Porsche HP underrating?
Rennlist Member
Joined: Feb 2003
Posts: 29,828
Likes: 218
From: saratoga, ca
Thats the best part of the road and track tests. dont you remember seeing the chart they usually provide. 0-10, 10-20, 30-40mph.....etc you then extract your speed range and you compare the times. its how i knew i was going in the right direction with HP and the HP curve shape early on with my 4.7 part euro.
my goal was to get in the 6 second range for 60-100mph, and with the 5.0L and the newer Holbert car, im there (actually, with my new 85 cams, timed slighly different, im measuring near 5.8 seconds 60-100mph, so off to the dyno to see what i actually have now!)
Mk
my goal was to get in the 6 second range for 60-100mph, and with the 5.0L and the newer Holbert car, im there (actually, with my new 85 cams, timed slighly different, im measuring near 5.8 seconds 60-100mph, so off to the dyno to see what i actually have now!)
Mk
Originally Posted by michaelathome
I know I might get flamed but Oh well. I have ben wondering the same thing. I know that Car and Driver and Road and Track do tests on cars. It would be nice to see the:
0-60mph
30-60mph
45-75mph
times for various cars. I know that our cars are in some cases older than 20 years but it would still be nice. I guess that an afternoon in a decent library might be in order to get/gather that kinda info.
I can get alot of the info for the some of the 928s here on this board but it would be harder to find as many as I would like to see. Maybe something like a chart against mustangs, G35's, camaros bmw's and so forth from the cars when they came out.
Michael
0-60mph
30-60mph
45-75mph
times for various cars. I know that our cars are in some cases older than 20 years but it would still be nice. I guess that an afternoon in a decent library might be in order to get/gather that kinda info.
I can get alot of the info for the some of the 928s here on this board but it would be harder to find as many as I would like to see. Maybe something like a chart against mustangs, G35's, camaros bmw's and so forth from the cars when they came out.
Michael
Rennlist Member
Joined: Feb 2003
Posts: 29,828
Likes: 218
From: saratoga, ca
by the way chuck, I posted two curves of two porsches . 1st one is a GT3 cup car (race car) vs a street GT3. and a turbo porsche, with 3 different boosted graphs.
If you doubt anything im saying, just try and look at only torque and tell me where your shift points are, assuming a 1500rpm drop shift spread. (or 70% or whatever) I think we all would be curious to see how you do that , especially without breaking out a calculator.
Now, if you look at HP curves, you can see to figure this out, its almost too easy. Just look at the HP arch, and choose the two points that will give you the curve that yeilds the highest average HP over that 1500rpm or 70% rpm drop range.
If you want to race and be fast, you need to know this stuff and what to do with it.
no insults, just relavant info: acceleration = power/(mass x velocity)
Mk
ps answers:
if you maximize torque, your shift points are 4000rpm to 5500rpm (450ave TQ)
if you maximize Hp your shift points are 4700 to 6200rpm (460 ave HP)
If you use the maximized torque RPM range, (4000rpm to 5500rpm) your average HP is near 420.
so, by using the best aveage torque range, you loose near 40hp of accelerative forces. and proportional amounts of torque to the wheels at those speed ranges. proof that f=ma , but at the wheels is what counts!
this is far more dramatic with our cars where its not uncommon to make peak torque twice, once at 3000rpms and once at 4000rpms!
If you doubt anything im saying, just try and look at only torque and tell me where your shift points are, assuming a 1500rpm drop shift spread. (or 70% or whatever) I think we all would be curious to see how you do that , especially without breaking out a calculator.
Now, if you look at HP curves, you can see to figure this out, its almost too easy. Just look at the HP arch, and choose the two points that will give you the curve that yeilds the highest average HP over that 1500rpm or 70% rpm drop range.
If you want to race and be fast, you need to know this stuff and what to do with it.
no insults, just relavant info: acceleration = power/(mass x velocity)
Mk
ps answers:
if you maximize torque, your shift points are 4000rpm to 5500rpm (450ave TQ)
if you maximize Hp your shift points are 4700 to 6200rpm (460 ave HP)
If you use the maximized torque RPM range, (4000rpm to 5500rpm) your average HP is near 420.
so, by using the best aveage torque range, you loose near 40hp of accelerative forces. and proportional amounts of torque to the wheels at those speed ranges. proof that f=ma , but at the wheels is what counts!
this is far more dramatic with our cars where its not uncommon to make peak torque twice, once at 3000rpms and once at 4000rpms!
Last edited by mark kibort; Jan 23, 2006 at 02:34 PM.
Race Car
Joined: Nov 2004
Posts: 4,458
Likes: 5
From: Chantilly VA
Kinda found a place that gave some info on car specifications. It has quite a variety of car information available online. Take a look. http://www.auto-specs.com/
Michael
Michael
