Does a dynamometer tell the turth ?
Instructor
Joined: Nov 2013
Posts: 220
Likes: 17
From: Pasadena MD
I have both the GTECH & Dynolitious. both are not very accurate for me vs track times, but this doesn't mean they are not useful. I also run at 2200 ft elevation which may be why my readings are off.
I like using the G's curve which shows me how its pulling and at what RPM the g's start to fall off. The phone app I could never get it to work but I am still using the old 3GS phone.
I like using the G's curve which shows me how its pulling and at what RPM the g's start to fall off. The phone app I could never get it to work but I am still using the old 3GS phone.
Safety Car
Joined: Jan 2009
Posts: 3,736
Likes: 56
From: anchorage ak
DO MA NEU!
Thread Starter
Melting Slicks
Joined: Jun 2011
Posts: 3,116
Likes: 598
actual track 1/4 13.2 gtech 12.6 I find 1 in 6 runs is within 1/10th. I would be happy if it was +/- 2/10th most of the time. But the G's graph is what I most look at. HP ratings are all over the place from 244-325 ? MPH trap speed it is always high by 7-12 MPH.
But its still a better tool for quick checking vs your own impression.
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
Does a dynamometer tell the turth ?
Well my only experience with my auto trans camaro on a dyno says it lies about an automatics hp & torque but is still invaluable as a tuning tool. The automatic trans torque converter has a viscous coupling that at some speeds doesnt even engage and at other speeds it becomes a torque multiplier. Also it is a hydraulic pump and using the pump laws for power the speed of a hyd pump is proportional to the cube of the power input meaning the faster the pump goes the more power is needed to make it go faster by a exponential factor of 3.
Use the dyno for a tool, not for absolute numbers. The true test of how much power a car is making or how fast a car is, is by trap speed in the 1/4 mile...
On a chasis Dyno, there is way too many variables to skew the readings, a stall converter can kill 50-75hp on a chasis dyno, yet make you faster at the track.
Thats very correct and even with a manual trans your not going to be able to control air temperatures inside the dyno shop - sometimes even oxy levels in the shop are harmful to power (and the people inside - be careful). Lack of wind resistance on the car reduces the engine load at the dyno but a factor at the track. Using a tailpipe HEGO sensor wont see the same gas as a wideband HEGO in the header.On top of it all dyno time is expensive. If u can get a Gtech to work and have the roads to test it with your really doing the same process - referencing improvements for changes and modifications.
Advanced
Joined: Aug 2013
Posts: 53
Likes: 0
From: meas az
+1
Use the dyno for a tool, not for absolute numbers. The true test of how much power a car is making or how fast a car is, is by trap speed in the 1/4 mile...
On a chasis Dyno, there is way too many variables to skew the readings, a stall converter can kill 50-75hp on a chasis dyno, yet make you faster at the track.
Use the dyno for a tool, not for absolute numbers. The true test of how much power a car is making or how fast a car is, is by trap speed in the 1/4 mile...
On a chasis Dyno, there is way too many variables to skew the readings, a stall converter can kill 50-75hp on a chasis dyno, yet make you faster at the track.
Pro
Joined: Nov 2013
Posts: 730
Likes: 37
From: Catoosa Okla
The auto versus the stick makes no difference. If the guy running the dyno is experienced, he's looking to pull at a 1 to 1 ratio. On our old girls it's high gear. With an overdrive the operator needs to select the gear that puts them closest to a 1 to 1 ratio, meaning they might perform the pull in 3rd or whichever gear is closest. 15 to 20 loss through the driveline is about on par. My LS swap engine is somewhere north of 600 hp....at the crank. I'm hoping for at least 450 hp at the wheels. Now you know what ate up a LOT of hp trying to get it to the ground.
Safety Car
Joined: Oct 2004
Posts: 3,926
Likes: 739
From: Youngstown Ohio
Drifting
Joined: Apr 2005
Posts: 1,917
Likes: 451
From: Central NJ
Converter also can really affect what the chassis dyno "reads"
My old motor made north of 750 hp and only showed a 536 at the wheels on the chassis dyno
Car ran mid 9's all day on motor alone so it doesnt tell the whole story not even close.
My old motor made north of 750 hp and only showed a 536 at the wheels on the chassis dyno
Car ran mid 9's all day on motor alone so it doesnt tell the whole story not even close.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Safety Car
Joined: Jan 2009
Posts: 3,736
Likes: 56
From: anchorage ak
Safety Car
Joined: Oct 2004
Posts: 3,926
Likes: 739
From: Youngstown Ohio
OK, I misunderstood........the testing procedure is the same, but the auto definitely uses more power than the stick car. Mine on my current sb427 came out to 22% loss. Many sticks are closer to 15%.
Le Mans Master
Joined: May 2006
Posts: 9,993
Likes: 1,136
From: League City Tx
I went from 657hp/675tq on the engine dyno..(I dynoed it personally) to 460hp/480tq in the car... That's going from 2" dyno headers and no exhaust to 1 7/8" car headers and full 3" exhaust/muffs, full accessories, T400 w/10" converter, heavy IRS diff/half shafts, drag radials. Both engine and chasis dynos were in SAE....So that's roughly 30% loss in my car.
Yet at 3660lbs it has been 128mph... Which obviously is stronger then 460 rwhp would indicate...
Point being is, don't sweat dyno numbers..
Yet at 3660lbs it has been 128mph... Which obviously is stronger then 460 rwhp would indicate...
Point being is, don't sweat dyno numbers..
Safety Car
Joined: Jan 2009
Posts: 3,736
Likes: 56
From: anchorage ak
I went from 657hp/675tq on the engine dyno..(I dynoed it personally) to 460hp/480tq in the car... That's going from 2" dyno headers and no exhaust to 1 7/8" car headers and full 3" exhaust/muffs, full accessories, T400 w/10" converter, heavy IRS diff/half shafts, drag radials. Both engine and chasis dynos were in SAE....So that's roughly 30% loss in my car.
Yet at 3660lbs it has been 128mph... Which obviously is stronger then 460 rwhp would indicate...
Point being is, don't sweat dyno numbers..
Yet at 3660lbs it has been 128mph... Which obviously is stronger then 460 rwhp would indicate...
Point being is, don't sweat dyno numbers..
DO MA NEU!