intake 31° btdc 64° abdc
again, exhaust..
exaust 75° bbdc 30° atdc
you gotta be one of them self inflicted blowjobs that posts on abodiesjoe's lame forum..
T67POWER
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he asked a simple question right? really?:banghead::banghead:
dude whats up:angry7: your the guy who knows everything:thebirdm::thebirdm:
well since you know everything:sleepy2:28 man i might as well ack like i do to.
let me give a lesson in why single pattern cams work and all the hype with new cam profiles is so they sell more cams and everything that goes with it. they still sell single pattern cams dont they.duel pattern cams are just another option but the new thing is not always the best.{{ even roller cams }} the combination is the key.a cam is not a combination
the way you started this off looked cool {[ pick a cam for fun ]}
but you sound like you picked a fight.relax
lesson #1
:read2:
Longer Exhaust Duration: Is this really necessary?
Most stock camshafts from American production V8, V6 and 4 cylinder engines manufactured today are ground with the longer exhaust lobe duration. Or, another way of looking at this is that they are ground with shorter intake durations! The former embraces the viewpoint that either the Exhaust Ports or Exhaust Pipe system is somewhat restrictive, and is in need of an assist. The latter suggests that the intake system is rather efficient and cam timing can be trimmed back a bit with out much sacrifice in power, in order to maximize throttle response and cruising efficiency.
Take your pick here. There is no absolutely correct viewpoint - because both are probably true! In a stock engine running at conservative RPM levels, for the sake of overall efficiency, fuel economy and a quiet smooth running engine, this staggering of intake and exhaust duration is quite common and appropriate.
However, High Performance is another thing entirely. Change one factor, let's say in this case, the exhaust system (installing headers and larger pipes) and you have just negated in most cases, the need for that longer exhaust lobe. Now couple this change with a different intake system and camshaft and you have really scrambled the equation. But, wait just a moment. Why is it that so many people (racers & cam grinders alike) insist on running a cam with longer exhaust duration regardless of what equipment is employed? The answer is "habit". Most of them have been somewhat successful in doing it their way and will probably never change unless virtually forced by circumstances to do so.
Before we go any further however let's review what it actually is we are trying to do with an engine when we attempt to make more power. Our best result comes when we are cognizant of the fact that an engine is basically an air pump. We pump it in and out (although in a different form) and we have problems when one side or the other is restricted. Balance or the equilibrium or flow should be our objective, unless of course we are not trying to make more horsepower!
Example #1 (Oval track racing) Here, I have often observed that the most experienced drivers are those who are most likely to run a single pattern (equal on intake and exhaust duration) cam. Why? Because such cams always, [[[[[ I repeat always make more torque! ]]]]] These veterans have a more educated foot and greater experience in feathering the throttle in the corners. They can therefore, utilize the benefit of added torque, in the lower to mid RPM range, to their advantage.
Their counterparts, the younger drivers on the circuit, generally are not as experienced and may at times actually get "crossed up" in the corners especially with a lighter car or when they are learning the ropes. In their case, a longer exhaust duration is often the more appropriate choice. It will often help them to drive better, more "flat footed" if you will, without consequence. But please for the sake of accuracy, let us be truthful. The benefit comes from an actual bleeding off of low to mid range torque, which is always what happens when Exh. Duration is lengthened, not from any improvement. The improvement, (if any) would come because of an improvement in scavenging at the extreme upper end of the power curve and would usually be marginal at best. Yet the so-called "extra power" potential of a longer Exh. Duration cam is most often why they are touted - power most people are backing away from at the end of the strait away!
Example #2 (Drag Racing) At the drag strip it's a little different and I feel more honest. Here, racers have long enjoyed longer exhaust and longer durations across the board (If I may add specifically for the purpose of "killing" low-end torque) to keep the tires from too easily breaking lose. This has been successful and sometimes actually results in a slight increase in top end power - something you can actually use in drag racing since it is a full throttle endeavor through the lights. Keep in mind here though, it's quite possible that a longer duration cam overall would have done just as well or better. {{{In other words if you needed that longer exhaust for top end, perhaps the intake could have benefited from such a lengthening as well.}}}
One of my favorite expressions is how "The Drag Racing mentality has infiltrated the ranks of Oval Track". Many have crossed over and made the switch in the past 10-15 years and some have brought their preconceived notions about how to cam an engine with them.[[[[[ A few may actually read these concepts and if they do so will at least come away with a better understanding of what they are doing.]]]] On the other hand they also could find that this information might actually help their cars to run just a bit faster!
i have a buddy of mine who had indy build him a hemi {over 20 grand!!!!}
INDY PUT A ROLLER CAM IN IT BUT HE DIDNT LIKE HOW IT RAN.
SO HE GAVE THE MOTOR TO RAY BARTON AND HE WENT THREW THE HOLE MOTOR FOR 10 MORE GRAND BUT HE MADE 30 MORE HORSE WITH AND IT RUNS PERFECT ON THE STREET.
MISTER Z28 MAN
DO YOU KNOW WHAT YOUR REALLY TALKING ABOUT.
WELL I NO RAY BARTON DOES:read2:
HE USED A SOLID NON ROLLER CAM {{{ WHY? }}}
BECAUSE HE KNOWS HOW TO MAKE POWER.
I DONT KNOW EVERYTHING AND NEVER WILL BUT I LEARN SOMETHING EVERYDAY AND KNOW ENOUGH TO ONLY OPEN MY MOUTH WHEN I HAVE A GOOD QUESTION FOR SOMEONE SMARTER THEN ME AND THEN LISTEN AND LEARN.
BUT THE BIGGEST THING IS WHEN TALKING TO PEOPLE WHO DONT KNOW MUCH ABOUT SOMETHING AND TO HAVE RESPECT FOR THERE IGNORANCE BECAUSE IF THEY LISTEN AND LEARN BETTER THEN YOU DID (((((THEY MIGHT BE THE ONE IN THE WINNERS CIRCLE)))) AND YOU WILL BE ONLINE MAKING FUN OF PEOPLE
dude whats up:angry7: your the guy who knows everything:thebirdm::thebirdm:
well since you know everything:sleepy2:28 man i might as well ack like i do to.
let me give a lesson in why single pattern cams work and all the hype with new cam profiles is so they sell more cams and everything that goes with it. they still sell single pattern cams dont they.duel pattern cams are just another option but the new thing is not always the best.{{ even roller cams }} the combination is the key.a cam is not a combination
the way you started this off looked cool {[ pick a cam for fun ]}
but you sound like you picked a fight.relax
lesson #1
:read2:
Longer Exhaust Duration: Is this really necessary?
Most stock camshafts from American production V8, V6 and 4 cylinder engines manufactured today are ground with the longer exhaust lobe duration. Or, another way of looking at this is that they are ground with shorter intake durations! The former embraces the viewpoint that either the Exhaust Ports or Exhaust Pipe system is somewhat restrictive, and is in need of an assist. The latter suggests that the intake system is rather efficient and cam timing can be trimmed back a bit with out much sacrifice in power, in order to maximize throttle response and cruising efficiency.
Take your pick here. There is no absolutely correct viewpoint - because both are probably true! In a stock engine running at conservative RPM levels, for the sake of overall efficiency, fuel economy and a quiet smooth running engine, this staggering of intake and exhaust duration is quite common and appropriate.
However, High Performance is another thing entirely. Change one factor, let's say in this case, the exhaust system (installing headers and larger pipes) and you have just negated in most cases, the need for that longer exhaust lobe. Now couple this change with a different intake system and camshaft and you have really scrambled the equation. But, wait just a moment. Why is it that so many people (racers & cam grinders alike) insist on running a cam with longer exhaust duration regardless of what equipment is employed? The answer is "habit". Most of them have been somewhat successful in doing it their way and will probably never change unless virtually forced by circumstances to do so.
Before we go any further however let's review what it actually is we are trying to do with an engine when we attempt to make more power. Our best result comes when we are cognizant of the fact that an engine is basically an air pump. We pump it in and out (although in a different form) and we have problems when one side or the other is restricted. Balance or the equilibrium or flow should be our objective, unless of course we are not trying to make more horsepower!
Example #1 (Oval track racing) Here, I have often observed that the most experienced drivers are those who are most likely to run a single pattern (equal on intake and exhaust duration) cam. Why? Because such cams always, [[[[[ I repeat always make more torque! ]]]]] These veterans have a more educated foot and greater experience in feathering the throttle in the corners. They can therefore, utilize the benefit of added torque, in the lower to mid RPM range, to their advantage.
Their counterparts, the younger drivers on the circuit, generally are not as experienced and may at times actually get "crossed up" in the corners especially with a lighter car or when they are learning the ropes. In their case, a longer exhaust duration is often the more appropriate choice. It will often help them to drive better, more "flat footed" if you will, without consequence. But please for the sake of accuracy, let us be truthful. The benefit comes from an actual bleeding off of low to mid range torque, which is always what happens when Exh. Duration is lengthened, not from any improvement. The improvement, (if any) would come because of an improvement in scavenging at the extreme upper end of the power curve and would usually be marginal at best. Yet the so-called "extra power" potential of a longer Exh. Duration cam is most often why they are touted - power most people are backing away from at the end of the strait away!
Example #2 (Drag Racing) At the drag strip it's a little different and I feel more honest. Here, racers have long enjoyed longer exhaust and longer durations across the board (If I may add specifically for the purpose of "killing" low-end torque) to keep the tires from too easily breaking lose. This has been successful and sometimes actually results in a slight increase in top end power - something you can actually use in drag racing since it is a full throttle endeavor through the lights. Keep in mind here though, it's quite possible that a longer duration cam overall would have done just as well or better. {{{In other words if you needed that longer exhaust for top end, perhaps the intake could have benefited from such a lengthening as well.}}}
One of my favorite expressions is how "The Drag Racing mentality has infiltrated the ranks of Oval Track". Many have crossed over and made the switch in the past 10-15 years and some have brought their preconceived notions about how to cam an engine with them.[[[[[ A few may actually read these concepts and if they do so will at least come away with a better understanding of what they are doing.]]]] On the other hand they also could find that this information might actually help their cars to run just a bit faster!
i have a buddy of mine who had indy build him a hemi {over 20 grand!!!!}
INDY PUT A ROLLER CAM IN IT BUT HE DIDNT LIKE HOW IT RAN.
SO HE GAVE THE MOTOR TO RAY BARTON AND HE WENT THREW THE HOLE MOTOR FOR 10 MORE GRAND BUT HE MADE 30 MORE HORSE WITH AND IT RUNS PERFECT ON THE STREET.
MISTER Z28 MAN
DO YOU KNOW WHAT YOUR REALLY TALKING ABOUT.WELL I NO RAY BARTON DOES:read2:
HE USED A SOLID NON ROLLER CAM {{{ WHY? }}}
BECAUSE HE KNOWS HOW TO MAKE POWER.
I DONT KNOW EVERYTHING AND NEVER WILL BUT I LEARN SOMETHING EVERYDAY AND KNOW ENOUGH TO ONLY OPEN MY MOUTH WHEN I HAVE A GOOD QUESTION FOR SOMEONE SMARTER THEN ME AND THEN LISTEN AND LEARN.
BUT THE BIGGEST THING IS WHEN TALKING TO PEOPLE WHO DONT KNOW MUCH ABOUT SOMETHING AND TO HAVE RESPECT FOR THERE IGNORANCE BECAUSE IF THEY LISTEN AND LEARN BETTER THEN YOU DID (((((THEY MIGHT BE THE ONE IN THE WINNERS CIRCLE)))) AND YOU WILL BE ONLINE MAKING FUN OF PEOPLE
Snake
Mopar Nut
Wow well said.
T67POWER
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Yo Snake
Whats Up
Check Out Those Questions
Then We Can Narrow Your Problem Down.
Whats Up
Check Out Those Questions
Then We Can Narrow Your Problem Down.
moper
Well-Known Member
First, in terms of cylinder pressure... The only way to have the same cylinder pressure without changing anything but intake closing event is impossible. The physical cylinder gets sealed at the same time (in degrees), and therefore there will be the same amount of pressure trapped in there. Now this is a little misleading anyway.... as cranking compression is ultra low rpm and there are inertial affects on the airstreams. So as inertia helps, the actual pressures will rise as more "stuff" is put in the same size hole up until the valve seals the cylinder.
Looking at the cams... I wouldnt run either one at 113° LSA. 4" arms have higher pistons speeds and will encourage that inertial affect earlier and get more power with more overlap. I tend to look for 108°-106° LSA on this type of build with an intake center line around 110-112. On the lift... If you reduce the lift taking into account the loss for lifter/pushrod angles and the hydraulics, you're looking to loose around .030-.040 of lift off those. So these two cams are both way under the head's theoretical "sweet spot" and the main flow will be around .350 and with that theoretical cam the piston will have reached the hardest "pull" before the valve has been fully opened. It will run like a truck engine. Add to that the single plane plenum size... this would just be a bunch of mismatch in my opinion. for kicks I ran it thru the PipeMax dyno simulator. it says both cams will make around 375hp, 390tq. That's what I think anyway.
lead69
hopeless car junkie
So you run the cam 4 degress retarded?,or did you mix up the lsa and IC?,just curious.
moper
Well-Known Member
No. Intake center line is where the intake lobe is in realtion to the piston/crank. The higher the number tha sooner the intake valve closes, which helps low end, response, and idle characteristics. LSA, Lobe Seperation Angle, is the distance in degrees between the intake and exh lobe centerlines. Tighter LSA means more overlap with most lobes, and even more on longer duration lobes that are not symmetrical (they open faster than they close). The spec'd 113 means very little overlap with the smaller duration and lift. Some Engine Masters stuff runs the LSA as tight as 93°.
mopar340dave
Well-Known Member
Z28, did you come on here for advice or to get stroked?
You do not appear to be wanting any opinion, only agreement.
There is no magic, just sound mechanicals. The engines we are working on are not new and they have been put together in virtually every possible combo. What works has been figured out...for the most part. When a pro engine builder puts an engine together, he matches all of the components. You don't wanna run your .500" lift heads with your "almost god-like" roller cam, but you can if you want to. I would not.
Of course, the Hemi's use voodoo....
You do not appear to be wanting any opinion, only agreement.
There is no magic, just sound mechanicals. The engines we are working on are not new and they have been put together in virtually every possible combo. What works has been figured out...for the most part. When a pro engine builder puts an engine together, he matches all of the components. You don't wanna run your .500" lift heads with your "almost god-like" roller cam, but you can if you want to. I would not.
Of course, the Hemi's use voodoo....
Petzschler
→Welcome backâ†
never looked at it like that. thats some good info, thanks moper. i kinda figured those 2 hypothetical cams would make
around the same power.. just in different ways. you would figure the single plane intake would be good for the first cam
but do to the reasons you stated... it's not. this is sound info coming from a guy (you) whos on top of his game.
the specs you listed seem very good.
give the first cam these timing events:
intake open 29° btdc close 64° abdc
exaust open 75° bbdc close 30° atdc
LSA 110°
intake centerline 106°
think that'll work better? is there a need for 1.6 rockers with it?
lead69
hopeless car junkie
I understand camshaft theory,your post is worded wrong,if you have a cam ground on a 108 lobe seperation and installed on a 104 intake centerline thats 4 degrees advanced,so if that cam is now installed on a 112 thats 4 degrees retarded,and if its installed on a 108 thats stright up.
moper
Well-Known Member
I guess I dont understand what your saying. I dont believe I ever said where I installed the cams in terms of installed center line. Only what the ICL is typically ground on. LSA has nothing to do with ICL or installed ICL. As an example: Let's say I have a cam ground on a 112 intake lobe center line. It has a 108° spread between the intake lobe centerline and the exh lobe center line. I can install it at 110(2° advanced), 106(6° advanced), or 114(2° retarded) and it will still have 108° between the exh lobe centerline and the intake lobe centerline. Intake Center Line is what the cam is ground to. Installed Intake Center Line is where the centerline of that lobe is in relation to the crank/piston position. I apologize if I'm not wording it right.
lead69
hopeless car junkie
In the above example a cam ground on a 112 intake centerline with a 108 lobe seperation would be retarded in relation to the crank at tdc.You can change the intake centerline on a cam so it is not ground in per say,you cannot change the lobe seperation as you mentioned so it is ground in.When designing a cam as you know most all manufactuers set up the cam to be installed four degrees advanced in relation to the crank at tdc hence a comp cam having a lobe seperation of 110 and a intake centerline of 106,to retard the cam from their specs it would have an intake centerline of 107 or greater in relation to tdc which can easily be done,but as you metioned you cannot change the lobe seperation.A true straight up cam installation at tdc would be cam installed on an identical intake centerline in relation to the lobe seperation such as a 110 lobe seperation and a 110 intake centerline,anything below 110 on the intake centerline is advanced and anything above 110 is retarded to the crank at tdc.In your original post you specified a cam with a lobe seperation of 106-108 and an intake centerline of 110-112,that is exactly backwards of most all cam manufatuers install reccomendations and would be considered retarded.Not trying to be picky but alot of people confuse these angles and their terminology so its important to get the correct understanding.
moper
Well-Known Member
You're right Lead... I went and double checked myself. I had it backwards. Thanks for clarifying that.
lead69
hopeless car junkie
No problem,just trying to look out for the newbies,theres alot of numbers in this game lol and when your as active as you are your bound to make a misprint-at least I know I make my share.
moper
Well-Known Member
Yup.
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