Horsepower 101...
08-21-2004 | 05:32 PM
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Horsepower 101...
For those of you that are looking into upgrading your turbos and are being lured into the wrong direction here are some things to consider.
What is the RPM range that you do most of your driving in?
Looking at dyno sheets you want to pay attention to the torque curve. Peak HP is nice but it is more important to calculate average HP over the RPM range that is most important to you. This is why the K16 based turbo will out shine the K24 in most applications. Further benifits of the hybrids are the larger compressors available to allow better flow.
Lets look at two dyno charts from the same dyno.
K24 based 993
http://www.awe-tuning.com/media/dyno.../993tt_k24.jpg
K16 hybrid based 996
http://hobbystage.net/porsche/media....2636544-010203
....K24's............K16 stage 2 hybrids
2400...85hp............2400..110hp
3800..215hp...........3800..305hp
4500..325hp...........4500..380hp
Don't flame me for compairing two different cars. I am only trying to point out the fact that we all get hung up on peak#'s when its the average HP in the most important RPM range that matter.
What is the RPM range that you do most of your driving in?
Looking at dyno sheets you want to pay attention to the torque curve. Peak HP is nice but it is more important to calculate average HP over the RPM range that is most important to you. This is why the K16 based turbo will out shine the K24 in most applications. Further benifits of the hybrids are the larger compressors available to allow better flow.
Lets look at two dyno charts from the same dyno.
K24 based 993
http://www.awe-tuning.com/media/dyno.../993tt_k24.jpg
K16 hybrid based 996
http://hobbystage.net/porsche/media....2636544-010203
....K24's............K16 stage 2 hybrids
2400...85hp............2400..110hp
3800..215hp...........3800..305hp
4500..325hp...........4500..380hp
Don't flame me for compairing two different cars. I am only trying to point out the fact that we all get hung up on peak#'s when its the average HP in the most important RPM range that matter.
Last edited by K24madness; 08-22-2004 at 01:20 PM.
08-22-2004 | 10:33 AM
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Madness
That second link is for a 996tt - the low end torque curve will always favour the 996tt ('cos of the variocam) over the 993tt -did you post the wrong link ? What the first link shows is that the K24s seem to have a very similar low end torque curve as a stock 993tt in this particular set up
That second link is for a 996tt - the low end torque curve will always favour the 996tt ('cos of the variocam) over the 993tt -did you post the wrong link ? What the first link shows is that the K24s seem to have a very similar low end torque curve as a stock 993tt in this particular set up
08-22-2004 | 11:51 AM
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I am not sure your narative matches your examples?? FWIW I drive a 993TT with K24's and have ridden in a 996TT with K24's and there really is not much comparison of basic hp/tq. The 996TT had roughly 100 more of each as measured on a dyno and in feel on the track. They are two totally different beasts. (Both had similar bolt on mods and GIAC ECU mods.)
But yes I would agree with what you are saying regarding the hybrids K16's vs K24's for a 993TT and trying to keep power coming on sooner in the power band.
But yes I would agree with what you are saying regarding the hybrids K16's vs K24's for a 993TT and trying to keep power coming on sooner in the power band.
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08-22-2004 | 03:42 PM
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I thought for once that I would see the definitive answer (of which I am convinced, but just how much difference is there), as mentioned earlier, these 2 examples are not comparable. 
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08-22-2004 | 04:34 PM
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Jean
I don't know if you have seen these during your research - they are Cargraphic's dyno diagrams (I think that Cragraphic use mainly RS Tuning components and Software and presume the dynos are from that source) - the 520PS dyno certainly looks very similar to a typical RS stage 2 single plug/no head sealing type curve.
You will see the turbos stated are stock, KKK1624 and KKK24RS (which I think are the same as I have.) I have no idea what the KKK1624c are but they are listed as separate from stock GT2 KKK24 in the catalogue - they will be some sort of hybrid no doubt.
On the lag issue you have to remember the dyno curves are for full throttle - at 2500rpm we have 425NM stock, 412NM KKK1624, 412NM KKK24RS and about 405NM KKK24RS with cams. Because these are full throttle curves, they don't really illustrate what happens on the road on part throttle or when coming onto the throttle etc -but still interesting
http://www.cargraphic.de
I don't know if you have seen these during your research - they are Cargraphic's dyno diagrams (I think that Cragraphic use mainly RS Tuning components and Software and presume the dynos are from that source) - the 520PS dyno certainly looks very similar to a typical RS stage 2 single plug/no head sealing type curve.
You will see the turbos stated are stock, KKK1624 and KKK24RS (which I think are the same as I have.) I have no idea what the KKK1624c are but they are listed as separate from stock GT2 KKK24 in the catalogue - they will be some sort of hybrid no doubt.
On the lag issue you have to remember the dyno curves are for full throttle - at 2500rpm we have 425NM stock, 412NM KKK1624, 412NM KKK24RS and about 405NM KKK24RS with cams. Because these are full throttle curves, they don't really illustrate what happens on the road on part throttle or when coming onto the throttle etc -but still interesting
http://www.cargraphic.de
Last edited by TB993tt; 08-23-2004 at 08:55 AM.
08-22-2004 | 07:33 PM
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TB
Very interesting stuff, thanks for the info. These are not the first dynos that I look at where a K16 hybrid and a K24 have the same torque output at low RPMs. There are two things that are important;
One of them, and the most meaningful, as you pointed out, dyno conditions do not reflect how turbos actually perform on the street under acceleration, which explains why people using Kevin's ZC turbos feel their car is pulling faster from low revs, the boost buildup and delivery is faster, although at the same RPM, on a dyno, torque could be the same vs a K24.
The second thought is that hardly any big European tuner (and American I presume) use standard stock turbos on high hp applications (500+), each one of them does his own little tweeks, although very few do them in-house. From my contacts with them, a "K24" from RS, Sportec, Manthey, Roock, PSI, etc..as such, is not a stock K24, so the turbos mentioned above all have modified internals, and perform differently than a stock K24, therefore the K16-K24 dyno comparison is not meaningful, again back to your point .
0-200kph, and 100-200kph are very meaningful comparisons in my view, where for similar weight and specs, different turbos can make a real difference.
I decided to go with Garretts, turbo durability is not a real concern for me, I want the fastest 0-200 kph acceleration I can get, and my tuner is building the engine around that objective.
I could be wrong, and I know many on the board can bring much more meat into this topic than me, but it is a very interesting one indeed.
Very interesting stuff, thanks for the info. These are not the first dynos that I look at where a K16 hybrid and a K24 have the same torque output at low RPMs. There are two things that are important;
One of them, and the most meaningful, as you pointed out, dyno conditions do not reflect how turbos actually perform on the street under acceleration, which explains why people using Kevin's ZC turbos feel their car is pulling faster from low revs, the boost buildup and delivery is faster, although at the same RPM, on a dyno, torque could be the same vs a K24.
The second thought is that hardly any big European tuner (and American I presume) use standard stock turbos on high hp applications (500+), each one of them does his own little tweeks, although very few do them in-house. From my contacts with them, a "K24" from RS, Sportec, Manthey, Roock, PSI, etc..as such, is not a stock K24, so the turbos mentioned above all have modified internals, and perform differently than a stock K24, therefore the K16-K24 dyno comparison is not meaningful, again back to your point .
0-200kph, and 100-200kph are very meaningful comparisons in my view, where for similar weight and specs, different turbos can make a real difference.
I decided to go with Garretts, turbo durability is not a real concern for me, I want the fastest 0-200 kph acceleration I can get, and my tuner is building the engine around that objective.
I could be wrong, and I know many on the board can bring much more meat into this topic than me, but it is a very interesting one indeed.
08-23-2004 | 02:16 AM
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Originally Posted by Jean
TB
Very interesting stuff, thanks for the info. These are not the first dynos that I look at where a K16 hybrid and a K24 have the same torque output at low RPMs. There are two things that are important;
One of them, and the most meaningful, as you pointed out, dyno conditions do not reflect how turbos actually perform on the street under acceleration, which explains why people using Kevin's ZC turbos feel their car is pulling faster from low revs, the boost buildup and delivery is faster, although at the same RPM, on a dyno, torque could be the same vs a K24.
The second thought is that hardly any big European tuner (and American I presume) use standard stock turbos on high hp applications (500+), each one of them does his own little tweeks, although very few do them in-house. From my contacts with them, a "K24" from RS, Sportec, Manthey, Roock, PSI, etc..as such, is not a stock K24, so the turbos mentioned above all have modified internals, and perform differently than a stock K24, therefore the K16-K24 dyno comparison is not meaningful, again back to your point .
0-200kph, and 100-200kph are very meaningful comparisons in my view, where for similar weight and specs, different turbos can make a real difference.
I decided to go with Garretts, turbo durability is not a real concern for me, I want the fastest 0-200 kph acceleration I can get, and my tuner is building the engine around that objective.
I could be wrong, and I know many on the board can bring much more meat into this topic than me, but it is a very interesting one indeed.
Very interesting stuff, thanks for the info. These are not the first dynos that I look at where a K16 hybrid and a K24 have the same torque output at low RPMs. There are two things that are important;
One of them, and the most meaningful, as you pointed out, dyno conditions do not reflect how turbos actually perform on the street under acceleration, which explains why people using Kevin's ZC turbos feel their car is pulling faster from low revs, the boost buildup and delivery is faster, although at the same RPM, on a dyno, torque could be the same vs a K24.
The second thought is that hardly any big European tuner (and American I presume) use standard stock turbos on high hp applications (500+), each one of them does his own little tweeks, although very few do them in-house. From my contacts with them, a "K24" from RS, Sportec, Manthey, Roock, PSI, etc..as such, is not a stock K24, so the turbos mentioned above all have modified internals, and perform differently than a stock K24, therefore the K16-K24 dyno comparison is not meaningful, again back to your point .
0-200kph, and 100-200kph are very meaningful comparisons in my view, where for similar weight and specs, different turbos can make a real difference.
I decided to go with Garretts, turbo durability is not a real concern for me, I want the fastest 0-200 kph acceleration I can get, and my tuner is building the engine around that objective.
I could be wrong, and I know many on the board can bring much more meat into this topic than me, but it is a very interesting one indeed.
Thank you, point well taken. Your comment sounds like voice of reason, I almost gave up on this forum.
08-23-2004 | 05:03 AM
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Originally Posted by gooseNSJ4
Jean,
Thank you, point well taken. Your comment sounds like voice of reason, I almost gave up on this forum.
Thank you, point well taken. Your comment sounds like voice of reason, I almost gave up on this forum.
What I am saying is basically what TB did, and we all like to see tangible data that could prove a point, although we know that the real test is in engine behaviour under driving conditions.
Corte, el que tu sabes
