Camshaft discussion: CFM requirements by RPM.
04-28-2004, 03:52 PM
#182
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You guys are taking the equation a bit too far. Not quite that easy to peg your duration. 
You are definitely thinking correctly though.
Imagine it this way. Using the "calculated" 279cfm:
You're currently using a TR224 with stock heads @ 240cfm, stock LS6 intake manifold and you have pretty good results. You're happy with the way the car drives around town, you like the rpm range, but just like the rest of we idiots you want to push some more power to the ground.
You go out and buy a set of ported LS6 heads flowing 320cfm. Considering the continued restriction of the LS6 manifold on those nice 320cfm heads, do you need to increase, decrease, or stay the same with your duration? We're talking in generalities here of course and not considering that the TR224 could be improved upon to begin with. We will also assume no change in compression ratio.
Key points:
1. You've increased cylinder head flow
2. You like your current rpm range.
3. You have not changed displacement.
You are definitely thinking correctly though.
Imagine it this way. Using the "calculated" 279cfm:
You're currently using a TR224 with stock heads @ 240cfm, stock LS6 intake manifold and you have pretty good results. You're happy with the way the car drives around town, you like the rpm range, but just like the rest of we idiots you want to push some more power to the ground.
You go out and buy a set of ported LS6 heads flowing 320cfm. Considering the continued restriction of the LS6 manifold on those nice 320cfm heads, do you need to increase, decrease, or stay the same with your duration? We're talking in generalities here of course and not considering that the TR224 could be improved upon to begin with. We will also assume no change in compression ratio.
Key points:
1. You've increased cylinder head flow
2. You like your current rpm range.
3. You have not changed displacement.
04-28-2004, 04:10 PM
#183
Originally Posted by DenzSS
You guys are taking the equation a bit too far. Not quite that easy to peg your duration.
You are definitely thinking correctly though.
Imagine it this way. Using the "calculated" 279cfm:
You're currently using a TR224 with stock heads @ 240cfm, stock LS6 intake manifold and you have pretty good results. You're happy with the way the car drives around town, you like the rpm range, but just like the rest of we idiots you want to push some more power to the ground.
You go out and buy a set of ported LS6 heads flowing 320cfm. Considering the continued restriction of the LS6 manifold on those nice 320cfm heads, do you need to increase, decrease, or stay the same with your duration? We're talking in generalities here of course and not considering that the TR224 could be improved upon to begin with. We will also assume no change in compression ratio.
Key points:
1. You've increased cylinder head flow
2. You like your current rpm range.
3. You have not changed displacement.
You are definitely thinking correctly though.
Imagine it this way. Using the "calculated" 279cfm:
You're currently using a TR224 with stock heads @ 240cfm, stock LS6 intake manifold and you have pretty good results. You're happy with the way the car drives around town, you like the rpm range, but just like the rest of we idiots you want to push some more power to the ground.
You go out and buy a set of ported LS6 heads flowing 320cfm. Considering the continued restriction of the LS6 manifold on those nice 320cfm heads, do you need to increase, decrease, or stay the same with your duration? We're talking in generalities here of course and not considering that the TR224 could be improved upon to begin with. We will also assume no change in compression ratio.
Key points:
1. You've increased cylinder head flow
2. You like your current rpm range.
3. You have not changed displacement.
If you get 280 thru the intake ~224 the cam duration should stay about the same. I would want a cam with more lift than the TR-224 since LS6 heads flow very well above the TR-224 max lift. Maybe a set of 1.75 (should give .579 lift) or 1.85 (should give .612 lift) rockers would do the trick with the TR cam.
04-28-2004, 04:19 PM
#184
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You're hitting it.
My answer would be close to the same.
Either:
Stick with what you have and retune.
or
Take it to a pro and have them refine what you have. You know your rpm range, you know how the TR224 handles the job. You have everything you need to polish up the design of your camshaft. You know enough to give them good insight into what you actually want.
There are at least two people I know of in this thread that design camshafts for a living. The most the rest of us can do is to have a good basic understanding and learn how to talk intelligently to a camshaft designer. That basic understanding also makes a great
detector.
My answer would be close to the same.
Either:
Stick with what you have and retune.
or
Take it to a pro and have them refine what you have. You know your rpm range, you know how the TR224 handles the job. You have everything you need to polish up the design of your camshaft. You know enough to give them good insight into what you actually want.
There are at least two people I know of in this thread that design camshafts for a living. The most the rest of us can do is to have a good basic understanding and learn how to talk intelligently to a camshaft designer. That basic understanding also makes a great
detector.
04-28-2004, 04:36 PM
#185
Yea Denz I'm assuming my heads flow about 320CFM and 280FCM w/the Ported LS6 intake on them.I still see the 224 cam being a pretty good starting point if u ask me but my 224 has 580 lift,not 563 
Again I'm still a 346,I shift at 6500 but yes the setup does flow better than stock..I know theres got to be more info into picking the right cam for the setup than alittle math.
Again I'm still a 346,I shift at 6500 but yes the setup does flow better than stock..I know theres got to be more info into picking the right cam for the setup than alittle math.
04-28-2004, 04:36 PM
#186
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Originally Posted by DenzSS
You guys are taking the equation a bit too far. Not quite that easy to peg your duration.
You are definitely thinking correctly though.
Imagine it this way. Using the "calculated" 279cfm:
You're currently using a TR224 with stock heads @ 240cfm, stock LS6 intake manifold and you have pretty good results. You're happy with the way the car drives around town, you like the rpm range, but just like the rest of we idiots you want to push some more power to the ground.
You go out and buy a set of ported LS6 heads flowing 320cfm. Considering the continued restriction of the LS6 manifold on those nice 320cfm heads, do you need to increase, decrease, or stay the same with your duration? We're talking in generalities here of course and not considering that the TR224 could be improved upon to begin with. We will also assume no change in compression ratio.
Key points:
1. You've increased cylinder head flow
2. You like your current rpm range.
3. You have not changed displacement.
You are definitely thinking correctly though.
Imagine it this way. Using the "calculated" 279cfm:
You're currently using a TR224 with stock heads @ 240cfm, stock LS6 intake manifold and you have pretty good results. You're happy with the way the car drives around town, you like the rpm range, but just like the rest of we idiots you want to push some more power to the ground.
You go out and buy a set of ported LS6 heads flowing 320cfm. Considering the continued restriction of the LS6 manifold on those nice 320cfm heads, do you need to increase, decrease, or stay the same with your duration? We're talking in generalities here of course and not considering that the TR224 could be improved upon to begin with. We will also assume no change in compression ratio.
Key points:
1. You've increased cylinder head flow
2. You like your current rpm range.
3. You have not changed displacement.
Let's see...
At last count I have 23 different camshaft lobes available with 224* duration at .050" lobe lift... All with totally different ramps and lobe configurations resulting in a wide variety of .006" thru .450" duration specs. Then there's the fact that some are symetrical and some are assymetrical and have an effect on performance when not matched to the flow numbers of the heads. Cripe, it's really easy doing this development work...
Now... since the events being discussed are actually only "one" moment in the engine's cycling, you should not generalize and say a TR224* (or whatever 224*) camshaft is correct for the particular application, just because it fits with the CFM per RPM equation. There's a lot more to it... head flow, intake flow, exhaust type, weight of vehicle, application etc....
There have been plenty of camshaft profiles which I have provided for customers that "big name" dyno shops claimed would fail miserable because they were not the "status quo" that they were used to seeing. Thank God the customers didn't listen to them and continued on with their projects. Many a "dyno-king" were surprised at the end results which were obtained. Both at the racetrack "and" on those "single gear horsepower guessers" (dynos)
All leads to a couple of conclusions when looking this closely at camshaft parameters...
1) No mathematical "formula" or equation is going to give you absolute or completely accurate real world results. They don't have "all" the parameters available to make a clear cut judgement. These formulas are fun to dabble with but they can only provide a basic direction on where to proceed from.
2) There are some combinations that, in spite of their apparent obsurdness or "out of the box" concepts, will always perform better than the average "box" combination. Just because they've been well designed and engineered...
Bottomline:
Success or failure of a camshaft design is really not shown on a dyno or flow bench. It's shown with the customer's end results. If a street car criteria is requested, it's focus is totally different from a max-effort race car and neither result should be compared. Goals are goals and no one should be the judge of the success or failure of a combination other than the owner of said combination...
Damn... where's my Moroso dream wheel and Desktop Dyno disc...
Ed
04-28-2004, 04:41 PM
#187
Few Observations:
Since the LS1/LS6 intakes are so restrictive. . .IMO that cylinder heads need to be flowed with the intake bolted on to be able to properly cam the engine. If you guess at it you are leaving some on the table.
Once the valve leaves the seat on the "duration ride" it is letting air in. . . depending on how good the heads are affects the camshaft duration.
Example
Lift Set A SetB
.100 64 59
.200 128 123
.300 189 179
.400 236 230
.500 278 288
.600 290 298
SetA may need duraton of 230 @.050 and 136@.200 Head starts off with a bang but tapers off. Set B may need duration of 234@.050 and 126 @ .200. head is slow at first but comes on stronger later. This is wear most miss the boat. I don't stress flow numbers to race benches, I stress them because they are just part of a long equation to figuring out a camshaft for an engine.
Chris
Since the LS1/LS6 intakes are so restrictive. . .IMO that cylinder heads need to be flowed with the intake bolted on to be able to properly cam the engine. If you guess at it you are leaving some on the table.
Once the valve leaves the seat on the "duration ride" it is letting air in. . . depending on how good the heads are affects the camshaft duration.
Example
Lift Set A SetB
.100 64 59
.200 128 123
.300 189 179
.400 236 230
.500 278 288
.600 290 298
SetA may need duraton of 230 @.050 and 136@.200 Head starts off with a bang but tapers off. Set B may need duration of 234@.050 and 126 @ .200. head is slow at first but comes on stronger later. This is wear most miss the boat. I don't stress flow numbers to race benches, I stress them because they are just part of a long equation to figuring out a camshaft for an engine.
Chris
04-28-2004, 04:46 PM
#189
Thats exactly what I thought,Ed.
I wish I wouldve flowed my heads myself with/without the intake.
Looks like this winter is gonna be a tear down..
You guys (Denz/ED) WILL be hearing from me,I still say TQ is king in a heavy auto car looking for MAX ET.
Thanks for the info...
I wish I wouldve flowed my heads myself with/without the intake.
Looks like this winter is gonna be a tear down..
You guys (Denz/ED) WILL be hearing from me,I still say TQ is king in a heavy auto car looking for MAX ET.
Thanks for the info...
04-28-2004, 07:31 PM
#193
Originally Posted by 99 Black Bird T/A
Just for fun I calculated what sized cam my old JPR Stage LS6 heads would need based on flowing a peak of 239 cfm with the LS6 intake in place.
(346/2)*6500/1728 = ~651 cfm
651/8 cylinders = ~81.4 cfm per cylinder
244 cam /720 = .3388
81.4/.3388 = ~240 cfm
Looks like about 244 sized cam is what it would take to move required ~280 cfm of air with those heads.
(346/2)*6500/1728 = ~651 cfm
651/8 cylinders = ~81.4 cfm per cylinder
244 cam /720 = .3388
81.4/.3388 = ~240 cfm
Looks like about 244 sized cam is what it would take to move required ~280 cfm of air with those heads.
04-28-2004, 10:13 PM
#194
FormerVendor
""JS,
Just always remember, Torque is MEASURED, HP is TALKED ABOUT!!!
Chris""
Chris, HP is measured sometimes and TQ calculated like on an inertia dyno. A water brake use a strain gauge voltage that infers TQ by stretch and then it's multiplied by RPM for power so it indirectly measures TQ and computes power.
No one cares how much TQ someone has unless they know the rpm which means power. Otherwise you really know nothing. HP is what makes race cars accelerate.
I have one car that makes 400 ft pounds of TQ and another that makes 500 ft pounds of TQ. They both weigh the same but which is faster? You can't even answer without knowing the power that each makes. Knowing ONLY the horsepower you CAN estimate how fast the car will be down a quarter mile however. I can change RWTQ to whatever I want with the right gear but I can not gain HP with gears because it is a fixed parameter. TQ can be almost anything at the wheels which really accelerates the car not engine TQ anyway.
Saying all that I love TQ and I love big engines that make TQ so I don't have to spend mega bucks to go fast with Ti valves etc.
Just always remember, Torque is MEASURED, HP is TALKED ABOUT!!!
Chris""
Chris, HP is measured sometimes and TQ calculated like on an inertia dyno. A water brake use a strain gauge voltage that infers TQ by stretch and then it's multiplied by RPM for power so it indirectly measures TQ and computes power.
No one cares how much TQ someone has unless they know the rpm which means power. Otherwise you really know nothing. HP is what makes race cars accelerate.
I have one car that makes 400 ft pounds of TQ and another that makes 500 ft pounds of TQ. They both weigh the same but which is faster? You can't even answer without knowing the power that each makes. Knowing ONLY the horsepower you CAN estimate how fast the car will be down a quarter mile however. I can change RWTQ to whatever I want with the right gear but I can not gain HP with gears because it is a fixed parameter. TQ can be almost anything at the wheels which really accelerates the car not engine TQ anyway.
Saying all that I love TQ and I love big engines that make TQ so I don't have to spend mega bucks to go fast with Ti valves etc.
04-28-2004, 10:52 PM
#195
Eirk lets sau u have a HEAVY 3550lb street/strip 10 Sec car and its running an auto.
Do u run a HIGH HP PEAKING setup with this car?
Answer IMO NO...
Thats for a lighter car that wants to leave at 6000 and be shifted to the moon...
I'd look for a nice broad TQ curve with a broad HP curve that peaks around 6000 to 6200 and use it to your advantage?
Am I wrong in thinking this way?
If its vertered properly,geared accordingly it'll lay down a number.
Look at the Colonels S2E/CHICKEN CAM SETUP,That baby flies with fairly mellow stuff.BROAD HP AND TQ and it works,His car is 3500 plus and has 3.23's.
I rest my case...
Do u run a HIGH HP PEAKING setup with this car?
Answer IMO NO...
Thats for a lighter car that wants to leave at 6000 and be shifted to the moon...
I'd look for a nice broad TQ curve with a broad HP curve that peaks around 6000 to 6200 and use it to your advantage?
Am I wrong in thinking this way?
If its vertered properly,geared accordingly it'll lay down a number.
Look at the Colonels S2E/CHICKEN CAM SETUP,That baby flies with fairly mellow stuff.BROAD HP AND TQ and it works,His car is 3500 plus and has 3.23's.
I rest my case...
04-29-2004, 12:53 AM
#196
FormerVendor
""Eirk lets sau u have a HEAVY 3550lb street/strip 10 Sec car and its running an auto.
Do u run a HIGH HP PEAKING setup with this car?""
Yes! The car we won the Clash of the Titans NA stuff with that many of the LS1Tech guys saw was a 3200-3600 pound Malibu depending on the rules of that series with over 500 cubes that had a 7500 stall converter and went through the lights at a little over 9000 rpm. We went as fast as 8.80s at 155 with a huge fat PIG that never even saw close to peak TQ ever like most race cars never see.
If you did want a nice street car with a tight converter though you are right that you need low end power. But to go fast you need power no matter where you make it and a clutch, converter and/or gears that keep you there all the way down the track.
Do u run a HIGH HP PEAKING setup with this car?""
Yes! The car we won the Clash of the Titans NA stuff with that many of the LS1Tech guys saw was a 3200-3600 pound Malibu depending on the rules of that series with over 500 cubes that had a 7500 stall converter and went through the lights at a little over 9000 rpm. We went as fast as 8.80s at 155 with a huge fat PIG that never even saw close to peak TQ ever like most race cars never see.
If you did want a nice street car with a tight converter though you are right that you need low end power. But to go fast you need power no matter where you make it and a clutch, converter and/or gears that keep you there all the way down the track.
04-29-2004, 07:24 AM
#198
Originally Posted by Cstraub
Few Observations:
Since the LS1/LS6 intakes are so restrictive. . .IMO that cylinder heads need to be flowed with the intake bolted on to be able to properly cam the engine. If you guess at it you are leaving some on the table.
Chris
Since the LS1/LS6 intakes are so restrictive. . .IMO that cylinder heads need to be flowed with the intake bolted on to be able to properly cam the engine. If you guess at it you are leaving some on the table.
Chris
Your preaching to the choir on that one!
I've been saying the intake flow numbers for LS1/LS6/Gen III heads are not meaningful UNLESS they are with the LS6 (or LSX now) intake in place for a long time.
04-29-2004, 08:12 AM
#199
FormerVendor
Originally Posted by Cstraub
Erik,
I'll keep doing what I have been doing for customers, giving them a flat torque curve over their operating range, seems to win championships.
Chris
I'll keep doing what I have been doing for customers, giving them a flat torque curve over their operating range, seems to win championships.
Chris
04-29-2004, 08:50 AM
#200
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Originally Posted by EDC
1) No mathematical "formula" or equation is going to give you absolute or completely accurate real world results. They don't have "all" the parameters available to make a clear cut judgement. These formulas are fun to dabble with but they can only provide a basic direction on where to proceed from.
Ed