My engine shop builds all kinds of hot rod motors, and they told me that because I am running a 4 speed manual, I will better be able to take advantage of the 108 LSA. 05 To ensure our stroker combo had sufficient airflow, we installed a set of Chevrolet Performance CNC-ported LS3 heads from Gandrud Chevrolet. Lobe seperation cant be seperated from duration,the 2 are connected.the old duntov cam had a lot less duration than many new cams so the valve overlap was not extreme and the engine ran with a gentle lope.Increase the duration by 20* and this cam would shake a 283 out of the car at idle,but then increase the lobe seperation by 4* and the motor will have a gentle lope again. Say you have a cam ground on a 115 and the other on a 110. Ed JTO learn to park Joined May 31, 2009 180 Posts Really wide lobe separation angles are used in boosted applications. I would say 114-117* would be a normal 1960's stock cam range and 117* to 120* is more what we see on modern engines. A tighter LSA is always going to have more overlap, which allows the exhaust and intake systemif they're tuned wellto work together.". 108: 110: 112: 114 . What happens when you change ONLY. LSA is the distance from the centerline of the intake lobe to the centerline of exhaust lobe. Lobe separations on 383-406 cids.104-106-108-110? "It's not having what you want, it's wanting what you've got!" in some cases,, the average torque can equal out. 292S-112: 292/292 - 240/240 - .495/.495 - 112* - 3400-7200. An icon used to represent a menu that can be toggled by interacting with this icon. Chuck Lawrence of Jon Kaase Racing Engines was asked to give a 520ci BBF a Pro Stock sound, so he went with a 108 LSA in place of a more conventional 112 LSA. 110 LSA: But here, quite surprisingly, you have to face the reduction of the EGR effect due to the 110 LSA. A Pro Stock engine builder may prefer a wide LSA to help keep the power from breaking traction tOo early. So, the 110 LSA engine is a suitable choice for people prone to be the fan of a powerful engine with mighty acceleration power. If the overlap phase occurs too early, it will create an overly rich condition in the exhaust port, severely decreasing the gas mileage. In this segment, I am going to compare those two lobe separation angles based on a couple of mechanical factors. 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That was all, and we have already reached the concluding point. 108 versus 110 will drive the power band down. I have Crane hydraulic link bar style roller lifters, so I dont have to use the spider style. I don't know about 13 to one but I have seen 12 to one on a 350 chev in hot rod article, BUT the guy soft petals around on the street with no full throttle use and puts racing gas in at the track. Aluminum flywheel & pullies. Is There a Sequence? This cam also offered the highest torque output at 4,000 rpm with 522 lb-ft. Based on the peak numbers alone you might be tempted to grab the one with the tightest (108-degree) LSA, but there is more to a cam test than power. I had a 110 cam in my beetle and I didn't like it-the bottom end was doggy. I have 108 for LSA and my headlights take awhile to go up when the car is idling. It affects the amount of valve overlap; that is the brief period of time when both the intake and exhaust valves are open.. by bug1914 Tue May 13, 2003 2:56 am, Post "Ninety-nine percent of cranking compression is dictated by static compression ratio and intake-valve closing point," said Comp Cams' Billy Godbold. Pretty much standard for an RV type cam. On the surface, the camshaft's job is simpleopen and close the valvesbut beyond that topical description, it's one of the most mysterious and misunderstood engine components. Now lets move to the exhaust. Tests have shown that, for a given cam profile, a tighter (smaller) lobe center will produce more average horsepower and a quicker revving engine. Brul spun the engine over with the dyno's starters and recorded 185 psi of cranking compression. It creates an unsteady manifold vacuum condition that, on a fuel-injected engine, confuses manifold air pressure (MAP) sensors, making it hard for them to regulate fueling. But, after comparing these two LSA based on a few mechanical aspects, such as maximum Torque, RPM, powerband, oil consumption, and many more, you will find the 106 LSA with better performance output. This is ground into the cam and can't be changed without changing cams. 12 In terms of power production, the stroker LS3 performed best with the tightest lobe separation angle. So, this LSA is suitable for your engine and its components. The takeaway from this test is camshaft LSA is a double-edged sword. The introduction of Lunati'snew Bootleggerhydraulic series - with its wicked 108-degree lobe-separation angle, fast opening profile and plenty of area under the lift curve - will serve only to fuel the flames on this heated bench-racing topic. Generally speaking, decreasing the lobe centerline angle increases overlap. The reduced rate of the EGR effect lowers oxygen circulation in the engines combustion chamber. If you compared these two cams side by side in identical engines, the first cam would actually have a slightly better idle and would produce slightly more peak power at upper RPM's. However, it is fixable. These favorable mechanical features depict the powerful acceleration capacity of the engine with higher oil and energy consumption rate, overheating problems, and other mechanical problems. 114LSA +4 puts the intake centerline at 110 degrees before top dead center. Given that nitrous works best in the mid- to upper-rpm range, nitrous-powered engines need a wider lobe separation, like 112 . 4-Link72, do you run racing gas or pump with 10.5:1 CR? I normally run a 106 to a 108 because I like the "hit" a tighter LC cam has when it come up on the came. LSA helps determine the cam's behavior; you can take a given set of lift and duration figures, change the LSA, and get cams with vastly different characteristics. We borrowed Westech Performance's shop mule, a 370ci small-block Chevy and its SuperFlow 902 engine dyno and spent a day running each cam back-to-back to gauge its effect on peak horsepower, peak torque, cranking compression, idle vacuum, and the powerband as a wholeall the variables that define an engine's character on the street and track. by ANT Tue May 13, 2003 1:08 pm, Post Well get out of that stocker and build a hipo motor for your VW. The same is true for intake valve closing. A good amount of idle vacuum or increased idle vacuum found at 110 LSA advances the engines efficiency. On the cranking. Engine builders Chuck Lawrence, left, and Doug Patton. Required fields are marked *. You can research your heads to find out where yours are, but honestly I don't think it will be worth the effort on a tow vehicle. JavaScript is disabled. by mrsmythe Tue May 13, 2003 5:45 am, Post Hey guys, can anyone tell me how rough of a idle a cam would be with a 108 lobe separation? dont sound like a verry street friendly motor butany thoughts? I probably would have gone with 3.55 gears had I knows better.. So, you can enjoy a mighty acceleration power at 110 LSA. Coupled that with the low first gear of the five speed, it ought to create some real traction problems. It really comes down to the application. If two cams are identical with the exception of lobe separation angle (we'll say 108 and 114) the cam with 114LSA will make more low end power than the 108LSA cam? They also reduce stress on the outdrive. 110 LSA: But, contrarily, at 110 LSA, you dont have to face the problem of engine knocking. Selecting a camshaft for a given engines purpose usually involves a compromise between low- or high-end power options, and the lobe separation angle (LSA) is one of those factors where engine builders have to make a choice between those priorities. The graph above compares intake valve closing points of the three cams used in the test. It is dangerous to be right in matters on which the established authorities are wrong. While most of our customers know what lift and duration are, most are unfamiliar with the term Lobe Center and how it affects the engines performance. Because during the lower units oil change, you can go through the issue that the lower plug, Read More Yamaha Lower Unit Drain Plug Size [Explained Everything]Continue, Among the crucial parts of a vehicle ignition system is the ignition coil, also called a spark coil. Post Now here is where it gets tricky. The 114o lobe will add a lot more vacuum at idle. I had an XE 274 in it. A cam with 110 lobe center will pull approximately 14-18"of vacuum is borderline for that type of application. Because the lobes are closer together on the 101 LSA cam, the intake closing point is advanced (closes earlier) and the piston has more time to build compressionexactly what the gauge showed. That lopey idle that is universally loved, and part of the allure of a tight LSA cam, is actually misfire caused from a combination of exhaust dilution in the intake manifold and poor cylinder filling at idle. Our content is merely suggestive, not intended to use without proper safety precautions and advice. A wider lobe center will give you more overall torque (comes in earlier and stays later). Not a HUGE, but a significant difference between 110 and 112, but those are the trends. If it occurs too late, it will lean out the cylinder and greatly hinder the performance of the engine. Tight LSA cams make excellent low-end torque and have a beautiful power curve. i have a 4 bolt 351C, stock bore, 10.5 cr with 351C Boss heads ,boss crank and rods. It should still make close to 600hp and 600tq in my 512" stealth headed big block. To reiterate another point, I realize that wider LSAs tend to broaden the power band, but for a car I would like to bracket race a bit, as well as enjoy on the street, I was told that a narrower LSA will help the car accelerate at a faster rate. The wider lobe separation angle closes the intake valve later and reduces cylinder pressure, so that is where it's detonation resistance comes from. That is why 106 LSA consumes less oil. The custom cams we selected all featured 0.624-inch lift (both intake and exhaust) and a 232/242-degree duration split. This form of short-term memory is supported by the prefrontal cortex (PFC) and is believed to rely on the ability of selectively tuned pyramidal neuron networks to persist in firing even after a to-be-remembered stimulus is removed from the environment. After spending 8 years in plant production engineering, Noah wanted to join Engine Addiction as a key member of all cars specific guides, reviews, repairs, suggestions, and more. (You can find an instructional video of how to do just that on our Clay Smith Cams YouTube Channel;https://www.youtube.com/watch?v=57gfBu8uc6k&t=1s ). It will sound lovely I'm sure. not exactly true, Ive seen custom grinds that are on 108 lca, smooth idle, high vacuum an even able to run efi, usually on an off the shelf cam it is true. This is why the LS series, and many other modern engines, can make great power on top and bottom with wide LSA camshafts and why a plethora of factory cylinder heads are flowing near (or above) 300 cfm. The taller lobe seperation will have a longer powerband but will have to rev higher to make the power than the lower lobe seperation! Typically, narrower lobe separation develops peak torque at lower rpm and widening the separation tends to build peak torque higher in the rpm range. AquaTraction Vs SeaDek: Which One Is Better For you? 110 LSA: Oppositely, the cylinder pressure is comparatively lower at 110 LSA than at 106 LSA. BUT, 114 will have more vacuum at idle, which will work better with some fuelinjection. Depending on the engine combination, the opposite results can occur. However it is at the expense of a small amount of bottom end power and idle quality, due to the increased overlap. Some of the confusion on this subject comes from what the meaning of "bottom" and "top" is to the speaker, I suppose. But nothing comes without a cost, and idle vacuum suffers as LSA shrinks. Re: Lobe separations on 383-406 cids.104-106-108-110. Comparison Table Between 106 Vs 110 Lobe Separation Angle. Another related thought to consider when selecting a cam is inches of vacuum for your engine application when deciding upon a Lobe Center. by trmnatr Sat Dec 06, 2008 10:45 pm, Post such as 290 @.050? FWIW. by mrsmythe Mon May 12, 2003 11:15 am, Post To illustrate the differences offered by changes in the LSA, we had Crane cams grind us three cam profiles that shared the same lift and duration figures, but differed only in the LSA. Lobe Separation or Lobe Centers is another way of expressing the Valve Overlap, which was the term formerly used by cam manufacturers before industry standard verbiage changed. This wave tuning is what helps performance engines achieve volumetric efficiencies of more than 100 percent. A 112-114 degree lobe center will have a better idle and produce more vacuum with less overlap. Simply put, the lobe separation angle (LSA) is a measurement of how the intake and exhaust lobes are phased with each other. Maybe even 114. Howards Cam Vs Comp Cam: Which Is The Best Option For You? Leave the 108 for solid rollers turning big rpms. Most cars use more than, Read More Does It Matter Which Ignition Coil Goes Where? My duration will be about 230 degrees. All testing was performed with an Aeromotive fuel pump feeding a set of 42-lb/hr injectors. The article was called "Separation of Power" and they tested 5 cams ranged from 106 to 114 LSA. changing just the LSA on my cam wouldnt make a bit of difference on vacuum operated items E ericnova72 More for Less Racer Joined Jan 13, 2007 22,026 Posts You are using an out of date browser. Lobe Separation Angle "LSA "Jump to Latest Follow 1 - 17 of 17 Posts . Engine knocking generally occurs when the burning of the fuel by the engine is uneven. The Wastegate works by releasing the pressure built inside, Read More What Are The Wastegate Stuck Open Symptoms?Continue, Oops! For a better experience, please enable JavaScript in your browser before proceeding. The lobe separation angle is a comprise of what the engine needs depending on the compression, combustion chamber, rpm, engine size, head volume, and many, many other variables. 106 LSA: There is a scale of standard cranking compression of the engine. Bolander says those cams help promote torque in a controlled and predictable manner, especially in no-wake zones and around the docks. somthing to that aspect. As you can see in the graph, the 101 LSA cam actually had the highest cranking compression of the batch: 185 psi. Lucky for us, Brian Tooley Racing stepped up with a dual spring package that allowed us to safely run our 0.624-lift cam. Hopefully It will do fine in my 2276 mostly drag bug. Has anybody experienced it/ tried it? But you always have a cam card with the engine. The only reason the advance or retard a camshaft profile is to get the timing events where they need to be. A lower efficient compression rate leads to a higher fuel consumption rate by your engine to produce higher power. I'm surprized at these questions as well as some of the replies. " by bigjoe1 Sat Dec 06, 2008 10:48 pm, Post Brul slid the 113-LSA cam, the widest of the test, into the engine's heart and set about putting all the pieces back in place. The 108 LSA offered the lowest idle vacuum of the three (down 4 inches). Simply put, both 106 and 110 lobe separation angles have many advantages and disadvantages. Either learn to fix it, or learn to write checks. Idle vacuum showed a considerable spike to 14.7 in-Hg, likely the difference between being able to run power brakes and a mandatory leg workout. For a better experience, please enable JavaScript in your browser before proceeding. I bet you won't see a bit of difference. After the next three pulls, it was clear the 113 cam was way down on low-end torque. The power and torque curve lay directly in between the last two cams, as did the peak horsepower and torque, 488.7 at 6,200 rpm and 487.1 at 4,600 rpm, respectively. It idles very well at 650 rpm with a nice lope and runs strong. When you purchase through links on our site, we may earn an affiliate commission, which supports our community. Before we all start suffering from separation anxiety, we need to understand what lobe separation angle actually is and then how it affects your engine. LSA is a result of valve timing events. I've seen that Webcam cams can be ordered with either of the above. We even treated them to some chamber work before installation. Cam swaps are all the rage and for good reason. An RV or towing camshaft, which is considered a mild performance or an economy cam, will often have a narrower LSA, between 112 and 114 degrees. Big strokers like tighter LCA but it really depends on your combo and usage, theres great OTS cams but for a custom engine a custom cam is the way to go With identical cam lobes you won't see a bit of difference. JavaScript is disabled. 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. Overlap is the amount of time that both valves are open in the same cylinder.
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