Larry Herman

Finally, a practical use for a bunch of dirt bags!

Professor Helmüt Tester

A circular definition. To be precise...

HP = torque (lbs ft) x 2π x rot speed (rpm) / 33000

Just sayin.

mark kibort

Yeah!

Just sayin' that Acceleration= power/(mass x velocity), so if they have the same power, or HP-seconds down a straight, they will have the same acceleration anywhere on the track. (if they weigh the same and all that stuff )

Relaxed90

That car is capable of reaching 148mph before the esses. Some Evos in the same class are even faster.

kurt M

If so why is he turning lap times that are slower than some cars that are not able to hit 148 in that section? VIR has some great straights that high speed cars can make time over high handling cars on. He is pulling some nice times but there are cars that make lower times and are slower in that section.

Not that it matters to this thread but I bet someone could time the vid and do a time X distance calc.

Circuit Motorsports

Post 37 shows a similar powered Subaru touching 146 in that same section.

The reason his lap times are the way they are is that the car is a pig in the corners and atrocious in the braking zones compared to the other cars it's running against.

He spends probably spends a full second or two more getting to 5a than Watts does thanks to the better handling BMW.

Potomac-Greg

Having looked into Time Trial stuff myself, it's important to note that this guy did not NEED to have all of the safety equipment he had. I'm pretty sure that TT has the same equipment requirements a DE. Good for him that he had a full cage and other equipment.

mark kibort

Im racing this weekend with NO aero mods to see if I can tell the difference. problem is, its the maiden voyage for the new racer, and Ill be running some really old tires. (my fixed rims are not full built up yet,and the car has not had the spiltter built yet, so i wont be using the Gt3 cup car rear wing)

I bet Ill be a couple of seconds slower, but 1 second of that, for sure will be old tires and scared driver.

Larry Herman

*warning - this is strictly my opinion - no facts were harmed in it's making*

From what I have found, most of the aero on our cars has a minor but tangeable benefit. We are not generating many hundreds of lbs of downforce that will keep the car stuck if we can keep our speed up. Mostly we are eliminating lift and producing downforce generated stabilty. When I had my GT3, the change to the RS wing allowed me greater stability in the high speed esses at VIR. When I pulled the element from the 3.8 wing on my RSA at Daytona, I had a few mph greater top speed, paid for by noticeably greater instability in the braking zones for turns 1 and the bus stop. This is incremental gains, not OMG transformations.

944TURBOS

Man I am driving in the Redline Time Attack this season in a WRX STI...going to make sure our aero is set up properly....That is a scary crash!

kurt M

I figure there is a a lot to this but it just does not quite add up to me. (that's not saying much) What does a DP hit in this section? They have good power to weight and far better handling.

Larry Herman

Kurt, I would think that a DP car has considerably more drag (due to aero) than the Subies would, limiting it's top end acceleration as compared to them. I remember that my GT3 was faster down the back straight at VIR than a cup car because of less drag.

SundayDriver

You are exactly on the right path. Lap times are far more about cornering speed than top speed. And aero takes away top speed. Look at the lap times of an SRF with a top speed at most tracks of less than 110 mph vs street cars that top out at 140+. SRF is usually a faster lap time and it doesn't have any aero.

DPs in their first couple of years, ran almost exactly the same lap times (most tracks) as a DSR but were 30mph faster down a long straight. They have very limited, and under-developed aero.

Finally, consider the car in my avatar. Can match a moderatly prepped Viper or Vette in a drag race, but only up to about 120 mph, then it gets left behind. Why? It has a lot of drag from a lot of downforce and not much HP (just under 200).

So, cornering speed wins in the corners (obvious) but it also wins in the first half of the straights because of the higher exit speeds. Plus 2-3 g's and taking corners flat that you never imagined could be done flat, is a lot more fun.

LDadrenaline

Joe also touched on something very true too in his post. Braking zones. With the car prepped the way it was, it weighs right around 3,000lbs or possibly even up to a hundred more. The brakes on the car definitely don't stop it like it should. Even with bigger brakes, the master cylinder on the subarus doesn't provide nearly enough pressure (a problem I ran into on my car). I can't imagine how long it would take to slow down a car that literally made twice the horsepower that mine did. i.e. 300whp vs. 600whp.

kurt M

A DP is 2275 pounds and 500 HP. 4.7 or so pounds per HP and the Riley has a top speed of 200 mph so it can't be too much of a brick. 200 mph with 500 hp is something like .32 Cd. The DP has better power to weight, better handling yet is slower than the subie the end of a short straight?
The same straight that was fed into by a set of turns that the DP should have made a heck of a run out of?
I have watched them come out of that section and they look like slot cars tearing up the hill. Still does not add up for me but it is not important to this thread so I will give it a rest.