Engine Analyzer is our basic Engine Simulation program and lists for $109.95. This program offers over 90 examples of complete engine setups for a good starting point to modify and see what your changes will do. And with over a thousand different offerings (heads, intakes, turbos and etc) you will have plenty of options to choose from.

Engine Analyzer Plus is our mid level program. Listing at $199.00 it is a good option for people who are not quite ready for our top of the line program. It builds off of our basic version by adding:

• Alternate Fuels
• Estimate Piston-to-Valve Clearance
• More graphing features
• Import Head files from Performance Trends’ Port Flow Analyzer flow bench software
• Variable Valve Timing (V V T)

• And more

And finally Engine Analyzer Pro. This is our Top of the line Engine Simulation program and sells for $469.00. The Pro builds on the Plus version by adding:

• Spark advance
• Low lift versus high lift valve flow
• Ring leakage on blow-by
• Cam Profile, valve spring forces and valve train weights on valve toss
• Cam Profile and valve flow curve interaction on torque and HP

• Rod length on piston Gs, piston thrust, piston velocity
• And more
  

For more information on the differences between these 3 programs we have made an Engine Analyzer Comparison Table to help you make an informed decision to choose the best version or your needs.

The graphics I supplied and some explanation are what follow in this blog.  It deals with how port volume, or more precisely intake runner cross sectional area, affects performance.  I simulated 3 cases in our Engine Analyzer Pro – Engine Simulation program where the ONLY thing changed in the 3 cases was the intake port and runner cross section.  You will see significant differences in performance.

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This Engine Analyzer Pro graph shows the absolute pressure at the intake valve during the intake stroke.  During mid stroke, you can see this pressure is low, well below atmospheric as the piston tries to suck in the intake charge, identified as ” Max Piston ‘Demand’ “.  Then when it gets the charge moving, it wants to keep moving well past TDC until intake closing.  If you properly size the intake cross section and runner length, you will make maximum power.

Graph showing pressure at intake valve as valve is closing

The graph shows the very high “ramming” pressure in the intake port as the valve is closing.  For the 3 cases shown, the ONLY thing that was changed was the cross section of the intake port and manifold runner.  If you figure 14.7 psi is atmospheric pressure, then the “ramming” pressures at intake valve closing is from 10 to 20 psi above atmospheric pressure.  That is similar to running a supercharger at 10 to 20 psi of boost, and why the volumetric efficiency for these 3 cases is in the 120% range.

This screen shows the specifications the Engine Analyzer Pro uses for simulation.

Case 1)  If you size the cross section too small, you get high ramming pressure from the higher velocities, but the peak occurs too late (after intake closing) to fill the cylinder.  This case made 1133 HP with 111.2 volumetric efficiency on the Engine Analyzer Pro’s simulation.

Case 2)  If you size the cross section correctly, you get good ramming pressure and it occurs when the valve is closing to get the best cylinder filling.  This case made 1211 HP with 119.3 volumetric efficiency.

Case 3)  If you size the cross section too big, you get lower ramming pressure from the lower velocities.  This case made 1165 HP with 116.2 volumetric efficiency.

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Note:  There is still MORE to cylinder heads than flow and cross sectional area.  These include mixture motion (swirl and tumble), port velocity mapping (high and low velocity areas in the port), fuel distribution (wet flow testing), combustion efficiency (cylinder pressure measurements and spark timing effects), and more.  Most all of these are considered “black art” and true trends can not be determined accurately for all cases without significant “cut and try” testing.

Ramey Motorsports

Blaine Ramey of Ramey Motorsports is a Ford Engineer and long time friend of Performance Trends.  Lately he’s been working with us on his 2010 Ford Cobra Jet Mustang.  In just their 4th outing, they won their NHRA Super Stock SSBA class (which is a Bracket Racing class) at Mid Michigan, July 11 with Charley Downing driving.  This is the FIRST win for the “Drag Race specific” Cobra Jet in this division.

Weather Readings

Blaine has been using Performance Trends Drag Race Analyzer Pro “Team Engineer” version that utilizes our DataMite Mini USB Weather Station with Wind Wizard to predict his Dial Ins.  For those not familiar with modern drag racing, Super Stock (and other classes) lets vehicles with very different performance compete against each other.  What happens is the slower car gets a head start.  How much head start is determined by both drivers predicting their ET, their “Dial In”.  If the slower car has a dial in 2 seconds slower than the faster car, they get a 2 second head start.  If a driver goes quicker than their dial in, they “break out” and loose.

Long story short, being able to exactly predict your vehicle’s performance, and cutting a perfect light is key to winning.  With changing weather and wind conditions, changing track vehicle conditions, driver variations, engine performance variation, etc., your ET will change slightly.

For things you can control, you want to keep the car as consistent as possible.  That’s why this class is almost exclusively automatics.  There are also lots of electronic controls to keep the launch and shifts consistent.  The drivers do lots of practice to hone their reaction times to be consistent on Practice Trees.  And Charley Downing is an outstanding driver.

For things you can not control, like weather, you want to be able to predict how these will effect the ET.  With a couple of rain showers over the July 10-11 weekend, weather conditions were changing quickly.  And in this sport of thousandths of a second, you need to be able to predict these changes exactly.  The Drag Race Analyzer Pro has some very precise weather prediction capabilities, especially in the area of aerodynamics and engine performance.  Blaine used these to his full advantage.

The electronic shifter (again to obtain greater consistency) did not come together for this weekend.  So Blaine used the Drag Race Analyzer Pro to determine which shift RPM would be best for consistency with a “human shifter”.  He’d try a shift RPM, then try again with a certain amount of driver error in the shift RPM.  The shift RPM which had the smallest change in ET for a given amount of error was best shift point.

He has also been using our Drag Racing DataMite Data Logger to monitor the vehicle’s launch.  He quickly saw that their new suspension tweaks were not working and went back to his earlier, more predictable set up.   The logger also let him  monitor temperatures to cool down to the exact same conditions for each pass, again for greater consistency.

Ramey Motorsports

The car has been to the track four times now and Blaine was able to come home with a win in one of the most popular divisions. Blaine and his team beat some very stiff competition that had much more experience and funding.  But his engineering of the situation, using Performance Trends tools, helped bring home the hardware.

To quote Blaine:

This was the 1st time out with your great tools and we won!

- Drag Race DataMite
- Drag Racing Analyzer Pro – Team Engineer
- Weather Station

The DataMite allowed me to quickly adjust the suspension to consistently launch the 1000 HP Cobra Jet on a very slippery track. Using the weather station and Drag Racing Analyzer I was able to predict vehicle performance to 0.005 seconds.  This was crucial since we had to contend with constantly changing weather conditions.

Thanks for your support
Blaine Ramey

Congratulations to Ramey Motorsports!

Ramey Motorsports

CR is the ratio of the cylinder’s volume at it’s greatest volume (piston at Bottom Dead Center), compared to the volume at it’s minimum volume (piston at Top Dead Center).  At BDC, the volume is the cylinder’s swept volume PLUS the combustion chamber volume.  At TDC it is just the combustion chamber volume.  Since the swept volume is the engine’s displacement per cylinder, and is easily calculated from bore and stroke, the more complicated part of the calculation is calculating the combustion chamber volume, which is made up of LOTS of separate small volumes.  That’s why it’s nice to have the  Compression Ratio Calculator to do that hard work, and keep all the math straight.

Compression Ratio Calculator Main Screen

Well, there are some downsides to high CRs:

• The amount of improvement you get going from 9:1 to 10:1 (typically about 4%) is much greater than the improvement going from 16:1 to 17:1 (more like 1%).  The benefits of very high CRs diminishes rapidly.
• It gets difficult to quickly and completely burn a mixture in such a thinly squeezed “pancake” of a combustion chamber.
• With such an increase in pressures, there can be more stress on internal engine components.
• It gets difficult to produce such a small combustion space and still package the spark plug, valves, valve reliefs for clearance to allow for any overlap for valve timing (needed for good, high RPM “breathing”).
• An most importantly, there is is the ever present danger of “piston destroying” Detonation (spark knock).

Detonation:  The higher the CR, the higher the temperature and pressure when the spark ignites the charge.  The flame travels across the chamber in all directions from the spark plug to eventually completely burn everything.  This takes some time, 60-80 degrees of crank rotation, and is why you fire the spark plug at, say, 35 degrees before TDC and not at TDC.  These higher temperatures and pressures can cause the unburned mixture away from the spark plug to auto-ignite, or detonate.  This drastically raises temperatures and pressures and can bust out piston ring lands, blow holes in pistons, cause the spark plug to get very hot and glow and cause pre-ignition, and generally “wreck your weekend”.  To avoid detonation, you  use a higher octane fuel and keep the CR to a reasonable level.

So we can see that it is important for engine builders to know the engine’s compression ratio.  Some race classes even limit Compression Ratio, so you want the highest CR you can get but not get disqualified in tear down. That is why Performance Trends developed Compression Ratio Calculator.  It makes it much easier to keep track of all the little volumes which make up the total Combustion Chamber volume.

The Compression Ratio Calculator includes things you may not have considered, that the head gasket may be a different ID than the bore, the piston top OD is significantly smaller than the bore, providing a space above the first compression ring, etc.  The program also includes various engine building features like determining the “deck height stack up” (piston compression height, rod length, etc) to fit inside the engine.  We’ve also included several utility calculators (some companies call these “wizards”) to calculate piston dome or dish volume, find the needed piston dome (or some other parameter) to produce a desired CR, find engine and  cylinder swept volume from bore and stroke, and much more.

We are always improving our software and that is why we are now on our third version of this program.  For version 2.3 we now have two options, the Basic version and the new Plus version.

In the Basic version you can:

• Calculate compression ratio, cylinder volume and engine displacement.
• Find a desired compression ratio using chamber CC’s, deck height clearance and other inputs.
• Determine how much of a contribution various dimensions have on the overall compression ratio.
• Calculate Bore – Stroke ratios and Rod – Stroke ratios, boring and or stroking effects (if you are looking for a desired displacement you can determine the required bore and stroke)
• Calculate cranking compression pressure and dynamic compression ratio.   (Dynamic compression ratio does not use the entire swept volume in the equation, but only the volume in the  cylinder at the point where the intake valve has closed.)
• Determine piston dome volume or piston dish volume.
• Enter head gasket volume as Bore and Thickness or Volume CC’s directly.
• Determine any of the following: rod length, deck height, deck height clearance, piston compression height or stroke based on you specifying the other four.
• Allow for English or metric units.
• Like most other Performance Trends programs you can save your changes to compare with other versions of your inputs or print out the report to share with your workers, engine builder or your customers.

If you choose to upgrade to the Plus version (you can choose to upgrade at a later date) you will get the following inputs on top of all the inputs described above:

• Calculate Effective Compression Ratio that is used by supercharger companies to show requirements for boosted engines.
• Estimate the rod bolt loads, piston speed and G’s at a specific RPM.
• If you are looking for a better estimate of the Cranking Compression you will have more input details to do so.
• Pick the Gasket Bore Diameter from preloaded, known FelPro and other manufacturers of gaskets.
• If you are going to mill the head this program can calculate the effect of the heads CC chamber.
• Calculate the Piston dome CC’s based on simple geometry (not from CCing the piston).

Our Compression Ratio Calculator is many engine builder’s best friend.

Cycle Data Graphs

You can also use the “See-Engine” option at the top of the tabular results. Click on “See-Engine” to bring up the Piston-to-Valve Clearance screen. There you can watch the interaction of the valve lifts, piston position, cylinder and port pressures and flows to truly better understand what goes on inside the engine. There you can also click on Options to bring up the See-Engine Options screen, where you can choose to export Tabular Data of the data used on this screen to Notepad.

See-Engine Output Options

You can also use the “ASCII File” option at the top of the tabular results. Click on “ASCII File” to bring up the Export ASCII File screen. There you can chose most any RPM Data or Cycle Data to export to an ASCII (text) file in various formats. This file can be imported to Excel for most any analysis you wish.

Options to Export Cycle Data

By looking “inside” the engine, you can gain tremendous understanding about how modifications affect engine performance.

First, a little background: Stall RPM is the engine RPM with the engine at full power but with the converter output RPM (also vehicle speed) at zero or “stall”. This is the RPM you see on your tach when you first launch the car at full power. Pick the right converter and you will stall (launch) the car at an optimum engine RPM for quickest ET.

The common misconception is that a converter has a particular stall RPM built in. You buy a 5000 RPM converter and it should stall at 5000 RPM, right?

Think about your everyday 6 cylinder “grocery getter” with an automatic. From a standing start,if you give the engine a little gas, say 1/4 throttle, the engine revs up some (maybe to 1000 RPM) and the car moves. Give it 1/2 throttle and the engine revs higher and you accelerate a little harder. Go full 100% throttle and the engine revs higher to the afore mentioned “stall RPM” and accelerates as hard as this engine/converter combo will allow. For your “grocery getter”, this may be 1800 RPM.

But think, for the 3 situations, all 3 were at the stall RPM for the amount of engine torque you were producing. For a small 2 cylinder engine at full throttle, it may be only be able to produce the torque that your 6 cylinder produced at 1/4 throttle. With the exact same converter, the stall RPM is only 1000 RPM for that 2 cylinder engine. On the other end of the scale, if you replaced your 6 cylinder with a 500 CID V-8, this same converter could stall at 3200 RPM.

The point being a converter does NOT have a stall RPM built in. The stall RPM depends on the engine’s torque curve in front of the converter. If something increases the torque, the stall RPM increases.

What a converter DOES have built in is something called “capacity”, sometimes called “K factor”. The automakers measure the capacity with 2 large dynamometers, one driving the input and the other absorbing the output. They measure torque and RPM in and out, and calculate speed ratio, torque multiplication, efficiency, capacity and more from stall (0 output RPM) to the point ehere the converter locks up (at a speed ratio from 90-98% or so). This requires an expensive test rig and most aftermarket converter suppliers can not afford this. Therefore you typically don’t get a capacity number or performance curves for racing converters. It would be great if you could.

It would be especially great to have these performance curves when it comes to doing a drag race simulation, like done with our Drag Race Analyzer. Because these performance curves are not available (including even the simplest real converter specs like capacity and torque multiplication at stall), we must estimate these critical specs from info the user has. And, typically the user only has some estimate of Stall RPM from the converter supplier. Or, they know their own converter’s stall RPM with their engine from experience at the track.

The Drag Race Analyzer asks for Torque Converter Capacity as an input, but has a method to estimate the capacity from the torque curve you have entered into the program, and the converter’s stall RPM. Capacities range from 80 for a very tight converter up to 400 or higher for very high stall (loose) converters. You can enter the stall RPM, and the program shows the required converter capacity to produce that stall at the current weather conditions with the current torque curve.

Drag Race Converter Capacity or Stall RPM input screen

The disadvantage of this method is the average user may not understand why they can not just enter the converter’s stall RPM directly. The advantage of this method is that when you go to a different condition, like weather or engine modification, the program will accurately predict the new stall RPM and the new launch, ET and MPH.

For example, say you have a typical big block with a “5000 RPM stall converter”. The Drag Race Analyzer will show the following stall RPMs for the 3 different “air” conditions. These conditions were simulated by changing the elevation from 0 to 1000 to 5000 ft.

Elevation         Stall RPM
0 ft                   5090
1000 ft              4980
5000 ft             4530

The table shows a 450 RPM drop in stall RPM for a 1 mile increase in elevation. Anyone who has raced at tracks with very different elevations will say the converter stall RPM does drop when the elevation goes up. Now, even if it is harder to understand, wouldn’t you want your drag race simulation program to do the calculations accurately?

To improve the power to drag ratio, you want to increase the power and reduce the drag, which makes sense.  To go faster, you need more power and you want to make the car more aerodynamic.  However, what you may not know, is that to go twice as fast, you need eight (8) times the power.  If your 200 HP car can top out at 120 MPH, you would need 1600 HP to top out at 240 MPH.   (You would also need some really good tires to hold together, and good aero downforce to stay on the road).

Most all racers have some idea on how to improve the engine’s power.  Engine power can be fairly reliably simulated with our Engine Analyzer computer programs, and these can all be tested with an engine dynamometer and our Dyno Datamite software.

The biggest contributors to aerodynamic drag are the vehicle’s frontal area (silhouette of vehicle when viewed from the front) and it’s drag coefficient (a rating of how easily the vehicle slices through the air for it’s frontal area).  Drag coefficients vary from a high value of about .8 for an upright rider on a vintage motorcycle, to .6 for an older pickup truck,  to .4 for a modern aerodynamic sedan, to .35 for a modern sports car, to an incredibly low .15 of “pencil shaped” land speed record cars like the Blue Flame.

To optimize the aerodynamics of your particular vehicle, you should read everything you can get your hands on.  The basic shape has a large effect, but subtle things like windshield moldings, vehicle rake (lowering the front end), underbody protrusions all add up to huge improvements.  Typically you just make these mods you have read about and hope for the best, because it is very difficult to measure if  your aerodynamic mods have made any really improvement.

The best way to actually measure the effect of aerodynamic mods is to rent a wind tunnel, at around $50,000 per day.  For the rest of us, we can preform coastdown tests.  This is where you get your car up to a top speed, throw it in neutral and let it coast to a lower speed.  For this to be accurate, you should use the same stretch of very flat road, and do the test in both directions to minimize the effects of wind and slight grade of the road.  If the coastdown times, from say 100 to 60 MPH has increased 3%, it means you have made a 3% improvement (reduction) in drag coefficient.

The best way to do coastdown tests it to do several and average the results.  It is also best to use some type of data logger so you get lots of accurate data and the driver can concentrate on driving.  From doing coastdown tests myself, I can say that this requires lots of tests and patience to get good results.  Also, the higher the speed (not on public roads), the better the results.  There is also software which can separate how much of the coastdown drag is from the tire rolling resistance and how much is from aerodynamic effects, and come up with actual numbers, like your drag coefficient is .322.

OK, so we’ve talked about the power to drag ratio contributors.  But there are other, secondary effects which also have an effect.  These effect how efficiently you take advantage of the power to drag ratio you have to work with.  For example, top speed tracks vary in length, from Maxton’s Monster Mile at just 1 mile, to El Mirage’s 1.33 miles, to Bonneville’s legendary 5 miles.  To get the optimum top speed, you want to get to top speed quickly, to optimize acceleration at all times.  This gets back to the drag race idea.  You don’t have to worry about 60 ft times or pulling wheelies, but you do want to optimize your shift points.  A quick El Mirage computer simulation showed a .6 MPH improvement on a 140 MPH car by shifting quickly at optimum RPMs, vs “lazy” shifting at RPMs about 1500 RPM off optimum.

Total gear ratio is critical.  You want to put the engine at it’s peak HP RPM when the vehicle reaches top speed.  The peakier the power curve, the more critical this is.

Another aerodynamic effect is lift.  The lift coefficient  determines how much your vehicle acts like an airplane wing.  If you have a high lift coefficient, you loose traction at the tires and loose steering control.  Too much negative lift coefficient, and your tires have to do more work and rolling resistance increases.  This is another item which will require you reading up what others have done.  Lift coefficient is very difficult to measure, but you should be aware of its effects as it has a huge effect on safety.

Another detail is a hood scoop efficiency.  An effective hood scoop at high speed produces significant boost pressure for the engine to improve power.  For example, a perfect hood scoop at 200 MPH will produce .75 psi boost, which equates to approximately a 5% power improvement.  However, if you have to increase the drag 10% with a big, protruding bump on the hood, it’s probably an overall loss to top speed.

To truly understand all the things which affect “real world” top speed performance, you need a vehicle simulation programs like Drag Race Analyzer or Drag Race Analyzer Pro which lets you modify things like we’ve talked about, which include:

• Actual engine power curve through entire RPM range
• Drag coefficient and frontal area (and possibly lift coefficient).
• Transmission and final drive ratio
• Hood scoop efficiency
• Tire type (to estimate rolling resistance)
• Track length
• Shift RPMs and shift type (fast, slow, power shift, etc).

We carry many other programs that can be used for Land Speed Record applications including: Drag Racing DataMite, Rotating Inertia Calculator and our Engine Analyzer programs.

You also want to read up on what ever you can find on top speed racing.

Circle Track Log Book

Organized records are incredibly valuable to a race team.  Written log books are nice and easy, but have limitations.   However, Performance Trends Circle Track Log Book can help you keep track of you vehicle’s setup from race to race, and track to track. It keeps records of your Chassis, Springs, Front Suspension, Rear Suspension, Tires and Track Results. Plus it even let you put in User Defined values just in case you have something on your car that is not in the program.

Some of the chassis parameters you can keep track of are: the Corner Weights, Brake Pads, Frame Height and Fender Height. Other chassis inputs could be aerodynamic parameters like the Nose Height and Width, Roof Height, the Rear Spoiler Angle, Height and Height above ground.  Other inputs are Pinion Angle and Gear Ratio, even any Ballist weight and location.

Suspension parameters you can record include the springs, like recording your Spring Rating and giving each spring a description. And you are able to record your Shock Rating Bump and Rebound, shock travel, and again you can give each shock a description.  Sway Bars go hand in hand with the springs and you can record both front and rear as well.  Circle Track Log Book will remember different components you’ve entered, like springs.  This way you can build up a library of components, and you don’t have to type them in again next time.  You can just pick from a list you’ve already entered.

Circle Track Log Book

Other suspension parameters include: Caster, Camber, Toe In, the length and angle of your upper and lower A arms, plus the percentage of Anti-Dive or Anti Squat.  Some of these parameters are not straight forward measurements, like percentage Anti-Dive or Anti-Squat, and would have to be handled in a suspension analysis program.  Circle Track Log Book will actually link up with Circle Track Analyzer to have these calculations performed automatically.

Tires are one of the most important and most difficult to record. But Circle Track Log Book will help you with this chore. You can give the tires a Description and record the Compound. Plus you can record the tires PSI, Circumference and Stagger when they are both Cold and Hot and record the difference.  Most importantly, you can record the tire temperatures for the Inside, Center and Outside of the tread.  This recording keeping program can produce valuable suspension tuning suggestions based on tire temperature analysis.  These suggestions would include basics on tire inflation pressures, to suggesting changes to camber, cross weight, stagger, etc.

And of course you need to remember what track you were at and how you performed. You can name the track, record the track type and the banking, make Comments on the car’s handling on the corner entrance and exits, record weather data, plus your lap times.

Once you start keeping your records in a computer readable form, you can easily search for when changes were made, or make comparisons between setups.  Now you will know exactly what changed you have made, and what setup you should be running for this track.

A lot of things affect dyno repeatability, like engine temperatures, fuel type, weather conditions, how the test was run, engine condition and build (like air cleaner type, spark timing) etc. For those things which you CAN control, you want to do things exactly the same each test. For example, engine water and oil temperature can have a significant effect on engine power, and are things you have some control over. You can install coolers and have them hooked up to temperature controllers. Or you can make sure you start each test with the same temperatures.

However, weather is something very difficult to control, and it has a large effect on the results. For example, a drop in barometric pressure from 30 inches to 29 inches would reduce power output by 3-4%. That’s more effect than many modifications you want to test for. Fortunately, there is an answer to “controlling” the weather for dyno testing.

First, here’s a little background info. An engine makes power from the fuel it burns, the more fuel, the more power. However, we all know that you can’t just keep richening up the carb and expect to keep making more power. That’s because there would not be enough oxygen to burn all the fuel. What actually limits the power an engine can make is the amount of oxygen you can pump through the engine. Most race modifications are designed to get more air through the cylinder, like reducing flow restrictions, more cubic inches, supercharging, etc.

Well, weather changes are much like supercharging. Superchargers make power by raising the density (pressurizing) of the air entering the engine. The same thing happens when the barometric pressure goes up, the air density (and therefore oxygen density) goes up. As the air temperature comes down, the air density goes up (like what an intercooler does). As the humidity goes up, the water vapor displaces the oxygen in the air and oxygen density comes down, reducing the engine’s power.

This all may seem quite complicated, but fortunately a lot of work has been done to understand these effects. Formulas have been developed to “correct” the power output measured on a dyno with some particular weather to what it would have produced on some standard day.

The first thing to decide is “what is a standard day?” For most race dynos, a standard day was 29.92” barometer with 60 degrees air temp and completely dry air (0% humidity). These conditions are much better for producing power than what most people would see driving their car. So the Society of Automotive Engineers (SAE) came up with a more typical day of 29.60” barometer, 77 degrees and 36% humidity. Dyno power curves corrected to the SAE conditions will show about 4% less power than curves corrected to the Race Dyno conditions.

Say you measured 182 HP in some actual weather that had weather conditions much worse than the standard day. The Dyno Correction Factor formulas would increase the 182 HP to, say, 192 HP if you use the SAE correction factor, or 200 HP using the Race Dyno correction. Theoretically, if you ran this engine on a day with the Race Dyno conditions (29.92”, 60 deg F, 0% Humidity), you would measure 200 HP on the dyno.

If you ran this same engine on a day with weather BETTER than the standard conditions, you could measure 212 HP. Again, but applying the Race Dyno correction factor, the “Corrected HP” should be brought down to 200 HP, the exact same as when you ran it in the bad weather. See the table below.

      Weather conditions      Bad Air        29.92” *         Good Air
                                                              60 Deg

      Measured HP  **           182              200                 212

      Corrected HP                200              200                 200

      * Standard Race Dyno weather conditions.

      **  Measured HP is many times called “Observed HP”

As you can see, the HP you measure (Observed HP) can vary significantly with weather conditions. However, the engine repeats exactly (200 HP) if you only look at the Corrected HP.

Notes:

If we had chosen the SAE correction factor, the trends would have been the same, just that the 200 HP number would have been 192 HP instead.

The example data shows the dyno correction factor working perfectly. In the real world, it does not work perfectly. However, the corrected data is almost always more repeatable than observed data, providing the weather sensors are repeatable, and care is taken to eliminate all other testing variables.

The effect shown on Observed HP is very much the same as seen with Observed Torque.

Summary:

This shows the basic function of Dyno Weather Correction Factors. Because weather affects power, we factor the measured torque and HP up or down the proper amount to make it more repeatable from day to day. Because the Corrected data is more repeatable, when you DO see a change in Corrected Power, you can have more confidence the change is real.

Sometimes you have a system that has been working for 10 to 20 years. Then one day it is no longer working.  Or with the Cam Dr, which only works on old DOS computers, you can no longer find one of these old DOS computers.  The last thing you want to do is throw it out and buy a new cam profiler. You can save yourself thousands of dollars if you use some of the old parts and just buy Performance Trends items that will get it up and running again.

A Cam Dr Retrofit Kit would include some electronics to read your existing lift and rotation sensors, and new Windows software (Cam Analyzer) to read these sensors.  The electronics typically can be read with a serial port (com port), or through a USB port with a USB-Com adapter.  So you can now use most any new Windows computer, even a laptop.  And with the updated software, you get an easier mouse driven interface, with many more analysis features, and printouts of graphs and reports on most any new printer, even color.  That is one HUGE improvement over being tied to some old DOS computer.

Cam Analyzer

If you are interested in Retro Fit Prices follow the link and scroll down to “Cam Dr. Retro Fit Kit” or you can give us a call at 248-473-9230 if you have other needs.