It seems most here are pretty mild and have a stock cam. I'm not most and I'd like to go with a somewhat aggressive cam.
I've got a 5.3 so I've also got to consider that I've got less cubes than a 5.7 so that will make a cam seem more aggressive. I'm not worried about springs, pushrods etc. I know all that will need to be upgraded to suit the cam. My engine is undergoing a full rebuild and will have ported 799 heads with long tube headers so I should stand to gain a fair bit of power with a decent cam.

Another thing to consider is rear end gear. I haven't got my diff yet, but I'm looking for an 8.8 out of a T Bird or Cougar. Neither of which came with anything above like a 3.73. All these LS cams are made for LS1/t56 combos that aren't the same gearing. So that could possibly have me too low in the RPMS at certain speeds and end up at a dead spot in the powerband.

So who's running what on what setup?

 

Check this out: LS Cam Test Comparison - Car Craft Magazine

To answer your question, I'm running the GM 'hot cam' in an LS3, but will be going to something closer to a ASA grind. ..with T56 and CTSV rear w/ 3.42 gears

 

Thanks, I've read that article and done tons of searching. Was posting here for more application specific opinions. As I'm sure you know a cam that might be great for a camaro might not be ideal in a miata.

 

Remember to take in account tire height/size when selecting your rear end gearing. A smaller diameter tire will make a gear seem "taller" than it actually is.

 

Decide on desired performance & start there.

 

Correct! I'm trying to do one system at a time so that I don't get overwhelmed or off course. I'd really prefer not to flycut, so I don't want to get a cam with too much lift/duration. I've been looking at the 228R from Texas Speed, but I've wondered why it's a symmetric cam? isn't that old technology/theory?
Thanks for the advice.

as for the motivational pic, I've been to the dragon many many times. I'm quite anxious to finish my car and be able to drive it there.

 

Lift isn't an issue w/ PTV clearance because the piston is @ the bottom of its' stroke @ max lift. Duration is the main factor in PTV collisions. I personally, don't get concerned over what's old or new technology as much as the performance we're looking for. Sometimes cams are changed simply to lower emissions. If the HP/TQ curves look good through the intended RPM range, we'll use it.

 

Well, my cam being for a few more cubes doesn't make it relevant, but I know I'm at .650 lift, and 114 degree LSA, I forget the rest of the specs... The springs will have to be upgraded as you know, its basically mandatory on most LS motors w/a decent cam. With my lift, my PAC springs have a 2-3 year life expentancy, so realize you'll have to add that to the list of maintenance items if you go over the .600 lift area with the 5.3. My engine builder claims sub .600 you don't require as aggressive a spring and will get more life out of the springs. Just sitting not moving they are under enormous tension, so will wear out if the car drives or not. The second thing is he helped me focus on a relatively light valvetrain. We ended up adding weight over stock, due to the solid exhaust valves and YT rockers, however, anywhere you can keep it light I recommend. Stock rockers should be fine in your case, if you keep the lift reasonable.

Incase you don't know, at a minimum, replace your rocker bearings with the comp-cams trunion kit as a precaution. At least, I would, based on failures people have had with them across the LS line. A comp cams cam bolt retainer kit is another cheap insurance option I added to the list, because its so cheap, and saves me from worrying about cam bolts backing off.

As far as your head goes, have you considered aftermarket castings over ported 799/243s? Some of the aftermarket heads are pretty good out of the box. You mention Texas speed, that's one place I'd go to. I almost went with one of their setups, however I opted for CNC+hand porting by a pro. We shall see what the dyno says.

An ls6 intake or fast 92 would be on the list for me, as well. But the cubes you are running limit the power you will get from things like this. I'd be looking at a 6.0/6.2 block if you are hell-bent on going much past 400rwhp. I'd say diminishing returns happens after the cam/head work from what I've read, the fast intake may be worth 15-20 hp with a throttle body, but you are looking at $1,000 or more if you need a new fuel rail, or go cheap and buy used, nothing wrong with that. Tons of dyno data on LS1tech for you to browse.

Here's an example of where I'd aim for.
http://ls1tech.com/forums/generation...102-worth.html

 

I can't tell you how many hours of study I put into the cam decision. Probably the only real valuable thing I learned is that there is no perfect cam for everything you want out of your car and odds of getting it right the first time are slim.

I got a lot out of this article GM Performance Parts LS1 Engine - V8 Camshaft Install - Car Craft Magazine and the how to pick a cam section in this article. LS1Howto.com

For a first pass at it I would stay on the safe side and not try to squeeze every last hp out of the thing you can. The old saying you can have tons of HP, reliability or cheap pick any 2 still applies. To that I would say +1 to the ASA cam Gator mentioned but I would suggest the Howards cam version of it. That GM puts a warranty on their crate motors with that cam is a plus for me. Yes it leaves a some lift on the table but you will never need to change valve springs or be concerned about them on the way to Atlanta.

If you want a bump bigger you might check out the GM performance parts stage 2 cam. Again it is very easy on the valve train but still packs quite a punch. Specs are I227 E239, .551 lift and 108 LSA. Again that same folks that build the engine came up with this cam and that is a plus for me.

For what it's worth I'll give you my saga. I'm on my 3rd cam and it's the Howards ASA at 226i/236e .525" 110 LSA. I chose it primarily for the very flat power band it has which is much improved over the cam before that was very spikey at mid RPM range. (220i/224e .575" 112 LSA) And of course the whole easy on the valve train thing for road trips because Alaska is on my bucket list! How long that stays in the motor I can't say but with 6000 miles on it so far I have been very happy with it. If nothing else I really like the exhaust note of the thing!

 

The best way to get the perfect cam is to 1) define the purpose and rpm range you desire from your engine, 2) choose heads, intake, throttle body, headers, exhaust, etc. that are just large enough to not restrict flow near the rpm peak, and 3) choose the cam LAST by conferring with a custom cam expert that specializes in your engine family. The additional cost is small and the results improvement will range from worthwhile to remarkable, depending on how close you otherwise "guess" at the ideal timing specs.

There is really only one set of cam timing specs that provides the highest torque curve across the rpm range with any given combination of components. So once you have defined the engine's purpose, rpm range and vehicle weight, you should be choosing the right cam for that particular combo. That done, the cam itself is neither aggressive or mild, it is just matched to your components and chosen rpm range. If your components are intelligently matched and your vehicle subsequently displays "nasty" street manners, it is because you ill-defined the vehicle's purpose and chose an inappropriate rpm range.

A cam is simply the mechanical brain that manages the unique airflow characteristics created by the induction and exhaust components you have chosen.

Choosing a "milder" cam to "fix" a combo where the cam was actually calculated for it will result in significant loss of performance simply because it no longer optimizes the interaction of those components. Choosing a "more aggressive" cam may give you more HP at the very top of your defined rpm range, but both acceleration and daily manners will be compromised, again, because those timing specs are not optimum for the specific components and rpm range you chose.

One caveat to "only one set of best timing specs" is when working with EFI. Sometimes the optimum cam timing may have a tight lobe separation angle that results in low vacuum and "confuses" the EFI. The best course of action, if you want maximum performance, is to stay with the optimum cam timing and modify or replace the EFI control system to work properly with it. In many cases that may be too involved/expensive for practicality, which might make choosing a wider LSA a better practical choice, although it will result in some loss of ultimate power production under the rpm curve.

The best cam timing specs depend not only on displacement, but also bore, stroke, compression ratio, head flow at all lift heights, induction components upstream of the heads, header diameter/length, etc. A custom cam specialist will use something like Cam Master software that receives data input for all actual engine parameters and then calculates the cam timing based on the dynamic interaction of all mechanical parameters and flow factors. He will then, based on his personal experience with the engine family, decide if any mitigation of optimum timing is advisable in order to play nice with the EFI, etc.

Some might deem the extra $100 or so to hire the custom cam guy unacceptable (sounds like a dumb decision I've made a couple of times, including lately). In that case, assuming you know the actual, true parameters of head flow at various lifts, static compression, and all other engine parameters, you can make a good choice among off-the-shelf grinds by plugging their published timing specs along with all your other engine specs into something like Desktop Dyno or equivalent software. Speaking for my experience with Desktop Dyno, the actual torque and HP numbers you will get are typically a bit optimistic, but the comparative differences in power curves between various cams should be very accurate.

Bottom line: Only one set of cam timing specs is "best" for any given combo and a custom cam specialist is the best way to get that. However, using a simple dyno simulation program may get you close enough that you won't feel the difference in the seat of your pants.

It's not necessarily old technology/theory; it depends on what heads and other components you pair it with.

I have a custom cam in a Ford 347 with AFR heads. The exhaust ports are particularly efficient in these heads. The cam actually has slightly shorter timing on the exhaust as well as a slightly slower ramp rate due to the high flow at low lifts. This is a good example of "one size does not fit all," i.e., the best cam timing depends on all the other components in the overall system.

"Dual pattern" cams (longer exhaust than intake timing) have become popular for engines where the factory heads typically have relatively poor exhaust flow compared to the intakes. (Windsor Fords are a good example). However, in some good factory heads and many aftermarket heads where average exhaust flow across the lift range may approach or exceed 80% of intake flow, more exhaust timing will only hurt performance. Again, there's only one optimum cam timing, depending on all components.

Duration has a high impact (pun?), but ramp rate does as well. Some shorter duration cams with high ramp rates will crate PTV interference where a longer duration, slower ramp cam may not.

One more thought and then I'll get off my silly soap box about optimum cam timing. It is common to assume that if you go with a longer duration cam you would automatically go with higher lift.

That harks back to the "more aggressive" versus "only one right answer" argument. You need to look at the flow figures for your heads. Many heads show a sharp leveling off of flow increase somewhere north of .500 lift. (A current set of heads I have, prior to porting, were completely done on the exhaust at .400 lift)! If your heads stop increasing in flow rate at, say, .550 lift, there is no reason to select a cam with more lift, and several reliability, maintenance, and performance reasons not to.

Similarly, if you have a primarily street machine that racks up some miles and you'd like both performance and a decent time spread between hard parts valvetrain maintenance, consider this. Say your heads only flow 8 cfm more at .600 lift than at .550, and only 12 cfm more at .650 and above. You might want to choose a cam with around .550 lift and a suitably fast ramp rate, rather than a .650 lift monster. You'll never feel the difference in the seat of your pants, but the cost, reliability, and maintenance requirements will all be greatly improved.

So, to give the dead horse one final whack, cam timing specs are only relevant in the context of the combo they serve.

When TBone says "taller" I'm sure he means "higher numerically," which sometimes we refer to as "shorter" gearing. That can be confusing...a state with which I am intimately familiar.

Bottom line, as he suggests, look at road speed with the gearing and tires combo you choose; don't think about ring and pinion ratio in a vacuum...'cause that would suck.

 

Yes, ramp rate can be an issue. The point was related to lift. Another reminder as to why I usually stay clear of cam threads.

 

only if there was a surrounding atmosphere.

 

Great posts everyone. You've all got valid points of consideration. I emailed Lunati a couple weeks ago and spent a good amount of time filling out their info sheet and he recommended this cam... I personally thought that the lift was a bit high for my setup.
RPM Range - 2200-6800
Advertised Duration - 278/282
Duration at .050 - 227/231
Lift -.651/.651
LSA/ICL - 112/108

 

Do you have port flow figures for the heads you are using? If you could see your flow numbers at say, .500, .550, .600, and .650, you'd have a pretty good idea what you would be gaining with the higher lift, compared to a grind that ramped the valves open quickly but flattened out at a lower lift figure and allowed a less stressed valve train.

The 227/231 duration figures "seem" a little mild for a 6800 rpm engine, but of course it depends on how well the heads flow, displacement, and lots of other stuff. Besides, I am the last person I would ask for a cam recommendation, LOL. That's why I either pay someone who knows what they're doing, or at least use dyno software to predict the outcome of my shade tree mechanic guesstimations.

 

Sunshine guy is right, I would be asking the pros. Katech and Tony mamo are top names, as is WCCH... those are vette names, though I think Tony would be a good consult.

The one caveat, I don't think .651 lift w/1.7 ratio rockers is a good idea. JMHO, I wouldn't do it.

 

+1 way too much lift. Tons of stress on the VT and I bet there would be almost no difference in performance if it was only .625. My hunch (and that's all it is) is that cam would be dead as a dog under 3 and spike like hell at 4500.

+1 to what Sunshine says on the pro but full disclosure for myself I would never pay anyone to do something I can guess at like this.

 

here's what I've found from research for Stock heads. Still undecided if I'm going to port or not.
Stock Head Flow Numbers
Chamber 64.45 cc-------0.100---0.200--0.300--0.400---0.500---0.550---0.600
Intake 210 cc------------62------126----184----224-----251----256----257
Exhaust 75 cc------------57------108----143----163-----176----180----183

 

799/243s are a good factory head out of the box. Nothing wrong with 799s, ls6 intake, ls6 cam combo, Many do that for a good factory like power setup.

Again, if budget is a concern, check out aftermarket head castings, such as texas speed. Good mix between budget/performance.

 

These heads are a classic example of this principle:
Looking at the port flow of your heads at .500, .550. and .600, you should be able to squeeze about 97% of the maximum power potential with a .500 lift cam, regardless of cam duration. Moving up to .550 lift gets you so close to 100% it makes no sense, IMO, to go any higher on anything less than a full-on, never-street-driven race car.

The key is to employ a custom cam specialist who will look at the maximum design RPM and determine the appropriate ramp rate that gets you up to, and down from, that .500 or .550 lift ASAP without creating an unacceptable level of valve train wear, flex, spring harmonics, seat bounce, etc. That's where these guys earn their keep.

 

I had a cam specd for me by Martin @ tick performance
here's what he recommended
227/231 .630/.600 111+2
I told him that I was going to be using ported 799 heads, a Fast 92mm Intake, and 1 3/4" long tubes on a rebuilt L33. (along with all the other things that you guys already know, miata, t56, small diameter tires, etc)

 

Well, I ended up going with a comp cam. XR281HR
.571/.573 228/230

54-428-11 - XFI? RPM High Lift
Worst comes to worst I'll change it out down the road. I'll have lifters and all the expensive parts taken already so it will be as cheap as a cam and a timing cover gasket.

 

An off the shelf middle of the road cam like that is always a safe choice and a great place to start. Odds of hitting what you want the first time out of the gate are slim anyway and better to be too tame and live with that than so much cam you hate to drive it. It is funny how tastes change though. Every new cam I have tried I liked at first and after a year or 2 wanted more...

 

I mentioned earlier in this thread using dyno simulation software to predict the characteristics of a motor with a particular cam and combo. For grins and giggles I've attached the Dyno2000 simulation for your engine with this cam.

My experience with dyno sim software is it will be somewhere around 10% optimistic across the board. I suspect that missing 10% is partially due to theoretical mechanical perfection versus real-world realities, and partially due to the software developers wanting to produce numbers that make the average car buff (their main target market) happy (a dumb idea, but putting two sizes smaller than reality on the tags of designer fashions has sold a lot of ladies clothing).

Results assume there are no significant mechanical issues like valve train problems, ignition problems, poor fuel tuning, etc. limiting output. In other words, it's built right and tuned right.

When doing dyno simulation, the more specific parameters you provide, the more accurate the outcome. Translation: Garbage in, garbage out. Here are the parameters I used.

1. GM 5.3LS engine, standard 3.78" bore, 3.622" stroke
2. Used the flow figures for L99 heads provided in this thread
3. Used Comp's published cam timing figures @ .006" (See below)
4. Selected "sequential fire injection, 850 cfm flow" as intake system
5. Selected "small tube headers with mufflers" as exhaust choice
6. Selected 10 to 1 as static compression ratio (see below)

The two choices in the software for cam timing are "seat to seat" or "timing at .050". Comp gives timing at .006". This should be close to SAE seat to seat depending on rocker ratio, ramp rate, and a bunch of other variables. .050" timing produces more reliable results; I emailed Comp and asked if they could provide those figures.

I looked online to fine stock compression ratio of the 5.3L is 9.49; I used 10 to 1 because I figured you probably would mill the heads with this much cam timing. Subtract 1.5% from the results at 9.5 to 1; add 1.5% at 10.5 to 1, and you'll be close.

I know the cam description says "up to 7200 rpm," but it would probably take more head flow to get there. However, I find that RPM unrealistic from a practical standpoint for a street motor, anyway. First, with the long, 3.622" stroke on the 5.3L motor that puts mean piston speed around 4300 feet per minute. IMO, that is really pushing your luck with real-world (especially stock) components in a passenger car engine. It would be about the same mechanically as revving a 1960's era 327 Chevy to 8000 rpm. It can be done, but it takes cubic money to get to reliability.

Sport motorcycles and F1 cars these days are up around 4900 FPM mean piston speed, and they are employing ultra lightweight, ultra strong, exotic materials in the reciprocating assemblies to get them to hang together. I personally think about 4000 is a more realistic ceiling for a street driven V8. And my opinion plus $3.00 will get you a cup of coffee at Starbucks...

Second issue is using hydraulic roller lifters at this rpm. Without going into my usual, too long thoughts of dubious value, hydraulic rollers are too heavy for those speeds. You can use valve springs strong enough to control them, but then at 6000+ rpm the g forces begin to build to where they partially collapse the plunger in the lifter, effectively shortening valve timing. Shortening valve timing defeats the whole purpose of revving that high. I'm leaving out about 10 paragraphs of supporting argument on this, but my (again dubious) opinion is you are best advised to limit engine speed to not much over 6000 rpm with hydraulic roller lifters, and at over 6500 rpm you should really be looking at solid rollers.

According to the Dyno sim predictions, this cam puts you right on that bleeding edge of pushing the envelope, which I think is where you wanted to be. Overall, this cam looks to me to be well-matched to your combo. It has a nice torque spread between 3500 and 5700 rpm. It hits its HP peak at 6000 rpm and holds it until 6500 rpm. Looks good to me!

 

That graph would make for a fun motor/car!

 

Man you guys make my brain hurt! Funny thing about the hours I spent researching cams. After weighing all the specs, mapping the torque curves and charting the endless array of choices, I picked a cam in 10 seconds after hearing a Camaro idle on youtube!