Lobe separation angle 110 vs 114

The specs on those cams are: 270/276, 218/224, .512"/.512".As small as those specs are, do you think the 112 version would have drivability issues or cuase problems with a A9L computer or is the 114 a safer choice? Overlap on the 112 is -3 degrees and the 114 version is -7 degrees. Both seem pretty mild! I'm sure the 112 sounds meaner.

Table of Contents Show

What is a good lobe separation angle?
What does a higher LSA do?
Is more lobe separation better?
What does 112 LSA mean?

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Be honest with you neither are gonna sound too "mean" they both have a negative overlap & will be plenty fine on vacuum a9l computer, heck that 114 cam has almost the same specs as stock, actually it has less duration on the intake side so if you looking for stock go 114 but to be honest with you I would look for something else as that cam is going to be a waste of work unless your really only looking for that small of a difference. we can spec ya just let us know if you want good mileage/street car or mega lumpy, drag, etc, etc, sounds like you need alittle more duration & less lobe seperation, I'd say 278/282 512/540 on a 112 by the sounds of it. (Trickflow stg2) ??/

I though LSA was built into the blank, ie you can't regrind to a new LSA? Or am I thinking cam centerline?

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A good grinder like Oregon cam can put that lobe anywhere on the core they want. I sent them my slant cam that was on a 111 LSA from the factory. Now it's on a 105. I sent them my 331 Hemi cam that was 112 LSA, now it's a 106. It all demends on where the lobes are now and how much meat there is on the base circle. My Hemi cam after grinding has the base circle even with the cam core. It looks funny like some of them early cheater cams, but it's gonna work good. Course I will need different pushrods....and I am gonna run adjustable pushrods anyway so it's no big deal. They told me both my cases were not the norm though. They said that usually the LSA cannot be moved much. Both of my regrinds were exceptions. They are very good at what they do though and I think they were a little modest.

StrokerScamp said:
I assure you, that is not correct. By both experience as well as computer simulation, I have seen otherwise. A 114 LSA compared to a 108 LSA all things equal makes more torque down low on the desktop dyno every single time....without fail. In fact, it's usually a huge difference. The reason for that is because cylinder pressure bleed off is also RPM dependant. The more RPM, the more cylinder bleed off. A wide LAS will build more cylinder pressure down low in the RPM range. They also generally build more pressure in lower compression (under 9:1) engines. I don't know the whys and wherefores, but that much is true. I have verified it in person with a compression gauge many times. The narrow LSA does indeed take away from bottom end torque.

I’ve been looking at cam specs for the Summit Racing Pro LS Truck camshafts and I have a question. I’ve noticed that many of the specs now list the lobe separation angle (LSA) spec with a plus number added. The cam I’m looking at is the Pro LS Truck 8718R1 cam. The LSA specs are listed as 112+2. But the actual specs say the LSA is 112 degrees. So what does the +2 refer to? It’s something new that I’ve never seen before and I’m not sure what it means.

J.L.

This is a great question with, for once, a simple answer.

But don’t worry, we’ll expand our answer just so everyone understands what we’re talking about. The short answer is that the +2 refers to how the cam is ground relative to the LSA and the cam’s intake centerline. The +2 in this instance means it has been machined with two degrees of advance built into the cam, placing the intake centerline at 110 degrees BTDC.

But let’s take a closer look to make sure everyone understands this explanation. Lobe separation angle is the angle between the intake and exhaust lobes for a given cylinder and is expressed in camshaft degrees. Using the COMP Cams illustration at the bottom of this article, you can see that the intake lobe centerline (the left lobe) and the exhaust lobe centerline (on the right) are both displaced 116 degrees away from the TDC centerline.

The lobe separation angle is the sum of the two angles divided by two or 116 + 116 = 232 / 2 = 116 degrees. If we advance the intake lobe two degrees to 114 degrees BTDC, then the LSA would be 114 + 116 = 230 / 2 = 115 degrees. This is accomplished during the actual grinding of the camshaft and cannot be altered. Cam companies often add this advance because this improves low-speed torque. Not all cams are ground with advance built in, but it is very common.

Before this shortcut description, the best way to figure out if the cam had been ground advanced was to check the intake centerline figure. If the intake centerline number and the LSA number are both the same, then the cam is not round with advance. But if the intake centerline is 110 degrees and the LSA is 112 degrees, then the cam has been ground with 2 degrees of advance built into it.

In the case of the Summit Racing Pro LS Vortec Truck Swap Camshaft, the LSA is expressed as 112+2. As you suspected, the cam is ground with a 2 degree advance with a LSA of 112 degrees. This means that if you were to degree the cam, you would find the intake centerline would measure 110 degrees BTDC. In this case, there is no reason to further advance the camshaft because the factory has done it for you. The new listing as 112+2 merely points out that the cam has been ground with two degrees advance in the cam. This shorthand description tells you everything you need to know.

What is a good lobe separation angle?

Some engine specialists refer to it as that 106 sound—the NASCAR and short track oval sound where preferred lobe separation is usually specified between 104 and 106 degrees. The primary function of narrow lobe separation is to impel urgent acceleration off the turns when the throttle is opened.

What does a higher LSA do?

A wider LSA moves intake- and exhaust-valve events farther apart and creates less overlap, which hurts intake-wave tuning. "When you've properly tuned a performance motor, you create high- and low-pressure waves in the intake and exhaust that help cylinder filling," said Comp Cams' Billy Godbold.

Is more lobe separation better?

“On a naturally aspirated engine, the lobe separation angle has an effect on whether the engine reaches peak torque a little earlier or later in the rpm range. Typically, narrower lobe separation develops peak torque at lower rpm and widening the separation tends to build peak torque higher in the rpm range.

What does 112 LSA mean?

As you suspected, the cam is ground with a 2 degree advance with a LSA of 112 degrees. This means that if you were to degree the cam, you would find the intake centerline would measure 110 degrees BTDC. In this case, there is no reason to further advance the camshaft because the factory has done it for you.