05-30-2008, 01:07 PM
in today's performance market, many people are trying to develop products that make power for cars - some of them work - some don't - some show gains on charts, but do nothing in reality - some don't show gains on charts, but do in reality - how is anybody supposed to sift through all of the hype and promises, see real data, and make an educated decision?
well, the first thing is to understand how the testing works
dynos are the most commonly used tools for showing performance gains - they measure the force applied to the roller, and calculate that to horsepower and torque - but, all dynos are not created equal
some apply an approximation of load to the equation - this varies from dyno to dyno, based on model, roller size, brake motor, etc - most can calculate forward to the flywheel, but they all do it differently
the tolerance of most high quality dynos is =/- 1% - on our engines that can mean every bit of 2hp, or more
you also have to consider the ambient conditions - these can change dramatically, and affect the results by as much as 10% - things like the temperature of the transaxle can make huge differences - intake temp, heat soak, sensor location, wheel size, wheel weight, tire size, tire weight, tire pressure, humidity, and strap tension, all play large roles too
octane is a HUGE factor in results - testing on 91 versus 93 will result in a 2% change all by itself
so, how do you know if a test is accurate, or worth the paper it's printed on? the short answer is, usually you don't
tests are worthless if they don't do comparisons on the same dyno, on the same day, on the same car - the conditions must be identical to provide accurate results - calculations for conditions are only approximations, and are limited in accuracy to the tolerances of the devices used
this is especially true when trying to compare things like chips - the differences between them is small enough that in order to get any real data, you have to take a lot of steps to insure a fair test - you have to carefully measure all of the temperatures and such, as well as the times between runs, and take care to insure that the runs are equal
so, ignore any claim by any manufacturer that is not supported by before and after tests, showing the conditions of the tests to be the same
also ignore the peak numbers, and focus on the area below the curve - that is a better real world indicator of what you will see - peaks are great for advertising, but pretty much useless for real world driving - peaks are generally outside the area that most people drive - mid range gains are the most useful for most drivers - peaks may come into play on race cars though, where every little bit helps, and a lot of time is spent in the upper rev range
ignore the final numbers too, and look only at the increase percentages - as an example, a chip that makes 20hp on a car taking it from 240 to 260 fwhp is actually making less power than a chip that makes 15hp on a car taking it from 187 to 202 fwhp
it can be done, but this stuff takes a lot of time and money - it pretty much takes all day to compare 2 chips, and do it well - you cannot do it in an hour with 3 runs - anybody who tells you otherwise has an agenda, or is trying to sell you something
be careful -p.t. barnum said it best - "a sucker born every minute" - ignore the hype - check with your friends or other people using something - there are a lot of good products out there - in the end though, you may well end up trying things yourself to see what works for you, and trusting manufacturers you know
well, the first thing is to understand how the testing works
dynos are the most commonly used tools for showing performance gains - they measure the force applied to the roller, and calculate that to horsepower and torque - but, all dynos are not created equal
some apply an approximation of load to the equation - this varies from dyno to dyno, based on model, roller size, brake motor, etc - most can calculate forward to the flywheel, but they all do it differently
the tolerance of most high quality dynos is =/- 1% - on our engines that can mean every bit of 2hp, or more
you also have to consider the ambient conditions - these can change dramatically, and affect the results by as much as 10% - things like the temperature of the transaxle can make huge differences - intake temp, heat soak, sensor location, wheel size, wheel weight, tire size, tire weight, tire pressure, humidity, and strap tension, all play large roles too
octane is a HUGE factor in results - testing on 91 versus 93 will result in a 2% change all by itself
so, how do you know if a test is accurate, or worth the paper it's printed on? the short answer is, usually you don't
tests are worthless if they don't do comparisons on the same dyno, on the same day, on the same car - the conditions must be identical to provide accurate results - calculations for conditions are only approximations, and are limited in accuracy to the tolerances of the devices used
this is especially true when trying to compare things like chips - the differences between them is small enough that in order to get any real data, you have to take a lot of steps to insure a fair test - you have to carefully measure all of the temperatures and such, as well as the times between runs, and take care to insure that the runs are equal
so, ignore any claim by any manufacturer that is not supported by before and after tests, showing the conditions of the tests to be the same
also ignore the peak numbers, and focus on the area below the curve - that is a better real world indicator of what you will see - peaks are great for advertising, but pretty much useless for real world driving - peaks are generally outside the area that most people drive - mid range gains are the most useful for most drivers - peaks may come into play on race cars though, where every little bit helps, and a lot of time is spent in the upper rev range
ignore the final numbers too, and look only at the increase percentages - as an example, a chip that makes 20hp on a car taking it from 240 to 260 fwhp is actually making less power than a chip that makes 15hp on a car taking it from 187 to 202 fwhp
it can be done, but this stuff takes a lot of time and money - it pretty much takes all day to compare 2 chips, and do it well - you cannot do it in an hour with 3 runs - anybody who tells you otherwise has an agenda, or is trying to sell you something
be careful -p.t. barnum said it best - "a sucker born every minute" - ignore the hype - check with your friends or other people using something - there are a lot of good products out there - in the end though, you may well end up trying things yourself to see what works for you, and trusting manufacturers you know
94 Midnight Metallic Blue Cab Porsche 968 w/deviating cashmere/black interior and WAY too many mods to list - thanks to eric for creating www.968forums.com
"It isn't nearly as expensive to do it right as it is to do it wrong."
