wide lobe center vs narrow

"the camshaft is the right camshaft for that engine,"


Assumed to be the right camshaft would be a better statement.

It gets a little over simplified I guess when cam companies list two of the same grinds on different LSA's, like the Isky 280's. I always assumed they where the same lobes just spaced (ground) at a different angle. I can follow how all the valve events will be changed, and the cams will perform slightly different, but I also think LSA has it's place when choosing a grind for a build, along with many other factors. When you get into the custom cams, then you can really play with the events and have the LSA come out like you want, but for shelf grinds it's a little harder.

supervel45 wrote:It gets a little over simplified I guess when cam companies list two of the same grinds on different LSA's, like the Isky 280's. I always assumed they where the same lobes just spaced (ground) at a different angle. I can follow how all the valve events will be changed, and the cams will perform slightly different, but I also think LSA has it's place when choosing a grind for a build, along with many other factors. When you get into the custom cams, then you can really play with the events and have the LSA come out like you want, but for shelf grinds it's a little harder.

"LSA cpome out the way you want" . The total cam events set the LSA. You missing the point others have said? you are on track the LSA gives an idea of what the cam is used for. Thats all it is general info
the right intake and exhaust lobe installed at the correct center line sets the LSA.

then there is the ramp lift per degree, but that another story

rmcomprandy wrote:

supervel45 wrote:So a cam with a 106LSA will run as good with a SuperCharger or Nitrous as one with a 114LSA with the same static compression ratio?

What Chris is correctly saying is that having the valve EVENTS so, the camshaft is the right camshaft for that engine,
Intake valve OPENING
Intake valve CLOSING
Exhaust valve CLOSING
Exhaust valve OPENING


WILL yield a particular, certain LSA.
SO ... alone, the LSA is actually a meaningless term, except to know what it is.

Changing JUST the LSA, and at least 2 of those events will be wrong for that engine in that situation so, they need to be changed as a combination and changing the one or all of those degrees WILL automatically change the LSA.

Well put. Thank you sir.

supervel45 wrote:It gets a little over simplified I guess when cam companies list two of the same grinds on different LSA's, like the Isky 280's. I always assumed they where the same lobes just spaced (ground) at a different angle. I can follow how all the valve events will be changed, and the cams will perform slightly different, but I also think LSA has it's place when choosing a grind for a build, along with many other factors. When you get into the custom cams, then you can really play with the events and have the LSA come out like you want, but for shelf grinds it's a little harder.

LSA is the result. 2 cars lined up at the Tree. The cars are the EVENTS the win light is the LSA. They have to have the race before you have the RESULT.

Lem Evans wrote: "the camshaft is the right camshaft for that engine,"


Assumed to be the right camshaft would be a better statement.

I am only as good as the info I get from the customer. If the info is good then the camshaft will be right and will make max power in a given rpm range. It is then up to the customer to gear the car to operate in the rpm range.

Straubtech wrote:

supervel45 wrote:It gets a little over simplified I guess when cam companies list two of the same grinds on different LSA's, like the Isky 280's. I always assumed they where the same lobes just spaced (ground) at a different angle. I can follow how all the valve events will be changed, and the cams will perform slightly different, but I also think LSA has it's place when choosing a grind for a build, along with many other factors. When you get into the custom cams, then you can really play with the events and have the LSA come out like you want, but for shelf grinds it's a little harder.

LSA is the result.  2 cars lined up at the Tree.   The cars are the EVENTS the win light is the LSA.  They have to have the race before you have the RESULT.

When the masters are placed onto the grinder to grind the cam are they placed by the events or by their centerlines?

rmcomprandy wrote:

DaveMcLain wrote:

When the masters are placed onto the grinder to grind the cam are they placed by the events or by their centerlines?  

When the masters are installed on a Van Norman or Peterson Berco grinder they are "keyed" so they can only go on two ways; forward or reversed.
The lobe CENTERLINE is manually controlled by the vernier on the grinder head.
SEPARATION is the difference between the intake and exhaust lobe CENTERLINES on that camshaft NOT the masters centerline on the grinder.

Now, with automatic grinders like the Norton that will be different as there is a separate master lobe for every lobe on that camshaft ... CNC grinders like the Landis don't use any physical masters at all.

I see. When I had masters made recently I had the keyway placed on their centerline but I guess it could actually be placed arbitrarily.

Few of us here ( myself included) are good enough to pick a cam based PURELY on opening and closing events. As Chris mentioned camshaft numbers are all simple math. Let's say you want an intake opening of 30 btdc @.050 and a closing of 70 abdc.  30+180+70= 280 total duration. To find the Intake centerline or ICL you take 1/2 of the 280 duration minus the intake opening and find a 110 ICL The same can be done for the exhaust using the exhaust closing number. If the ICL and ECL are not the same , the cam is advanced or retarded basd on which one is smaller.
     The rest of the guys "wing it", go by past experience, or ask for help from those with more experience.

I got this email today:

Sent: Wednesday, September 02, 2015 10:56 AM
To: Chris Straub
Subject: RE: FW: XXXXXXXX Cam Shipping

I'm not sure how often you hear this, but I'm very suprised of the idle quality of a 107 lobe seperation! I had this thing idling at like 600 rpms. My old cam on a 110 lobe seperation idle worse then this one.

The ASSUMPTION is that with cam LSA you can tell how something is going to idle.

gt350hr wrote:Few of us here ( myself included) are good enough to pick a cam based PURELY on opening and closing events. As Chris mentioned camshaft numbers are all simple math. Let's say you want an intake opening of 30 btdc @.050 and a closing of 70 abdc.  30+180+70= 280 total duration. To find the Intake centerline or ICL you take 1/2 of the 280 duration minus the intake opening and find a 110 ICL The same can be done for the exhaust using the exhaust closing number. If the ICL and ECL are not the same , the cam is advanced or retarded basd on which one is smaller.
     The rest of the guys "wing it", go by past experience, or ask for help from those with more experience.

This works if the cam profile is symmetrical, many lobe profiles are not symmetrical these days.

LoL You forgot to read the first and last sentence of his post.

supervel45 wrote:LoL You forgot to read the first and last sentence of his post.

That doesn't mean I'm a novice when it comes to camshafts. I just don't pick them the same way as Chris does. My day job has me working with camshaft numbers all the time. I see what people run in all kinds of engine combinations.

The sim programs like those numbers, and it does sound like you go from experience, is what I was getting at. We all to that I believe, and try to pickup what we can. Yes I give the guys with dyno time and years of experience more creed and Comp Cams has some good info out there too. I stick by my statement, if you are buying a shelf Hyd. cam, LSA needs to be considered, and cannot be changed by lash adjustments much, if at all. With the mechanical cams you have some leeway with the lash adjustments and can move the LSA around at the expense of lift and duration depending which way you are going with it. I doubt anyone will ever agree on camshaft selection either.

I'll just say this. I would say 90% of the cams I supply are 2nd and 3rd shafts for the same engine. Some of the stuff I see is so far off I have to wonder if the cam company had a bunch on the shelf and it was selected as the "cam of the day".

To many spend a ton of money on "engine assemblies". Good parts but they are just assemblies. An "Engine Combination" is what one needs to build and the camshaft is the Brain of the that combination. I have a good customer with a C Headed 532CID up north that is a puller. This C headed engine makes 1200HP. The cam I put in the combination is sub .800" lift and it makes peak around 8400 rpm. The truck pumps 532CID but has to pull in the Outlaw class because of its reputation. This weekend out of 30 truck at an Outlaw pull this "combination" had 25 trucks behind him including 6 Hemi Headed 650CID engines. So even 12/14 year old technology can compete if the engine is a "Combination".

supervel45 wrote:The sim programs like those numbers, and it does sound like you go from experience, is what I was getting at. We all to that I believe, and try to pickup what we can. Yes I give the guys with dyno time and years of experience more creed and Comp Cams has some good info out there too. I stick by my statement, if you are buying a shelf Hyd. cam, LSA needs to be considered, and cannot be changed by lash adjustments much, if at all. With the mechanical cams you have some leeway with the lash adjustments and can move the LSA around at the expense of lift and duration depending which way you are going with it. I doubt anyone will ever agree on camshaft selection either.

Im with Chris on this one. Lobe separation is a measurement available after a cam is selected. The selection properties should be solely based on when do you need the intake valve open, and when should it close? Same on the exhaust side.... Then there are the sacrafices to an optimal cam made to help control the valves......

Straubtech wrote:I'll just say this.  I would say 90% of the cams I supply are 2nd and 3rd shafts for the same engine.   Some of the stuff I see is so far off I have to wonder if the cam company had a bunch on the shelf and it was selected as the "cam of the day".  

To many spend a ton of money on "engine assemblies".  Good parts but they are just assemblies.   An "Engine Combination" is what one needs to build and the camshaft is the Brain of the that combination.   I have a good customer with a C Headed 532CID up north that is a puller.   This C headed engine makes 1200HP.  The cam I put in the combination is sub .800" lift and it makes peak around 8400 rpm.   The truck pumps 532CID but has to pull in the Outlaw class because of its reputation.   This weekend out of 30 truck at an Outlaw pull this "combination" had 25 trucks behind him including 6 Hemi Headed 650CID engines.  So even 12/14 year old technology can compete if the engine is a "Combination".

So what you're saying here is that this 532 has more power than all of the competition including all of the 650" hemis. Or is it the "combination" of the pulling truck at hand?

I was thinking about this thread a bit this morning and I believe that ALL modern engines have cams that have a "wide" LSA. If you consider an engine with an Otto cycle cam, 180 degrees seat to seat timing giving events for the exhaust of 0 BBDC, 0 ATDC, intake of 0 BTDC, and 0 ABDC tiiming the LSA ends up being only 90! with the cam in on a 90 degree centerline intake and exhaust!

It seems like these characteristics would only work in a very very low compression, very very low speed engine. When thinking about what events are needed to produce reasonably good results even in an engine that's considered to be low speed by modern standards the differences are great. The duration is greatly extended and the lobe separation is also greatly widened to produce optimum results.

Bret Powell wrote:

Straubtech wrote:I'll just say this.  I would say 90% of the cams I supply are 2nd and 3rd shafts for the same engine.   Some of the stuff I see is so far off I have to wonder if the cam company had a bunch on the shelf and it was selected as the "cam of the day".  

To many spend a ton of money on "engine assemblies".  Good parts but they are just assemblies.   An "Engine Combination" is what one needs to build and the camshaft is the Brain of the that combination.   I have a good customer with a C Headed 532CID up north that is a puller.   This C headed engine makes 1200HP.  The cam I put in the combination is sub .800" lift and it makes peak around 8400 rpm.   The truck pumps 532CID but has to pull in the Outlaw class because of its reputation.   This weekend out of 30 truck at an Outlaw pull this "combination" had 25 trucks behind him including 6 Hemi Headed 650CID engines.  So even 12/14 year old technology can compete if the engine is a "Combination".

So what you're saying here is that this 532 has more power than all of the competition including all of the 650" hemis. Or is it the "combination" of the pulling truck at hand?

Bret,
I am saying the combination is using what is has. The powerband the engine produces is very flat in the intended rpm range and it does not choke...tight or loose.