Miscellaneous

Planet-9 FAQ

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Acronyms

Acronyms

Acronyms

In this day of information overload, acronyms are used everywhere you look - websites, car manufacturers, even politicians (remember WMDs?) rely heavily upon the use of acronyms to get as much information to you in the shortest amount of space and time. It is very easy to get confused (particularly when a certain car manufacturer feels the need to add their name as a prefix to every option).

The following is a list of the more common acronyms you’ll encounter on this site, in your Cayman Owner’s Manual, or in conversations with other Porsche enthusiasts. If you come across another acronym that you think should be added to the list, just drop us a note.

Note: Those terms with active hyperlinks will take you to other FAQs (see, they’re everywhere!) or other websites that further define the term.

Porsche Acronyms (terms relating to your car)
ABD Automatic Brake Differential
ABS Anti-lock Brake System
ASR Anti Slip Regulation
PASM Porsche Active Suspension Management
PCCB Porsche Ceramic Composite Brakes
PCM Porsche Communication Management
PIWIS Porsche Integrated Workshop Information System (diagnostic tester)
POSIP Porsche Side Impact Protection
PSE Porsche Sport Exhaust
PSM Porsche Stability Management
SC Sport Chrono Package
TIP Tiptronic S transmission (automatic)
TPMS Tire Pressure Monitoring System
   
   
Porsche Model Numbers (internal codes used to identify different cars)
C2S Porsche Carrera 2S - 993 available 1997-1998
C4S Porsche Carrera 4S
CS or C7S Porsche Cayman S
TT Twin Turbo, usually added to a platform number like 993TT
901 Original model number given to the 911.  Changed to 911 because Peugeot owned the rights to all 3 digit model numbers with a 0 as their center digit.
904 Limited production mid engine car made in 1964 and 1965.  Powered by a 4, 6 or 8 cylinder engine.  aka - Carrera GT, Carrera GTS, 904/6 and 904/8.
906 Replacement to the 904.  65 were made in 1966.  aka - Carrera 6
911 The most quintessential Porsche model, made from 1964-1989.  Always powered by a rear mounted 6 cylinder engine.
912 Entry level 911 powered by the 356's 4 cylinder engine, 1965-1969.
914 A mid engine entry level street Porsche made from 1969-1976.
924 Entry level Porsche made from 1976-1988 w/front mounted water cooled 4 cylinder engine.
928 GT car was made from 1978-1995 w/front mounted water cooled V-8.
944 Front engine all Porsche version of the 924 built from 1982-1991.
951 Porsche 944 Turbo from 1986 - 1991
964 The replacement to the 911, sold from 1989-1992 sharing the 911's rear engine format and looks.
968 The ultimate evolution of the 944, sold from 1992-1995.  This was the first Porsche to ever have Vario-Cam.  Known as a great daily driver.
986 Porsche Boxster platform from 1997 - 2004
987 Porsche Boxster / Cayman platform from 2005 - up
993 Replacement of the 964, sharing the 911's rear engine format and looks.  Sold from 1993-1998.  The first 911 derivative to use hydraulic lifters.
996 Replacement of the 993.  Sold from 1999-2004.  The first water cooled 4 valve per cylinder derivative of the 911.
997 Replacement of the 996 sold from 2005-present.
   
   
Car Club Acronyms (terms relating to car club events)
AX or AutoX Autocross (Porsche Club of America)
DE Driver Education track event (Porsche Club of America)
ET Elapsed Time
HPD High Performance Driving School
PCA Porsche Club of America
PCNA Porsche Cars North America
   
   
General Auto Acronyms (terms you're likely to encounter on this and other websites)
BB Boxster Board (Boxster Board Forum)
BT Blue Tooth
CAN Controller Area Network (internal high speed network)
CAI Cold Air Intake
CATBACK Aftermarket exhaust system from the CATalytic converters BACK to the tips (as opposed to a FULL system)
CC Cayman Club (www.caymanclub.net)
CROC Slang term for the Porsche Cayman referring to it's name sake the Caiman Crocodilus
DFI Direct Fuel Injection DFI delivers fuel directly into each combustion chamber using an electromagnetic injection system.
ECU Electronic Control Unit
HID High Intensity Discharge (also known as Xenon lights)
LED Light Emitting Diode
MAF Mass Air Flow Sensor
MOST Media-Oriented Systems Transport (fiber optic network for multimedia)
OBD/OBD II On-Board Diagnostics (EOBD - Europe On-Board Diagnostics)
MY Model Year
P-CAR Porsche Car/Vehicle
PDK Porsche DoppelKupplung - Virtually instantaneous, zero power interruption dual-clutch auto-manual transmission. Replaces Tiptronic.
PP Panamera Pit (Panamera Talk)
ROW Rest Of World (cars made for markets other than USA)
WOT Wide Open Throttle
   
   
Internet Expressions (general terms you're likely to encounter on this and other websites)
BTW By The Way
IMHO In My Humble Opinion
OTOH On The Other Hand
PM Private Message
ROFL Rolling On the Floor Laughing
ROFLMAO Rolling On the Floor Laughing My Ass Off
WTF What the F*** (expletive) [not very polite]
WTH What the heck / What the h*** (expletive)
   
   

FAQ Author:

This FAQ was written by racerboy
Last Revised: August 2010

Cayman vs. Cayman S

I have often read threads asking about the exact differences between a Cayman and a Cayman S, and often times the replies are full of inaccurate or incomplete information.  Here is an exact break down of every difference I can find between the two models.

Technical & Equipment Differences (Model year 2008):

  Cayman Cayman S
Base Price: $49,400 $59,100
Engine 2.7 Liter, 245 bhp, 201 lb.-ft. 3.4 Liter, 295 bhp, 252 lb.-ft.
(not available as an option)
Brakes (F):
(R):
11.8" x 0.9" rotors w/8.30 sq-in. pad surface
11.7" x 0.8" rotors w/7.44 sq-in. pad surface
12.5" x 1.1" rotors w/9.61 sq-in. pad surface
11.8" x 0.9" rotors w/7.44 sq-in. pad surface
(not available as an option)
PCCB Availability: Not Available Optional
Wheels (F):
(R):
6.5" x 17" - 205/55
8.0" x 17" - 235/50
8.0" x 18" - 235/40
9.0" x 18" - 265/40
(option code 401 - $1,235)
Standard Transmission: 5 Speed Manual 6 Speed Manual
(option code 249 - $690*)
Sound System: 50 Watts, 4 Speaker Sound Package Plus, 180 Watts, 9 speakers
(option code 490 - $715)
Front Spoiler Lips: Black Body Color
(option code CNJ - $485)
Interior Trim: Volcano Grey Aluminum Look
(option code CDE & CDF - $810)
Instrument Dials: Black faces. Speedometer limit is 175 MPH. Aluminum Look faces. Speedometer limit is 190 MPH.
(option code XF? - $690)
Exhaust Tip: Single Opening Dual Opening
(not available as an option)
Curb Weight (manual): 2,866 lbs. 2,976 lbs.
Curb Weight (Tiptronic): 2,998 lbs. 3,064 lbs.

Performance Differences (Model Year 2008):

Fuel Consumption (manual): 23 City / 32 Highway 20 City / 28 Highway
Top Speed (5 Speed manual): 160 MPH N/A
Top Speed (6 Speed manual): 162 MPH 171 MPH
Top Speed (Tiptronic S): 157 MPH 166 MPH
0-60 Times (Manual)**: 5.8 seconds 5.1 Seconds
0-60 Times (Tiptronic S)**: 6.7 seconds 5.8 Seconds

* The 6 speed transmission is only available in the Cayman with PASM for $2,680.  For comparison purposes, the price difference shown above is assuming that both cars are equipped with PASM.
** Most magazines have reported faster 0-60 times.  Because it's impossible to pick any one magazine as a benchmark, Porsche's claimed performance numbers have been used in this comparison.


Upgrading a Cayman to Cayman S specifications:

Some of the differences can be added to a Cayman as options, some cannot.  If a Cayman was equipped with all available Cayman S options, the price difference between it and a Cayman S would be $5,075, without the engine and brakes.  Adding bigger brakes and 50 horsepower to a Cayman in the aftermarket would cost far more than $5,075.  The Cayman is a fantastic car with lots of abilities, but for the driver who wants or needs the added performance of the Cayman S, the relatively small difference in price is actually an incredible value.

Informative Threads:


FAQ Information:

This FAQ was written by Gator Bite.
Last Revised: November 2007

Tiptronic Tips

Tiptronic Tips

(By KS-CS)
 


BASICS:
The 5-Speed Porsche Tiptronic has 2 modes: Drive (auto) and Manual. It is possible to switch back and forth between these modes, even while driving, by moving the selector right or left. On the right side of the instrument cluster, beneath the coolant temperature gauge, is the indicator for the transmission. It shows which gear you are in, and whether you are in Drive (D) or Manual (M) mode.

DRIVE (AUTO) MODE:
In D mode, the transmission behaves like most automatic transmissions, with a couple of unique features. First of all, when you place the transmission in Drive, or when you slow to a stop, the Tip will normally start out in 2nd gear. The advantages of this appear to be smoother acceleration in traffic or stop & go driving, better gas mileage, and less chance for wheel spin on slippery surfaces. If you prefer to start out in 1st gear, it is as simple as pressing the downshift button on the steering wheel to select 1st gear. The gear indicator will temporarily show you in M mode, until the car shifts on its own into 2nd, and you will be back in D mode.

Many drivers are initially unaware that you can use the steering wheel switches to both downshift or upshift at any time while you are in D mode. Anytime that you use the buttons to shift, the Tip will stay in M mode for about 8 seconds, and then revert to D mode if you don’t do anything else. This feature is useful if, for example, you want to downshift in advance of a turn, or in preparation to pass another vehicle.

You can also downshift by activating the kick-down function with the accelerator pedal as well.  This can be performed by a quick jab of the accelerator pedal (it is not necessary to mash the pedal to the floor).  In this way, you can use the kick-down to downshift for the same reasons you might otherwise manually downshift.

You may note that the Tiptronic rev-matches on downshifts, which lends to the sporty character and driving experience.

MANUAL MODE:
When you move the gear selector to Manual, you will note that the instrument panel indicator will also show you are in M mode. If you start the engine, and then put it into Manual without moving prior, it will go into 1st gear to start; after that however, like in D mode, it will go into 2nd gear at a stop, unless you manually downshift into 1st.

M mode also functions differently depending on your PSM setting. If you leave your PSM active, then under acceleration the M mode will hold in the selected gear until the redline, but it will upshift automatically at the redline. If you turn off the PSM, then the car will accelerate all the way to the rev limiter if you let it. In M mode, the car will still automatically downshift all the way to 2nd gear if you come to a near or complete stop (or if the revs would fall below the idle range in higher gears).

A word about the steering wheel selector buttons: it may appear that there are separate upshift and downshift buttons on each side, but in reality, it is just a toggle switch with a ridge in the center.  The ergonomics of this design are such that, you can leave your thumb in one position, e.g. over the + button to upshift, and still downshift by pressing down on the dividing ridge of the switch, without moving your thumb or hand position.

SPORT CHRONO OPERATION:
The Sport Chrono option on a Cayman affects the Tiptronic function as well. In D mode, it alters the shift maps so that the car will hold revs higher before upshifting, and it shortens the actual shift time. It will also downshift sooner than with the SC off. In M mode, upshift suppression will occur the same as if you turn off the PSM, so that the engine can be run all the way to the rev limiter.

TIP ON THE TRACK:
The following link is from a Boxster driver with his recommendations for driving the Tiptronic on the track:

Driving Porsche Tiptronic at Track Days

MORE INFO:

Cayman S Tiptronic Info from 2006 Technik Service Manual


FAQ Information:

This FAQ was written by KS-CS.
Last Revised: February 16, 2008

Tourist Delivery

Options Code: TD5

Price: $2,250

Description:

Tourist Delivery is an option that allows you to take delivery of your new Cayman at the Porsche Factory in Zuffenhausen Germany and drive it around Europe before it's sent to your home country. 

The process is a bit complex.  Educating yourself on it can eliminate many surprises and make the experience more enjoyable.

Benefits:

Imagine driving your new Porsche on the Autobahn, through the Alps or on the Nürburgring.  Imagine showing your car to your friends back home and being able to say that you picked it up at the factory in Germany and drove it at 170 mph legally.  Incredible scenic roads, highways with no speed limits, the worlds most famous race track, European food and drink and a vacation in which you get to know and drive your new Porsche.  This can be a dream come true for most Porsche enthusiasts.  There is no better way for to explore Europe than in their own new Porsche. 

Drawbacks:

Lots of waiting, a hefty VAT deposit, break in on the autobahn and holes in your front bumper. (To drive your car in Europe you will need to have two license plates on your car.  There is no way around this.  Your front bumper WILL be drilled.) 


What's Included in Tourist Delivery:

  • Transport of your car from Uusikaupunki Finland to the Porsche Factory in Zuffenhausen Germany
  • Preparation of your car for street use in Europe
  • Temporary European registration and license plates (yours to keep as souvenirs after your trip)
  • Appropriate Insurance Coverage for your vehicle during your trip (16 days included - US insurance is void in the EU)
  • Legally required First Aid Kit and Emergency Triangles (yours to keep)
  • Lunch passes for 2 to Porsche's Executive Dining Lounge (5 star dining room)
  • Transport of you car from Zuffenhausen to your home dealership
  • One nights hotel accommodations in Stuttgart.  There are 3 different hotels to choose from.
  • Reimbursement for your transportation between the hotel and the factory.
  • A full tank of gasoline. (That's a value of >$120 in Germany)

Other Important Considerations:

If you want to take advantage of tourist delivery, there are several key considerations to keep in mind. 

  • You can only request Tourist Delivery on a purchased vehicle, not on a leased vehicle. 
  • You will need to order your vehicle several months before your desired delivery date. (at least 3 months)
  • Your car must be paid for (either by cash or auto loan) 45 days before your delivery date.
  • You will need to post a refundable $10,000 deposit to cover the German VAT tax.
  • Your car will take 6-8 weeks to make it's journey home.  Be prepared for an excruciating wait. 

Preparation for Tourist Delivery:

  • Approximately one month before your delivery date you will receive a tourist delivery package.  This will contain a welcome letter explaining the process, a voucher for a nights stay in one of three different hotels, a map of the Stuttgart area, a brochure about the Factory Tour and the Porsche Museum.
  • It's important to have a cell phone on a trip like this.  Call your cell service provider before your trip to inquire about your phones ability to work in Europe and any applicable international calling fees.  If your cell phone doesn't work in Europe, you can rent one that does. 
  • There are a lot of insects in the German country side.  It would be a real good idea to come prepared.  Bring some speed shine,  windshield cleaner, bug remover, car wash and some micro fiber towels with you.
  • The Steigneberger Graf Zeppelin (one of the hotels you can choose) is a 5 start hotel that is located right above a train station that provides convenient transport to/from the airport.  There is also a very nice city center with lots of nice shops and good food within walking distance.
  • Will you be bringing a portable navigation device?  If so, make sure you have European Maps loaded into it.
  • Call your credit card company and let them know you will be making charges in Europe.  Otherwise, they may flag your unusual activity as fraud and shut your card down.  Program their international customer service phone number into your phone just in case you need it (not the 1-800 number, that won't work from Europe).

Once you're in Germany:

  • Make sure you program the phone number for Porsche Road Side Assistance into your telephone before you leave the factory.  Cars can break, and if yours does you will be very happy that you prepared for it.
  • You will want to switch your speedometer to km/h.  You can learn how to do this on page 94 & 134-135 of the 2007 Owners Manual.
  • Pay attention to German speed limit signs.  When there is a speed limit, the Germans take it very seriously.  There are many photo radar cameras around the country and they will ticket you for as little as 5 km/h over the limit.  Passing on the right is strictly prohibited.  Never do this.
  • Gas stations are not nearly as plentiful in Germany as they are in the U.S.A..  If you're low on gas and you see a gas station, fuel up.  You can literally drive 30 miles before you see another one.
  • Pay attention at the fuel pumps.  Leaded fuel is still available in Europe and if you put it into your car Porsche will not allow it to leave the country until the car has been repaired at your expense.
  • Your car will have a long journey home, and although the chances of it being damaged are very small, if it is damaged it will be hard to determine if you caused it or if they did.  Before you leave your car in Germany, it's a really good idea to clean it and take a few dozen pictures to document its' condition.  There is a Coin Operated Self Wash just 2 blocks away from the factory where you can wash your car before your return it ('Gottfried Keller Strasse' Longitude:9.15945E / Latitude:48.83512 N).  Once you're back in the Porsche parking lot, completely unload your car, take pictures of your odometer showing mileage and time and take a wide angle shot of the surrounding area so there is no disputing when and where you took the pictures.  Then take pictures of every exterior panel, the front spoiler lips, your seats, your glove box opened (so you can see the contents), your cargo net, your empty trunk and hatch, your wheels, etc....

Questions and Answers:

Q. Do you save money by doing Tourist Delivery?

A.  No.  Contrary to popular belief, Porsche Tourist Delivery actually costs more money.  $2,250 more to be exact.

Q.  Do I have to buy my car in Germany if I want to do tourist delivery?

A.  No.  You buy your car at your local dealership and request this option.  This is where you will pick up your car after tourist delivery, and this will be your dealership for support and service.

Q.  Why do I have to post a $10,000 deposit?  What is a VAT?

A.  In Germany, cars are not subject to normal sales tax.  They are subject to a Value Added Tax (VAT).  That's similar to a sales tax, but instead of a simple percentage, there are different tiers of tax based on a car's value.  If you bought a Cayman in Germany you would need to pay this tax and it would be about $10,000.  If your car doesn't leave Germany, Porsche will have to pay this tax as if you bought the car there.  For this reason Porsche insists that you provide a security deposit.  Once your car clears customs in the United States (or your home country), the deposit is refunded (with a small amount of interest).

Q.  I don't have an international drivers license.  Can I drive in Europe?

A.  Yes, the European Union recognizes most driver's license as valid permission to drive in Europe.

Q.  I can't speak German.  How will I communicate with people in Germany?

A.  English is a required study from grade 6 to 13 in Germany.  Almost all Germans can speak fluent English and are happy to try.

Q.  I want to check out of my hotel room on the day of delivery.  Can I bring my luggage to the factory?

A.  Yes.  They have a locker room there where you can store your bags while you are taking the tour, eating lunch and taking delivery.

Q.  I'm an ace negotiator.  What kind of discount can I expect to negotiate on tourist delivery.

A.  Don't take it personal there Sparky, but Porsche will NOT discount the tourist delivery option by even one dollar.  You may be able to get a discount on your car and every other option, but be prepared to pay full price for this one.

Q.  Does Porsche provide a discount on airfare?

A.  Kind of.  They have partnered with Lufthansa (see Special Airfare Offer) to get you a regular coach fare with no restrictions.  But if you shop around you are likely to find a much better price on a restricted ticket from your favorite airline.

Q.  My wife loves to shop.  Can we leave her shopping spree acquisitions in our car so we don't have to take them on the plane?

A.  Only if you never want to see them again.  The port will remove all items that do not belong in the car because all items entering the country need to be declared through customs.  (They even took my CD out of the radio.)

Q.  I was hoping to drive to Italy and tour the country but I only have 2 weeks.  Do I need to take my car all the way back to Zuffenhausen when I'm done?

A.  No.  There are many drop off points around Europe where you can leave your car, for an additional fee of course.  Take a look at the Alternative Drop Off Point list.

Q.  When will I get my VAT deposit back?

A.  Typically within 30 days of your car's arrival in the USA.

Q.  I really don't want holes in my bumper.  Can I provide Porsche with a tow hook mounted license plate holder?

A.  No.  They can not and will not mount any accessory onto a vehicle unless it is TÜV certified.

Q.  Once back home I don't plan to use a front license plate.  I really don't want to see those holes in my bumper.  Do I have any other options?

A.  Yes.  Bumper plugs cost only $24.95.  They look a lot better than holes and if anyone ever says, "What are those", you will be invited to tell them all about your adventure and how you drove your car in Germany where a front license plate is required.  (See Installation Article)

Q.  Speaking of license plates, I saw a picture of those cool little European plates that they put on the cars over there.  Is there any way I can take them home as souvenirs?

A.  You're in luck.  The plates are yours to keep, but they must remain on your car until it clears customs.  Make sure that your salesperson knows that you want and will be expecting your Tourist Delivery plates when you pick up your car.

Q.  I'd love to tour the Alps, but I have no idea where to start.  Any suggestions?

A.  Buy the book titled 'Motorcycle Journeys Through the Alps and Corsica' by John Herman.  It contains lots of great suggestions for great drives through the Alps (Southern Germany, Switzerland, Italy, France). [Special thanks to Kim who made this suggestion.]

Q.  You mentioned that they will give me emergency triangles and a first aid kit.  Why? 

A.  It's a legal requirement in Germany that all cars contain these items.  In European Porsches, there are holders on top of the tool kit that hold the emergency triangles.  If you'd like to store your triangles this way, you can order the following parts from one of our sponsors for under $10. (997.551.801.00.02A , 997.551.802.00.02A , 999.073.362.09 x 2) [Special thanks to S.3G for sharing this info.]


More Information:

Porsche Web Site - European Delivery

Porsche Tourist Delivery Sales Conditions

Tourist Delivery Acknowledgement of Terms


Informative Threads:

Tourist Delivery Day 1 , Day 2 , Day 3 , Day 11 , Day 12


FAQ Information:

This FAQ was written by Gator Bite.
Last Revised: November 2007

Understanding Dynamometers

Understanding Dynamometers
 

There are lots of different wheel dynamometers (we'll call them dynos from here on out), but they all work in one of 2 ways.

"Steady-state" dynos (also called sustained load dynos) hold the wheels at a steady speed, measure the wheel torque and speed and compute power using the formula: Power = Torque*Rotational Speed. By doing this at lots of different speeds, the curve of wheel power can be mapped out as a function of engine rpm. This can be done in any gear - ideally you'd get the same result in any gear, but the conventional wisdom is that it's best to use a gear that has a ratio near 1:1 (4th is usually used on a Cayman). Note that since the measurement is steady, the result cannot be influenced by the rotational inertias of the engine, flywheel, wheels, drum that the wheels are driving (if present - see Dynapack dynos for a superior approach that eliminates the tires and their losses from the system), or anything else. In addition to the Dynapack, Dyno Dynamics also makes a steady-state dyno, and there are probably others. Steady state dynos are regarded as more accurate, since the results are not affected by the inertias in the system, but they are more costly to acquire, and the dyno run takes longer since you must pause at each rpm of interest, make sure everything is holding steady, and then take data before moving on to the next rpm.

Note that the steady state dyno only measures wheel torque & power. There is no way to know what the drive train loss (defined as flywheel power minus wheel power) might be unless you take the same engine and test it on an engine dyno that can directly measure flywheel HP. You can estimate the drive train loss by testing a stock car, assuming that the engine makes its rated power, and attributing the difference between the measured wheel power and the rated engine power to drive train loss.


The second type of dyno (and the type that is, by far, the most common) does not directly measure wheel torque. This type of dyno uses transient, unsteady data to deduce the wheel torque, based on how rapidly the car can accelerate a drum with a known inertia. The math is pretty easy, rotational speed as a function of time is the integral of applied torque as a function of time divided by the rotational inertia. rotational_speed(t) = integral( applied_torque(t) / rotational_inertia ).

A key feature of this approach is that although the rotational inertia of the drum that is driven by the wheels is known, the rotational inertia of the rest of the system (engine, flywheel, transmission, differential, driveshafts, wheel, tires, etc.) is not known. So the system must 1st be "calibrated" for the vehicle of interest to measure the unknown vehicle inertias. This can be done by running the system up to speed, putting the car in neutral, and then applying a known torque and measuring how fast the speed decays. You then use the above integral to deduce the total inertia. Note that this omits the flywheel and engine, and this introduces the need for some sort of correction or an error will be introduced. Once the total inertia is known, then the wheel HP can be measured. Errors can be introduced if the operator is lazy and uses an inertia from another similar car. Then if your car has different tires or whatever, the results will be in error. An advantage of this approach is that the data can be acquired very quickly - the car is accelerated from low speed up to redline, and you've got a continuous trace of wheel HP, instead of a set of discrete points of HP vs. rpm with the steady-state dyno.

Note that, just like a steady-state dyno, the transient dyno does not directly measure engine HP or drive train loss. Again, the only way to know what the drive train loss is would be to directly measure the engine HP on an engine dyno, or to assume that it makes rated power.

The main item that contributes to drive train losses is friction at every step of the way. There is friction in the transmission bearings, in each of the transmission gearsets, at the bearings and gearsets in the differential, sloshing and slinging of oil in the transmission and differential housing, the CV joints in the drive shafts, the bearings in the wheel hubs, maybe a little brake drag, and then large losses to roll the tires. The tire losses can be increased on wheel dynos by the need to hold the car tightly onto the drum so no slippage occurs. This unknown and potentially inconsistent (how tight are the straps?) tire loss is a major reason why the Dynapack dynos that bolt directly to the wheel hubs are more accurate. The magnitudes of the various items that contribute to the total drive train loss are poorly understood, and thus the endless debate about whether they are 10%, 12%, 15%, or 18%.

Many people assume that they can apply an average drive train loss to their dyno run to calculate BHP.  There is no reason to expect that the drive train loss is a constant percentage. It is not likely to be a constant power, either, the truth is that the loss is an unknown function of engine speed, gear ratio, vehicle speed, weight on the tires, etc, and it will vary from car to car, dyno to dyno.

Informative Threads:

Discussion about Dynos , How to read a Dyno Dynamics print out , 15% Power Train Loss , What's a Negative Run , Wheels & Horsepower Loss


FAQ Information:

This FAQ was written by Fort Felker.
Last Revised: September 2008

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