Interesting test of 3 cams with the same lift and duration. The tested cams all appear to be based upon the Comp 230/236 XFI. Tested variations include 58 degrees of overlap/113 degree LSA, 70 degrees of overlap/107 degree LSA, and 82 degrees of overlap/101 LSA. Which is best?

https://www.motortrend.com/how-to/ca...ted-explained/

Note: The intake valve closing chart does not seem to jive with comps cam specs. Don't know what's up with that, but you can't trust everything that you read. Otherwise pretty good information. Would love to see the sane test with a well-tuned EFI system and appropriate intake.

Worth noting is that these cams are quite a bit more aggressive than those typically discussed on this board, but even L98s can benefit from more overlap but with no need for long duration. Perhaps we've all been leaving something on the table by going too mild from an overlap standpoint. I agree that the 101 LSA cam would be tough to tame and live with, but something in the 106-108 range should be manageable for MAF cars. S/D cars may need to compromise a bit more.

reference material for cam timing and overlap calculation (based upon advertised duration):
https://www.compcams.com/xfi-230-236...oller-sbc.html
https://www.texas-speed.com/t-calc-overlap.aspx

 

Results seem on part with all of my previous testing.

Despite someone's recent claim here that you need a higher LSA to retain low end torque (won't mention his name because he's impossible to deal with), every time we've went with lower LSA cams we've picked up big numbers down low. I was even told by some of the "cam gurus" that going with low LSA in my turbo engines was a bad idea because the characteristics of the camshaft and the characteristics that turbos need in a camshaft were polar opposites. Going from a 115 LSA cam to a 110 and then 108 LSA camshaft with near identical duration, lift, and cam advance netted HUGE numbers with no significant loss in power up top.

Haven't Engine Masters tested something similar with camshafts?

 

To quote a friend "went to a lower LSA to help out power leaving a turn." I'd have no problem running a 108. I just found the 112 easier to tune at the sacrifice of some area under the curve.

Edit for clarification: the 108 should kill the 112 for the otherwise same pattern cam.

 

Too late, I'm here. I don't think I said increasing LSA lowers the torque peak. I was saying that it tends to spread/broaden the torque and power curves, which is what this article also says. I also was talking about how it will provide a better idle and better manners and pull right off idle, whereas a lot of overlap makes idle pretty rough and it takes a few RPM to "clean up" the running so it can start pulling cleanly. In the case you refer to, when someone is worried about how an engine will pull from 1500rpm, then too much overlap will become problematic for that concern.

I will say I didn't realize more overlap tends to lower the peak torque RPM. I thought it stayed the same but the amount of torque was just reduced and spread out more. So I learned something there for sure. That actually correlates well with my engine, which had tiny duration but aggressive lobes and 110 LSA, so more overlap than most people seem to want to run. It was a low/midrange champ.

 

For all out street/strip stuff that 106-108 lsa works real well in sbc. If youre willing to live with it.
Crane makes (old grind) an energizer? cam that is in the mid teens/@050 not a bunch of lift but uses a 106lsa.
Real popular back in the day til the 268H came out. That little cam made real good power for what it was
Like to see someone run it in a TPI the idle was pretty decent

 

I thought crane went out of business?

 

Maybe I misunderstood you here, but it definitely seemed as though you meant a lot of LSA would help with low-end power (it doesn't).
I picked up 40 ft-lbs at 3000 RPM by dropping my LSA 5 points on 2 camshafts with identical duration.
N/A results wouldn't be this way, no, but the extra grunt if gave me immediately off idle through the early RPM to help with turbo spool.
N/A results would have been ~15 ft-lbs with this particular combo (small engine).

 

I just didn't state what I meant clearly...at all. My fault there.

 

Comp bought them out yrs ago, some investment group. Lunati and numerous other brands, same thing.

 

fair enough. Last time I went on their site it was a dead link. I always felt you got a better product for the same price with crane. IE billet cores on most of their roller grinds.

 

Crane was bought by S&S Cycles back in 2009 but they dropped them in 2015 so Crane is gone now. Comp Cams has been bought by the owners of Edelbrock and Lunati is now independently owned.

 

All you need to know is that any cam can be a nitrous cam if you want it to be.

 

Who did comp sell lunati too. Crane before being bought was top notch quality..excellent grinds that worked, too.
All those companies are owned by large investment groups. Even AFR

 

I'm a little curious about lunati too, their site still mirrors comps so I guess it was very recent.

 

From Lunati's site,

By the mid 1990’s Lunati Cams & Cranks had grown to become a profitable, sizeable operation with a shop filled with high quality machinery and a stable, highly skilled workforce. Seeing the potential in Lunati, Holley Carburetors made Joe an offer he couldn’t refuse. The Holley ownership lasted for several years, but after weathering tough times through over expansion within the market during the early 2000’s, the financial managers at Holley decided it was time to divest of one of their holdings, placingLunati Cams on the sales block. In late 2007, a viable prospective buyer had been located and a deal was struck. The investors are an exclusive ownership group made up of industry and racing veterans who are dedicated to providing racers with cutting-edge technology at affordable prices.

Best i can find out is it was a group of private investors out of North Carolina.

Was sorry to see Crane fold, they made some quality products, their gold rockers were some of the best out there.

 

Interesting. I guess its the same company building all the website engines for everyone now then. Even the howards engine seems similar now (I got curious)

I wonder who's making the GMPP cams now? They were mostly cranes.

Edit: i jumped down the research hole seeing who owns what and its a mess to try and keep straight lol. Crane is gone. Thats the important part. Otherwise I had more questions than answers after skimming some of the conflicting articles.

 

Back to the subject cams with more overlap can be advanced to improve low end performance. At the same time cams with tighter overlap can be retarded to reduce low end torque and raise power band. Back in the day there were some very cool parts made to allow quick cam timing adjustments to Chevrolet engines.

 

Yes, the Crane 274H06 is the cam. Old dirt track lift rules(450 max) cam : 218 218 450 450 106 lsa. I ran it for awhile in my carbed 84 C4 with 700R4 with mild stall and 3.07 rear. Lots of low and midrange punch but would have worked better with a little more rear gear. 3.55 or so. Friend of mine has one in his 81 C3 4 speed with 3.73 rear 260hp crate motor and it sounds bad *** out of his headers and side pipes! Tpi would require some major tuning to make it work!

 

Also available to buy in the "Elgin" brand. Competition Products has them.

 

There is a great thread that is now a sticky over on LS1Tech forums. You can see it here.

It does a great job explaining what LSA is and isn't. It also goes into overlap. What I gather from that write up and others are that LSA and overlap alone in STREET CARS won't change top end significantly but will drastically change drive-ability and tune-ability. So if it's a street application and you want to be able to idle at a stop sign and you want it to be easy to tune then you need a cam that will give up power everywhere. Just like increasing lift and duration can increase power so can changing the LSA but all of these dimensions can and will effect "drive-ability". The thing is that concept is subjective to the individual.

I could care less if the motor has chop. Also I don't care if I leave 5 to 10 hp on the table so to speak. My criteria in a camshaft is low cost, and easy tuning with a cam that can meet my power goals. This is why I always go with an off the shelf cam that was designed for factory length push rods. I totally avoid the custom or re-ground cams.

Companies like Elgin and Summit Racing have done an amazing job making good low cost performance cams that are easy to tune. But again this is for a street car. If this is a racing application then it is a totally different scenario and far outside of my wheel house.