PCA Club Racing GT rule change-928
09-14-2007, 08:13 PM
#31
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Here:
8 cyl 2 valve 90hp/l
8 cyl 2 valve turbo 145hp/l
8 cyl 4 valve 100hp/l
8 cyl 4 valve turbo 165hp/l
A 5.0L 4 valve motor 928 motor in a 2950lbs car w/ driver
(2950/(5.0*100))*100=590 GT3
Same car with a 4.5l 2V engine
(2950/(4.5*90))*100=728 GT4
8 cyl 2 valve 90hp/l
8 cyl 2 valve turbo 145hp/l
8 cyl 4 valve 100hp/l
8 cyl 4 valve turbo 165hp/l
A 5.0L 4 valve motor 928 motor in a 2950lbs car w/ driver
(2950/(5.0*100))*100=590 GT3
Same car with a 4.5l 2V engine
(2950/(4.5*90))*100=728 GT4
03-16-2008, 07:50 PM
#32
So which rules were implemented? I know someone pointed me to the published specs, but I can't find them. Too much googling.
03-16-2008, 10:12 PM
#33
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Brendan
Thats the formula.....its a point based system where lower= higher class.... I think a very light 4.7-4.9L 16V would be competitive in GT4....
03-16-2008, 10:18 PM
#34
But you would be in a different class with the 32V?
Because we now know that the 4.5L engines are good for 400 on pump gas at least.
It would be a very cheap race car. early trans, early TT, 4.5L engine with "expensive" heads and intake, aftermarket EFI (would that be legal?) - and tons of boost.
Because we now know that the 4.5L engines are good for 400 on pump gas at least.
It would be a very cheap race car. early trans, early TT, 4.5L engine with "expensive" heads and intake, aftermarket EFI (would that be legal?) - and tons of boost.
03-16-2008, 10:41 PM
#35
Race Director
Brendan
1 problem with the formula is its power/weight essentially....so you could have a stupid light car with a small engine with little power but will still compete against cars with similar power/weight..... I still think a 16V racecar could be built under 2500lbs....maybe less? Anderson weighs 2600lbs and has almost 600hp....But he still would be in GT2
1 problem with the formula is its power/weight essentially....so you could have a stupid light car with a small engine with little power but will still compete against cars with similar power/weight..... I still think a 16V racecar could be built under 2500lbs....maybe less? Anderson weighs 2600lbs and has almost 600hp....But he still would be in GT2
03-16-2008, 11:09 PM
#36
Brendan
1 problem with the formula is its power/weight essentially....so you could have a stupid light car with a small engine with little power but will still compete against cars with similar power/weight..... I still think a 16V racecar could be built under 2500lbs....maybe less? Anderson weighs 2600lbs and has almost 600hp....But he still would be in GT2
1 problem with the formula is its power/weight essentially....so you could have a stupid light car with a small engine with little power but will still compete against cars with similar power/weight..... I still think a 16V racecar could be built under 2500lbs....maybe less? Anderson weighs 2600lbs and has almost 600hp....But he still would be in GT2
03-17-2008, 12:04 AM
#37
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Brendan
1 problem with the formula is its power/weight essentially....so you could have a stupid light car with a small engine with little power but will still compete against cars with similar power/weight..... I still think a 16V racecar could be built under 2500lbs....maybe less? Anderson weighs 2600lbs and has almost 600hp....But he still would be in GT2
1 problem with the formula is its power/weight essentially....so you could have a stupid light car with a small engine with little power but will still compete against cars with similar power/weight..... I still think a 16V racecar could be built under 2500lbs....maybe less? Anderson weighs 2600lbs and has almost 600hp....But he still would be in GT2
03-17-2008, 01:22 AM
#38
Rennlist Member
Its better, but they are averaging HP/liter, and showing preference for 2valves vs 4 valves. based on statistics, its probably right, but as IceMan says, it still makes no sense. Well, its better than no sense, but its still bad. People take this racing seriously, so it matters where they stack up. Most everyone does their own level of justifications of their performance based on the REAL factors(of the car alone), those being, HP/weight, and absolute weight, COMBINED!
Then, if they want to get real accurate like most racing organizations, they can start looking at aero, tire sizes, suspension/chassis, etc. Driver then becomes the dominant factor, and thats what every race organization strives for.
POC does a good job with their classing, based on PCA starting points. sometimes those starting points are flawed, seriously. (mostly in the areas of 928s) I think the classes are so screwed up in PCA, the only way out is to have it set up simply, like this.
GT1 anything goes, with Turbo
GT2 anything goes
GT3 anything goes with a lower HP/weight and absolute weight
GT4 lower still
GT5. etc
maybe everything beyond GT2 should follow the NASA GTS rules.
in the end, the PCA has made a move to put the 928 in a more fitting class, which is good, but if anyone has noticed, GT3 times are usually just as fast as GT2.
mk
Then, if they want to get real accurate like most racing organizations, they can start looking at aero, tire sizes, suspension/chassis, etc. Driver then becomes the dominant factor, and thats what every race organization strives for.
POC does a good job with their classing, based on PCA starting points. sometimes those starting points are flawed, seriously. (mostly in the areas of 928s) I think the classes are so screwed up in PCA, the only way out is to have it set up simply, like this.
GT1 anything goes, with Turbo
GT2 anything goes
GT3 anything goes with a lower HP/weight and absolute weight
GT4 lower still
GT5. etc
maybe everything beyond GT2 should follow the NASA GTS rules.
in the end, the PCA has made a move to put the 928 in a more fitting class, which is good, but if anyone has noticed, GT3 times are usually just as fast as GT2.
mk
Anderson has one of the lightest 928s out there and I thought he only had around 500rwhp. John V has 550rwhp and the car weighs over 2700. Going by John's conversion (16V->32V plus dry sump), you could build a 16V car about 90lbs lighter than Mark's (after completely stripping and acid dipping it).
03-17-2008, 02:43 AM
#40
Rennlist Member
Just did some quick calc's for a 928 GT4 "ringer".
A 16v 5L would have to weigh a minimum of 3010lbs.
A 32v 5L would have to weigh a hefty 3400 lbs.
Could these cars even be competitive? I think the 32v 928 at 3400lbs is out of the question. Could a 16v 5L stand a chance even with a full tilt motor, around 320 RWHP?
A 16v 5L would have to weigh a minimum of 3010lbs.
A 32v 5L would have to weigh a hefty 3400 lbs.
Could these cars even be competitive? I think the 32v 928 at 3400lbs is out of the question. Could a 16v 5L stand a chance even with a full tilt motor, around 320 RWHP?
03-17-2008, 02:54 AM
#41
Rennlist Member
DOH, didn't see the chart on the PCA website, that makes the weight classing easier.
Brendan, did a quick calc for your car:
They seem to class all 928's as 5 liters, but if you can have them class yours as a 4.5L, you get:
2800/(4.5x145 )x100
2800/652.5) x 100
4.29x100 = 429 Performance Index = GT2
Which would be sweet, you be at the very top of the GT2 class (PI= 426max to 550min)
If not, and PCA insists on classing your motor as a 5L:
2800/(5x145)x100
2800/725x100
3.86x100=386 Performance Index = GT1 (PI= 425 and below)
You are deep into GT1 with this PI.
These both assume a weight of 2800lbs. I don't know how realistic that is, but it looks like you've put in a lot of detail in the weight management department.
Brendan, did a quick calc for your car:
They seem to class all 928's as 5 liters, but if you can have them class yours as a 4.5L, you get:
2800/(4.5x145 )x100
2800/652.5) x 100
4.29x100 = 429 Performance Index = GT2
Which would be sweet, you be at the very top of the GT2 class (PI= 426max to 550min)
If not, and PCA insists on classing your motor as a 5L:
2800/(5x145)x100
2800/725x100
3.86x100=386 Performance Index = GT1 (PI= 425 and below)
You are deep into GT1 with this PI.
These both assume a weight of 2800lbs. I don't know how realistic that is, but it looks like you've put in a lot of detail in the weight management department.
03-17-2008, 12:01 PM
#42
2800 is perfectly doable Adam. Thats a stripped body with cage and not much else.
03-17-2008, 12:07 PM
#43
I think the other issue is what cars are in each of these classes - are you competing with GT4 cars that are high-powered 914s?
Because depending on weight of the car - maybe a 928 could be competitive with a very high output 4.5L - it could get that way with very high compression and alot of cam and work on heads. Spin it really high. Maybe.
Because depending on weight of the car - maybe a 928 could be competitive with a very high output 4.5L - it could get that way with very high compression and alot of cam and work on heads. Spin it really high. Maybe.
03-17-2008, 12:11 PM
#44
Wait, thats 2800 with driver? Jesus.