supercharger camshaft lobe separation

IC 34ABDC EC 7ATDC. The intake valves with respect to the exhaust valves: and this is usually described in terms of. Effect Of Changes In Cam Timing And Lobe Separation Angle The following tables illustrate how variations in lobe separation angle and cam timing will effect the behavior of the engine in which the camshaft is installed. You can see on by the dyno results that by reducing overlap and properly tuning the car the power peak not only increased by 25 horsepower, but more importantly shifted up by 1000 RPM’s due to increased supercharger high rpm efficiency from reduced overlap. Of course, when cruising and thus not building boost, nothing more than a normal camshaft is required. Upgrade to lighter valve train, with stiffer springs or dual valve springs to have more control over the valve with this steeper cam profile. Camshaft Selection. Copyright 2021 Leaf Group Ltd. / Leaf Group Media, Comp Cams: Effects Of Changes In Cam Timing And Lobe Separation Angle, "Turbo: Real World High-Performance Turbocharger Systems"; Jay K. Miller; 2008. The more lift you have, the less the valve is a restriction to incoming air because it is farther away from the direct path of entering or exiting air. The high and low pressure pulses created by the design and runner lengths of the intake and exhaust manifolds.It would make sense to open the intake valve just as the reflected pressure waves in the intake manifold reach the intake valve as a high pressure portion of the wave, thus opening the valve at this high pressure point gives a ‘ram air’ effect through volumetric efficiency resonance tuning increasing air ingestion which increases power. While most of our customers know what lift and duration are, most have no idea what the term Lobe Center means, or how it affects the engines performance. In piston engines, the camshaft is used to operate the intake and exhaust valves.The camshaft consists of a cylindrical rod running the length of the cylinder bank with a number of cams (discs with protruding cam lobes) along its length, one for each valve.A cam lobe forces a valve open by pressing on the valve, or on some intermediate mechanism, as it rotates. You will typically find that performance with a blower will not be significantly enhanced below these speeds with a cam change. This is quite possibly the most crucial element of supercharger camshaft selection, since the supercharger cannot push more air in if there is already exhaust gases in the cylinder. Lobe separation, or lobe separation angle, is the distance (in camshaft degrees) that the intake and exhaust lobe centerlines are spread apart. These cams work with your blower or turbo to help provide the most power possible. Lift is good, but usually people don’t try to radically increase lift on their aftermarket cams because of a few considerations: I know this is a somewhat complex topic, but I need to make sure we’re speaking the same language before we go into how this relates to superchargers. Acquire a cam with more exhaust lift and duration. At the same time, the high rpm efficiency improvement from the reduction of overlap will also boost power production with a more conservative cam. Rowe studied engineering, philosophy and American literature at Central Florida Community College. The use of the proper supercharger optimized cam shaft can go a long way towards supercharger tuning and give considerable power gains for the money invested. The Lobe Separation Angle (LSA) is the distance between the centerlines of the intake and exhaust lobes on the camshaft. Purchase a cam designed for use with roller-lifters. If either (or both) intake or exhaust valves are open you will not be able to neither compress nor combust the mixture, and the absolute duration of time (in degrees of rotation) that your mixture is combusted and allowed to reach peak cylinder pressures is affected by camshaft selection and cam timing. Crankshaft and rods Conversely, you would have the least possible scavenging if you had valves that were at a narrow angle (zero degrees at the extreme) between each other, so that the air would essentially have to make a U turn to come in through the intake and get pulled out the exhaust. In this case it is OK to sacrifice some supercharger high rpm efficiency for preventing high-load & low-rpm detonation. Valve Lift INT 0.605 - EXT 0.624 . Depending on where the pistons is in the stroke, and where we are in the combustion cycle, then opening the valves will exploit the pressure difference between the cylinder and the intake and exhaust manifolds. The exhaust cam duration and lift for a supercharged version of the motor should be similar to a nitrous camshaft, in the sense that the exhaust cams on nitrous specific builds have: 1- Very healthy cam duration & very healthy cam lift to allow a severely elevated amount of exhaust gases to be able to efficiently exit the motor when the nitrous is activated and the horsepower (and thus the exhaust gasses) have both doubled in quantity. Installing a camshaft designed specifically for a supercharged engine is best. A supercharger can overcome inadequacies in a stock cam up to about 4,500-5,000 rpm. If this is the case, my first recommendation would be to upgrade to a high flow, low pressure exhaust system because of the potential power gains; however, I do know that some of our readers have cars that they are setting up for their parents or for dual use where their partner or the laws in their location …etc are really strict when it comes to any added exhaust noise or any aftermarket exhaust. Some cards also include overlap and valvespring specs. Videos. Since we already established an intake closing point (and therefore have a good idea of the intake duration), we have most of what we need to create a good blower cam. Complementing your boost maker with a performance exhaust, free-flowing intake, and an aftermarket camshaft (or camshafts in the modular or Coyote engines) can net you another 50 … Normally 112-114 lobe separation is best for a street blower. Settings are below. “Forced-induction engines require less overlap area than a naturally-aspirated engine for exhaust scavenging and to fill the cylinder,” says Herheim. It’s like a ramp, the shorter the duration and higher the lift, the steeper the ramp. But often the existing camshaft works surprisingly well, and those with lobe separation angles of between 112 to 116 degrees are ideal. The result is the intake valve closing further into the compression stroke thereby reducing dynamic compression which will most significantly effect low end power. Valve Lift INT 0.623 - EXT 0.623 . © Copyright 2020 by Total Car Diagnostics. Install cam straight up. I have taken valve timing at 10 thou (which is valve clearance for this engine) and at 40 thou, which is how some others setup these cams. Here is a great example of how cam tuning can affect supercharged power: The car is a 1.8 liter Honda motor equipped with: The black line is the baseline run with all of these modifications before tuning with peak power coming in at: 223 wheel hp @ 7600 rpms. Additional duration, increasing overlap by opening the intake valve earlier and closing the exhaust valve later, is commonly found on performance camshafts. “The cam timing for the intake cam would ideally be retarded which would move the intake cam opening event farther away from the exhaust valve closing event so as to reduce or eliminate overlap, and as a side effect the power stroke duration will increase by retarding the intake cam which can also compensate for the lost power from the duration reduction.” The effect upon power stroke when retarding the intake is stated incorrectly. Its a vintage car with long stroke engine 110mm stroke. Camshaft tuning is an essential part of supercharger tuning. Camshaft tuning is an essential part of supercharger tuning. While increasing pressure in the intake manifold can shove more air into the cylinder, that air may well go to waste if the engine itself is not set up to accommodate the blower. Therefore the biggest obstacle to overcome when selecting a cam profile, is selecting the Lobe Center. Blower cams … Duration @ .050 - INT 217 - EXT 245. View All Close. In this case, I would consider RPM and compression my primary power adder, and my supercharger as my secondary power adder (that is unless I decided to change that and went ahead and lowered the compression ratio of the motor). There are two other areas of camshaft specs you need to know before you buy:Lobe Separation and hoe to figure out the duration you need in engines larger or smaller than 350ci. 10 thou clearance Installing a camshaft designed specifically for a supercharged engine is best. Therefore the biggest obstacle to overcome when selecting a cam profile, is selecting the Lobe Center. Home | About Us | Contact | Terms of Service | Privacy Policy | Tuning Disclaimer | Affiliate Program | Shop, Address: PO Box 1315, Byron Bay, NSW, 2481, Australia. Most performance cams use more lift and duration on the intake side to pull more air in; you will want to utilize a cam with exhaust lift and duration at least ten percent higher than the intake. The result is a cylinder that is only 85% filled with fresh air or an engine that is literally 15% smaller in displacement! Requires DOD to be disabled & #7228 valve springs. It includes lobe lift, net valve lift, timing points at the advertised duration, duration at 0.050-inch lift, lobe separation angle, and the installed intake centerline. If the supercharger is geared to 7psi of boost for example, then during overlap, the cylinder sees 7psi of boost on the intake side, and 10psi of back pressure on the exhaust side, the net result is that air will flow from the high pressure zone (the exhaust) to the lower pressure zone (the intake) and so your cylinder will start to fill with exhaust gases. Lobe separation is 113 degrees, which is appropriate for a forced-induction engine. Specs. Determine where you want your power-band to be. Supercharger tuning through cam selection and cam timing. An LHT ported “S” supercharger inlet tube, An LHT ported intake manifold ( Non intercooled). Lobe Separation Angle (LSA) or Lobe Centerline Angle (LCA)- is the only camshaft specification rated in cam degrees, not crankshaft degrees. Contact a cam manufacturer for lifts and durations that best suit your application. Camshafts orchestrate the valve opening and closing events in the engine and decide whether what comes out of our motor is beautiful high power music, or a mess of dysphonics. According to the Comp Cams catalog, “The lobe separation angle (LSA) is equal to 1/2 the angle in crankshaft degrees of rotation between the maximum exhaust … The piston position inside the cylinder. If you do not have the correct drive ratio for the blower it may also build less boost. Furthermore, to overcome the overlap inherent in this kind of high rpm normally aspirated power-plant it would be very advisable to use a centrifugal supercharger that is capable of producing more boost and flow with increased rpm rather than a roots type charger that will easily run out of boost and flow capacity (CFM) when facing an aggressive camshaft ‘leaking’ boost away. Picking the right cam for use with a supercharger or turbo comes down to ensuring that the waste gases can get out of the motor as efficiently as the pressurized air goes into the motor. This is not a strict necessity; you could go with an old-school flat-tappet camshaft, but you are losing out on horsepower, torque and quite possibly fuel efficiency. The differences between nitrous / supercharged engines, and naturally aspirated engines is the cam profile (and the compression in some cases). These blower and turbo camshafts from COMP Cams are available in a variety of mild-to-aggressive styles. So what happens here is that if your valve train isn’t light enough and well controlled (Through proper valve springs or hydraulic lifting and damping) to operate that rapidly then lift will give you improved performance at lower rpms (where there is a lot of time to move the valve to peak lift) but reduced performance at higher rpms, where there are more rounds per minute and so less time per round, and thus less time to go up the steep ramp and push the valve out to full extension. All of our cams have been in house designed and tested to make more power than … Effect Of Changes In Cam Timing And Lobe Separation Angle The following tables illustrate how variations in lobe separation angle and cam timing will effect the behavior of the engine in which the camshaft is installed. Brian takes a moment to explain what LSA means, how it's calculated, and why it ISNT the end all decision maker for your cam needs! The lobe separation angle is the angle in camshaft degrees between the maximum lift points, or centerlines, of the intake and exhaust lobes. The Lobe Separation Angle (LSA) is the distance between the centerlines of the intake and exhaust lobes on the camshaft. (This information should be listed on your Cam Card. Positive-displacement or "Roots-type" superchargers tend to produce massive power at low rpm and taper off higher in the rpm range; centrifugal superchargers (which are really just belt-driven turbos) work only in the rpm range. If so, the exhaust air can directly pull in new air. Lobe Separation 112+Adv. Lobe Separation or Lobe Center is simply the distance between the peak opening points on the Intake and Exhaust lobes. Lobe separation angle (LSA): This is the number of degrees between maximum intake lobe lift and maximum exhaust lobe lift, also expressed in degrees. The cam timing for the intake cam would ideally be retarded which would move the intake cam opening event farther away from the exhaust valve closing event so as to reduce or eliminate overlap, and as a side effect the power stroke duration will increase by retarding the intake cam which can also compensate for the lost power from the duration reduction. Lobe Separation 120 +Adv. Dyno tested to 7500+ RPM. Nitrous and supercharger cams generally employ very similar profiles because both do their best work at high rpm. Support phone: (+61) 401 605 241. I've wondered this myself, as I have a sbf dart block 9.5 deck out to 454, and the short block was built to n/a specs with a comp cam .600 lift, 110.0 lobe separation, hyd roller. How to use MGI’s Camshaft Calculator When shopping for camshafts from different manufacturers, enter each of their supplied cam card specs into MGI’s Camshaft Calculator. Avoid any cam with more than 30-degrees of overlap. Lobe separation is the angle in camshaft degrees between the maximum lift points of the intake and exhaust valves. A slightly lower (about one-degree) lobe-separation angle will increase cylinder pressure and low-rpm torque without adversely affecting the engine's octane tolerance or idle quality. An interactive camshaft calculator where engine builders can see how valve overlap (and boost efficiency) is affected by a camshaft’s physical design. So we see here that the end result here a lop-sided camshaft with a conservative duration, high lift cam on the intake side, and a normal duration, high lift cam on the exhaust with minimal lobe separation angle and minimal (but not necessarily no) overlap. If the camshaft has less than a 110 lobe separation it can cause the boost pressure to bleed out of the exhaust instead of building cylinder pressure. A 110-degree lobe separation means that the peak opening points of the Intake and Exhaust lobes is 110 degrees apart. Supercharger Tuning Through Cam Selection and Cam Timing, Custom Tuning Car Tuning To Unleash Your…, 9 Top Rated Car Diagnostic Tools Review 2021, OBD1 Scanner: The 5 Best on the market Review 2021, Cheap OBD2 Scanner: The 10 Best Choices (Under $100) Review 2021, The Ultimate Way To Avoid Spending A Ton On Car Repair. For a street motor, this approach is a good compromise. So exhaust cam timing can be advanced or retarded, depending on the exhaust modifications and the intake cam selection and thus must be dyno-tuned. You can calculate the LSA using the centerlines of the intake and exhaust lobes. I am interested on your thoughts for a supercharged engine 6psi boost, max rpm 6,000, and valves at 180 degrees in combustion chamber with low backpressure exhaust (straight through, with tuned runner lengths). In fact, the cam … Find COMP Cams Blower and Turbo Camshafts and get Free Shipping on Orders Over $99 at Summit Racing! It’s important to note that with all of these changes in cam selection , overlap, power stroke duration, and cam timing, that the power stroke duration is effected and if it is effectively shortened then we may need to retune the car’s timing advance on the dyno (for increased advance) to regain losses in duration of the power stroke (again this against popular thinking of never to advance timing on forced induction cars, if we have a shortened power stroke, or an application with significant overlap then it may be necessary to do so). Similarly the more overlap we have, the harder the supercharger will have to work because of what we explained earlier about either exhaust reversion into the intake, or the supercharger pressurizing the exhaust. The basics of what you want in a nitrous (or supercharger) friendly cam is a wider lobe separation than what most “performance” or “race” cams have. 2- As little or no overlap if possible, as any overlap would mean that nitrous would be sprayed from the intake side and out the exhaust, which is wasteful of our limited supply of nitrous. You can calculate the LSA using the centerlines of the intake and exhaust lobes. So if we put the two concepts of longer exhaust duration along with a wider lobe separation angle, we have the makings of a decent supercharger or turbocharger engine camshaft. Home /   Technical /   Supercharger Tuning Through Cam Selection and Cam Timing. The use of the proper supercharger optimized cam shaft can go a long way towards supercharger tuning and give considerable … The lobe separation angle or LSA is the angle in camshaft degrees between the maximum lift points, or centerlines, of the intake and exhaust lobes. Cam duration is the number of degrees of the entire 360* rotation that the intake or exhaust valve is open. Richard Rowe has been writing professionally since 2007, specializing in automotive topics. However for optimum performance at higher rpms, a more aggressive camshaft will provide substantial power … Camshaft Lobe Separation Angle ; Lobe Center; Lobe Center . Specify your cam with the wide lobe separation angle to ensure the lowest possible overlap. In this type of application, if you use a more conservative cam, and dial out all the overlap, and increase the power stroke, in combination with an already high 11:1 compression ratio and a healthy amount of boost pressure (7psi or above) you will end up with a motor that produces extremely high peak cylinder pressures and those intense pressures and heat may easily start off a chain reaction of pre-ignition and detonation and you will find that no matter how much you retard the timing that the setup will end up both powerless and still not that safe.

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