C2 Dyno Results with Graph & Video
#17
Rennlist Member
Car had 1-2% leak down and 52k miles at the time it now has 60k miles. I have no doubt the initial condition of the engine had a lot to do with the results.
Protosport does some amazing work. John was curious about that as well so he straps meters to the car and will test the car on the road monitoring real life numbers to gain the most he can and feel safe about it. In the end we determined it was fine as is. Considering the number of track miles since and that it is still as strong as the day I last tested it I will assume he was correct in his findings. My most recent leak down last year was up to around 3-4% so I am sure there is a change but nothing my seat tells me.
The chip was designed for 91 octane since it was a dual driver and 93 is not always available.
#18
Rennlist Member
#19
RL Technical Advisor
FWIW,.....
Since we have both an engine dyno & a Dynojet, its been easy to make comparisons between BHP & RWP (Dynojet only) for accuracy.
I've found that the difference is 12% between Dynojet results and what we see on the engine dyno. Your figures more or less mirror the similar engines we have done with those modifications.
Hope this helps,
Since we have both an engine dyno & a Dynojet, its been easy to make comparisons between BHP & RWP (Dynojet only) for accuracy.
I've found that the difference is 12% between Dynojet results and what we see on the engine dyno. Your figures more or less mirror the similar engines we have done with those modifications.
Hope this helps,
#20
Rennlist Member
FWIW,.....
Since we have both an engine dyno & a Dynojet, its been easy to make comparisons between BHP & RWP (Dynojet only) for accuracy.
I've found that the difference is 12% between Dynojet results and what we see on the engine dyno. Your figures more or less mirror the similar engines we have done with those modifications.
Hope this helps,
Since we have both an engine dyno & a Dynojet, its been easy to make comparisons between BHP & RWP (Dynojet only) for accuracy.
I've found that the difference is 12% between Dynojet results and what we see on the engine dyno. Your figures more or less mirror the similar engines we have done with those modifications.
Hope this helps,
#21
Rennlist Member
Thread Starter
That's good to know Steve, but I like using 15% since it's over 300 bhp.
Seriously though, thanks for the input. Out of curiosity what do stock 964s put down on your dynojet 220-230 rwhp?
Seriously though, thanks for the input. Out of curiosity what do stock 964s put down on your dynojet 220-230 rwhp?
#22
RL Technical Advisor
LOL,...gotcha! I can make 300+ BHP in those things, however it requires a realistic budget to do that.
Yessir,...thats the ballpark. Many variables are work that include engine condition, cam timing, AFR's, exhaust, and fuel.
Seriously though, thanks for the input. Out of curiosity what do stock 964s put down on your dynojet 220-230 rwhp?
#23
Rennlist Member
I've always used a # of ~10% for drivetrain loss on porsche when getting WHP. Nice to see a real comparison.
#24
Rennlist Member
Would the loss be different if tested on a dynapack vs a dynojet?
#25
Rennlist Member
Thread Starter
I would think so and also different for a mustang dyno. I've always used a dynojet as they seem to be the gold standard. It's nice to be able to do an apples to apples power comparison, as long as you use the SAE correction.
#26
I have a dyno printout but have no idea what dyno it was done on. Will different dynos plot the same graph and just vary on the peak numbers?
#27
FWIW,.....
Since we have both an engine dyno & a Dynojet, its been easy to make comparisons between BHP & RWP (Dynojet only) for accuracy.
I've found that the difference is 12% between Dynojet results and what we see on the engine dyno. Your figures more or less mirror the similar engines we have done with those modifications.
Hope this helps,
Since we have both an engine dyno & a Dynojet, its been easy to make comparisons between BHP & RWP (Dynojet only) for accuracy.
I've found that the difference is 12% between Dynojet results and what we see on the engine dyno. Your figures more or less mirror the similar engines we have done with those modifications.
Hope this helps,
One of the biggest headaches of Dynojet's go-it-alone chassis-dyno project was figuring out how to assign meaningful power numbers in the face of unknown inertia from the moving parts of the hundreds or thousands of engine, drivetrain, and tire combinations. Wrestling to fully understand inertia and powertrain losses, Dobeck and his team quickly realized that the standard physics formula of weight, time, and distance for converting acceleration into horsepower simply didn't work-the derived number was always lower than accepted numbers. They poured on resources and burned up time and money investigating it, but no matter what they did, the math never added up.
Dynojet's final number-fudge was arbitrarily based on a number from the most powerful road-going motorcycle of the time, the '85 1,200cc Yamaha VMax. The VMax had 145 advertised factory horsepower, which was far above the raw 90hp number spit out by the formula. Meanwhile, existing aftermarket torque-cell engine dynamometers delivered numbers that clustered around 120. Always a pragmatist, Dobeck finally ordered his Chief Engineer to doctor the math so that the Dynojet 100 measured 120 hp for a stock VMax. And that was that: For once and forever, the power of everything else in the world would be relative to the '85 Yamaha VMax and a fudged imaginary number. Dobeck's engineering staff was dismayed by the decision, but the Dynojet 100 exclusively measured surplus power available to accelerate the vehicle's mass-no more, no less-and that was true even if the modification was a low-inertia flywheel or lightweight wheels.
Dynojet's final number-fudge was arbitrarily based on a number from the most powerful road-going motorcycle of the time, the '85 1,200cc Yamaha VMax. The VMax had 145 advertised factory horsepower, which was far above the raw 90hp number spit out by the formula. Meanwhile, existing aftermarket torque-cell engine dynamometers delivered numbers that clustered around 120. Always a pragmatist, Dobeck finally ordered his Chief Engineer to doctor the math so that the Dynojet 100 measured 120 hp for a stock VMax. And that was that: For once and forever, the power of everything else in the world would be relative to the '85 Yamaha VMax and a fudged imaginary number. Dobeck's engineering staff was dismayed by the decision, but the Dynojet 100 exclusively measured surplus power available to accelerate the vehicle's mass-no more, no less-and that was true even if the modification was a low-inertia flywheel or lightweight wheels.
#28
Rennlist Member
Thread Starter
That's why I really like Dynojets as I can compare my numbers with anyone anywhere and the SAE correction will adjust for things like altitude, temperature, and humidity as best as possible. Dynojets also let you save the run digitally so I can send my run to someone else so they can overlay it on to theirs which is very nice for comparison purposes.
If you have a dyno chart, post it up and maybe someone will be familiar with the format and be able to tell you the brand of dyno used.
#29
Pro
Interesting stuff. I had a full engine rebuild on my C2 last year which included 993RS Cams, Schrick valve gear and a Steve Wong Custom chip and on a power it made 290BHP with 270 Ib/ft Torque, so similar mods with very close results.
It's probably worth adding that on the same rolling road, prior to rebuild it recorded 252BHP and from memory around 240 Ib/ft Torque.
It's probably worth adding that on the same rolling road, prior to rebuild it recorded 252BHP and from memory around 240 Ib/ft Torque.
#30
RL Technical Advisor
Oh hell yes,....
All chassis dynos give different results: Dynojet, Mustang, Dynapak, Superflow, etc.
The only one that gives reliable results that exclude any operator shenanigans is the Dynojet and thats precisely why sanctioning bodies use them.
All chassis dynos give different results: Dynojet, Mustang, Dynapak, Superflow, etc.
The only one that gives reliable results that exclude any operator shenanigans is the Dynojet and thats precisely why sanctioning bodies use them.