Cam LSA [Archive] - Team Camaro Tech

: Cam LSA


Ramrodd 69
Jan 13th, 10, 01:42 PM
I am installing a new cam in my 540 Shafiroff Ultra Str. The spec LSA is
112 both ways (not advanced when grinded). If I sound stupid, just trying
to learn engine stuff. I want to advance cam 2 degrees to get more of
the rough idle sounding. Called Comp Cam and he said the 112 will have
that sound already and will not make much difference. Since car is street
driven it will help in lower, mid range hp, tq which would be more useful
str racing. But back to main question, does a 112 LSA have that killer
idle sound I'm looking for. If you need more info on cam: 714/714 lift,
262/270 dur@50 and is a roller. The car is driven weekends only so I am
thinking also the lower LSA should not take its toll on drive train (was
told low LSA is bad for street). Thanks for all replies. Bob

Everett#2390
Jan 13th, 10, 04:32 PM
With the duration listed @0.050", it's going to sound lopey.
You're gonna 'feel' the exhaust in the chest.
I would leave it straight-up. With a 540, you won't have to worry about getting to the next stoplight, unless you're up against a Sonny Leonard 632, 706, or his 800 inch.

Vegas69
Jan 13th, 10, 04:43 PM
The less LSA the lopier it sounds. I wouldn't pick a cam based on idle sound. That's just me...:D I do love a choppy idle I have to admit.

fatblock
Jan 13th, 10, 05:10 PM
I am installing a new cam in my 540 Shafiroff Ultra Str. The spec LSA is
112 both ways (not advanced when grinded). If I sound stupid, just trying
to learn engine stuff. I want to advance cam 2 degrees to get more of
the rough idle sounding. Called Comp Cam and he said the 112 will have
that sound already and will not make much difference. Since car is street
driven it will help in lower, mid range hp, tq which would be more useful
str racing. But back to main question, does a 112 LSA have that killer
idle sound I'm looking for. If you need more info on cam: 714/714 lift,
262/270 dur@50 and is a roller. The car is driven weekends only so I am
thinking also the lower LSA should not take its toll on drive train (was
told low LSA is bad for street). Thanks for all replies. Bob

Lsa is ground into the cam..nothing you will do alters this.Advancing the cam changes the intake center line but does not affect duration and overlap.Advancing the cam will grab more low rpm cyl pressure with an earlier intake valve closing but comes at a cost to high rpm cylinder filling.
I would advance your cam 2* not for sound..simply to take up chain slack in running engine.Typically..the wider the lsa(112-116)=less overlap.The tighter the lsa(110-104)=more overlap.
Wider lsa,s..the broader the torque curve..tighter lsa,s..more torque in a smaller operating window and not so extended.
The rough idle comes from intake dilution and low manifold vacuum typical with tight lsa,s and lotsa overlap.
Imo..112* lsa and up belong in large cube engines and forced induction.
Your 540 is a large cube engine.Advance that cam 2* for chain stretch only and she will be plenty lumpy with your @ .050" numbers.

Ramrodd 69
Jan 13th, 10, 07:02 PM
Would advancing the cam also help it on str running since it would
lower the rpm power band. I know it would effect the higher rpm's
but since car is str driven advancing cam would put hp and tg in
lower rpm power band which would be good for that running(racing).

mtrhead
Jan 13th, 10, 07:29 PM
Do you have the specs on the cam "in the motor" as purchased? we can compare to your new one that you listed.
lift, duration@.050, centers, mech/hyd, roller? (cam grind number? usualy at end of cam etched in)

Ramrodd 69
Jan 13th, 10, 07:45 PM
Do you have the specs on the cam "in the motor" as purchased? we can compare to your new one that you listed.
lift, duration@.050, centers, mech/hyd, roller? (cam grind number? usualy at end of cam etched in)

Cam in Motor
651/651 lift, 255/262 dur@50, roller, Grind# CB-4220B-4221B-R114,
Lobe Lift: intake .3830 exhaust .3830

New Cam
715/715 lift, 262/270 dur@50 (dur@50), roller, Grind# CB-4015B/4018B-R112,
Lobe Lift: intake .4210 exhaust .4210

Everett#2390
Jan 14th, 10, 03:17 AM
Be sure to check piston-to-valve clearance with the new cam advanced 2 with clay to avoid limited space or kissing between the two. I think the standard clearance is 0.080" min between the two.

mtrhead
Jan 14th, 10, 06:22 AM
From my experience running more duration only increases the loopiness of the idle sound quality. I don't have any experience in Shafiroff motors but the cam principles apply to all motors. Compression or cylinder pressure must be factored into the equation. To much duration without enough compression will kill performance down low and make the idle real loopy but not that strong/choppy. Real authoritative exhaust notes have duration and compression. I don't know where you started in compression or cylinder pressure but I would assume Shafiroff optimized this cam for this motor. Moving up 10 degrees will shift the curve upward in the RPM range. Also, yes a 108 or 110 will go in the direction your looking for more than the 112 but the difference in idle sound is very minor compared to the loss of street performance.
I agree with FatBlock's response

Greg O
Jan 14th, 10, 06:24 AM
What are your goals for the car? What is it about the current cam that makes you want to change it? i.e. sound, won't RPM, not enough power, etc.

What is str? Do you mean street racing?

It sure seems the cam in it is a good one. Think about it...you are talking about going to a bigger cam, which hurts low end torque, then advancing it to make more low end torque. Kind of a circle there. A 540 is going to have more torque than the tires can handle on the street anyway.

As close as the 2 cams are, you could probably add higher ratio rockers and get the same result.

zdld17
Jan 14th, 10, 08:05 AM
With the duration listed @0.050", it's going to sound lopey.
You're gonna 'feel' the exhaust in the chest.
I would leave it straight-up. With a 540, you won't have to worry about getting to the next stoplight, unless you're up against a Sonny Leonard 632, 706, or his 800 inch.

X2 , On a Shaffiroff 540, sound will be decieving. Guys won't be looking for you.

Not sure which 540 you got but the last one I witnessed , had BB3 heads on it and dynoed over 1000 hp.

Ramrodd 69
Jan 14th, 10, 09:09 AM
Thanks for all the replies. what I was doing was trying to squeeze out
a little more hp, tq for the compression I have (10.5). Had Mike at
Shafiroff make the cam since they built the motor and he would know
exactly how far to go (so to speak). So I'll just leave it alone and go
with what cam he had made. As I said, just learning this stuff. I am
gaining knowledge on this site so once again, thanks for the help.

zdld17
Jan 14th, 10, 10:18 AM
Thanks for all the replies. what I was doing was trying to squeeze out
a little more hp, tq for the compression I have (10.5). Had Mike at
Shafiroff make the cam since they built the motor and he would know
exactly how far to go (so to speak). So I'll just leave it alone and go
with what cam he had made. As I said, just learning this stuff. I am
gaining knowledge on this site so once again, thanks for the help.

Mike, thats the guy we dealt with, Trust him.

ace's68
Jan 15th, 10, 05:47 PM
If those numbers listed @.050 are correct, it's gonna sound GOOD.
I saw the specs on a friends 565" shafiroff, the cam was something like 360* ADVERTISED on a 113 lsa and almost a full inch of lift, sounded sick.
Even a motor (maybe not a huge ci) with a cam that has 230* @.050, it will have a lopey idle. 230* seems to me as if it's the magic number, and you are way above that.

Ramrodd 69
Jan 16th, 10, 07:38 AM
I hope it sounds better. That's one of the reasons cam was changed
along with performance. Not sure though if this change will give me
some of the "sick" sound I want but what and see. From other replies
I had from previous posting awhile back, most thought even the cam
change was not doing much better performance anyway. From what
I have learned on this site, dur@50 is the main thing for the "sick"
sounding cam and I went from a 254/262 to a 262/270 and the replies
to this were "its not much of a change" and may not see much of a
"sick" sound difference. The lift did change though from a 651/651 to
714/714. Now mind you, I'm talking the idle "sick" sound here. Yes, the
performance will increase a little but also wanted "the sound". Mine
now, to me, and as others have said with similar cams that is in it now,
sounds wussy but does run very well. Just like to have the killer sound
when sitting their idling. Since cam cannot be returned, have to wait
and see what idling sound I get. As always, thanks to all for your
replies, learned alot on this site. Bob

PS - incase someone may ask why then did you get this particular
cam, I talked to Mike at Shafiroff and he had the cam made saying
it would be one to use since comp is 10.5 and weekend street driver.
He probably kept streetability in mind. Hey, who knows. maybe I will
get some "sick" idle sound. Time will tell soon, cam going in next week