If a GPS observed top speed of 123mph is recorded for a 2006 K3500, Allison 6spd, 3.73 gear ratio, running 285/75/16 rubber, what are the estimated horsepower and torque numbers? Weight with gear and driver = 7500#.
If a GPS observed top speed of 123mph is recorded for a 2006 K3500, Allison 6spd, 3.73 gear ratio, running 285/75/16 rubber, what are the estimated horsepower and torque numbers? Weight with gear and driver = 7500#.
Last edited by Mark Rinker; 04-28-2010 at 14:36.
2011 Chevrolet Tahoe 5.3L daily driver
- Previous owner of two 1994 6.5L K3500s, '01, '02, and '05 6.6L K2500s, '04 C4500, '06 K3500 dually, '06 K3500 SRW, '09 K3500HD SRW, '05 Denali
- Total GM diesel miles to date : ~950K
HP/TQ can only be calculated by speed if time is also in the equation. If you were to make a full throttle run up to 123 MPH, on a purely level surface, with the vehicle weight known, the HP/TQ could be known. Otherwise, no. HP = work performed over time. This is how the G-Tech and inertial dyno's calculate power levels.
If you could, then your HP/TQ #'s would be right up there with the Prius. They can go 123 MPH.
http://vlsicad.ucsd.edu/~sharma/Potp...est_intro.html Time is not an input with this calculator, it only asks for torque. However, I couldn't get it to read any higher than 117mph...regardless of the torque #s input...?
This is basically what I did.
As for the Prius... http://www.youtube.com/watch?v=mzFK56epaHI Elsewhere a 112mph top speed is sited.
So, without time numbers...what is estimated TORQUE produced to attain 123mph, with specs listed above?
Last edited by Mark Rinker; 04-28-2010 at 16:07.
2011 Chevrolet Tahoe 5.3L daily driver
- Previous owner of two 1994 6.5L K3500s, '01, '02, and '05 6.6L K2500s, '04 C4500, '06 K3500 dually, '06 K3500 SRW, '09 K3500HD SRW, '05 Denali
- Total GM diesel miles to date : ~950K
I left out the time factor in the quote (although I stated it earlier). Without time, you can't calculate HP or TQ, with just speed as an input. If you were to use your top speed to calculate, you would have to be at maximum power usage, with all other factors known (weight, grade, wind drag, etc.), and not just against the governor, which is where you were unless your governor has been adjusted. If you know your torque at a specific RPM, then you could know your your HP, as well. HP = (Tq x RPM) / 5252. At 5252 RPM, HP and TQ are the same. Under no circumstances can HP be calculated without the time factor. It can be measured by other means, but guaranteed, time is part of that equation. HP is a representative figure of work performed over time. Nothing else. Tire size, weight, gear ratio, etc. have nothing to do with engine output power. They add to the drivetrain parasitic loss factors. They are, however, factors with how much power is available where the rubber meets the road (RWHP).
The Prius speed is limited electronically. Yours was too.
JK - was I up against a speed limiter on your tune of 123? There was alot of wind noise, and I did feel a 'surge' but lifted rather than see if it repeated.
2011 Chevrolet Tahoe 5.3L daily driver
- Previous owner of two 1994 6.5L K3500s, '01, '02, and '05 6.6L K2500s, '04 C4500, '06 K3500 dually, '06 K3500 SRW, '09 K3500HD SRW, '05 Denali
- Total GM diesel miles to date : ~950K
Sheeez Einstein my assumption was that I had arrived at 123mph as my max speed, not rev OR mph limited, but wind drag limited.
From the calculator previously posted, I had tried to estimate torque by inputing various values, until receiving an output speed of 123. However, 117 was the highest output the calculator would give, regardless of torque figure input.
Again...anyone have a reasonable estimate of torque - based on the following assumptions:
AN ESTIMATE AS REQUESTED IS OKAY!!!
- 123 is the drag limited top speed;
- all other specs are accurate as listed above;
- level surface, no wind, one earth atmosphere, at sea level, etc. etc. etc.
(On edit: I routinely pick Prius' out of my grille while refueling.)
2011 Chevrolet Tahoe 5.3L daily driver
- Previous owner of two 1994 6.5L K3500s, '01, '02, and '05 6.6L K2500s, '04 C4500, '06 K3500 dually, '06 K3500 SRW, '09 K3500HD SRW, '05 Denali
- Total GM diesel miles to date : ~950K
Kennedy Diesel-owner
More than just a salesman-I use and test the products that I sell on a daily basis!
Superflow Lie Detector in house
2002 Chev K2500HD D/A CC Long LT 11.77@ 124mph at 7700# fuel only-e.t. needs help
2005 Chev K3500SRW D/A CC Long LT(SOLD)
2007 Chev K2500 Classic EC Short LT (Sold)
2012 GMC K3500SRW D/A CC Long LTZ Happy Birthday to me! Built 1 working day after my birthday and delivered 7 days later.
2016 GMC K3500SRW D/A CC short LTZ
Custom tuning in house using EFI Live tuning software!
2011 Chevrolet Tahoe 5.3L daily driver
- Previous owner of two 1994 6.5L K3500s, '01, '02, and '05 6.6L K2500s, '04 C4500, '06 K3500 dually, '06 K3500 SRW, '09 K3500HD SRW, '05 Denali
- Total GM diesel miles to date : ~950K
Sure
The accuracy would be in the speedo vs tire size (rollout) at the given speed which I'm sure will be different than the tire size at normal speeds.
Kennedy Diesel-owner
More than just a salesman-I use and test the products that I sell on a daily basis!
Superflow Lie Detector in house
2002 Chev K2500HD D/A CC Long LT 11.77@ 124mph at 7700# fuel only-e.t. needs help
2005 Chev K3500SRW D/A CC Long LT(SOLD)
2007 Chev K2500 Classic EC Short LT (Sold)
2012 GMC K3500SRW D/A CC Long LTZ Happy Birthday to me! Built 1 working day after my birthday and delivered 7 days later.
2016 GMC K3500SRW D/A CC short LTZ
Custom tuning in house using EFI Live tuning software!