A question thats been bugging me for a while. Can I extract a bit more H/P from my current set up?
My Fatbob 103 as a Stage2 kit , the custom map is set up for low to mid range performance, the Freedom dual pipes I'm happy with at the moment.
The last Dyno reading gave me 108 rear wheel torque and 94 rear wheel H/P aprox.
The sprocket upgrade on the front pully has increased the Torque at the rear but my H/P fugures will be down.
The question is if I replaced the K&H big sucker air filter to the screaming eagle exposed racing pod would I gain anymore H/P?
A supercharger will give a few extra gg's.
Hilly
What cam would you suggest for a dyna/softail? I've been lloking at the S&S585 TW-555 TW77 with headwork????
I currently have the Andrews 57H with stock heads (94.5HP/110 lb/ft) and with the D&D lowcats - awesome throughout the rev range but I might "need" more later on :-D
TIA
45
45WL, I see your figures are very similar to mine. I think if you want more out of what you have just change the front pully. You won't know the bike. It's similar to changing from a stage1 to 2 and for under a 1k well worth it or spend 8k for 10/10 change in performance through a shop. I first read it in Heavy Duty Magazine and then read some forums from people that have done this upgrade. Sure more H/P would be great but this is a really noticable change if your looking for a more pointed performance from your bike.
Hilly I probably don't need more now.... But you 'never' know I'm pretty happy atm and don't particularly ride to the right of the curve in anycase and don't have deep pockets atm
never considered the 4°?? Is that a common mod with the 57h? A bump in the compression wouldn't hurt
Wozza
I forgot to mention I changed out both sprockets dropped 2 teeth in front to a 30T and added to teeth to the rear - 68T. Stock belt. Totally transformed the ride - I have power in every gear including 6th
I've been thinking about why the 54h cam was choosen over a 57h cam in the origanal design breif.
It was because I wantad all my power to come on strong low in the rev range to the mid range, not so much top end.
The 57h cam comes on from mid to top end.
This also gives me greater scope to flow the heads without changing out the cam to get the most out of it.
The 54h is similar to a 555 cam.
The disadvantage is my top end H/P figure will be down and that shows in the dyno chart figure. The reality is in a mild set up it's 1 or 2H/P
No offence taken. I'd like to have a bit more time to do my own work. I've got a 1965 truimph 650 sitting in the garage as well that needs some love.
Wozza re those Andrews cams, I think you have it the wrong way around. The 57h is designed for stock compression and will give more torque down low than a 54h cam in the same stock bike.
Like Hilly said, the 54h will provide more torque down lower when it's got a bump in compression. Andrews suggest it for comp at 10.2:1. Interestingly, Andrews state that when these cams are installed with suited compression, their powerbands are roughly the same, around 2,200-5,600 rpm. Obviously the 54h in a 10.2 comp engine would perform better than the 57h is a stock comp engine. If you were going to go the trouble of headwork and increasing compression, you'd probably consider increasing comp above 10.2 which opens up to more, better cam options again.
Below is the table of Andrews cams from their website. And below that is a table of the Wood cams as you mentioned the 555 cam which the 54h is similar to. The 57h has slightly more lift than both the 54h and 555 cams but with stock heads you cannot take advantage of the higher lift of any of these cams anyway.
this is posted on a few of the forums on the net, its regarded as a very accurate write-up on cams and engine work. part 1 covers most of the stuff
manufacturers say the cam will run from 2000rpm to redline?
Explaining How Cams Work and What the Numbers Mean: What you need to know about Cams. #1 - the most common camshaft error made by people is to OVER cam the engine. #2 - is selecting a cam that is not compatible for the RPM range that we plan to operate the engine in. There are a number of things, which affect the cam’s performance. Cylinder head flow rates: The cylinder heads must be able to flow enough air for the time that the valves are open. Compression Ratio: Static compression ratio and cam choice should be considered as a system. Intake: The intake must also flow enough air to support the cam and cylinder fill. Exhaust pipes: The exhaust pipe must not only flow enough, they must be designed so that the reversion pulse is compatible with camshaft timing. There is a little clue here for you sharpies and that is the word AIRFLOW. Airflow is everything and the camshaft is the controller of the airflow. It determines how much, when and how long. The result of all the camshaft specifications is where in the RPM band the motor will make the best power. Now one more thing before we dive in to the mystery and that is we need to understand our objective here. For the purposes of these articles I'm not interested in RACING motor but rather street motors and street motors need to develop TORQUE and they need to develop TORQUE in the 2500 to 4500 RPM range, as this is the range we most often operate the engine in (freeway cruising). There is a law of camshafts we need to keep in mind. - If you have it at the top, you will not at the bottom and if you have it at the bottom, you will not at the top. We cannot have it all. In a STREET motor, we do not need it at the top, we do need some at the bottom, but we really need mid-range. So here is where we are going to look for our torque. Now we also have to look at the bike we ride. A dresser is going to need more bottom end than a FXR due to the weight and wind resistance. All right, so now that we have all this behind us we can move on to the cam itself. Intake Closing: The intake closing point has more effect on engine-operating characteristics than any of the other three opening and closing points. The earlier it occurs, the greater the cranking pressure. Early intake closing is critical for low-end torque and responsiveness and provides a broad power curve. It also reduces exhaust emissions while enhancing fuel economy. As RPM increases, intake charge momentum increases. This results in the intake charge continuing to flow into the combustion chamber against the rising far past BDC. The higher the engine's operating RPM, the later the intake closing should be to ensure all the charge possible makes it into the combustion chamber. Of course, closing the valve too late will create significant reversion. It is a fine balancing act. In a perfect world, the optimum intake closing point would occur just as the air stops flowing into the chamber. It would get the valve seated quickly and not waste time in the low lift regions where airflow is minimal and there is no compression building in the cylinder. It wouldn't be so fast the valve bounces as it closes, allowing the charge to escape back into the intake port and disturb the next charge. And in hydraulic street cam applications, it would insure that the closing ramps are not so fast that they result in noisy operation. A late closing intake valve will yield poor compression and will cause poor performance over most of the entire RPM range. A semi-late closing intake will have a good mid range and good top end but not the best. An early closing intake (30-35 degrees) is what we like for a heavy bike because it will give an excellent bottom end performance and a good mid-range. The intake valve closing point is intimately related to an engine's dynamic or "effective" compression ratio. Compression ratio is also dependent on cam duration. A mild cam with an early intake valve closing point will work well at low RPM. However, at high RPM the intake valve will close before the maximum amount of air/fuel mixture has been drawn into the cylinder. As a result, performance at high RPM will suffer. If a high static compression ratio is used with a mild cam (i.e. and early intake valve closing point) then the mixture may end up being "over-compressed.” This will lead to excessive compression losses, detonation and could even lead to head gasket or piston failure. On the other hand, an aggressive cam with a late intake valve closing point will work well at high RPM. However, at low RPM the intake valve will close too late for sufficient compression of the intake charge to occur. As a result, torque and performance will suffer. If a low static compression ratio is used with an aggressive cam (i.e. a late intake valve closing point) then the mixture may end up being "under-compressed.” Thus, a high performance cam with long duration should ideally be combined with a higher static compression ratio. That way the engine can benefit at high RPM from the maximized amount of intake charge afforded by the late intake valve closing, and still achieve sufficient compression of the mixture as a by-product of the dynamic compression ratio. Intake Closing AGAIN!: The most important cam event. This sets the engine's effective RPM range, effective dynamic compression. An early closing (30 - 38 ABDC) = high dynamic compression, great low to mid RPM torque for a very broad power band, requires lower static compression (which means less stress and strain on the engine, less risk of heat damage and detonation, more reliability)....but engine RPMs are limited, the engine will "quit pulling" around 4800 RPM. As intake valve closing gets later (40-45) the power band moves up about 250 -300 RPM, narrows slightly unless more static compression is built in (e.g. thinner head gasket). Torque remains about the same, but due to higher RPMs, HP increases slightly. Throttle response off of idle drops slightly. Head temperatures increase slightly, making detonation a realistic risk, fuel management/tuning becomes even more critical. And exhaust pipe diameter, length, back-pressure designs become more influential. The engine will pull thru 5000 RPM. Closing the valve even later (+45 ABDC) shift the power band way up the RPM scale. Increased static compression is necessary to achieve any TQ/HP. Typically, it will exceed 12:1. Fuel management/tuning are very critical to reduce detonation and the risk of heat damage. Higher compression shortens the engine's life. Because this cam only functions well at higher RPMs, the other cam specifications can take advantage of this and be optimized for more power. What's lost is smooth idling and some usable power/torque at low to mid RPMs, crisp throttle responses from idle, engine heat issues become critical. Think about a bad-ass quarter mile drag bike: won't idle for crap, pops & snorts until the throttle is twisted nearly WFO, when it finally begins to roar - the engine is barely manageable - but damn, what a ride! The intake closing point has more effect on engine-operating characteristics than any of the other three opening and closing points. The earlier it occurs, the greater the cranking pressure. Early intake closing is critical for low end torque and responsiveness and provides a broad power curve. It also reduces exhaust emissions while enhancing fuel economy. As RPM increases, intake charge momentum increases. This results in the intake charge continuing to flow into the combustion chamber against the rising far past BDC. The higher the engine's operating RPM, the later the intake closing should be to ensure all the charge possible makes it into the combustion chamber. Of course, closing the valve too late will create significant reversion. It's a fine balancing act. In a perfect world, the optimum intake closing point would occur just as the air stops flowing into the chamber. It would get the valve seated quickly and not waste time in the low lift regions where airflow is minimal and there is no compression building in the cylinder. It wouldn't be so fast the valve bounces as it closes, allowing the charge to escape back into the intake port and disturb the next charge; and in hydraulic street cam applications, it would insure that the closing ramps are not so fast that they result in noisy operation. The most important timing event is the intake valve closing angle. The intake closing point determines the minimum RPM at which the engine begins to do its best work. The later the intake valves close, the higher the RPM must be before the engine gets "on the cam." If you have one of the late closing cam designs installed, say one that closes the intake valves later than 40 degrees, then you cannot expect excellent performance at 2000 RPM. No carburetor adjustment, ignition adjustment or exhaust system can change this. Intake Opening: Looking at the intake valve, its opening point is critical to vacuum, throttle response, emissions, and gas mileage. At low speeds, and high vacuum conditions, premature intake opening during the exhaust stroke can allow exhaust gas reversion back into the intake manifold, hurting the intake pulse velocity, and contaminating the fresh intake charge. A late opening intake gives smooth engine operation at idle and low RPM, and it ensures adequate manifold vacuum for proper accessory operation (assuming the other three valve opening and closing points remain reasonable). As RPM increase, air demand is greater. To supply additional air and fuel, designers open the intake valve sooner, which allows more time for the intake charge to fill the cylinder. With an early opening intake valve, at high RPM, the exiting exhaust gas also helps draw the intake charge thru the combustion chamber and out the exhaust - that's good for purging the cylinder of residual gas, but it also increases fuel consumption by allowing part of the intake charge to escape before combustion and can make for a rough idle. Early usually means overlap, less throttle response at low to mid RPMs, rough idle, more emissions, poor fuel economy. However, by opening the intake valve early, we can slightly increase the volumetric efficiency of the engine...if the heads will flow any better. This is where stock heads fall short compared with ported heads. However - like cams, bigger is not always better when it comes to ported heads. Big ports and big valves will drop the intake and exhaust velocities, which can cause a host of problems, as well as a loss of volumetric efficiency. Most ported Twin Cam heads with stock diameter valves/seats, used with stock intakes and SE or K&N air filters usually flow their max CFM near 0.350" - 0.450" valve lift. Using a cam that has the intake valve open that far by the time the piston is at max velocity maintains the max intake charge velocity - which makes the best use of the momentum supercharging effect between idle and 3500 RPM. Using a cam with even more lift (+0.500"" border="0" src="/DesktopModules/NTForums/themes/_default/emoticons/wink.gif" /> only reduces this effect - and power (along with adding more unnecessary wear and tear to the valve train). A stock, un-ported head has a very restrictive exhaust port, and therefore limits volumetric efficiency even further - making a cam with high lift even less effective. The thing to remember with cam timing is that the intake valve opens before TDC and closes after BDC. Exhaust Opening: Overall, the exhaust valve opening point has the least effect on engine performance of any of the four opening and closing points. Opening the exhaust valve to early decreases torque by bleeding off cylinder pressure from the combustion that is used to push the piston down. Yet the exhaust has to open early enough to provide enough time to properly scavenge the cylinder. An early opening exhaust valve may benefit scavenging on high-RPM engines because most useful cylinder pressure is used up anyway by the time the piston hits 90-degrees before BDC on the power stroke. Later exhaust valve opening helps low RPM performance by keeping pressure on the piston longer, and it reduces emissions. Early opening exhaust - here we loose our entire bottom end and our mid range will be lazy what it will do is run hard on the top. Semi-early opening exhaust. This timing will give us good cylinder scavenging which results in a cleaner cylinder mixture at high RPM the low end will suffer some but the mid range will be very good. Late closing exhaust here we end up with a narrow RPM band the low end will be good as well as the mid-range but we will have an engine difficult to use. Stock cams typically open the exhaust valve late (36 BBDC) to maximize the burn time and pass emission tests easier...but suffer from pumping losses because the piston has to work harder to mechanically push out the burnt gases. If the cam opens the exhaust valve a little sooner (40-43 BBDC), we can use blow-down (the expansion of burning A/F) to help scavenge the cylinder. This gets the burnt gases moving, reduces the piston effort, and decreases pumping losses...up too about 4000 RPM. However if the cam opens the exhaust valve too soon ( 45+ BBDC) the blow-down will bleed off much of the expansion pressure of the power stroke from idle thru about 2500 RPMs. The RPMs must be higher to overcome the time available for blow-down. Exhaust Closing: Excessively late exhaust valve closing is similar to opening the intake too soon- it leads to increased overlap, allowing either reversion back up the intake, or the intake mixture to keep right on going out the exhaust. On the other hand, late closing events can help purge spent gasses from the combustion chamber and provide more vacuum signal to the intake at high RPM. Early exhaust valve closing yields a smoother operating engine. It does not necessarily hurt the top-end, particularly if it is combined with a later intake valve opening. As engine operating range increases, designers must move all the opening and closing points out to achieve earlier openings and later closings, or design a more aggressive profile to provide increased area under the curve without seat timing increases. Exhaust Valve Closing - usually between 4 (early) and 20 (late) deg ATDC. An early closing = less overlap, late closing = large overlap. Less overlap (exhaust valve closes at 4) makes it easier to pass a smog test, smooth idle, great fuel economy. A mild overlap (exhaust valve closes at 8-12) makes good low to mid RPM range power, better throttle response, fair fuel economy, slightly more emissions. And large overlap (exhaust valve closes at 13-20) allows a lot of intake charge dilution/loss (bad emissions), poorer fuel economy, rough idle, less throttle response from idle, and makes most of the power at higher RPMs. Note: the amount of overlap also depends on the cam's intake valve opening specifications. Early exhaust valve closing yields a smoother operating engine. It does not necessarily hurt the top-end, particularly if it's combined with a later intake valve opening. As engine operating range increases, designers must move all the opening and closing points out to achieve earlier openings and later closings, or design a more aggressive profile to provide increased area under the curve without seat timing increases.
