Listener Stuart Watson sent us this email discussing dry sump engines, and their benefits and design details. Stuart pointed us at this link for more information.
The majority of road bikes use wet sump lubrication, the ‘sump’ being a pan beneath the crankshaft where the oil is stored. A pump picks it up from here and forces it around the engine into the various bearings, spray jets and so on. After the oil has passed through the high pressure part of the system it drains back down into the sump purely under the influence of gravity.It’s simple and inexpensive, but there are disadvantages. The first is the size of the sump. Usually this will have to hold around 4 litres, maybe more. This is quite large – look at a 5 litre oil can to get an idea – and clearly it has to be at the lowest point, so the engine has to sit higher than might be ideal. Under hard acceleration or braking, or when the going is very bumpy, the oil in the sump can slosh around. In extreme cases this can mean the oil pump’s pick up tube becomes open to the air, and air bubbles are passed around the lubrication system, causing a lot of wear and damage. But it also means the oil can wash up against the crankshaft, which usually spins just above the surface of the sump oil. This causes a lot of drag, reducing engine performance as well as causing the oil to become foamy, which degrades its lubrication abilities.
The alternative is dry sump lubrication. Instead of storing the oil beneath the engine it’s kept in a separate tank somewhere else on the bike – in the frame on the Aprilia RSV Mille for example, or in the swingarm on air-cooled Buells. This means the engine can be positioned lower in the frame (very useful with naturally tall engines such as the V-twins mentioned), and the problems associated with oil sloshing around are eliminated. It’s easier to increase the oil capacity this way too, which means extended service intervals. The penalty is increased complexity (and hence cost), as you now need a separate tank and two oil pumps. One pump scavenges the oil draining down to the bottom of the engine and feeds it up to the oil tank, while a second, more powerful pump takes oil from the tank and feeds it back into the lubrication system under pressure.Some bikes though use a semi-dry sump system, including many off-road machines as well as the BMW. What this really means is that the system is to all intents and purposes a dry sump design, with two oil pumps, but the oil tank is still incorporated inside the engine cases. In the F800’s case it’s still stored beneath the engine, but not directly beneath the crankshaft.It’s a little more complex but by doing it this way the designers have more scope for lowering the engine and making it more compact.
This week the guys are talking with listener, friend, and all around great guy - despite the orange scooter - Ryan Hettenbach. Ryan rode along for some of the Pace Podcast Barber Museum trip in September, and recalls some of his impressions riding with a group, as well as riding longer days and longer miles on the scooter.
Ryan also talks about his preparations for next year's Scooter Cannonball Run, running from East to West in 8 days.
After talking with Ryan, the guys try to discern: is it live or Memore... er... Is it a motorcycle or a scooter? We're talking about the Aprilia SRV800; it's got a frame-mounted engine, chain drive, scooter body styling and ergonomics, an auto trans, sport-sized tires. What is it?
Listener Chris Harr sent us this great description of the various Aprilia APRC electronics components as originally posted online by AF1 Racing; what they do, how they work, and their benefits for the rider and the overall performance of the motorcycle. Thanks, Chris!
Aprilia Performance Ride Control Explained
All of the APRC systems work together to produce quicker lap times. Aprilia Launch Control gets you off the line faster; Aprilia Quick Shift lets you get up to top speed faster; Aprilia Wheelie Control lowers the front end under hard acceleration and out of bends; Aprilia Traction Control lets you explore cornering limits with 8 levels of sensitivity.
Components:Â front and rear wheel speed sensors; ride-by-wire with three switchable maps; joystick control; +/- buttons; instrument display; two gyroscopes (one lean, one attitude), two accelerometers (acceleration and turn); ECU; gear position sensor, throttle position sensor, pressure sensor on shift lever.
Aprilia Traction Control (ATC)
Process:Â The rider presses the mode button and selects the desired level (1-8, 8 being most intervention) using the + and - buttons. Each level contains a minimum and maximum slip threshold. While riding, the speeds of the front and rear wheel are constantly compared, alongside parameters for the roll angle and longitudinal acceleration. Depending on the TC level selected and upon exceeding the minimum slip threshold for that level, the Traction control system enters a control state. The APRC light flashes rapidly when ATC is limiting torque. The rider is then able to modulate slip up to a maximum threshold, a point which cannot be exceeded. As the bike becomes more upright, a higher degree of longitunal slip is allowed by the system.
The ECU reduces torque accordingly in two different ways - â€œpartializingâ€ throttle valves (gentle) and reducing ignition spark advance at the coils (hard). The ATC system primarily reduces torque through the throttle valves.
Effect:Â Rather than a severe cut to limit acceleration and reduce rider control, the ATCâ€™s logic allows a significant degree of rider control within specified slip parameters. Even while the system is limiting torque, the rider can effectively work within a range â€“ modulating the throttle for more slide or vice versa. The system is constantly re-evaluating, so if youâ€™re power sliding out of a corner, the more upright the bike becomes the more slip is allowed. Maximum acceleration is achieved with a limited degree of rear tire slip, which enables the rider to more to fully exploit the bikeâ€™s performance potential safely.
Aprilia Wheelie Control (AWC)
Process:Â The Wheelie Control is able to determine when a wheelie begins and ends. Due to the accelerometer, AWC can actually determine when a wheelie is occurring rather than involuntarily reacting to differing wheel speeds. Wheelies are thus controlled much more smoothly. Using the mode button and + /- buttons, the rider selects AWC from one of three levels (3 being the most conservative). Acceleration data from the accelerometer and relative speed between front and rear wheel is compared to determine conditions for a â€œwheelie.â€ If a wheelie is detected, traction control is momentarily disabled and the length of the wheelie is controlled by limiting torque via ignition advance and throttle valve aperture, just like ATC. Level 1 allows longer wheelies and level 2 and 3 shorter wheelies. Even with the Wheelie control turned off, the Aprilia traction control is still active as long as the front wheel is in contact with the ground. With the wheelie control turned off, the ATC system allows a wheelie for 30 seconds and inhibits a wheelie if the roll angle exceeds 25 degrees.
Effect:Â Wheelies become a separate variable from TC in the ECU. This is especially useful while cornering, where front wheel lift could cause the bike to run wide, yet over-harsh correction could limit performance. Instead, the bike holds the front wheel on the ground while permitting maximum possible acceleration.
Aprilia Launch Control (ALC)
Process:Â Rider selects one of three levels using the mode button and +/- buttons; 1 is the fastest launch level. ATC and AWC are disabled for start, but traction and wheelie control is handled by unique programming when Launch Control is enabled. Rider holds the throttle fully open while the ECU maintains a constant 10,000rpm (levels 1 and 2) or 9,500rpm (level 3).
To launch, rider simply holds throttle open while feeding out clutch. During first phase of launch, wheelies are PREVENTED with ignition advance while a variable rev limit is applied, allowing more revs as speed increases. Once the clutch is fully engaged a limited degree of wheelie is permitted. Once the bike crosses 100mph and a gear higher than 2nd, ALC disengages and AWC and ATC automatically reengage at their previously set level.
Effect:Â Race starts become accessible to less-experienced riders and predictable for experts. Maximum possible acceleration is achieved thanks to wheelie control in conjunction with the Aprilia Launch Control. The ALC is the only launch control system on a production bike.
Aprilia Quick Shift
Process:Â Rider holds throttle wide open, doesnâ€™t use clutch. Pressure on the gear selector is detected, triggering the system to evaluate throttle map, throttle position, gear position and acceleration - ultimately determining the speed of the shift. Torque is cut by reducing ignition advance and injection times, enabling the next gear to smoothly engage. Torque is then gradually fed back in to smooth the shift.
Effect:Â Upshifts are completed without closing the throttle or disengaging the clutch, making them faster and limiting RPM loss. The rider can snap home instantaneous shifts on track or smooth, easy shifts on the road.
This week we talk about Chris's new Zook, deliver some good news from HD, some bad news from Suzuki and we try real hard not to pick on Honda too much. Zero has a new bike, L.A. has a new plan and we have Scott Bolton's AMA season Preview.
In the immortal words of Jed Clampett â€œWeeeell, doggies!â€ have we got a show for you this week. Of course we do. We have a show almost every week. This week, however we open with a contribution from someone who actually know stuff about stuff we don't know all that much about. Then we talk about a whole bunch of Kawasakis including a potential partnership with Bajaj and KTM. We'll talk about a couple Italians and there are leaks-o-plenty from Triumph and BMW. My bike lost it's spark, Chad's prizes are on the way and we have an announcement or two.
This week we announce the winners of our first contest; best â€œmust haveâ€ gear item. We opine away on the Z750R and we talk about Harley-Davidson agreeing to stay in the home of Public Enemies. Speaking of bike makers, we link you to an interview with Stuart Garner, CEO of Norton. Is Norton the next Triumph? Continuing the opining, we (o)pine away for the Dorsoduro from Aprilia. Price is as yet unannounced, but being the experts on all things Aprilia (snerk!), we havenâ€™t a clue on the pricing but guess itâ€™ll be in line with the other big($) trailies. In gear talk James gives us some info on Shoei helmets including a new model to replace a long-standing favorite. Chris explains how when your Angel ST tires tell you itâ€™s time to park it, you really should listen. Some feedback and follow up, the contest announcements, and we exit with a quick tease of next weekâ€™s Female Riders show.
This week we recap our stellar record in predicting the results of the Cycle World Top 10. We are then joined by Chris Harr while we talk about Suzuki's triumphant "return" to the U.S. market, Gladiator Rio's review of the Super Tenere and an iPhone app called TripCast from Jeep. That's right, Jeep. We close it out with a great conversation about Mr. Harr's very drool-worthy Aprilia RSV4.