[BLKG8]

What is the purpose to go with an LSA of 112 +4 or any other + number?

I've been following a lot of cam builds, reading a lot about cam specs, and most importantly trying to make sense of it all. I have seen several LSA specs with a +1,2,3,and 4 and have read where comments are made about the +4 helps to make more tq down low. But couldn't one achieve the same result of low end tq by changing other specs of the cam and keeping the LSA at + 0 ?

Thanks for any shared knowledge.

 

[mongoose591]

Bump! I've been slowly learning about cam specs but they still make my head spin.

 

[Bo White]

Lsa is the spread between the intake and exhaust lobes which is ground into the cam. Its not adjustable. +4 or what ever amount you buy is the intake center line of the intake lobe degree. If you buy a cam with 112 + 0 then the intake center line is also 112. If you buy a cam with 112 + 4 then the intake center line is 108. Rule of thumb is advancing the cam gives more bottom end and retarding the camgives more top end. The intake center line is ground into the cam but it is adjustable through the timing set.

 

[jgeorger]

The intake center line Bo mentioned is the point in crankshaft degrees after top dead center that the intake valve attains maximum lift. It is through this number that you can translate your camshaft valve events into crankshaft degrees, like when the intake valve closes, the exhaust opens, etc.

To answer the OP question, no, simply changing the ICL cannot be compensated for by other cam variables. A 112 +4 cam has an ICL of 108. If you went with a 108 +0, the intake lobe would be the same, but the exhaust events would be that much earlier....

 

[BLKG8]

Thanks bo and jgeorger. That information definitely helps.

I've been really leaning towards a cam that was speced for stock stall, gears, and designed to make great low end power under the curve. Cam is 219/223 .625/.625 112+0 But then I got to thinking hmmm what would this cam be like if a +4 was added to that 112? would it make even more low end?

 

[Todasi]

Sub'd for the answer

 

[Bo White]

219/235-113+4. That's the smallest shelf grind from comp cams for the rectangle port engines. Use that one.

 

[jgeorger]

Thanks bo and jgeorger. That information definitely helps.

I've been really leaning towards a cam that was speced for stock stall, gears, and designed to make great low end power under the curve. Cam is 219/223 .625/.625 112+0 But then I got to thinking hmmm what would this cam be like if a +4 was added to that 112? would it make even more low end?

In theory advancing the cam moves the powerband down in the rpm range, so you get more low end but lose top end. Where a cam peters out is also a function of the duration, as most know. So perhaps the +0 was specified to give you an acceptable rpm range. Hate to see your power peak at 4500! I see you've given business to Pat and Rick, they are the hands-on experts. Nothing like real world testing. I went very conservative on my cam, but since I am learning how to self-tune, didn't want to bite off more than I could chew. Plus I am still running stock exhaust - cam was selected based on that, will see how it dynos soon. If I go headers a new grind would not be out of the question...

 

[BLKG8]

219/235-113+4. That's the smallest shelf grind from comp cams for the rectangle port engines. Use that one.

I don't want a "shelf grind". The cam I listed above 219/223 .625/.625 112+0 was speced for me by rick and would be a lunati cam.

After learning more about the + option I wonder if adding some + to that would make even more low end...?

 

[BLKG8]

The cam ive mentioned suggested to me by rick, has never been ran on any of our cars so although it specs seem like they would work exactly for what im looking for I also like stuff that's been done before and "proven". Part of me wants to choose a cam that some of the NC guys are running because they are proven BEASTS, but I don't really care about track numbers and want something that is gonna feel best for the street. Therefore why I want low end tq and power under the curve.

Here's a good article testing the cam I'm considering on an LS1 setup. Would do even better on a LS3 setup.
http://www.gmhightechperformance.com...t/viewall.html

 

[Bo White]

Proven cam in a g8 gt is the 223/231. Its been used widely on here and has great results every time.

 

[Troy Trackbeast]

The cam ive mentioned suggested to me by rick, has never been ran on any of our cars so although it specs seem like they would work exactly for what im looking for I also like stuff that's been done before and "proven". Part of me wants to choose a cam that some of the NC guys are running because they are proven BEASTS, but I don't really care about track numbers and want something that is gonna feel best for the street. Therefore why I want low end tq and power under the curve.

Here's a good article testing the cam I'm considering on an LS1 setup. Would do even better on a LS3 setup.
http://www.gmhightechperformance.com...t/viewall.html

go with what Rick has spec'ed and dont think twice! You won't be dissapointed

 

[DavesWhiteHot]

Proven cam in a g8 gt is the 223/231. Its been used widely on here and has great results every time.

As long as it's not cut on a 116 LSA like my VMS 1.5 cam was. It was a very mediocre cam. A 223/231 on a 112 + 0 is apparently quite the winner though. Ask Troy. Mine is a 223/230 on a 112 + 2 and it has good top end but the biggest thing I notice about my cam is awesome light/medium throttle in the low to mid RPM power range just scooting around town. It's extremely responsive and peppy around town which I love.

 

[Ghostnotes]

My cam was ground "straight up" +0. However I can advance or retard my cam +/- 4* with the adjustable timing chain. Takes about 30 minutes to make the change. So if i want some lower end street torque I can advance it, or retard it for track or road courses. Not for everyone obviously but does the trick for me.

 

[BLKG8]

When you make the adjustments on the timing chain do u have to follow that with a new tune? If so I assume you do it yourself with hp tuners?

 

[Ghostnotes]

Yeah tou have to tweak it a little. Injectors and idle but its relitive to how much physical changes you make. So after I have my base tune at +/- 0 its just simple math afterwards then watch for kr and fuel trims. Its extra work and like I said its not for everyone but I like the flexibility.