Hi guys,
Take a look at my dyno sheet from last weekend. Its my car on 94 octane with a 200 shot. I know the green arrows are a loss of the RPM pick up but what is the wide swing in the osolation [sp?] in the lower rpm [black arrows]?
Did I get into the converter flash on the second pull?

http://www.hotrodhawk.com/dyno.htm

 

Hawk and everyone,

That dyno chart has a virus attached to it.

Exploit-MhtRedir.gen is the name of it....

Bret

 

Just letting you know I did six passes with the g-tech this afternoon.
Same stretch of road, going both directions to factor wind, incline, etc.

Received some interesting results. I'm going to try again in the morning
to confirm and post the data.

Back to "average torque". I guess that's the wrong term to use, but explain
why having a lower torque value at 5000 RPM, would yield more power than
3000 RPM in my dyno graph.

The engine is doing more work, or the same work in less time?

IOW, the time to complete a combustion cycle is much less at 5000 RPM.

According to the G-Tech, I`m not far off in the comparisons.
I`ll try to recalibrate the meter and redo the tests.

EDIT: Transmission is M5.

 

What the relative acceleration rate will show is not going to simply reflect the torque curve of your engine. Most important confounding factor will be drag and friction, which are going to go up as the road/air speed increases. Also, if your car is an automatic the torque converter will operate differently at high vs. low rpm.

The problem with data is after you get it, you have to figure out what it means! As far as hp v. torque, I again refer you back to that link which is the mopst understandable explanation I have found.

Rich

 

Think about the definition of horsepower:

1 hp = 33,000 lb-ft per minute

and the formula for horsepower:

HP = Torque x rpm / 5252


[Tino: If you want to derive the formula from the definition, remember there are 2 PI radians per revolution.]

 

1 HP = 33,000 ft./lbs. per minute.

So that essentially means, an engine with one horsepower will move a 33,000
pound load, one foot every minute?

Breaking that down further

1 HP = 33,000 ft./lbs. per minute / 60 seconds
1 HP = 550 ft./lbs. per second

= 33,000 ft./lbs. per minute
= 33,000 ft./lbs. / (2 * pi)
= 5252

Using my straight line graph @ 4000 RPM

1 HP = 33, 000 ft./lbs. per minute * 228.48
228.48 HP = 125,664 ft./lbs. per second

Stroke Duration
t1 = 1 / (RPM / 60 seconds)
t1 = 1 / (4000 / 60)
t1 = 1 / 66.67
t1 = 0.015 seconds

TQ = ((ft./lbs.)/sec * t1) / (2 * pi)
TQ = (125, 664 ft./lbs. per second *.015 seconds) / (6.28312)
TQ = 1884.96 / 6.28312
TQ = 300 ft./lbs.



Jon? Can I get some love?

 

OK up to here.

HP @ 4000 = 300 * 4000 /5252 or 228.48 as you said.


Not sure what this ^^^ really means.

So now if you do the hp calcs for 3000 and 5000 you will have answered your own question: "... but explain why having a lower torque value at 5000 RPM, would yield more power than 3000 RPM in my dyno graph."

Respect maybe, but you're on your own for anything else.

BUT FIRST, only if you start using lb-ft instead of ft./lb. Torque is a force (lb.) times a distance (ft), not a force divided by a distance.

Convention says "force" comes first in the name of the unit of torque, as lb-ft. It's easy to remember: just think of the metric unit, the Newton-meter. If you say meter-Newton, not only does it sound strange, folks who "think metric" will think you just fell off the turnip truck. Don't give them any more ammunition.

 

I used time to break down all of these formulas so I could understand what
all of the numbers mean.

Even while torque decreases, the distance remains the same, but the time
required to move the 'load' also decreases. Therefore power required will increase.

IE:

Using the same straight line graph @ 5000 RPM:

1 HP = 33, 000 lbs./ft. per minute * 285.61
285.61 HP = 157,083 lbs./ft. per second

Stroke Duration
t1 = 1 / (RPM / 60 seconds)
t1 = 1 / (5000 / 60)
t1 = 1 / 83.33
t1 = 0.012 seconds

TQ = ((lbs./ft.)/sec * t1) / (2 * pi)
TQ = (157,083 lbs./ft. per second *.012 seconds) / (6.28312)
TQ = 1884.96 / 6.28312
TQ = 300 lbs./ft.

Done. What brick head started using ft./lbs.?

Stay tuned for the G-Tech data.

 

Done?

Not so one would notice.

I find it easier to just plug and crank in these once you understand where they came from:

HP = Torque * rpm/5252

Torque = HP * 5252/ rpm

 

Been there, done that. Still trying to 'reprogram' my brain to understand what
I'm seeing because the horsepower curve was what I've always used to pick
shift points.

From that, I've assumed that because horsepower was increasing, that my
car would accelerate according to the HP curve.

Now, onto G-Tech:

I was right about my car pulling harder from 3000-4600

But…I was wrong about the torque curve. My engine apparently
peaks at 3900 RPM, not <3000 RPM that I was incorrectly informed of a while ago.

stock dyno charts for 3.8L V6 Camaro:

http://gmthunder.com/tino/v6dyno.jpg
http://gmthunder.com/tino/v6dyno2.jpg

It’s nice to know the G-Tech meter is easily calibrated and repeatable.
Notice the red and green line (nearly identical). The red and blue lines were taken yesterday; the green and black lines were taken this morning.

I would attribute the higher g's for green and black to be cooler engine temps
and weather.

http://gmthunder.com/tino/gforce.jpg

I held the motor at 2000 RPM in 1st gear (M5) and “staged” the meter.
It waits for a big change in g’s and automatically begins sampling when I floor
the accelerator pedal.

When I let off the throttle, the sampling stops.

Red and Green Lines – 2000 to 4000 RPM , 1st gear.
Blue Line - 3000 to 5000 RPM, 1st gear.
Black line - 3000 to 5500 RPM, 1st gear

Tomorrow, I'd like to try this with my Z28 and observe the g forces.

If the 'g' graph rolls off when I'm sampling at higher RPM, then I can put this
to rest...but it truly feels like I'm thrown back with more force at higher RPM,
even though the torque is rolling off.

I don't believe the torque converter is flashing beyond 3500 RPM (stall rating 2800 RPM).

Check out the math section. Wondering how the world got stuck on ft./lbs?

I see that in books and magazines quite often.

 

I was thinking that it might not be a better idea to base these questions on the GM EV1. That car has very little air and road resistance and has a truly flat torque curve from it's electric engine.

Power Rating: 102 kilowatts (137 horsepower) @ 7,000 rpm

Motor Torque: 150 Nm (110 lb-ft) @ 0-7,000 rpm

Transaxle Type: Single-speed with dual reduction gears

Drive Ratio: 10:946:1

 

Bret, The link too my dyno chart has the virus?
I'm uptodate on mcaffee and it's coming up clean??
weird :shurg:

 

Hawk,

It came up bad on one of the computers when the old man tried to look at it. Got me.

Bret

 

yeah it came up bad on my computer too. just a bunch of random special characters were displayed. and it jammed up my ie trying again and again to get through while my security software slapped it around.

 

I just looked at the link from my puter here at Ramchargers, ya it's all greek looking. I'll pull it down tonigt at home, where I have access too it. Sorry guys.
I'LL TRY AGAIN