Cam Gurus Chime In? Coming to an End Making sure on Cam for my Stroker!!!
12-29-2009, 10:14 PM
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Cam Gurus Chime In? Coming to an End Making sure on Cam for my Stroker!!! Just some things I would like to clear up, maybe someone here can help?
When trying to figure cam timing (ie IVO, IVC, Duration, and I/E Valve split), what do you base these things on to have an OPTIMAL (perfect) cam for a particular engine setup?
For instance my combo:
4" stroke 6 inch rod
Flat top 12.3:1 compresion; 0.060 over
Ported TFS heads, with 220 cc Intake runners, 2.055/1.60 valves,
Flow #'s are:
0.1 69 52
0.2 144 119
0.3 212 182
0.4 263 224
0.5 295 247
0.55 306 253
0.6 307 257
0.65 309 260
0.7 309 262
Ported Edelbrock LT4 intake with mono blade & 42# injectors: and yes I know this may hold me up some over the single plane option, but I want the stockish look rather than the carb'd race look.
What I have come up with is a tight lashed cam, using some Comp lobes that specs at: 276/284 Adv. 248/256 at 0.050 and .643/.656 lift on 112 LSA or I can use the high lift lobes that have 670/683 lift with same duration.
I have talked extensively with Matt from comp reguarding these lobes, and I plan to use the 643/656 lobes with Lunati hyd short travel race lifters, with a bit more spring pressure. IVO is 30 IVC is 66, what do you guys think?
The car is a 6 speed car, that will prob end up with 3.90 or 4.10 gear at most, as I plan to drive the car more than race; still has 3.42's in now and I will drive it with stock gearing to play with RPM to see what the car likes best before I decide on the gear. FOr this reason, I may mild the duration and or widen the LSA for more of a street driven application
Suggestions, help, ideas, debate welcomed!
thanks
KP
When trying to figure cam timing (ie IVO, IVC, Duration, and I/E Valve split), what do you base these things on to have an OPTIMAL (perfect) cam for a particular engine setup?
For instance my combo:
4" stroke 6 inch rod
Flat top 12.3:1 compresion; 0.060 over
Ported TFS heads, with 220 cc Intake runners, 2.055/1.60 valves,
Flow #'s are:
0.1 69 52
0.2 144 119
0.3 212 182
0.4 263 224
0.5 295 247
0.55 306 253
0.6 307 257
0.65 309 260
0.7 309 262
Ported Edelbrock LT4 intake with mono blade & 42# injectors: and yes I know this may hold me up some over the single plane option, but I want the stockish look rather than the carb'd race look.
What I have come up with is a tight lashed cam, using some Comp lobes that specs at: 276/284 Adv. 248/256 at 0.050 and .643/.656 lift on 112 LSA or I can use the high lift lobes that have 670/683 lift with same duration.
I have talked extensively with Matt from comp reguarding these lobes, and I plan to use the 643/656 lobes with Lunati hyd short travel race lifters, with a bit more spring pressure. IVO is 30 IVC is 66, what do you guys think?
The car is a 6 speed car, that will prob end up with 3.90 or 4.10 gear at most, as I plan to drive the car more than race; still has 3.42's in now and I will drive it with stock gearing to play with RPM to see what the car likes best before I decide on the gear. FOr this reason, I may mild the duration and or widen the LSA for more of a street driven application
Suggestions, help, ideas, debate welcomed!
thanks
KP
12-29-2009, 10:30 PM
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I have spoken with Comp (Matt), Lunati, and Lloyd; and each have given their choice of cam, but all have given fairly different cams, this one is what I have come up with after so many long nights on Dyno Sim Software. This one part is just so important to someone loving, hating, or just living with an engine setup. I really want to love my setup, from sound and performance. I honestly am looking for a bit more than 500 at the wheel, if possible, and retain as much under the curve as possible, for daily driving with 3.90 gear as preferred. I guess I am just second guessing my split and IV actions as they relate to my LSA.
Thanks again guys
KP
Thanks again guys
KP
12-29-2009, 11:36 PM
#3
I would go with Lloyd personally but you can also call up Advanced Research and speak to them and see what they!
http://www.advancedinduction.com/AiContact.html
http://www.advancedinduction.com/AiContact.html
12-30-2009, 01:29 AM
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I would go with Lloyd personally but you can also call up Advanced Research and speak to them and see what they!
http://www.advancedinduction.com/AiContact.html
http://www.advancedinduction.com/AiContact.html
Is Intake Valve timing based on stroke, and head size and flow more than anything?
12-30-2009, 02:02 PM
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The more people you reference the more differing recommendations you'll get. Seems they all have their own personal preferences.
The "perfect" cam, WOW! That's a TALL order; I wonder if it's even attainable.
What I did a few months back was essentially, in part, what you've done. I have Engine Analyzer Pro and I ran so many sims I lost count. What I did then was not so much concentrate on the power numbers but the DIFFERENCES. When I changed, for example, LSA, I looked to see what difference it made in the curve and ESPECIALLY the average power.
As with most things, the more accurate the information you punch in, the more accurate the output. So with EAP I did a LOT of research to find the exact specs for the parts I was running. Of course, these sims are just that. I believe the best way would be to do back to back dyno runs, each using a different spec cam and, after each cam swap, the fuel and timing curve optomized.
That's a bit unrealistic though since only those with BIG BUCKS and LOTS of time could take that route; places like the NASCAR engine development teams.
What I do when looking for a recommendation on something I'm stumped with is to FIRST decide on whose advice I value the most, then rely on him. Otherwise I get recommendations ALL OVER THE MAP.
There are SO MANY differing views, opinions, personal preferences and, yes, BAD information floating around it becomes a real chore to choose one from another. Of those, sorting out and discounting the BAD information is the real KEY.
Just on last thought: Be sure to inquire about the sensitivity of the lash setting on the tight-lash cam you're considering. Many years ago I ran a Crane Inverted Flank Roller in one of the race engines I built. Cam was AMAZING but VALVE LASH WAS CRITICAL! If the one you're considering is anything like the IFR, too loose on the lash can/will tear up your valve train. I never experienced that on the engine, but I recall Crane's WARNING.
Jake
West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!! Graduation Day Parade 20 May 2010!!!
The "perfect" cam, WOW! That's a TALL order; I wonder if it's even attainable.
What I did a few months back was essentially, in part, what you've done. I have Engine Analyzer Pro and I ran so many sims I lost count. What I did then was not so much concentrate on the power numbers but the DIFFERENCES. When I changed, for example, LSA, I looked to see what difference it made in the curve and ESPECIALLY the average power.
As with most things, the more accurate the information you punch in, the more accurate the output. So with EAP I did a LOT of research to find the exact specs for the parts I was running. Of course, these sims are just that. I believe the best way would be to do back to back dyno runs, each using a different spec cam and, after each cam swap, the fuel and timing curve optomized.
That's a bit unrealistic though since only those with BIG BUCKS and LOTS of time could take that route; places like the NASCAR engine development teams.
What I do when looking for a recommendation on something I'm stumped with is to FIRST decide on whose advice I value the most, then rely on him. Otherwise I get recommendations ALL OVER THE MAP.
There are SO MANY differing views, opinions, personal preferences and, yes, BAD information floating around it becomes a real chore to choose one from another. Of those, sorting out and discounting the BAD information is the real KEY.
Just on last thought: Be sure to inquire about the sensitivity of the lash setting on the tight-lash cam you're considering. Many years ago I ran a Crane Inverted Flank Roller in one of the race engines I built. Cam was AMAZING but VALVE LASH WAS CRITICAL! If the one you're considering is anything like the IFR, too loose on the lash can/will tear up your valve train. I never experienced that on the engine, but I recall Crane's WARNING.
Jake
West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!! Graduation Day Parade 20 May 2010!!!
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12-30-2009, 09:03 PM
#8
I've spec'd cams for a few motor builds with great success in meeting the owner's goals each time, and those were more street cars and roadracing cars than drag cars. When it came time for my own motor, to get the most out of it with a hydraulic roller and within the limitations of the GM PCM, I put my pride aside and let AI spec the cam, and boy oh boy am I glad I did. They exceeded what I would have expected from my own lobe selection by a good 20 hp.
I think, like you said, "milding" the duration would be a good idea. BUT, contrary to your comment on LSA, do not widen it. When all the valve events are dialed in for NA operation, it's unlikely to come up with a resulting LSA of more than 112 for any SBC 23 deg head. With great flowing heads, I really think you'll be happier with an intake duration in the 236-240 range and LSA in the 110-112 range for a driver like you indicated. And again, for a driver, I'd shy away from more aggressive high lift lobes you mentioned. And, for the same reason, in the interest of durability, I'd also shy away frrom taking any recommendations from bauer racing. I'm curious to know what LE recommended. Of the three (Comp, Lunati, LE) you mentioned talking to, I'd be most confident in LE's recommendation.
Shooting for 500 rwhp, I'd honestly be looking at solid roller cams. Either way, 500 rwhp solid or hydraulic, your valvetrain is not going to be daily driver friendly. It's going to require lots of attention.
I think, like you said, "milding" the duration would be a good idea. BUT, contrary to your comment on LSA, do not widen it. When all the valve events are dialed in for NA operation, it's unlikely to come up with a resulting LSA of more than 112 for any SBC 23 deg head. With great flowing heads, I really think you'll be happier with an intake duration in the 236-240 range and LSA in the 110-112 range for a driver like you indicated. And again, for a driver, I'd shy away from more aggressive high lift lobes you mentioned. And, for the same reason, in the interest of durability, I'd also shy away frrom taking any recommendations from bauer racing. I'm curious to know what LE recommended. Of the three (Comp, Lunati, LE) you mentioned talking to, I'd be most confident in LE's recommendation.
Shooting for 500 rwhp, I'd honestly be looking at solid roller cams. Either way, 500 rwhp solid or hydraulic, your valvetrain is not going to be daily driver friendly. It's going to require lots of attention.
12-30-2009, 11:09 PM
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Total Engine Airflow did my heads, I will ask them, but I haven't know them to be big on custom spec camshafts. I do know some LT1 guys with their heads, and have spoke with a 4 or 5 LS owners running their LS6 and 6.0 heads with outstanding sucess.
12-30-2009, 11:51 PM
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I've spec'd cams for a few motor builds with great success in meeting the owner's goals each time, and those were more street cars and roadracing cars than drag cars. When it came time for my own motor, to get the most out of it with a hydraulic roller and within the limitations of the GM PCM, I put my pride aside and let AI spec the cam, and boy oh boy am I glad I did. They exceeded what I would have expected from my own lobe selection by a good 20 hp.
I think, like you said, "milding" the duration would be a good idea. BUT, contrary to your comment on LSA, do not widen it. When all the valve events are dialed in for NA operation, it's unlikely to come up with a resulting LSA of more than 112 for any SBC 23 deg head. With great flowing heads, I really think you'll be happier with an intake duration in the 236-240 range and LSA in the 110-112 range for a driver like you indicated. And again, for a driver, I'd shy away from more aggressive high lift lobes you mentioned. And, for the same reason, in the interest of durability, I'd also shy away frrom taking any recommendations from bauer racing. I'm curious to know what LE recommended. Of the three (Comp, Lunati, LE) you mentioned talking to, I'd be most confident in LE's recommendation.
Shooting for 500 rwhp, I'd honestly be looking at solid roller cams. Either way, 500 rwhp solid or hydraulic, your valvetrain is not going to be daily driver friendly. It's going to require lots of attention.
I think, like you said, "milding" the duration would be a good idea. BUT, contrary to your comment on LSA, do not widen it. When all the valve events are dialed in for NA operation, it's unlikely to come up with a resulting LSA of more than 112 for any SBC 23 deg head. With great flowing heads, I really think you'll be happier with an intake duration in the 236-240 range and LSA in the 110-112 range for a driver like you indicated. And again, for a driver, I'd shy away from more aggressive high lift lobes you mentioned. And, for the same reason, in the interest of durability, I'd also shy away frrom taking any recommendations from bauer racing. I'm curious to know what LE recommended. Of the three (Comp, Lunati, LE) you mentioned talking to, I'd be most confident in LE's recommendation.
Shooting for 500 rwhp, I'd honestly be looking at solid roller cams. Either way, 500 rwhp solid or hydraulic, your valvetrain is not going to be daily driver friendly. It's going to require lots of attention.
Very good Info. I emailed AI today and they responded with a very detailed email to find out exactly what I have, and my intents. I was very please with the thorough and detailed questions to get a feel of what I wanted. I am looking forward to what they suggest. Lloyd and Comp were actually pretty close. Lloyd suggested a SR 280/288 248/255 with .668/.668 lift on a 112. said it will be definitely a drivable cam and make theoretically in the 590 - 630'sh range flywheel hp.
Matt from Comp worked very hard to get a cam that he and Mr. Billy Godbold felt would satisfy my requirements. They said to using the CSZ lobes would allow me to run either hyd or solid, and have a motor what is very responsive, and make more vacuum than most of the same duration @.050. And while they did not give me an estimated hp range, they bolth felt very confident that my goal that I stated to Matt of 520+RWHP should not be a concern. They spec'd out a cam of 272/280 244/252 .664/.677 on 112LSA. I just change their specs up to the next step up to get to the cam I stated I was thinking of running with the lower lift lobes, running it as hyd.
Lunati says use thier voodoo style lobes with 273/279 243/249 .578/.585 on a 110 LSA, but in paying with this cam, it turns out Lloyd is right that this motor (as far as sims go) seems to want a slightly larger duration, and a little later IVC point as my power got considerably better by retarding this cam.
So the fact of duration figures at @050 in the 242-248 range may be about right, but whether to use a shorter duration and wider LSA than 110 or to use a longer duration and shorter LSA etc. is where I am figuring my biggest concern is coming in at and how much actual split I actually need for these heads! The flow number on the exhaust are obviously flowed with a pipe, i believe thad on my flow sheet with a 2" stack.
What makes you say shy from Bauer Racing Cams, are they primarily race style cams, or not gonna be streetable, bad experience maybe. I sent them an email as well, but I would appreciate any heads up that I need to know about!
THanks again everyone
12-31-2009, 02:49 AM
#11
Realize that the cam spec'd by Lloyd is the mildest, since the lash on a SR results in less effective duration.
Be careful of simulation programs with the LT1 manifold; they underestimate the rpm range by a good 500 rpm. The fact thatyou mentioned retarding the cam resulted in better power with these already large durations, kinda reinforces my thought on that. How high do you intend to rev this motor? You're looking at over 7000 shift points to make use of the HR cams you've mentioned. You may be setting yourself up for disappointment by putting too much emphasis on a hp goal when talking to the cam guys.....they won't want to fail! I would rather give them the range I want to operate in and tell them to maximize the hp in that range. Apower peak at 6800 rpm is wasted if you're going to shift at 7000. My motor peaks at 6400 and I shift at 7000 for best ET's. And especially for a driver, achieving a peak hp goal is less important than a useable hp curve. I still think you'd be more satisfied with an intake duration closer to 240 and a LSA of 110-112.
Bauer can produce big power numbers, but the valvetrain is short lived.
Unless you're willing to spend the time and money maintaining the valvetrain from hell, I'd pass. You can make 98% of that power and have a valvetrain that will live in a driver.
If it weren't for the dyno graph, I'd never believe my power peak is down at 6400 rpm; it pulls like a freight train to the PCM cutoff. The reason is that the lobes are mild enough to keep the valvetrain under control at the higher revs despite a modest HR setup.
...... as my power got considerably better by retarding this cam.
So the fact of duration figures at @050 in the 242-248 range may be about right, but whether to use a shorter duration and wider LSA than 110 or to use a longer duration and shorter LSA etc. is where I am figuring my biggest concern is coming in at and how much actual split I actually need for these heads!......
So the fact of duration figures at @050 in the 242-248 range may be about right, but whether to use a shorter duration and wider LSA than 110 or to use a longer duration and shorter LSA etc. is where I am figuring my biggest concern is coming in at and how much actual split I actually need for these heads!......
Bauer can produce big power numbers, but the valvetrain is short lived.
Unless you're willing to spend the time and money maintaining the valvetrain from hell, I'd pass. You can make 98% of that power and have a valvetrain that will live in a driver.
If it weren't for the dyno graph, I'd never believe my power peak is down at 6400 rpm; it pulls like a freight train to the PCM cutoff. The reason is that the lobes are mild enough to keep the valvetrain under control at the higher revs despite a modest HR setup.
12-31-2009, 06:40 AM
#12
bret was somewhat.... abrasive on the boards. Calls out a lot of sponsor bullshit, and since L$1tech is a money making machine... he was banned awhile ago. But he does know his **** when it comes to a SBC. Remember with an LTX you've got no intake runner length and a relatively low rpm limit. This does funky things with your LSA and IVC. Trying to throw duration at it, but keeping the rpms within the 7200 rpm limit keeps your IVC early, and thus a tight lsa. I'm making over 400rwtq at 2800 rpm but it still pulls strong to 7k. Waiting on final numbers due to valve float from me installing the springs too high, but i'm expecting 480+ rwhp. It made 440rwhp at 5400 rpm when it started floating. The cam bret spec'd me is a nitrous grind 24x/25x on a 107.5 lsa, mild SR lobes but I'm running early style Comp R HR lifters. Feel free to PM me as our setups are somewhat similar...
12-31-2009, 07:31 PM
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The lift is just what the lobes happen to be, but I really like the lobe, because of its shorter seat timing, should help the torque, vaccuum, and area under curve, in just my trial and error simming. I did not figure the lift to be that bad out considering the cam LE speced was a bit more lift than this and he only said it needed 12-16 thousands lash, which puts me back around where this cam is now, that I am considering. The other reason I like the lobe, besides its ramps is that it can be ran as a hyd roller will no real adverse pitfals. I chose to run the Lunati style lifters over the Comp short travel simply because they are designed to handle much higher seat and open spring preassueres; (ie 225 max seat 575 max open), and my springs righ now are set up on my heads at 185# seat and they would be 530 ish open with my 1.6 rockers and these lobes (hence the .643/.656 lift, because I already have shaft rockers in 1.6, had I not had these already then I could use a 1.5 and effectively have a .603/.615 lift cam)
12-31-2009, 08:45 PM
#16
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LT1 intake. I am using a short runner factory volume intake to represent the LT1. I am actually hoping I am close, but I am only using the sim to see what effects the different timing changes make to the curve,not to try an pinpoint a particular HP number.
How high do you intend to rev this motor? You're looking at over 7000 shift points to make use of the HR cams you've mentioned. You may be setting yourself up for disappointment by putting too much emphasis on a hp goal when talking to the cam guys.....they won't want to fail! I would rather give them the range I want to operate in and tell them to maximize the hp in that range. Apower peak at 6800 rpm is wasted if you're going to shift at 7000. My motor peaks at 6400 and I shift at 7000 for best ET's. And especially for a driver, achieving a peak hp goal is less important than a useable hp curve. I still think you'd be more satisfied with an intake duration closer to 240 and a LSA of 110-112.
240/248 110+2. I think I will love the midrange, and power in the cruising RPM's. I still used these same lobes, which puts my seat timing at 268/276, and lift at 630/643.
Thanks for the help with this, that is why I love the forums.
Now lastly, all you guys running Comp short travel race lifters (15850-16 or 875-16); what spring preassures are you running on the seat, and how are they reacting? These would save me some money in comparison to the Lunati 72530LUN lifters. What hot idle oild preassure do you have as well; Matt said the idle oil preassure has much to do with how tolerable they will be to higher spring preassures!
Last edited by LT1STROKER; 12-31-2009 at 08:54 PM. Reason: messed up the quotes
12-31-2009, 09:20 PM
#17
The software I am using does not even have a representation for the actual
LT1 intake. I am using a short runner factory volume intake to represent the LT1. I am actually hoping I am close, but I am only using the sim to see what effects the different timing changes make to the curve,not to try an pinpoint a particular HP number.
In taking your advice, I have played with some smaller lobes and I lost some top end (up to 23 hp all above 5000 RPM), but I gained so much torque, and the power band was moved to a much more respected peak around 64-6500. You were definitely right about peak rpm and shift, and in analyzing my curves, power peaks at @6700. with the cam I was trying to run. Your selection of 240 is a good rec'. My new grind I have is much more user friendly for driving and keeps my shift point under or at 7000. See if this sounds any better
240/248 110+2. I think I will love the midrange, and power in the cruising RPM's. I still used these same lobes, which puts my seat timing at 268/276, and lift at 630/643.
Thanks for the help with this, that is why I love the forums.
Now lastly, all you guys running Comp short travel race lifters (15850-16 or 875-16); what spring preassures are you running on the seat, and how are they reacting? These would save me some money in comparison to the Lunati 72530LUN lifters. What hot idle oild preassure do you have as well; Matt said the idle oil preassure has much to do with how tolerable they will be to higher spring preassures!
LT1 intake. I am using a short runner factory volume intake to represent the LT1. I am actually hoping I am close, but I am only using the sim to see what effects the different timing changes make to the curve,not to try an pinpoint a particular HP number.
In taking your advice, I have played with some smaller lobes and I lost some top end (up to 23 hp all above 5000 RPM), but I gained so much torque, and the power band was moved to a much more respected peak around 64-6500. You were definitely right about peak rpm and shift, and in analyzing my curves, power peaks at @6700. with the cam I was trying to run. Your selection of 240 is a good rec'. My new grind I have is much more user friendly for driving and keeps my shift point under or at 7000. See if this sounds any better
240/248 110+2. I think I will love the midrange, and power in the cruising RPM's. I still used these same lobes, which puts my seat timing at 268/276, and lift at 630/643.
Thanks for the help with this, that is why I love the forums.
Now lastly, all you guys running Comp short travel race lifters (15850-16 or 875-16); what spring preassures are you running on the seat, and how are they reacting? These would save me some money in comparison to the Lunati 72530LUN lifters. What hot idle oild preassure do you have as well; Matt said the idle oil preassure has much to do with how tolerable they will be to higher spring preassures!
Why such a wide split? Do you plan on spraying?
Your aftermarket TFS heads flow a hell of a lot better then stockers on the exhaust side, so you don't need so much exhaust duration. IMO you could pick up even more tq and increase drivability while also lowering overlap by bringing the intake and exhaust durations closer together. RPM range should drop even more as well. This would all be beneficial on a car that sees more street then track duty. Hell, you could probably go up a bit on the intake and down a bit on the exhaust, keep the hp range the same, and pick up tq across the board.
Big splits are really left-over train of thought from SBC heads whose flow heavily favored the intake duration so they jacked up the exhaust to compensate. Your heads are flowing on the exhaust what some level 1/2 ported stockers flow on the intake!
12-31-2009, 09:40 PM
#18
Matt from Comp worked very hard to get a cam that he and Mr. Billy Godbold felt would satisfy my requirements.
