Wow! I'm not used to not seeing a ton of cam related questions. I'll start this thread to gather them into a nice resourceful thread that we can search for in the future.

Any questions about how camshaft specs relate to engine dynamics? Ask away, we have a ton of cam experts here to help.

I'd rather not see a cam comparison type thread (is cam Z better than cam X?), lets use this thread to educate people well enough to make their own decisions on a cam that suits their requirements. That is the goal here - to learn!

Tony

 

Since you brought it up. I have noticed cams with a higher intake and a lower lift produce some awesome #'s., i.e., Chris Johnson's setup. I have the Lunati cam 221 221 558 558 lsa 112. I was looking at a dyno graph of Justins(Jsears) and my dyno graph and at points he is 10 to 15rwhp higher than my cam. According to an old post by him he used the short belt mod and he has a lighter flywheel, carbon fiber driveshaft, and I think that is about the difference between our cars.. Does those other factors play that much of a role in reading the dyno? He only dyno'd 8 rwhp more than I. Another thing, JMX mentioned that he has tried several cams and did not receive that much of a difference and that the cam I have is the one to stick with. Also, that big cam 234 234 595 595 lsa 114 that some are recommending because he cfm is higher at 600 lift. Why aren't those cars dominating and why those cars are not dyno'ing 450rwhp with 346cu? That will keep you busy for a while.. <img src="images/icons/smile.gif" border="0"> I am going to do some more studying and I'll be back..

 

I think this is a great idea to get thread going about cams and how they effect our LS1's. I have the Hotcam in my car and it is an A4. I do NOT have any PCM tuning and the car runs great. I will get the occasional surging on a cold start up but it doesn't last for long. The Hotcam is a great cam and i felt an enormous seat of the pants difference. With the Yank TT3000 installed also, it makes it that much better <img src="images/icons/grin.gif" border="0">

 

The lift of your camshaft should be closely matched to the flow capabilities of your intake port. Running a high lift cam on an intake port that stalls at around .525" lift will not do you much good. Also remember that high lifts are harder on valve springs and make high rpm valvetrain stability more difficult. Higher lift cams need their valve springs changed out more frequently due to fatigue of the springs. Some of the reasons why high lift cams haven't worked that well in some applications could be:

1) Flow characteristics of intake port are mismatched to lift.
2) Fatigued and weakened valvesprings
3) high rpm valvetrain instability

 

I've noticed that guys with insanely high lift numbers on their cams aren't making the same kinda power that mine is and I'm running a moderate .540/.540 lift, 220/220 duration GTP cam.

If RPM's aren't a matter of consideration, those big cams WILL make more power than mine, but under normal RPM ranges and normal driving needs, I've noticed that cams like the Hotcam and mine with moderate lift seem to be all around stronger performers. They generally seem a better all around cam.

 

[quote]Originally posted by vmoore:
<strong>What about my adjustable valvetrain question?</strong><hr></blockquote>

Factory LS1's do NOT have adjustable valvetrains (adjustable for lifter pre-load) like all other Chevy V8s. However, you can convert over to an adjustable set-up using aftermarket parts if you wish. This is necessary if you go to a solid roller cam.

[ November 13, 2001: Message edited by: 2quick4u ]</p>

 

Yea, LS1's are just torqued to 22lb-ft of torque, set em and forget em style.

As to the lobe seperation, I'm running 116 degree lobe seperation and the thing idles as smoothly as stock and is putting around 400 at the rear wheels.

 

Generally if you keep duration(lobe profile) similar and just increase lift we aren't talking about alot of horsepower here. On cars at the street level maybe 4rwhp - that's max though. There should also be a bit more area under the hp/torque curve also though.

I think quite a few people are expecting miracles from just the right cam combination, but when you get down to it - going from a 221 to a 224, etc. really isn't *that* big of a change. I would be suprised to see more than 5-6rwhp, if that even. And of course that depends on the rest of your setup.

When you change your camming to try and reach MaxVE you approach it assymptomatically - as you get closer and closer you get less "result" for your change - so if you are far off to begin with (stock cam) then yeah, you can see a large difference - but if we go to a larger cam (say 218/218) observing the same change again is not going to give us the same hp results.

When you already have a decent cam and talk about changing it, just realize that 10rwhp is probably pushing it unless you make a large change - and changes on the order of 5rwhp are more common. Now take your standard deviation on a normal dynojet and figure that it - it becomes something of a crap-shot to quantify this.

Yes there is more peak power to be made, and also more area under the curve (Depending on how the cam is set up) - but in the end they aren't phenomenal differences. That's why your goals are the most important thing when specing out a cam. If you want max effort no holds barred then that's fine - but if not, consider things like spring wear, valveseat wear, streetability, emissions, rpm band, etc. is 2-3hp here worth xxx rpm, etc. In the end it really depends on what you want out of the car - sometimes that's harder to figure out than the proper cam specs themselves.


Chris

 

That is true Chris. I am going to stay with my cam. I do not want to keep spending the extra dollars on cam swaps.. My car already kicks butt. With the minimal mods I have now this cam rocks.. Just last weekend a 396 LT4 had to spray me to beat me.. His car is setup for nitrous, but on motor he had nothing on me. He even has 3.73 gears. I have 3.42's. I am more into road racing and that is why I am going with the 3.73's for my setup.. I see 11's in my future on DR's with no problem..

 

Never can get enough camshaft knowledge <img src="images/icons/smile.gif" border="0">


How about Lift vs. duration for a thought??

Chris Johnson's car with a tiny lift cam, but HUGE duration made 441 rwhp on a stock short block, and cruised down the strip to an 11.x at 123 mph <img src="images/icons/shocked.gif" border="0"> . His dyno graph also shows that cam making tq all over the place, much more than almost any other cam I have ever seen.

However, it doesn't seem to be the same the other way around. Cam's with lots of lift but small duration's don't seem to make the desired power, from what I have seen anyway. Correct me if i'm wrong here.


So what's the secret to making the power? Lots of duration? Lots of lift&duration? Or a combo of both. I personally think the 224 cams are just about perfect for a stock short block car.


Cheers <img src="images/icons/grin.gif" border="0">


Josh

 

So you have noticed this too Josh.. I asked that in my first question. Did Chris Johnson get lucky or is there some logic behind his setup..?

 

[quote]Originally posted by vmoore:
<strong>So you have noticed this too Josh.. I asked that in my first question. Did Chris Johnson get lucky or is there some logic behind his setup..?</strong><hr></blockquote>


Vince, I don't really know. Chris's car was built with GTP products, which seem to be making some screamin setups. I guess they know something that other tuners don't. Who else would have though of only using a .515/.515 lift but huge duration(can't remember the exact duration #'s)

Crazy stuff....

Josh

 

[quote]
Who else would have though of only using a .515/.515 lift but huge duration(can't remember the exact duration #'s)
<hr></blockquote>

The stock elimiator guys do that all the time. <img src="images/icons/wink.gif" border="0">

 

Chris's cam is a 226/236 .515 114 I think.


Ryan

 

oh, I guess I'll throw in my opinion. I think anything in the 220-230 duration range works well. LSA is up to your opinion on idle. and lift is dependent on spring preference. I think the power is in the heads, myself, and any well matched, well tuned combo will simply scream. It depends on what you want/what you can live with.

Personally I think the B1/T1, TR 224 and others are matched well with stock heads (and of course will gain with better flowing heads), and other grinds, like Chris's Comp are matched to a set of worked heads and gain more with the combo than alone.


Ryan

 

Question. I'm looking at putting in Long tubes next month and heads/cam early next year. I'm more interested in a nice broad power band than I am in peak power. What kinds of cams should I be looking at?

TIA

 

MTI heads/cams are notorious for lots of area under the curve (broad, flat power). Call MTI. I recommend the Stage 2 heads, C1 (222/566/112) cam and LS6 intake with FLP's and the normal boltons. You should see 400+rwtq and 420 or so rwhp.


Ryan

 

There are so many variables it is hard to figure out which one really works. I wonder if a vendor has used a test mule and installed several cams in and dyno them with their best heads.. That would take a lot of time, but it would benefit them in the long run. I hate to say it. Some are using computer simulations to build the perfect engines. The sims are close, but we all live in different places..

 

Well, I can't get as technical as some of you guys on this subject, but I'm running one those "cams that are too big" with decent results. It's a 226/234 .55x/.57x 112. Cam cards at home; don't remember the lift #'s exactly. This cam has surprisingly good manners for a cam it's size.

 

.554/.575 <img src="images/icons/smile.gif" border="0">

Ryan