TSP- Totally changed tune on LS3 cams???
05-24-2017, 11:02 PM
#21
Youre saying a 224/224 with 4* of overlap would drive the same as a 224/234 with 4* of overlap? Its 2.5* diff in lsa for those that dont have a calculator.
I assume at some point scr and dcr have to come into the equation at some time right? and cid?
Or, how a customer of ours just finished a cam install with a cam of the same @050 dur and lsa (so same overlap) yet the new cam drives better with no surging like previous cam.
I assume at some point scr and dcr have to come into the equation at some time right? and cid?
Or, how a customer of ours just finished a cam install with a cam of the same @050 dur and lsa (so same overlap) yet the new cam drives better with no surging like previous cam.
05-24-2017, 11:14 PM
#22
Youre saying a 224/224 with 4* of overlap would drive the same as a 224/234 with 4* of overlap? Its 2.5* diff in lsa for those that dont have a calculator.
I assume at some point scr and dcr have to come into the equation at some time right? and cid?
Or, how a customer of ours just finished a cam install with a cam of the same @050 dur and lsa (so same overlap) yet the new cam drives better with no surging like previous cam.
I assume at some point scr and dcr have to come into the equation at some time right? and cid?
Or, how a customer of ours just finished a cam install with a cam of the same @050 dur and lsa (so same overlap) yet the new cam drives better with no surging like previous cam.
Two cams (228/236 110 and a 234/250 115) in the same engine with nothing changed other than the camshaft will have the same driving manners. That the combination isn't changed other than the camshaft I figured was assumed. This is assumed that the CID was the same for both cams, CR is the same etc.
Overlap has no effect on the DCR calculation, only IVC and static compression will change the DCR calculation. DCR calculators won't tell you cylinder pressure at peak torque, peak HP and everywhere in between. DCR is pretty much useless as it's a dynamic way of expressing a static measurement. IMO DCR is only good for cranking compression.
What were the specs of your customer's old cam and new cam?
Different lobes have different ramp rates, and can have different durations at lower lobe lift. If we have two cams that are both 230/230@.050 with 112LSA, and one camshaft has 280/280@.006 and the other has 285/285@.006 the cam with 280/280@.006 will drive better than the cam with 285/285@.006 because the 280@.006 camshaft has less overlap.
You should read this thread I made almost 3 years ago : https://ls1tech.com/forums/generatio...-t-matter.html
Last edited by Martin Smallwood; 05-25-2017 at 10:38 AM.
05-24-2017, 11:24 PM
#23
I did read it. I dont agree with it though. it still doesnt explain the second scenario.
Old cam is 219 227 112lsa new cam is 219 227 112lsa
Since overlap is what effects how a car drives and is changed by lsa then it does seem to matter. Esp since you dont like dcr either.
Old cam is 219 227 112lsa new cam is 219 227 112lsa
Since overlap is what effects how a car drives and is changed by lsa then it does seem to matter. Esp since you dont like dcr either.
05-24-2017, 11:30 PM
#24
Are they the same exact lobes? What else was changed when you changed camshafts?
So are you saying Cam Motion, BTR, Chris Straub and I are all wrong and you have it right?
I take it this isn't David?
Tell me how DCR accounts for cylinder pressure across the RPM band? How does DCR account for cylinder pressure at 3000rpm? 4000rpm? 5000rpm? 6000rpm?
LSA alone doesn't account for overlap. Duration AND LSA together. LSA is just a sum of numbers. It is what it is.
So are you saying Cam Motion, BTR, Chris Straub and I are all wrong and you have it right?
I take it this isn't David?
Tell me how DCR accounts for cylinder pressure across the RPM band? How does DCR account for cylinder pressure at 3000rpm? 4000rpm? 5000rpm? 6000rpm?
LSA alone doesn't account for overlap. Duration AND LSA together. LSA is just a sum of numbers. It is what it is.
05-24-2017, 11:41 PM
#26
Im not saying i have anything right.
You said that overlap alone determines how a car drives and based off a customers response the overlap was the same yet the car drives better with no extra tuning.
Like i said there are always exceptions.
Calm down. I just said i didnt agree with you, its ok.
You obviously know more than me and spec alot of cams etc and so do the others. Just because i dont agree doesnt mean i am right and you are wrong.
The original was the og hot cam, the other is a new designed cam we have based off of it. Dyno doesnt show what I had imagined for the diff, but there are explanations or excuses for that i guess. The curves are nearly exactly the same save for hp above 5500 then it takes off. Same icl also.
Its nothing special and prob a cam that has been made before doesnt use some super aggressive or lazy lobe either. Biggest difference is more lift, not even above .600 though as its designed to be a budget cam with easy lobes, easy to tune, and has a good idle to it just like the hot cam is. Uses out of the book comp lobes also.
You said that overlap alone determines how a car drives and based off a customers response the overlap was the same yet the car drives better with no extra tuning.
Like i said there are always exceptions.
Calm down. I just said i didnt agree with you, its ok.
You obviously know more than me and spec alot of cams etc and so do the others. Just because i dont agree doesnt mean i am right and you are wrong.
The original was the og hot cam, the other is a new designed cam we have based off of it. Dyno doesnt show what I had imagined for the diff, but there are explanations or excuses for that i guess. The curves are nearly exactly the same save for hp above 5500 then it takes off. Same icl also.
Its nothing special and prob a cam that has been made before doesnt use some super aggressive or lazy lobe either. Biggest difference is more lift, not even above .600 though as its designed to be a budget cam with easy lobes, easy to tune, and has a good idle to it just like the hot cam is. Uses out of the book comp lobes also.
05-24-2017, 11:49 PM
#27
Im not saying i have anything right.
You said that overlap alone determines how a car drives and based off a customers response the overlap was the same yet the car drives better with no extra tuning.
Like i said there are always exceptions.
Calm down. I just said i didnt agree with you, its ok.
You obviously know more than me and spec alot of cams etc and so do the others. Just because i dont agree doesnt mean i am right and you are wrong.
The original was the og hot cam, the other is a new designed cam we have based off of it. Dyno doesnt show what I had imagined for the diff, but there are explanations or excuses for that i guess. The curves are nearly exactly the same save for hp above 5500 then it takes off. Same icl also.
Its nothing special and prob a cam that has been made before doesnt use some super aggressive or lazy lobe either. Biggest difference is more lift, not even above .600 though as its designed to be a budget cam with easy lobes, easy to tune, and has a good idle to it just like the hot cam is. Uses out of the book comp lobes also.
You said that overlap alone determines how a car drives and based off a customers response the overlap was the same yet the car drives better with no extra tuning.
Like i said there are always exceptions.
Calm down. I just said i didnt agree with you, its ok.
You obviously know more than me and spec alot of cams etc and so do the others. Just because i dont agree doesnt mean i am right and you are wrong.
The original was the og hot cam, the other is a new designed cam we have based off of it. Dyno doesnt show what I had imagined for the diff, but there are explanations or excuses for that i guess. The curves are nearly exactly the same save for hp above 5500 then it takes off. Same icl also.
Its nothing special and prob a cam that has been made before doesnt use some super aggressive or lazy lobe either. Biggest difference is more lift, not even above .600 though as its designed to be a budget cam with easy lobes, easy to tune, and has a good idle to it just like the hot cam is. Uses out of the book comp lobes also.
If the lobes you used on the new cam have less duration @.006 versus the Hot Cam you pulled out, then yes the new cam will drive better because the new cam has less overlap. Which is why I gave the 230/230@.050 112lsa and the 280/280@.006 versus the 230/230@.050 112lsa and 285/285@.006 example above. If the Hot Cam had say for instance, 273/283@.006 and the new cam has 269/277@.006 then yes the new cam is going to drive better than the Hot Cam. Do you know why though? Overlap! The new cam would have less seat to seat overlap which would allow it to drive better. Which my example above covers.
Can you answer my question about DCR and SCR? How does a DCR calculation tell you what the difference in cylinder pressure will be at 3000rpm? 4000rpm? 5000rpm? 6000rpm? How does DCR and SCR effect the amount of vacuum pulled at idle?
05-25-2017, 12:00 AM
#28
It has more adv duration 4 degrees on intake and 2 on exhaust. id like to tell you the diff at .200 but gm doesnt advertise those specs.
Like i said you and all the other guys know more than me but there are always exceptions.
I dont have to answer your questions on dcr and scr, you wrote the sticky you know it well enough.
If i am coming across as a dick i apoligize i have had a rather rough week so far, but the answer is still the same.
Just like theories of using less exhaust lobe lift on cams over intake. I dont agree with it so i do not do it. Doesnt mean whomever does it is wrong and i am right, its prob just personal preference.
Like i said you and all the other guys know more than me but there are always exceptions.
I dont have to answer your questions on dcr and scr, you wrote the sticky you know it well enough.
If i am coming across as a dick i apoligize i have had a rather rough week so far, but the answer is still the same.
Just like theories of using less exhaust lobe lift on cams over intake. I dont agree with it so i do not do it. Doesnt mean whomever does it is wrong and i am right, its prob just personal preference.
05-25-2017, 12:10 AM
#29
So the old Hot Cam you took out has 4 degrees more intake duration @.006 and 2 degrees more exhaust duration @.006 than your new cam that you spec'd if I read that right? If so, the new cam has 3 degrees less overlap @.006 than the old Hot Cam.
At .200 duration on this sized camshaft you'll be well past overlap so that's OK as it wouldn't make a difference in relation to our discussion. Which this is a discussion!
DCR can't tell you the difference in cylinder pressure across the rev range, that's why it's relatively useless...in my opinion that is. Some guys swear by it and still have good running engines.
The main reason I engaged you is I have seen a few of your posts that seemed to be geared against some things I have said on this forum before. I wanted to have a real time discussion to see why you thought the way that you did. I accept your apology as we are all human and we all have good days and bad days, and sometimes we say things we really didn't mean to or couldn't articulate in a different way at the time. It happens, we're human. No worries on my end!
I would tell you why you don't have to use as much exhaust lift as intake lift, but that's for another time and place. Or you could just read my sticky again as it's in there....LOL
At .200 duration on this sized camshaft you'll be well past overlap so that's OK as it wouldn't make a difference in relation to our discussion. Which this is a discussion!
DCR can't tell you the difference in cylinder pressure across the rev range, that's why it's relatively useless...in my opinion that is. Some guys swear by it and still have good running engines.
The main reason I engaged you is I have seen a few of your posts that seemed to be geared against some things I have said on this forum before. I wanted to have a real time discussion to see why you thought the way that you did. I accept your apology as we are all human and we all have good days and bad days, and sometimes we say things we really didn't mean to or couldn't articulate in a different way at the time. It happens, we're human. No worries on my end!
I would tell you why you don't have to use as much exhaust lift as intake lift, but that's for another time and place. Or you could just read my sticky again as it's in there....LOL
05-25-2017, 12:12 AM
#30
No. You read it wrong. The new cam has 4 degrees more intake duration and 2 more degrees exhaust at .006.
Cammotion told me the same thing about less exhaust lift based off his theory in 2012. I still dont normally do it. If im wrong then im wrong but it still makes power i guess.
Cammotion told me the same thing about less exhaust lift based off his theory in 2012. I still dont normally do it. If im wrong then im wrong but it still makes power i guess.
05-25-2017, 12:12 AM
#31
To bring something slightly off topic to the table but relevant to the overalp and drivability scale... Martin, what would you consider the overlap scale for drivability to be?
On a 346, anything under 8 degrees typically drives about like stock or can be made to drive like stock with little to no surge with 4 degrees being truly perfect manners. As you get deeper and deeper into overlap, drivability suffers more and more. I think around 16 degrees is where it falls to a point of difficult to live with on the street in a daily driven scenario.
What about the LS3 with it's added CID?
Or say a 416 since it's a popular choice?
Any general rules of thumb you've noticed?
On a 346, anything under 8 degrees typically drives about like stock or can be made to drive like stock with little to no surge with 4 degrees being truly perfect manners. As you get deeper and deeper into overlap, drivability suffers more and more. I think around 16 degrees is where it falls to a point of difficult to live with on the street in a daily driven scenario.
What about the LS3 with it's added CID?
Or say a 416 since it's a popular choice?
Any general rules of thumb you've noticed?
Last edited by JakeFusion; 05-25-2017 at 12:18 AM.
05-25-2017, 12:18 AM
#33
The other thing you took offense to was not me saying you wrote anything and it was wrong. I said whomever said what that guy said was wrong i agreed with (cant find thread at moment). You didnt say it, which you clarified, and it wasnt a personal attack against you.
05-25-2017, 12:22 AM
#34
To bring something slightly off topic to the table but relevant to the overalp and drivability scale... Martin, what would you consider the overlap scale for drivability to be?
On a 346, anything under 8 degrees typically drives about like stock or can be made to drive like stock with little to no surge with 4 degrees being truly perfect manners. As you get deeper and deeper into overlap, drivability suffers more and more. I think around 16 degrees is where it falls to a point of difficult to live with on the street in a daily driven scenario.
What about the LS3 with it's added CID?
Or say a 416 since it's a popular choice?
Any general rules of thumb you've noticed?
On a 346, anything under 8 degrees typically drives about like stock or can be made to drive like stock with little to no surge with 4 degrees being truly perfect manners. As you get deeper and deeper into overlap, drivability suffers more and more. I think around 16 degrees is where it falls to a point of difficult to live with on the street in a daily driven scenario.
What about the LS3 with it's added CID?
Or say a 416 since it's a popular choice?
Any general rules of thumb you've noticed?
The LS3 although it is larger in displacement it has larger valves and flows more air at lower lifts where overlap occurs. Because of this I actually use less overlap on LS3 applications. Not to mention that the LS3 also has less P to V due to those larger valves. I like to stay around 2-4 degrees @.050 for a good driving LS3, 4-8@.050 for a street/strip combo and I don't like using more than 14 degrees .050 for a max effort SBE combo due to P to V constraints.
On the 416 example it would depend on the cylinder head choice.
05-25-2017, 12:23 AM
#35
According to gm published spec/cam card the hot cam has 271/280 218/227 112+3
This new cam has 275 / 282
Maybe if the actual measured numbers are more it has more overlap, but the same could be said for these lobes as well. Just going off whats published. Neither cam was degreed.
This new cam has 275 / 282
Maybe if the actual measured numbers are more it has more overlap, but the same could be said for these lobes as well. Just going off whats published. Neither cam was degreed.
05-25-2017, 12:26 AM
#36
For a LS1 and a customer that wants nice driving manners I try to stay around 4 degrees or less @.050. If he wants more of a street/strip combo and doesn't care that much about driving manners I like to stay around 6-10 degrees. If he wants something max effort I go anywhere from 12-16 @.050.
The LS3 although it is larger in displacement it has larger valves and flows more air at lower lifts where overlap occurs. Because of this I actually use less overlap on LS3 applications. Not to mention that the LS3 also has less P to V due to those larger valves. I like to stay around 2-4 degrees @.050 for a good driving LS3, 4-8@.050 for a street/strip combo and I don't like using more than 14 degrees .050 for a max effort SBE combo due to P to V constraints.
On the 416 example it would depend on the cylinder head choice.
The LS3 although it is larger in displacement it has larger valves and flows more air at lower lifts where overlap occurs. Because of this I actually use less overlap on LS3 applications. Not to mention that the LS3 also has less P to V due to those larger valves. I like to stay around 2-4 degrees @.050 for a good driving LS3, 4-8@.050 for a street/strip combo and I don't like using more than 14 degrees .050 for a max effort SBE combo due to P to V constraints.
On the 416 example it would depend on the cylinder head choice.
416 - with aftermarket LS3 heads for example. Push it up by 8 degrees for each tier?
05-25-2017, 12:39 AM
#38
That would necessitate a more expensive spring. The whole purpose was to make a budget cam kit just like gm, be roughly same price, drive good, still have a nice lope, and not be noisy. The pac1218 is the perfect drop in budget spring.
I did have an idea to make an ultra mega super high lift hot chili cam and use the pac1219x but that may wait til after the trademark on the name goes through. The cam kit is $515 cam and springs or $565 for cam springs and prs which is almost exactly retail on a new hot cam kit.
I did have an idea to make an ultra mega super high lift hot chili cam and use the pac1219x but that may wait til after the trademark on the name goes through. The cam kit is $515 cam and springs or $565 for cam springs and prs which is almost exactly retail on a new hot cam kit.
05-25-2017, 12:39 AM
#39
Jeez, it took me almost 20 minutes just to find the cam card online for the Hot Cam. Talk about blowing off the dust!
271/280@.006 for the Hot Cam, but I did find advertised duration numbers of 277/288 which are probably at a lower lobe lift than .006". Since Comp doesn't list anything smaller than .006" lobe lift in their catalogs we can't compare them that low.
Did the KPA at idle change any? That would honestly be the true tell all. I have found to take some customer's seat of the pants feel with a grain of salt, but sometimes there is useful information to be learned from their seat of the pants feel of the car.
271/280@.006 for the Hot Cam, but I did find advertised duration numbers of 277/288 which are probably at a lower lobe lift than .006". Since Comp doesn't list anything smaller than .006" lobe lift in their catalogs we can't compare them that low.
Did the KPA at idle change any? That would honestly be the true tell all. I have found to take some customer's seat of the pants feel with a grain of salt, but sometimes there is useful information to be learned from their seat of the pants feel of the car.
05-25-2017, 12:42 AM
#40
A spring with a 145 seat/380 open would control the LSG lobes if the valve is under 100g.
Take your pick of $229 spring kits that fit those parameters. PAC1204 is a good option, BTR Platinum... PAC1219 or PSI 1511 Beehives shimmed would get you there.
Take your pick of $229 spring kits that fit those parameters. PAC1204 is a good option, BTR Platinum... PAC1219 or PSI 1511 Beehives shimmed would get you there.