Thoughts on cams, HOW ABOUT OVERLAP (lsa or lca or lda)
08-10-2003, 12:19 AM
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Thoughts on cams, HOW ABOUT OVERLAP (lsa or lca or lda) As I have posted in the past, I am not an expert on this subject but find myself wandering about some aspects of these low numbers posted by combinations.
Has anybody picked up the GMHTP included with the popular hotrad magazine of this past month? An excellent article about cam timing and part of my fuel for this post.
I believe that a lot of our sponsors, tuners, and others are missing the bill on cam choices when maximum power within a given rpm band is selected. I see these 230+/230+ cams on a 114lsa. Why such a wide lsa (known as lobe separation angle, or lda= lobe displacement angle, or lsa= lobe serparation angle). More then likely because of the famous it will idle better response. If you have to widen the lsa because there is too much duration then you have chosen the cam poorly. I, as motivated from my own research which includes the article in GMHTP, my own cam and results {see sig.}, and other sources, believe that a proper lsa must be one of the first things chosen for a particular cam suited for maximum area under the curve. Think about it, scavenging is what creates more power in an n/a motor.
In My opinion, tighter lsas with smaller durations will always make more power then wider lsa with larger duration, both cams having the same amount of overlap. This allows for the intake valve to be opened later building more vacuum in the combustion chamber caused by the cylinder traveling down in its bore and the exhaust valve creating a vacuum effect on the combustion chamber and not allowing any or most of the intake charge being pulled from the combustion chamber during the intake stroke by exhaust scavenging. A higher exhaust velocity is also achiveid as the cylinder would start up in its bore before the exhaust valve was open causing the exhaust to come screaming out once the exhaust valve opens and creating even more of a vacuum on the exhaust side for greater scavenging. What does this do you might ask. CREATE MORE CYLINDER PRESSURE IN TURN CREATING MORE TORQUE THROUGHOUT THE RPM BAND WHICH INTURN CREATES MORE HORESEPOWER.
MY CAM:
To be honest with you I knew very little of what I know today when I chose this cam. I wanted a 224 cam because it was going in a 3.42 geared stock rear ended car. I wanted a 110lsa because I knew that more power potential was there and I wanted a nasty idle. I wanted four degrees of advance because all the other cams had it and I really didn't understand valve timing events that well at this point. I also chose 565 comp xe lobes (actually orderd xe-r but recieved xe lobes). I recieved a cam that made 380rwtq at the 2900+ rpm area and 406 rwtq at 4800 rpm (417 uncorrected. 405 hp at 5800-5900 (415 uncorrected) was attained. This was on stock heads and an independent dynojet and I have ls1 edit and tune by the seat of the pants method. I since have added 2 degrees of timng across the board and have leaned it out 4 percent with nothing but posative results. There was no wideband available at the time of this dyno.
http://members.aol.com/blueflame6469/images/dyno2.jpg
I would like to see more poeple try cams of tighter lsa nature with less duration. Hell, we try everthing else to go fast we might was well try this also.
THIS POST WAS NOT INTENDED TO OFFEND ANYONE WHATSOEVER. IT WAS INTENDED TO START INTELLIGENT CONVERSTATION OF VALVE TIMING EVENTS AND POWER MADE THROUGHOUT A GIVEN RPM BAND.
Has anybody picked up the GMHTP included with the popular hotrad magazine of this past month? An excellent article about cam timing and part of my fuel for this post.
I believe that a lot of our sponsors, tuners, and others are missing the bill on cam choices when maximum power within a given rpm band is selected. I see these 230+/230+ cams on a 114lsa. Why such a wide lsa (known as lobe separation angle, or lda= lobe displacement angle, or lsa= lobe serparation angle). More then likely because of the famous it will idle better response. If you have to widen the lsa because there is too much duration then you have chosen the cam poorly. I, as motivated from my own research which includes the article in GMHTP, my own cam and results {see sig.}, and other sources, believe that a proper lsa must be one of the first things chosen for a particular cam suited for maximum area under the curve. Think about it, scavenging is what creates more power in an n/a motor.
In My opinion, tighter lsas with smaller durations will always make more power then wider lsa with larger duration, both cams having the same amount of overlap. This allows for the intake valve to be opened later building more vacuum in the combustion chamber caused by the cylinder traveling down in its bore and the exhaust valve creating a vacuum effect on the combustion chamber and not allowing any or most of the intake charge being pulled from the combustion chamber during the intake stroke by exhaust scavenging. A higher exhaust velocity is also achiveid as the cylinder would start up in its bore before the exhaust valve was open causing the exhaust to come screaming out once the exhaust valve opens and creating even more of a vacuum on the exhaust side for greater scavenging. What does this do you might ask. CREATE MORE CYLINDER PRESSURE IN TURN CREATING MORE TORQUE THROUGHOUT THE RPM BAND WHICH INTURN CREATES MORE HORESEPOWER.
MY CAM:
To be honest with you I knew very little of what I know today when I chose this cam. I wanted a 224 cam because it was going in a 3.42 geared stock rear ended car. I wanted a 110lsa because I knew that more power potential was there and I wanted a nasty idle. I wanted four degrees of advance because all the other cams had it and I really didn't understand valve timing events that well at this point. I also chose 565 comp xe lobes (actually orderd xe-r but recieved xe lobes). I recieved a cam that made 380rwtq at the 2900+ rpm area and 406 rwtq at 4800 rpm (417 uncorrected. 405 hp at 5800-5900 (415 uncorrected) was attained. This was on stock heads and an independent dynojet and I have ls1 edit and tune by the seat of the pants method. I since have added 2 degrees of timng across the board and have leaned it out 4 percent with nothing but posative results. There was no wideband available at the time of this dyno.
http://members.aol.com/blueflame6469/images/dyno2.jpg
I would like to see more poeple try cams of tighter lsa nature with less duration. Hell, we try everthing else to go fast we might was well try this also.
THIS POST WAS NOT INTENDED TO OFFEND ANYONE WHATSOEVER. IT WAS INTENDED TO START INTELLIGENT CONVERSTATION OF VALVE TIMING EVENTS AND POWER MADE THROUGHOUT A GIVEN RPM BAND.
08-10-2003, 04:27 AM
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Re: Thoughts on cams, HOW ABOUT OVERLAP (lsa or lca or lda) I read that article, but it was so long that by the time I got to the end I forgot what I had just read. Now since what you wrote is basicly a summary of it, I completly understand. But you still have the fact that some people like to have a wild idle and dont really care about anything else but that.
08-10-2003, 05:57 AM
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Re: Thoughts on cams, HOW ABOUT OVERLAP (lsa or lca or lda) I would really love to make more power with stock heads, and not HAVE to swap out my LS1 intake to do it. If it were possible, I would, and I imagine it is, so I will, just waiting to see what will be best. Besides the fact I also like to spray, ok, thats an understatement...So, what cam do I look for? Raunchy idle....excellent as long as it will idle. Stock heads...even better. NA and N2O....now were talking.
08-10-2003, 09:00 AM
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Re: Thoughts on cams, HOW ABOUT OVERLAP (lsa or lca or lda)
building more vacuum in the combustion chamber caused by the cylinder traveling down in its bore and the exhaust valve creating a vacuum effect on the combustion chamber and not allowing any or most of the intake charge being pulled from the combustion chamber during the intake stroke by exhaust scavenging. A higher exhaust velocity is also achiveid as the cylinder would start up in its bore before the exhaust valve was open causing the exhaust to come screaming out once the exhaust valve opens and creating even more of a vacuum on the exhaust side for greater scavenging.
I have to get this article. It sounds like good reading. Which month Popular HotRodding is it?
08-10-2003, 11:21 AM
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Re: Thoughts on cams, HOW ABOUT OVERLAP (lsa or lca or lda) "You mean piston. "
You are correct, I wrote this at 1 in the morning wille drinking.
You are correct, I wrote this at 1 in the morning wille drinking.
08-10-2003, 11:22 AM
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Re: Thoughts on cams, HOW ABOUT OVERLAP (lsa or lca or lda) It is the october 2003 addition and can only be bought with the Popular hotrodding magazine of last month.
08-10-2003, 11:30 AM
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Re: Thoughts on cams, HOW ABOUT OVERLAP (lsa or lca or lda) annother reason for going with a wider lsa is that alot of us would like to use nitrous either now or in the future and a wider lsa means less nitrous is blown out the exhaust without being burnt. less nitrous wasted = more hp. plus you have a better idle which is usefull on an auto where some people have a very hard time getting one to that without a slew of problems.
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08-10-2003, 12:04 PM
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Re: Thoughts on cams, HOW ABOUT OVERLAP (lsa or lca or lda) i know articles are good and all but im all about real worl application. not to bash anyone but i happen to have a 224/110 and know of one other person that does too, IT ROCKS. now as far as the lsa goes, well i was told my tr230/224 111 was not ment for n20 but i ran some killer races with it and a 150 shot. ive never had a 114 cam and dont plan on it,(i have an A4 as well.) i think we are talking microscopic numbers here where when you refer to n20 being blown out and wasted HP and yada yadda yada/. its all good on paper but i honestly think its minute(sp?)build a motor for the best NA times then a some bug juice on it,, now if your planning on a 300 shot DP system of course its gonna need that special cam...but most of us run on the street and need that na performance just as much. this is aALL imo. so take it with a grain of salt.. 
08-10-2003, 12:11 PM
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Re: Thoughts on cams, HOW ABOUT OVERLAP (lsa or lca or lda) guess i should have read all the post first, lol, ill let ya know how it turns out after the programming...on a side note id like to see someone run 5.3 heads milled .030.
222/224 560/560 104icl 108lsa, just for ***** and giggles. forget that theory says and just try it, i thought a 224/110 was was overboard til, well ya know...
222/224 560/560 104icl 108lsa, just for ***** and giggles. forget that theory says and just try it, i thought a 224/110 was was overboard til, well ya know...
08-10-2003, 12:15 PM
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Re: Thoughts on cams, HOW ABOUT OVERLAP (lsa or lca or lda) I have been reading alot about specific engine combinations and trying a few during the whole process. My engine started out with handported heads and a 230 single pattern 114lsa cam. I switched to a 230 single pattern 110lsa cam and noticed worse idle but the car had more better power. I think I picked up a couple of MPH in the 1/4. A few generalization or thought....
11.1:1 compression ratio + 224/110lsa cam = ~230psi cranking compression will perform better than....
11.1 compression ratio + 232/110lsa cam = ~205 cranking compression BUT.....
if you can get the cranking compression to be equalivent to that of the 224/110lsa I would think that the bigger cam would have more power.
Phillip
11.1:1 compression ratio + 224/110lsa cam = ~230psi cranking compression will perform better than....
11.1 compression ratio + 232/110lsa cam = ~205 cranking compression BUT.....
if you can get the cranking compression to be equalivent to that of the 224/110lsa I would think that the bigger cam would have more power.
Phillip
08-10-2003, 12:47 PM
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Re: Thoughts on cams, HOW ABOUT OVERLAP (lsa or lca or lda) Damn straight. Tightening the LSA will create more power on an N/A setup. The main limitation is smog....most of the requests I get are for smogable cams. Well....that 224/224 110LSA cam has 8 degree more overlap then will pass the sniffer (generally). 8 degrees of additional overlap adds a great deal of power. Beyond smog, Piston to Valve clearance becomes an issue. With the proper valve events & lobes you can fit a few more degrees of overlap & increase power significantly. But you're still limited. Sure, you can easily notch the pistons & fit a wild little cam in there, but there comes a point of diminishing returns. Especially with the limiting intake selection the LS1 has. Stock heads can only do so much as well. I call it terminal aircharge velocity. Once you reach this point the only way to increase power is by eliminating the restrictions in the intake/exhaust.....or adding a poweradder of course.
As for smaller lobes with a tighter LSA....well....I do things a little different. I tend to choose the valve events for a particular setup first. Then find the lobes (profiles, ramp-rates, etc), LSA, & ICL that match the VE's. This makes it much easier to spec cams & equates to proper valve events with all of my cams. Some of my cam specs may look a little funny, but after all is said, a cam is simply Valve events & ramp-rates.
As for smaller lobes with a tighter LSA....well....I do things a little different. I tend to choose the valve events for a particular setup first. Then find the lobes (profiles, ramp-rates, etc), LSA, & ICL that match the VE's. This makes it much easier to spec cams & equates to proper valve events with all of my cams. Some of my cam specs may look a little funny, but after all is said, a cam is simply Valve events & ramp-rates.
08-10-2003, 12:50 PM
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Re: Thoughts on cams, HOW ABOUT OVERLAP (lsa or lca or lda)
I tend to choose the valve events for a particular setup first. Then find the lobes (profiles, ramp-rates, etc), LSA, & ICL that match the VE's.
08-10-2003, 01:08 PM
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Re: Thoughts on cams, HOW ABOUT OVERLAP (lsa or lca or lda) The average joe needs to study up BIG time. 
There are so many variables involved it's crazy. Actually, the LS1 is quite a bit easier to spec cams for then the 5.0 since the aftermaket is so limited. Specifically heads/intake/exhaust combinations. The 5.0 has at least 15 different aftermarket heads available without taking porting into account. Couple these different heads with all the different intakes out there..... (runner lengths vary from 11 inches to 18-20) ...it gets pretty damn complicated.
If you really want to learn the ins & outs of the cam I'd encourage any of you to call Brian Ebert at www.hitechmotorsport.com.
There are so many variables involved it's crazy. Actually, the LS1 is quite a bit easier to spec cams for then the 5.0 since the aftermaket is so limited. Specifically heads/intake/exhaust combinations. The 5.0 has at least 15 different aftermarket heads available without taking porting into account. Couple these different heads with all the different intakes out there..... (runner lengths vary from 11 inches to 18-20) ...it gets pretty damn complicated.
If you really want to learn the ins & outs of the cam I'd encourage any of you to call Brian Ebert at www.hitechmotorsport.com.
08-10-2003, 03:58 PM
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Re: Thoughts on cams, HOW ABOUT OVERLAP (lsa or lca or lda) 93Pony, thanks for your input. This stuff is surely confusing and we are lucky in the sense that we are only dealing with one head and one intake (ls6) manifold.
What do you think about my cam being retarded 4 (from a 106icl to a 110icl) degrees? Do you think the driveability will be alot worse? I wander if my peak numbers will increase or will they just occur at higher rpms?
What do you think about my cam being retarded 4 (from a 106icl to a 110icl) degrees? Do you think the driveability will be alot worse? I wander if my peak numbers will increase or will they just occur at higher rpms?
08-10-2003, 04:12 PM
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Re: Thoughts on cams, HOW ABOUT OVERLAP (lsa or lca or lda) I know a lot of people dont put much faith in Desktop Dyno, but I have fun plugging in different numbers to see what I can come up with. Although, I am suprised sometimes at how accurate the numbers and curves actually are once you put in LS1 head flow numbers. I am suprised more people havent tried cams on a 110 LSA. One other thing that really changes power is the ICL, which people always seem to change given two different LSAs..ie. a 112 cam run 4* advanced has an ICL of 108, and a 110 cam run 4* advanced has an ICL of 106. One that seems to produce really good results is a cam in the 224* range with a 110LSA run "straight up". The bad thing with driveability in mind is that for every 2 deg tighter on the LSA, you pick up 4 more deg of valve overlap. So a 224/224 110LSA cam has the same overlap @.050 as a 228/228 112LSA cam does, which happens to be +4 deg. With milled heads and big cams, a 106 ICL becomes a little dangerous with PTV clearances too. Great topic BTW
Daily-About retarding your cam, as I've said in the past, will definitely allow you to pick up a good 10+ peak hp with very little lost down low...'course this is just my $.02. At least it'd be fun to try and re dyno. Also, pick up some 4.10s man...you'll never go back
3.42s
Daily-About retarding your cam, as I've said in the past, will definitely allow you to pick up a good 10+ peak hp with very little lost down low...'course this is just my $.02. At least it'd be fun to try and re dyno. Also, pick up some 4.10s man...you'll never go back
3.42s
08-10-2003, 04:22 PM
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Re: Thoughts on cams, HOW ABOUT OVERLAP (lsa or lca or lda) I am going to give this a try on the near future. I already have a twelve bolt with 4.11s right now, just waiting on the spec clutch.
08-10-2003, 04:38 PM
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Re: Thoughts on cams, HOW ABOUT OVERLAP (lsa or lca or lda) I love this thread, its the kind that educates me, as well as entertains. Screw smog, max NA power with ability to run N2O (100-150 shot), and idle, raunchy is good!
08-10-2003, 05:15 PM
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Re: Thoughts on cams, HOW ABOUT OVERLAP (lsa or lca or lda) Ok this is with a 224/110 106icl
RPM HP TQ
2000 188 495
2500 229 482
3000 279 489
3500 330 496
4000 381 500
4500 409 477
5000 429 450
5500 441 421
6000 399 349
6500 360 291
7000 319 239
7500 276 193.
Now here it is strait up 224/110 110icl..
RPM HP TQ
2000 186 488
2500 225 473
3000 275 481
3500 326 490
4000 369 484
4500 404 471
5000 431 452
5500 441 421
6000 413 361
6500 379 306
7000 343 257
think i should run it as is or strait up? now to get it to a 110icl id have to retard it 4deg via my adj timing set, correct?
RPM HP TQ
2000 188 495
2500 229 482
3000 279 489
3500 330 496
4000 381 500
4500 409 477
5000 429 450
5500 441 421
6000 399 349
6500 360 291
7000 319 239
7500 276 193.
Now here it is strait up 224/110 110icl..
RPM HP TQ
2000 186 488
2500 225 473
3000 275 481
3500 326 490
4000 369 484
4500 404 471
5000 431 452
5500 441 421
6000 413 361
6500 379 306
7000 343 257
think i should run it as is or strait up? now to get it to a 110icl id have to retard it 4deg via my adj timing set, correct?
08-10-2003, 05:31 PM
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Re: Thoughts on cams, HOW ABOUT OVERLAP (lsa or lca or lda) Yes, to get it to a 110icl you will have to retard it 4 degrees with an adjustable timing chain.
Where in the world did you get those numbers from?
Where in the world did you get those numbers from?