Gas vs PSD
Fleet Mechanic
Joined: Feb 2007
Posts: 1,852
Likes: 39
Thanks for clarifying. I've never done a dyno run, but I would imagine that part of the process would be entering the tire size and axle ratio. I don't know, I could be way off with that. Feel free to educate me on the process.
If you did do it that way, then the machine could translate the force on the rollers directly into an actual engine torque number.
If you did do it that way, then the machine could translate the force on the rollers directly into an actual engine torque number.
Lead Driver
Joined: May 2011
Posts: 5,800
Likes: 455
yea there are tons of variables on dynos that can cause an inaccurate run. tire size and axle ratio is basically the only input data needed (different dynos/operators collect more info). MOST people who run dyno's know what the input of wrong values can mean. you really cant trust a dyno that 1)isnt regularly calibrated (like a very precise thermometer gets calibrated) and 2) if you dont watch the guy put the info in. it is common practice in the "dyno" world, to input slightly different tire size/gear ratios in order to inflate the numbers, or calibrate the % of drivetain loss to be small or non existant. this makes everyone who takes their cars/trucks to their shop think that the guys at the shop must be guru's of performance that cannot be matched by other shops. . .or, plenty of ppl just show up with wrong info so they can brag about how high their numbers are. i dont trust a dyno that im not running. luckily, i have the means to do this. in all reality, while it may not be precise, there is much greater probability of accuracy by calculating hp by 1/4 mile time, trap speed, and weight because there is less room for human error/ego.
Fleet Mechanic
Joined: Feb 2007
Posts: 1,852
Likes: 39
On the other hand, if you were testing mods to the same vehicle, I suppose it would be a fine method for getting relative data.
Lead Driver
Joined: May 2011
Posts: 5,800
Likes: 455
He put those miles on his truck since August 2010. For that kind of savings, wouldn't you at least consider an EGR delete? Some states are more strict on emissions than others. Being he's running an F450, I doubt many DOT guys could figure out if the EGR has been disconnected or not. I don't know of a single one that will climb under your truck (an F450 or so) for an inspection. I just had one done last week.
as for considering an egr delete, i'd be considering the average life lost by the egr system on a diesel. . .its impossible to tell just how damaging the egr is to a diesel. . .but the motor oil life is cut in 1/2 (at least) by the egr, and turbo's get gunked up and destroyed by them. as the 6.blow guys know best, the egr causes nothin but headaches. the poor 6.0 is a venerable motor (with good mileage) once theyre studded, all the emissions equipment are gone, and the stock turbo is gone. but theyll never come back from their reputation at this point. . .
Lead Driver
Joined: May 2011
Posts: 5,800
Likes: 455
Stealth 316 - Formulas for 1/4 mile ET & mph vs. hp & wgt
^ the above link (there are countless) seems like a good all around description of the hp calculator (i know you like numbers). i think also, no1 is calculating theirs by hand anymore, but rather punching their numbers into a "calculator" like the ones on the internet. . .engineers and mathemeticians have refined the equation a bit over the years, so it seems, in order to compensate for some of the variables. but just like it says in the link, no matter what its still a guesstimate.
my point was, the calculation is what it is. there isnt much you can do to except outright lie on the input data to get a faulty number, and you basically take anyone elses agenda out of the equation.
Postmaster
Joined: Oct 2006
Posts: 4,171
Likes: 12
From: SE Texas
o yea, there are a lot of variables to take into account. track conditions, driver error, wind resistance, even power loss via tire friction. some of the variables are actually nullified by the "mph" number.
Stealth 316 - Formulas for 1/4 mile ET & mph vs. hp & wgt
^ the above link (there are countless) seems like a good all around description of the hp calculator (i know you like numbers). i think also, no1 is calculating theirs by hand anymore, but rather punching their numbers into a "calculator" like the ones on the internet. . .engineers and mathemeticians have refined the equation a bit over the years, so it seems, in order to compensate for some of the variables. but just like it says in the link, no matter what its still a guesstimate.
my point was, the calculation is what it is. there isnt much you can do to except outright lie on the input data to get a faulty number, and you basically take anyone elses agenda out of the equation.
Stealth 316 - Formulas for 1/4 mile ET & mph vs. hp & wgt
^ the above link (there are countless) seems like a good all around description of the hp calculator (i know you like numbers). i think also, no1 is calculating theirs by hand anymore, but rather punching their numbers into a "calculator" like the ones on the internet. . .engineers and mathemeticians have refined the equation a bit over the years, so it seems, in order to compensate for some of the variables. but just like it says in the link, no matter what its still a guesstimate.
my point was, the calculation is what it is. there isnt much you can do to except outright lie on the input data to get a faulty number, and you basically take anyone elses agenda out of the equation.
My car is the perfect example of why.
It weighs 3670 lbs at the track.
12.16@111.78
Your "calculators" can't even agree on what HP it's making.
If I input MPH and weight, it says I'm making 418hp.
If I input E.T. and weight, it says I'm making 521hp.
So, which one is it?
JL
Lead Driver
Joined: May 2011
Posts: 5,800
Likes: 455
Those calculators are inaccurate.
My car is the perfect example of why.
It weighs 3670 lbs at the track.
12.16@111.78
Your "calculators" can't even agree on what HP it's making.
If I input MPH and weight, it says I'm making 418hp.
If I input E.T. and weight, it says I'm making 521hp.
So, which one is it?
JL
My car is the perfect example of why.
It weighs 3670 lbs at the track.
12.16@111.78
Your "calculators" can't even agree on what HP it's making.
If I input MPH and weight, it says I'm making 418hp.
If I input E.T. and weight, it says I'm making 521hp.
So, which one is it?
JL
using all of your above input variables, in this hp calc Horsepower Calculator from 1/4 mile ET and Trap Speed - DragTimes.com 397.58 at the fly is the result. . . sounds like you have a close-to-stock ls1 6 spd f-body
. . .w/ mild bolt ons at ~325 wheel (x1.15 = about 375 crank) and 3500lbs i ran a 12.6 @ 113. the calculator is pretty accurate. not precise, but accurate.
Postmaster
Joined: Oct 2006
Posts: 4,171
Likes: 12
From: SE Texas
my calculators? whatever is in that link that youre usin obviously isnt right, or theyre tryin to make a point of somethin else that you just didnt grasp (i didnt read the link, just browsed through it). . .you cant calculate hp without usin 1/4 mile time, mph, AND Weight. . .
using all of your above input variables, in this hp calc Horsepower Calculator from 1/4 mile ET and Trap Speed - DragTimes.com 381.33 at the fly is the result. . . sounds like you have a close-to-stock ls1 6 spd f-body. . .w/ mild bolt ons at ~325 wheel (x1.15 = about 375 crank) i ran a 12.6 @ 113. the calculator is pretty accurate. not precise, but accurate.
using all of your above input variables, in this hp calc Horsepower Calculator from 1/4 mile ET and Trap Speed - DragTimes.com 381.33 at the fly is the result. . . sounds like you have a close-to-stock ls1 6 spd f-body
. . .w/ mild bolt ons at ~325 wheel (x1.15 = about 375 crank) i ran a 12.6 @ 113. the calculator is pretty accurate. not precise, but accurate.It's an auto trans 4.6L N/A Thunderbird.
And when I plug the numbers in to the calculator you just linked, I get 401.74 hp.
JL
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Top 6 Best Deals Available on New Fords & Lincolns Right Now
Brett Foote
This Hennessey Takes the Expedition Tremor's Off-Roading Capability to the Next Level
Verdad Gallardo
Top 10 Fords at 2026 Carlisle Ford Nationals
Joe Kucinski
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Lead Driver
Joined: May 2011
Posts: 5,800
Likes: 455
edit: just redid my calc's on your car. . .musta put in 111 vs 111.78 for your car, worked out to be the 398 i originally posted with 111, 111.78 yields your numbers.
Postmaster
Joined: Oct 2006
Posts: 4,171
Likes: 12
From: SE Texas
The car has been on several dynos, at several different locations.
Mustang and Dynojet both.
The most it's ever put down on the rollers has been 270rwhp.
It's NOT losing 131 hp through the drivetrain.
JL
Lead Driver
Joined: May 2011
Posts: 5,800
Likes: 455
somethin is rotten in denmark. . . .is your gearing setup solely for drag racing (i.e. run across the line at redline in top gear)? also, if youre seein the same numbers on a mustang dyno AND a dynojet, somethin is wrong. . . .dynojet = inflat-o-meter.
Postmaster
Joined: Oct 2006
Posts: 4,171
Likes: 12
From: SE Texas
By using values from other similar vehicles and powerplants, my estimate is approx 310rwhp. But still-I'm not losing nearly 100hp through the drivetrain.
That's the point. Those calculators are NOT as accurate as some people think they are. The 4200 rpm stall converter, 4.30 gears,etc all make a huge impact on those calculations, along with the fact that the converter is only unlocked for the launch in 1st, and locked for the remainder of the run. The car 60's in the area of 1.67-1.70, so a very good 60' for the weight and power output also skews the calculator.
No, I'm not seeing the same numbers on a Dynojet and Mustang. Dynojets are usually 10-15rwhp higher.
The car has a 4.30 gear in it, and crosses at 6500ish RPMs. But it's by no means a "track only" setup.
JL
Lead Driver
Joined: May 2011
Posts: 5,800
Likes: 455
No, I do not.
By using values from other similar vehicles and powerplants, my estimate is approx 310rwhp. But still-I'm not losing nearly 100hp through the drivetrain.
That's the point. Those calculators are NOT as accurate as some people think they are. The 4200 rpm stall converter, 4.30 gears,etc all make a huge impact on those calculations, along with the fact that the converter is only unlocked for the launch in 1st, and locked for the remainder of the run. The car 60's in the area of 1.67-1.70, so a very good 60' for the weight and power output also skews the calculator.
No, I'm not seeing the same numbers on a Dynojet and Mustang. Dynojets are usually 10-15rwhp higher.
The car has a 4.30 gear in it, and crosses at 6500ish RPMs.
JL
By using values from other similar vehicles and powerplants, my estimate is approx 310rwhp. But still-I'm not losing nearly 100hp through the drivetrain.
That's the point. Those calculators are NOT as accurate as some people think they are. The 4200 rpm stall converter, 4.30 gears,etc all make a huge impact on those calculations, along with the fact that the converter is only unlocked for the launch in 1st, and locked for the remainder of the run. The car 60's in the area of 1.67-1.70, so a very good 60' for the weight and power output also skews the calculator.
No, I'm not seeing the same numbers on a Dynojet and Mustang. Dynojets are usually 10-15rwhp higher.
The car has a 4.30 gear in it, and crosses at 6500ish RPMs.
JL
310 x 1.2 (20% drivetrain loss which is typical (and somewhat a generous estimate) for a large ford rear axle and any auto) = 372 BHP. 30 BHP is MUCH LESS than the 40 wheel that you, yourself, admit the "highest" dyno run basically underestimated (so im being nice and not using your low"er" values generated by other dyno's).
Postmaster
Joined: Oct 2006
Posts: 4,171
Likes: 12
From: SE Texas
310 is still a lil low. . .so, if all the dyno's youve ran on yield 270 wheel (MAX, YIKES!), and the 1/4 mile calculator yields 400, and you admittedly have ~310 (which is still low) then which one was more accurate? the calculator! again, i never said it was precise. i said it was accurate (accuracy and consistency are twin brother/sister). . .neither a dyno or the calculator are precise (the calculator is what it is. the results "be what they be". . .a dyno is just as good as the people using/calibrating it).
310 x 1.2 (20% drivetrain loss which is typical (and somewhat a generous estimate) for a large ford rear axle and any auto) = 372 BHP. 30 BHP is MUCH LESS than the 40 wheel that you, yourself, admit the "highest" dyno run basically underestimated (so im being nice and not using your low"er" values generated by other dyno's).
310 x 1.2 (20% drivetrain loss which is typical (and somewhat a generous estimate) for a large ford rear axle and any auto) = 372 BHP. 30 BHP is MUCH LESS than the 40 wheel that you, yourself, admit the "highest" dyno run basically underestimated (so im being nice and not using your low"er" values generated by other dyno's).
It only take a certain amount of hp to turn a gearset. Increasing the hp of the engine does NOT increase that amount of power lost through that gearset be it trans or rear axle.
I'm not gonna sit here and argue with you all day about it either. Those calculators are nothing more than "getting you on the target" accurate.
JL
Lead Driver
Joined: May 2011
Posts: 5,800
Likes: 455
Drivetrain loss is not a straight up percentage.
It only take a certain amount of hp to turn a gearset. Increasing the hp of the engine does NOT increase that amount of power lost through that gearset be it trans or rear axle.
I'm not gonna sit here and argue with you all day about it either. Those calculators are nothing more than "getting you on the target" accurate.
JL
It only take a certain amount of hp to turn a gearset. Increasing the hp of the engine does NOT increase that amount of power lost through that gearset be it trans or rear axle.
I'm not gonna sit here and argue with you all day about it either. Those calculators are nothing more than "getting you on the target" accurate.
JL
so if drivetrain loss isnt a percentage (obviously different setups would be a different amount of loss) then what is it? certainly you cant say an axle takes X amount of hp to turn (which would be true) and that's that. . . .because an axlesoaks a certain amount of power to accelerate. . .that bein said, the harder the acceleration, the more hp it takes to keep the axle accelerating. of course, it takes a certain X amount of power to turn an axle X amount of rpm (which doesnt account for acceleration). . .so if drivetrain loss isnt most accurately described as a percentage, what best describes it? ? ? you'd be teachin me somethin. . .