Dyno'd viper today Not Happy!!!!!!!!!!

[Neil - UK]

Re: Dyno\'d viper today

Guibo's second dyno print out at Powerstation is where *** and I went in the RT, SUN dyno, not very convinced that place knows what they were doing either. Max speed for the cerbera manages a very lowly 147mph ? that cant be right. Doesn't help you out though Baz.

 

[Guibo]

Re: Dyno\'d viper today

Hi, Neil. What were your figures from Powerstation? P-drag?

 

[Neil - UK]

Re: Dyno\'d viper today

Hi, Neil. What were your figures from Powerstation? P-drag?

dont have the print out to hand it went to the current owner, but will make enquires

 

[VIPER BAZ UK]

Re: Dyno\'d viper today

It is the stock cam with Arrow RR and mopar big valves it was all put back together by ex Chamberlain tech....

 

[Guibo]

Re: Dyno\'d viper today

dont have the print out to hand it went to the current owner, but will make enquires

Should look something like this (Nadine's car from quite a long time ago):
http://vca2.viperclub.org/forums/showflat.php?Cat=&Board=UBB7&Number=10306

"P-eng 475.5 bhp
P-wheel 375 bhp
P-drag 100.5 bhp"

That P-wheel figure is only 7.4 hp off from VIPER BAZ's, although done in 5th. But P-drag (and consequently crank hp) is way different. Showing roughly 21% drivetrain loss. Not too far off from the Cerbera dynos, and about 2X as much as VIPER BAZ's. Pretty weird...

Some M5 owners in Europe have faced similar drivetrain losses (22% vs ~15% for US M5'ers).
http://www.m5board.com/vbulletin/showthread.php?t=16945
(E34 M5, but more or less the same phenomenon with the E39)

BTW, here's another rolling road result for a mildly modified Cerbera 4.2, done at the same place as in the first pic on the previous page (John Noble Motorsports). 96 hp loss through the drivetrain.
http://www.pistonheads.com/gassing/topic.asp?t=24533&f=6&h=0

F-Body in Germany with 77 hp loss through the drivetrain:
http://fbodyeurope.org/board/viewtopic.php?t=4397

 

[Neil - UK]

Re: Dyno\'d viper today

good search !! thats the day I went to, I'm on a mission now to dig that old slip out

 

[joe117]

Re: Dyno\'d viper today

ruckdr,
I don't see any real science in that article. It look's like they did some testing, got some values and decided that the drive train loss was a fixed percentage.
That may be the truth, I just don't see ant real engineering explanation.

Also,
The last paragraph says this might not be true for high powered race cars.
What kind of science is that?

 

[ruckdr]

Re: Dyno\'d viper today

This article, as you read it, is more analytical (analysis from testing) than theoretical (gobs of equations), which are only theoretical under the same and ideal conditions for which the equations are designed. Yes, the last paragraph asks the question, why does adding HP to the same engine, loose more HP through the same drive train?

"........Mustangs on the dyno, and they both agreed that extrapolating drivertrain horsepower loss via percentages is flawed. Lee believes that the stick Mustangs experience roughly a 35hp loss through the drivetrain, whether they make 200 hp or 400 hp. He did explain that ultra-high-powered vehicles - typically race cars - can be and exception to this rule, but that's a topic for another time."

http://www.superstang.com/horsepower.htm#realworld1

Later,