IcemanG17

While surfing today I found this

http://www.rbracing-rsr.com/aerohpcalc.html

yes it was designed intially for motorcycles, but the principles remain the same....(this doesn't account for rolling resistance or gearing limitations)... I entered the following for 928's

Cd of .36
Frontal area 21.28
weight of 3750lbs (with driver)

200mph: 448hp is needed (it doesn't say if its wheel or crank HP?)
210mph: 517hp
220mph: 593hp
230mph: 676hp
250mph: 866hp

So a 1000whp 928 in theory could go almost 262mph.....for some reason I really doubt it....

So guessing its wheel horsepower that means that Louie Ott could hit almost 220mph....the beast can do 210mph (thats pretty close really) & Todd's crazy SC will hit nearly 230mph.....

icsmike

Aw, **** brah..... wit my AEM stickers and Mugen intaken I hit 299 NO PROBLEM.

AO

Mugen =

Jim Morton

Brian:

One additional factor for top speed calcs is percent tire slippage. From the ORR runs I did in my 951, it's real and effects not only RPM needed but how effective the HP can be put to the ground. BAck in '97 when we were testing a 200+ SC 928, we figured about 10 percent slip at 200 given the slippage we saw on a rolling drum dyno. From my own observations in the 951, it was around 5-8 percent depending on conditions. Perhaps some of the other ORR folks can comment on their observations of this.

Back on the AEM / Mugen gig... definately glue a "R" on the back of any car and gain 100HP and 20+ MPH of top speed. Also, the sewer pipe exhaust is another must....

Rick Carter

One of the reasons the 928 Holbert/Kibort car was slower at the salt flats; salt doesn't provide great traction.

Brett928S2

Hi

I worked out that "in theory" with normal rear tyres and my diff , mine is "theoretically" capable of 235 mph...with the oversize tyres its now "theoretically" capable of 251 mph....

The above assumes that I have enough hp to push it that fast....which I just might but will be happy with over 212

Although if I hit my 212, I wont take my boot out until I figure even with my chute ,I wont stop in time



All the best Brett

IcemanG17

Interesting about tire slippage.....when you really think about it...thats SCARY at 200+...hell its scary at 100mph!!

UKKid35

172mph - 288bhp with those figures

Jim R.

It's a bit more interesting while on a liter class sportbike over 170mph.......

One more dumbass thing to live to tell about, but never do again on a bike!

Jim

Vilhuer

This is fairly good software to predict actual top speed:
http://www.cartestsoftware.com/cartest4.5/index.html
Or at least it works in predicting real stock model top speeds accurately once correct data is given for it. It might fail on high above 200 mph though same as it doesn't work too accurately on very fast acceleration numbers from standstill.

jthwan22

Is this including gear limited at top rpm?

Lizard928

no.

Lizard928

And the AEM package will also drop 50lbs off andrews car to "compensate"

dr bob

There's no input for Kp (pucker factor) at higher speeds.

IIRC, about 8% wheel slip is the max you'd ever consider safe on even a straight run with no crosswind. This may be a major limiting factor in Brett's top-speed challenge run, judging by the drag-strip results posted previously.

Glenn Evans

The hp figures you have calculated are at the rear wheels and include rolling resistance.