Sled CVT Dyno
Land & Sea's new DYNOmite CVT Dynamometer module, for snowmobiles or ATVs, allows simultaneous capture of both the engine's input power and the final output -after all belt and clutch pulley losses. At last, the most efficiency dependant power robbing tuning variables in a sled's driveline can be tackled scientifically.
Although affordable enough for serious racers and small after-market manufacturers, this is a serious OEM engineering caliber tool. Input power is captured without incurring any un-trunioned drive losses. Shaft torque readings are via strain gauge load cells, and occur upstream of ambiguous track losses – allowing precise and repeatable back-to-back comparisons. Inertia compensation algorithms, for crank-train, clutch, and flywheel masses, continuously monitor shift ratios. The software maintains separate calculations for the drive and driven shaft's independent accelerations.
The DYNOmite CVT module features variable clutch shaft center to center distances and is available for all popular tapers. Quick adjust frame mounting points and ski angles accommodate most production sleds. Removable guards provide for safe viewing of clutch/belt behavior during operation yet allow easy service access.
An integral inertia flywheel system, in conjunction with a DYNOmite water-brake, eddy current, or AC absorption unit, provides the inertial and parasitic components for simulating any vehicle's acceleration mass, rolling resistance, and exponential wind drag losses. The included DYNO-MAX 2000™ control software has operator input parameters (e.g. sled weight) allowing the electronics to accurately reproduce real-world acceleration, steady-state, and back-shifting operating conditions.
New diesel engine RPM pickup
Although monitoring and recording real-time engine RPM from most gasoline Otto cycle engines is relatively easy, Diesel cycle applications are not quite so tachometer friendly.
Typically an ignition system provides one or more places to capture a pulsed signal – suitable for wiring to the data accusation systems tachometer circuitry. Spark ignition systems are universally electric in nature. Even an old fashioned breaker-point system offers up a strong 12-volt range square-wave across the points. CD ignitions hitthec -and-sea.com coil's primary. Most multi-spark race ignitions provide a dedicated tachometer output signal. For applications where those solutions fail, you can usually detect a high-tension or primary wire's signal via an inductive pick-up clamp.
But for diesels, since there is no spark required for ignition, there is not any electrical ignition system to tap into. Except for those diesel applications that are kind enough to provide a special tach generator or engine management pulse, things get tough in a hurry.
For many engine dynoing applications the RPM can simply be read from the absorber – adding a gear ratio factor for other than 1:1 applications. However, if a shifting transmission is involved (e.g. chassis dyno work) both the engine and absorber RPM signals need to be read separately to support on-the-fly ratio calculations.
Previously we only had a couple of options. One was using the DYNOmite Optical RPM Pickup kit – where a photo-sensor reads a reflected light beam from a shiny spot or mirror tape patch placed on a rotating engine pulley. Or, sometimes an alternator is available to supply a sine wave signal – although the final RPM/frequency relationship must be scaled on a per-vehicle basis.
Now we have added another option, the DYNOmite Diesel Fuel Rail RPM Pickup kit (see picture on previous page). This simple clamp and amplifier works by reading the hydraulic injector pump's pressure pulses. Each time the engine's fuel pump delivers a squirt, its metal injector rails expand. Our small clamp-on Piezo electric transducer and amplifier module converts these mechanical shocks into electrical square wave pulses that the DYNOmite data acquisition computer then reads for engine RPM.
Question of the Month...?
“How much extra load does an absorber equipped dynamometer put on an engine vs. an inertia dyno?”
We seem to get variations of this question (misunderstanding actually) on a regular basis. But in-fact, the answer is pretty simple. A dynamometer does not put the load on an engine at all!
Whether the engine is in a vehicle on the highway or being evaluated on a dynamometer, the torsional loads (torque) applied to the crankshaft, drive line, etc. are all applied to the dyno by the engine (itself regulated by the operator's use of the throttle). The dynamometer's absorber simply supplies the resistance to any applied force. It substitutes for the vehicle's mass and drag – which provide the opposition to instantaneous acceleration on the road. For any given RPM and throttle opening, the pressures and forces applied to the piston domes and crankshaft are the same – no matter the source of the resistance provided at the flywheel.
Still, plenty of dyno operators have experienced melt-downs during a short pull on the dyno – frequently from combinations proven reliable after hours of in-vehicle operation! This scenario happens often enough to rule out coincidence. So, what is the difference?
Time! It is all a result of the extended and uninterrupted running time at significant throttle opening. Race tracks are usually too short to allow long and sustained pulls at high loads (except for Bonneville land-speed record vehicles and marine applications) . Too often dyno operators apply full-throttle much longer than they would (or could) out on the road or race course. This leads to soaring combustion temperatures, as pistons and chambers fully heat soak. Results often include detonation, piston meltdown, and cylinder seizure. If it's any comfort, a driver applying similar sustained throttle out on the open road would fail that “reliable” engine too.
It is up to every dyno operator to understand the limitations of each type of engine under test. Even an 8,000 Hp blown nitro-methane fuel dragster engine can be successfully dynamometer tested if the duty-cycle of the pull is adjusted accordingly. Just don't expect to open the throttle and take 5-seconds of data at every 500 RPM increment – as you might mapping out an economy car's engine.
DYNO-MAX Formulas 101
Every gauge, graph line, and data point listing in DYNO-MAX 2000 is formula driven. The program even includes several hundred built-in ones. Formulas are equations that calculate real-time display information from raw channel data and user entries.
Unlike mystery "black box" software approaches, you may easily examine DYNO-MAX's equations by selecting “Edit Formula List...” from its main menu. An alphabetical table displays with short explanations of each formula's purpose. For ones like “Engine Power (Hp),” the name alone pretty much describes what that formula calculates. This screen also allows globally changing a formula’s line colors, short name, display units, decimals, etc.
Expand the Engine Power formula (by clicking on its + symbol in the list) so you can view its entire equation logic. Note, that closed padlock icon means you can't actually edit this equation. This formula is straightforward, so it is a good one to learn from.
Engine Torque *
Engine RPM /
5252
Fx symbols in front of the Engine Torque and Engine RPM lines are reminders that those values derive from other sub-formulas. The # symbol indicates that 5252 is a fixed constant. Standard algebraic math operators are used to show that Engine Torque is multiplied by Engine RPM and then divided by 5252 to return Engine Power in Hp (the Units list's top entry denotes that formula's base units).
Next, expand the Engine Torque formula to see how it's calculated:
Observed Torque *
Correction Factor Selected +
If Info: Type Of Correction >= 1.000 {
If Info: Type Of Correction <= 2.000 {
(Correction Factor Selected
1.000) *
Friction Torque
Per algebraic rules, sub-formula Observed Torque is first multiplied by the Correction Factor Selected formula. Next, an If statement examines “Info: Type Of Correction" (which is the 0 to 7 selection choice you made in the Run Information -Weather tab's Final Correction Factor Method list). So, the three remaining “Friction Torque” calculations only execute for Standard and SAE methods which return 1 and 2 respectively.
Drilling down into the Observed Torque formula reveals more “if branches” (based on inertia compensation methods). Most call the Measured Torque sub-formula line which actually reads the DAQ board #1's “Torque” channel tab (Strain #1) hardware channel:
DAQ ID #1: Torque
If you bother to drill down into the Correction Factor Selected formula you can see it simply returns the Run Information Weather tab's Final Correction Factor (a multiplier value.).
Other formulas may be more complex, but examining their logic via this top down method is the secret to understanding their logic!
Customer Spotlight
CRS Dyno Service
…is an independent dynamometer facility located in North Central Indiana. Owner Terry Lightner began offering his testing expertise to the general public in early 2004. Today CRS provides dyno services to both local and worldwide race teams. The company's fully seasoned engine and chassis cell can be environmentally controlled and utilizes the latest DYNOmite data acquisition electronics – with a full array of sensors.
CRS's specialty is producing documented test results for a wide variety of two and four-cycles. Day-to-day testing includes most snowmobile engines, plus Yamaha, HPV, and Rotax powered karts. Their Bandolero direct crankshaft mount absorber allows verifying HP on both restricted and unrestricted sealed engines.
A session typically includes both baseline and post modification Hp and torque sweep (or step) pulls. Results are accurately recorded – even on the peakiest single cylinder engines that often develop their best results above 15,000 RPM.
CRS's graphs normally include air and fuel flow data that is vital for getting the most our of each engine – whether a “stock” 5 Hp kart or 300 Hp modified sled engine. Terry likes to push his DYNO-MAX 2000 “Pro” software's analysis capabilities hard. It helps teams find those little tweaks – ones that make the difference between winning and losing.
Terry just loves trying to find local racers the most horsepower for their karts and sleds. But when he's not in the CRS dyno cell, you just might find him at the local drag strip – running mid-ten second passes in his old reliable Duster.
CRS Dyno Services stands ready to conduct testing (in or out of the sled or kart chassis). To really prove your combination works, there is no alternative to accurate dynamometer data. For more information and a video of some actual tests, see their web site at: www.crsdynoservice.com or call 574-784-8256
PO Box 96 North Salem, NH 03073
Contact Us…
Land & Sea, Inc.
PO Box 96
North Salem, NH 03073
(603) 329-5645
www.land-and-sea.com
sales@land-and-sea.com
or visit your
DYNOmite Users' Forum
www.land-and-sea.com/forums
American Snowmobiler NSDRA Shoot-Out
Nearly 170 asphalt sleds turned out at US 131 Dragway in Martin Michigan for the 17th Annual National Snowmobile Drag Racing Association Super Sled Shoot-Out. The yearly event's organizers (American Snowmobiler, NSDRA, and Torco Fuels) reported that participants from Maine to Wyoming and Canada came to take a crack at the ¼ mile.
Dick Locke from Land & Sea was flown in to handle dyno testing of the stock class entries– just to keep everyone on their most honest behavior. In case you are curious, that little red Phazer was just shy of 80 Hp!
On the asphalt the quickest stockers were running 11.0s. By comparison, the modified sleds hit 8.05 at 159 MPH.
See us at this Fall's premier industry trade show events:
Once again Land & Sea will be exhibiting at most of the popular Fall seasons trade show events. This is a great opportunity for you to talk to your technical support guys in person, look at our new equipment, or just get a refresher on any of DYNO-MAX 2000's features.
As usual, the SEMA event is held in Las Vegas. This year it runs from October to November. If Las Vegas is too far way, then the relocated Performance Racing Industries show in Orlando, Florida may work better for you.
The east coast PRI event is slated to run much later than usual – from December 14 thru 16 – so bring your Holiday wish-list. We hope to see you there!
