lookin at 3 cams for my 5.7 vortec build.

crane 274 ho6 .450 lift, 106 lsa 218/218 duration

lunati brcket master 285: .455 lift, 114 lsa 230/230 duration

TPIS dual pattern .454 lift, 220/230 duration, 112 lsa

which is gonna make me more streetable fun power? its one of these 3, finally narrowed it down lol, im really confused on lsa because id like to get atleast 9.5+:1 compression since im using vortecs with flat tops, which cam guys? they all idle nasty like i want thanks!

 

What is the purpose of the car? Daily driver, weekend toy etc? Also I see you have a 700R4 in your profile, is it stock? Any plans for a converter? Any idea on gears?

Assuming you have 2.73's and a stock converter, I'd rule the lunati out right away. The duration of a cam dictates its operating power range. higher duration means the power will come on higher up in the RPM range. A cam with 230 degrees is ok on the street if you have the converter and gears to back it up, as it will give up some low end torque to make it up higher in the rpm range.

My understanding of LSA is it effects how choppy the idle will sound, but mainly effects how torque is produced through out the rpm range. I believe, and hopefully someone can correct me if i am wrong, but if you have 2 cams with the same duration and lift specs, but one is on a say a 106 lsa and the other on a 114lsa, the 106lsa cam's torque spread will be slightly higher, but be made over a narrower rpm range, where the 114lsa will be spread over a wider rpm range.

I've never seen many street cams with an lsa of 106. Usually they are in the 108-114 range for most of them. If I had to pick from the 3 listed there, I would probably go with the first one to get what you are looking for. If it was me, I'd probably try and find some other options.

 

I agree. If I HAD to pick from one of those 3, #1 is the lesser of evils.
However, for typical Vortec heads, and for your "streetable fun power", there are much better choices.
Like was already said, the specs of the cam you need will depend heavily on use, gearing, converter, intake manifold type,.... however you should probably end up with at least a 6 deg split and around a 108-110 LSA.
BTW, for someone who really knows how to spec a cam, you never start out assuming an LSA. LSA is simply a result of the chosen open and close points of the lobes, but not too many people actually have the data and knowledge to do that.

 

x2! You have 3 narrowed down cams based on LSA's but the lobes and durations on the 3 cams are drastically different! Completely different operation range.

I came into this thread thinking you had lobes picked out that were pretty similar but the cams came in different LSA's.

What are the supporting mods on this build? Is it carbed? Is it EFI? What intake? For a more mild car with a carb, out of those choices I'd go with the crane 218/218 however I'd think a typical 268 type cam around 224 deg would be a good cam with a 6-8 deg spread on exhaust. 108-110 lsa is what I'd run. COMP xe268 is popular with vortecs.

 

I have a lunati 60103LK for sale, no miles on it for 140 plus shipping or best offer... It's normally 200 bucks plus shipping brand new.

 

Correct, except that for Vortecs, you want no less than 10 degrees of split. Post up gearing and everything, then we can all collaborate on a set of specs for you a custom grind.

 

okay heres everything haha. 2.73's, stock converter with lockup, trangso 700 2-3 full manual kit (using full manual), stock flat tops, edelbrock 600, accel dist with super coil, air gap intake, heads are stock accept z28 style springs and fresh lap job. i will be eventually putting in my 3.23's and its mainly a daily driver id like to take to the track and have some fun with and hopefully get into the 12's with and take out them lil hondas which is why im confused on the cam, yet i require that mean idle and those are the three cams i like and can go with stock vortecs due to lift. the crane 274 poops out about 5500 but honestly think that may be the best choice, tho the lunati sounds much better and has a wider powerband due to lsa

 

but if anyone has any ideas on an even better cam please feel free! but it must be under .475 lift for reasons of stock heads and trying to save my wallet, a little. also dont forget the mean choppy idle lol

 

LSA really depends on the application... theres no real general rule of thumb. I just seen an old article about a 406" hyd roller max street effort type build. They tested same cam lobes but one was on a 107 lsa, one was on a 110lsa and one was on a 113 lsa. It had Brodix track 1 227cc heads and over 11 to 1 compression. It was tested with a single plane carb intake and a dual plane. As expected the dual plane restricted power to 6200 rpm peak while the single plane allowed the big 248/254 cam to peak in the 6600 rpm range.. It made near 609 hp I believe with the single plane.

Guess what had the best overall power curves and torque? The tight 107 lsa. 110 was last in power and torque and overall curve power. 113 was close behind the 107. For this particular motor the 107 with those cam lobes seemed to be best. Not gonna be that way for everything but most sbc's do ok with tighter 106-109 lsa's.


With press in rocker studs you also gotta be careful with rpm and pulling studs out from combination of rpm and spring pressure, although its mainly spring pressures. Pulling more rpm naturally means more spring pressure required to control the valves. Those bigger cams will want to pull more than 5500 rpm and can be at risk of valve float with hyd lifters. That being the case I'd go no more than 224 deg duration on the intake and have some exhaust duration split. 108-110 lsa IMO. SHould work well and give a nice mean idle. Vortecs/air gap intake, carb and 224/230 cams are generally well into the mid high 12's in a proper setup car thats not too heavy. Its a very popular combo

 

LSA doesn't matter to "power"; otherwise equal cams with different LSAs will make EXACTLY THE SAME power if you measure it as "area under the curve".

IN GENERAL: (there can easily be exceptions, but this is the GENERAL rule)

All else equal, a cam with a tight LSA will make higher peak torque at a lower RPM, idle worse, get worse gas mileage on the street, make peak HP at a RPM closer to the peak torque RPM which you would probably call "peaky", and will tend to win races in a purpose-built race car where the drive train is set up to keep the engine in between those 2 RPMs at all times.

All else equal, a cam with a wider LSA will idle better, get better gas mileage on the street, have higher idle vacuum, have lower peak torque & HP numbers, the power band will be extended out to a higher RPM, will be more fun all-around on the street, and will not be possible to sufficiently optimize the gearing and whatnot to beat the narrower LSA cam in a race situation.

There is also the question of ICL, and the whole interaction with the heads, intake, & exhaust, that can enter into the picture.

Trying to compare NOT otherwise equal cams on the basis of their LSA is a recipe for confusion and disaster.

IOW, it's not a question of universally "better" or "worse" in either case, rather, it's a matter of SUITABILITY FOR INTENDED PURPOSE.

 

You have a balancing act to perform. "Mean" idle and stock stall converters don't generally work well together. TIghtening the LSA is about the only way you can go to get a choppy idle without going to a longer duration cam. And big duration is NOT what you want in your application. It will send low-midrange power right into the toilet.

If you are looing at flat tappet cams that Crane 274 on the tight 106 LSA gets the nod.

The duration is still a bit much against a stock stall converter, but with the tight LSA it will work. It will build plenty of cylinder pressure at low RPMs and should pull like a beast in the 2500-5000 RPM range. It will fall off quick above and below that point, though. Idle will definitely have some chop to it.

 

It should be ok on stock stall. I've tuned a 230/236 .576" 113 lsa cam on a .060 over L98 with stealth ram and it drove ok on stock stall but 3.73 gears. Low comp too, mid 9s to one with aggressive timing curve. Even tho it's a 113 lsa it's still a big cam for a 360 and def had the idle lope to prove it

 

[QUOTE=Orr89RocZ;5289258]LSA really depends on the application... theres no real general rule of thumb. I just seen an old article about a 406" hyd roller max street effort type build. They tested same cam lobes but one was on a 107 lsa, one was on a 110lsa and one was on a 113 lsa. It had Brodix track 1 227cc heads and over 11 to 1 compression. It was tested with a single plane carb intake and a dual plane. As expected the dual plane restricted power to 6200 rpm peak while the single plane allowed the big 248/254 cam to peak in the 6600 rpm range.. It made near 609 hp I believe with the single plane.

I did not think this was a fair test..the Combo was skewed IMHO.


Those bigger cams will want to pull more than 5500 rpm and can be at risk of valve float with hyd lifters. That being the case I'd go no more than 224 deg duration on the intake and have some exhaust duration split. 108-110 lsa IMO. SHould work well and give a nice mean idle. Vortecs/air gap intake, carb and 224/230 cams are generally well into the mid high 12's in a proper setup car thats not too heavy. Its a very popular combo

To the above is very good tried a proven combo

 

LSA really depends on the application.

 

Hard to say. For that particular combination, I dont think the parts selection was bad. I thought it was stupid to test a dual plane intake since its obvious that motor wanted a single plane with the heads/cam being as large as they were. Dual plane is a restriction and with restricted top end, if you overcam, a tighter lsa is gonna show better results than if you just selected the right cam for the shorter rpm range of the dual plane intake in the first place.

What would have been better was to see each cam on the same intake centerline and then moved around until motor made its most power....then compare the numbers. Either way its a good example to show that SOMETIMES a narrow lsa can work well....its combination specific.

Agree, vortecs 224 cam and rpm air gap intake should be well into the 12's

 

I find it odd that most consider the LSA to be a "throw-in" value when it comes to spec'ing a cam.
If anything it's possibly the MOST important consideration when making a decision about what cam to run as it will define the characteristics of the engine as a whole.
The LSA, along with the duration values will determine the amount of overlap that results and it's this overlap that determines the idle vacuum, drivability and power characteristics.
The more an engine becomes undervalved, that is, more cubic inches for a given cylinder head, the tighter the LSA needs to be. Tighter LSA means more overlap for the duration spec'd and there's the main reason for determining what the LSA needs to be.
All of the rest, the vehicle combination and all that goes with it, are needed to come up with the ideal cam specification.
In order of importance it's accepted that the following are the critical values when choosing a cam.
Overlap, LCA(s), duration, ICL, lift and duration.
As an experiment, I've been trying to spec a new cam for my 350. Since I've enjoyed the old XR276HR for a long time, and by enjoy I mean a mid 12 second 3800 lbs, 107 mph daily driver that knocks down over 20 mpg on the hiway, I reverse engineered the cam profile using computer simulation. Finding that the overlap (seat to seat ) is 59° I've been choosing cams with that same amount of overlap but varying amounts of duration and LSA. The results are interesting but predictable.
Don't get me wrong, I'm not dismissing ANY of the advice given so far as it's all directed towards getting the best cam for the OP, I just found it different in the way the specs were being determined.

 

If you can provide the seat to seat (advertised) duration values as well as the ICL for all three cams, I'll run through a few simulations using stock Vortec flow numbers in a 10:1 350.
I can post up the graphs/tables for a little inspection.

 

LSA is an observed effect, not a cause. Same for duration. The idea is to correctly spec the best IC, EO, IO and EC, in that order, then calculate what duration and LSA that happens to result in. The specs may be compromised slightly to fit with readily-available lobes. You don't pick the LSA, you let it be whatever it will be, once everything else is the best it can be for the application.

 

You follow the David Vizard, possibly comp cams way I guess? Its a good method and it does work from many hundreds if not thousands of tests he has done. But its still not the end all way to determine a cam for a given motor. It gets you pretty close tho for most street builds and mild race applications.

But there is a problem with going by overlap and LCA or LSA alone. You can have 2 cams with same duration/lsa but with different valve events.

300* symetrical cam on 108 LSA---42-78-78-42, for 84* overlap
300* unsymetrical cam on 108 LSA---39-81-75-45, for 84* overlap

They will behave totally different on a motor. Cam lobe and opening/closing events I feel are most important. Some cam guys say intake valve opening and exhaust valve opening are most important, others think intake closing events are the most important.

Thats why I think LSA is a calculated value that really just ends up being where it needs to be based on the valve events one can experiement with and calculate.
Think of a twin cam ohv setup. One cam for intake lobes one for exhaust. They dont have LSA's they just do intake centerline angle and exhaust centerline angle. The average of those makes the "LSA" but they dont refer to it that way. SBC with a single cam has intake lobes and exhaust lobes too, and they perform 2 different functions. Intake needs to be on a certain ICL and the exhaust lobe needs to be on a certain ECL. They just happen to be on the same metal rod so you can "calculate" the separation angle. Thats the state of mind on camshafts I've been following based on discussions by cam experts like Mike Jones, and Harold Brookshire, and others on tech forums. If you think of the pressure variances and harmonic pressure waves in the motor chamber and intake/exhaust ports throughout the cycle, you can easily begin to realize how important the timing of valve openings and closings are. Where they occur will effect cylinder filling and peak chamber pressures.


But your right, undervalved restricted flow top ends will usually show better results with tighter LSA's given same cam lobes in a back to back test.

 

Personally, I'll go the overlap route and work from there. There isn't a single cam spec that has a greater impact on how a engine behaves than that.
Move ANY of the valve events or duration values and you'll affect the overlap. Put in a later intake closing and you'll have had to change duration or centre line. Even valve lift has a direct impact as it's not just the number of degrees but valve opening area (roughly lift x degrees) that makes the difference.
And yes, I've studied Vizards articles on cam profiling extensively. While some consider him outdated, his latest work is very current. Keep in mind that I'm referring to how it all relates to an normally aspirated SBC. As for how companies work out their spec's, that's a different matter. It's more for the common man who without being equipped with sufficient information will select a cam based on the averages. Cam companies don't want you to be unhappy with a purchase and so values are based on what's guaranteed to work. Overlap vs LSA and duration is a prime example.

 

okay here are the advertised in order.
crane: 274/274
TPIS: 276/286
Lunati: 285/285

 

but now i honestly feel the tpis cam would be best seeing it is a split pattern, wider lsa range, and gives me the sound i want, any opinions?

 

Any idea as to what the ICLs are?

 

Crane use LSA minus 5 degrees, the other 2 use LSA minus 4 degrees.

 

Wherever the timimg set (i.e. the whim of the installer) locates them.

 

now i honestly feel ill get a better powerband out of the TPIS and .00057574 better gas mileage haha

 

Tpis would be abit better if it was on a 108-110 Lsa.

 

Your ICL and mine are different. I'm referring to the amount of advance or retard ground into the cam, not the actual installed centre line.

 

Based on the info provided here are the tables for the three cams in question.

Crane PN# 100172 Grind # 274 HO6 (From the Crane website)
Adv dur. 274/274
106 LSA
102 ICL


Lunati PN# 00011 Grind# BM-II (from the Lunati website)
Adv dur. 285/285
114 LSA
109 ICL

The TPIS website blows and I can't find the cam in question. I need ALL the specs.

 

I vote for the Crane cam.
The shorter duration builds considerably more torque. The LSA is more suited to the 350 cubic inch displacement and the overlap in this case is more than the Lunati because of the wide lobe seperation.

 

Well the cam card specs are based on one centerline so that determines the advance ground in. Cam card may say 108 icl and Lsa is 112 so that's 4 deg "ground in" if installed dot to dot

 

Yes. I think sofa was referring to the installed centreline.
My reference to ICL is the amount ground into the cam and need to have it for calculations.

 

The engine has no way of knowing, or responding to, the "amount [of ICL] ground into the cam", separately from anything else that affects it.

All it knows about or cares about or is affected by, is when the valves open and close.

Doesn't matter what is responsible for the ICL, whether the timing set, the cam, or the installer's intent (or lack of it); all that matters, is the ICL as it really is.

 

In this case, I'm looking for the actual cam card data for the computer simulation.
In need advertised duration, LSA and ICL to complete the required in the program.
I know what your talking about regarding the actual INSTALLED ICL.
If we want to experiment further, the ICL can be advanced or retarded in the program data(which changes ALL the valve events) and observe the results.

 

Overlap is no help with shorty headers, you need long-tubes if you want to benefit from overlap.

 

Very true. It's my understanding the overlap is essential when doing a pulse tuned exhaust. Not just long tubes but a zero restriction exhaust system (due to backpressure) as well.

 

It's come to my attention that the dyno tables I uploaded my not be accesible to everyone.
I've converted them to PDF files which should make it easier.

 

That's a no-brainer, the Crane outright kills the Lunati. Where's the TPiS? Assume it has 4* ground in.

 

Here you go. One table for 112 LSA/108 ICL and another for 112 LSA/110 ICL.

 

goin with the crane, thanks guys!!!

 

Even before I look at the TPiS results, let me remind you that just because the Crane killed the Lunati for output, that doesn't mean it will be tolerable to live with. If you're willing to change the gearing, and the torque converter if applicable, then it becomes more livable, but even so, you may never be happy with it.

 

Thank you

 

Isky 201271

 

heys guys, how about an isky mega 270 vs the crane 274?? FINAL CHOICES lol