997SC: measured HP with GTech results
#1
02-23-2010 | 01:01 PM
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500HP 997SC, measured with GTech
A Gtech calculates HP from velocity, acceleration and vehicle weight. It only measures true NET horsepower, which takes aero drag and the rolling resistance of the road into account, so it's often a heartbreaker compared to dynos. Meaning Gtech readings are likely to be lower than a manufacturer’s or honest dyno’s wheel hp readings.
In any case, I've been running some tests, and below is a shot of a 396HP run I made last night, which was at the lower end of the range I’ve received. Its not varied too much though, anywhere from 394-412. I definitely need to make more runs to get a reliable average that I have confidence in. This is exactly in line with Stacy's results and output from this modified kit. The consistency is remarkable!
To try to make this apples to apples, you can conservatively add about 20HP for drag/ friction/ wheelspin due to the factors which bring down a Gtech’s numbers vs. other forms of measure, bringing this to 428rwhp. That’s about what a dyno would read, or at least that’s my assumption. Since I have a LWFW (and as a result suffer a bit less drivetrain loss than most) if we use 13% as the parasitic loss, that would mean that I am right around the magic number of 500HP at crank.
Before this starts a war, let me acknowledge that there is a lot of room for interpretation, variation, and assumptions here. The +20hp I added due to using a Gtech and the factor of road friction and drag is a little squishy, as is the 13% drivetrain loss assumption, etc.
But what’s certain is that my 997 SC is wicked! Although there are several folks who could tell you that themsleves, from people who have ridden in it to those who remain in the distance of my rearview mirror.
CATTMAN
In any case, I've been running some tests, and below is a shot of a 396HP run I made last night, which was at the lower end of the range I’ve received. Its not varied too much though, anywhere from 394-412. I definitely need to make more runs to get a reliable average that I have confidence in. This is exactly in line with Stacy's results and output from this modified kit. The consistency is remarkable!
To try to make this apples to apples, you can conservatively add about 20HP for drag/ friction/ wheelspin due to the factors which bring down a Gtech’s numbers vs. other forms of measure, bringing this to 428rwhp. That’s about what a dyno would read, or at least that’s my assumption. Since I have a LWFW (and as a result suffer a bit less drivetrain loss than most) if we use 13% as the parasitic loss, that would mean that I am right around the magic number of 500HP at crank.
Before this starts a war, let me acknowledge that there is a lot of room for interpretation, variation, and assumptions here. The +20hp I added due to using a Gtech and the factor of road friction and drag is a little squishy, as is the 13% drivetrain loss assumption, etc.
But what’s certain is that my 997 SC is wicked! Although there are several folks who could tell you that themsleves, from people who have ridden in it to those who remain in the distance of my rearview mirror.
CATTMAN
Last edited by Cattman; 02-23-2010 at 03:05 PM.
#2
02-23-2010 | 01:49 PM
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Joined: Aug 2004
Posts: 2,134
From: Chicagoland
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A Gtech calculates HP from velocity, acceleration and vehicle weight. It only measures true NET horsepower, which takes aero drag and the rolling resistance of the road into account, so it's often a heartbreaker compared to dynos. Meaning Gtech readings are likely to be lower than a manufacturer’s or honest dyno’s wheel hp readings.
In any case, I've been running some tests, and below is a shot of a 396HP run I made last night, which was at the lower end of the range I’ve received. Its not varied too much though, anywhere from 394-412. I definitely need to make more runs to get a reliable average that I have confidence in. This is exactly in line with Stacy's results and output from this modified kit. The consistency is remarkable!
To try to make this apples to apples, you can conservatively add about 20HP for drag/ friction/ wheelspin due to the factors which bring down a Gtech’s numbers vs. other forms of measure, bringing this to 428rwhp. That’s about what a dyno would read, or at least that’s my assumption. Since I have a LWFW (and as a result suffer a bit less drivetrain loss than most) if we use 13% as the parasitic loss, that would mean that I am right around the magic number of 500HP at crank.
Before this starts a war, let me acknowledge that there is a lot of room for interpretation, variation, and assumptions here. The +20hp I added due to using a Gtech and the factor of road friction and drag is a little squishy, as is the 13% drivetrain loss assumption, etc.
But what’s certain is that my 997 SC is wicked! Although there are several folks who could tell you that themsleves, from people who have ridden in it to those who remain in the distance of my rearview mirror.
CATTMAN
In any case, I've been running some tests, and below is a shot of a 396HP run I made last night, which was at the lower end of the range I’ve received. Its not varied too much though, anywhere from 394-412. I definitely need to make more runs to get a reliable average that I have confidence in. This is exactly in line with Stacy's results and output from this modified kit. The consistency is remarkable!
To try to make this apples to apples, you can conservatively add about 20HP for drag/ friction/ wheelspin due to the factors which bring down a Gtech’s numbers vs. other forms of measure, bringing this to 428rwhp. That’s about what a dyno would read, or at least that’s my assumption. Since I have a LWFW (and as a result suffer a bit less drivetrain loss than most) if we use 13% as the parasitic loss, that would mean that I am right around the magic number of 500HP at crank.
Before this starts a war, let me acknowledge that there is a lot of room for interpretation, variation, and assumptions here. The +20hp I added due to using a Gtech and the factor of road friction and drag is a little squishy, as is the 13% drivetrain loss assumption, etc.
But what’s certain is that my 997 SC is wicked! Although there are several folks who could tell you that themsleves, from people who have ridden in it to those who remain in the distance of my rearview mirror.
CATTMAN
Wheel spin? If your getting spin during a 3rd gear pull, it's time for a better set of tires.
#4
02-23-2010 | 06:25 PM
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Posts: 2,370
From: Vancouver
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GREAT results and as I posted in your other thread......I told you that I would make sure you were happy with the end result and with those numbers...."How couldn't you be,LOL"!
Nice work!
Stacy
Nice work!
Stacy
#5
02-23-2010 | 06:43 PM
Registered User
Joined: Aug 2007
Posts: 474
From: New York
Rep Power: 42
A Gtech calculates HP from velocity, acceleration and vehicle weight. It only measures true NET horsepower, which takes aero drag and the rolling resistance of the road into account, so it's often a heartbreaker compared to dynos. Meaning Gtech readings are likely to be lower than a manufacturer’s or honest dyno’s wheel hp readings.
In any case, I've been running some tests, and below is a shot of a 396HP run I made last night, which was at the lower end of the range I’ve received. Its not varied too much though, anywhere from 394-412. I definitely need to make more runs to get a reliable average that I have confidence in. This is exactly in line with Stacy's results and output from this modified kit. The consistency is remarkable!
To try to make this apples to apples, you can conservatively add about 20HP for drag/ friction/ wheelspin due to the factors which bring down a Gtech’s numbers vs. other forms of measure, bringing this to 428rwhp. That’s about what a dyno would read, or at least that’s my assumption. Since I have a LWFW (and as a result suffer a bit less drivetrain loss than most) if we use 13% as the parasitic loss, that would mean that I am right around the magic number of 500HP at crank.
Before this starts a war, let me acknowledge that there is a lot of room for interpretation, variation, and assumptions here. The +20hp I added due to using a Gtech and the factor of road friction and drag is a little squishy, as is the 13% drivetrain loss assumption, etc.
But what’s certain is that my 997 SC is wicked! Although there are several folks who could tell you that themsleves, from people who have ridden in it to those who remain in the distance of my rearview mirror.
CATTMAN
In any case, I've been running some tests, and below is a shot of a 396HP run I made last night, which was at the lower end of the range I’ve received. Its not varied too much though, anywhere from 394-412. I definitely need to make more runs to get a reliable average that I have confidence in. This is exactly in line with Stacy's results and output from this modified kit. The consistency is remarkable!
To try to make this apples to apples, you can conservatively add about 20HP for drag/ friction/ wheelspin due to the factors which bring down a Gtech’s numbers vs. other forms of measure, bringing this to 428rwhp. That’s about what a dyno would read, or at least that’s my assumption. Since I have a LWFW (and as a result suffer a bit less drivetrain loss than most) if we use 13% as the parasitic loss, that would mean that I am right around the magic number of 500HP at crank.
Before this starts a war, let me acknowledge that there is a lot of room for interpretation, variation, and assumptions here. The +20hp I added due to using a Gtech and the factor of road friction and drag is a little squishy, as is the 13% drivetrain loss assumption, etc.
But what’s certain is that my 997 SC is wicked! Although there are several folks who could tell you that themsleves, from people who have ridden in it to those who remain in the distance of my rearview mirror.
CATTMAN
#6
02-23-2010 | 07:13 PM
Registered User
Joined: Jan 2008
Posts: 2,370
From: Vancouver
Rep Power: 327
Looking at John's Gtech and the data recorded(speed) that he has been sending me....I would say 3rd gear!
Everything he has sent me HAS BEEN 3rd gear BUT I may be wrong!
Like John posted above It is remarkable how him and I have the same results/netRWHP numbers.....
I just wonder IF we didn't have what 101 mph(wind resistance) what kind of power it would be.......
I know because of all the variables we will never know this 'true' number BUT would be neat to know some sort of percentage!
There are a lot of brilliant people on this forum,I am NOT one of them,LOL........can someone figure out from the drag coefficient what that % may be(roughly,VERY roughly)?
Stacy
Last edited by justatoy; 02-23-2010 at 07:31 PM.
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