Horse power readings from car computers? - 2003-04 Mach 1 Registry Owners Club

codymach · 12-10-2003, 04:25 PM

Thought I would re-do this thread the other was confusing. I have been reading advertisements where it is claimed you can get an accurate horse power reading from a "plug in computer" in your car. If this is true how would this work? Also has anyone actually bought one of these and did the Horse power reading come close to an actual dyno? I guess if these work the dyno might not be as necessary....I'd love to hear these actually are accurate. I was guessing I weigh my car then the computer determines speed and distance and you get Horse Power? I can weigh my mach here in town for $5.00

ttown · 12-10-2003, 05:07 PM

I'm sure with the weight of the car, a known distance recorded, a know speed recorded you could calculate your torque/hp. I'd have to breakout my physics books. I do remember :

Force=Mass X Distance

and there are formulas to determine HP, Force should be in ft/lbs of torque if I remember my physics from 20 years ago.

You could probally get within 5 percent but you'd only know your calculated HP/TQ. The dyno is an actual measurement and if calabrated correctly is much more accurate.

The dyno also gives you A/F reading and allows you to tune with out a dangerous tune for max HP/TQ.

04Retro · 12-10-2003, 05:29 PM

They can get you in the ballpark but that is all...too many factors that the computer does not take into consideration...True HP figures are taken at the crank-so just yank the engine. Next option is RWHP on the dyno but that is subject to all types of variables. Same car, same day 2 dynos across town and 2 different sets of numbers. As to the 'computer' the basic physics will tell you you need X hp to push X pounds at X speed...That will give you a basic min number but not the true number. You might have 400 crank hp but the physics will tell you only 350 as that was what was need to push the vehicle--the computer doesn't take into account how much hp was lost in the drive train-not all drive trains are alike...it also doesn't take into account the drag coefficient of the vehicle--less hp needed to push a corvette to 65mph then a flat nosed van.........

ttown · 12-10-2003, 05:37 PM

Actually those number should be RWHP/RWTQ. Your moving in ft per second. So the calculation would be at the rear wheels not the crank.

That said you would only get a ball park and I don't know what good it would do you. I guess you could buy a tuner and play be could end up blowing your engine with a lean condition. The dyno can be monitored real time and is used for tuning more than just finding out HP/TQ figures.

Of course with temp/hum changes your numbers would vary, you would have to do an SAE # calcuation for those raw numbers to mean anything on a day to day basis. You dyno's have STD/SAE conversion calculations built into there program but you could do the formula with a calculator if you really wanted to.

I could be wrong but that's the way I see it off the top of my head.

DSG2003Mach1 · 12-10-2003, 05:47 PM

sounds like the new Gtech Pro and similar devices..I think those are mostly for people with no reasonable access to a dyno/track. Itll give you an idea if youre improving, or it a mod helped..just a guide really. Once youve made some 1/4 passes and compare the two, you can do some pretty accurate comparisons. I would think the same with the dyno...take the Gtech numbers compared to the dyno numbers and use it as a base...its no substitute for a dyno when it comes to tuning though

Joe91898 · 12-10-2003, 06:05 PM

Quote:

Originally posted by codymach
Thought I would re-do this thread the other was confusing. I have been reading advertisements where it is claimed you can get an accurate horse power reading from a "plug in computer" in your car. If this is true how would this work? Also has anyone actually bought one of these and did the Horse power reading come close to an actual dyno? I guess if these work the dyno might not be as necessary....I'd love to hear these actually are accurate. I was guessing I weigh my car then the computer determines speed and distance and you get Horse Power? I can weigh my mach here in town for $5.00

Is it the Road Dyno you are refering to? I have one of these units.
I use it mostly on my motorcycle. it hooks up to a plug wire and reads the pulses. You put in the gear ratio, rear end ratio, tire size, temp elevation, Baro pressure, etc and it takes the data and turns it into a graph and also has a run data numbers.
It has returned readings that were accurate to a point, but the variables have to be pretty much right on. If anything it's fun to play with. It does give an actual dyno graph. On my bike I do 3rd gear runs to redline. Fairly dangerous on regular roads. Tough to get two runs that have same numbers but they are usually close
I attached one of my runs which was inline with a regular dyno run. I got lucky with this run. I wouldn't rely on it for dead on numbers. I use it mostly for fun and to see what the curves look like.
On a regular Dyno jet Dyno I got 76hp and 72tq these would be SAE corrected at the wheel numbers for both runs. The RD also has a corection factor which can be used or not. I used it

cammer · 12-10-2003, 06:51 PM

I've been thinking about one of these too. Great info. It seems like it's better than seat of your pants, but not as good as a dyno or time slip.

Joe91898 · 12-10-2003, 06:53 PM

Here's the website for the Road Dyno
http://www.charm.net/~mchaney/roaddyno/

jrob350 · 12-10-2003, 06:59 PM

If you are refering to the GTech devices and other similar ones. They are fairly accurate. In true life they could be considered more accurate than a dyno because the dyno does not consider wind resistance, drag coefficient and other things. You will probably never get the same readings on these devices on different days, because air temp and weather have effects on horsepower and dyno runs will probably be more consistent since most are in a controlled environment. But the devices will probably give you a good reading plus or minus 3-4 HP

ttown · 12-10-2003, 08:46 PM

A dyno uses the same math as one of these devices. The operator puts in known values of your car. I didn't pay much attention but I know the final gear ratio was one and probally tire size. The dynojet know the size of it's wheel (5ft I think) and with the size of your tires it can calculate your RPM's using of simple ration formula.

It also solves using the same information you can get from the computer speedo that calculates distance. Your car is traveling on a big treadmill

The analog speedo won't be accurate because of varying spring tensions through it's ranges, but the computers digital info should be very accurate. This is the same math and technoloy that allows you to buy a speedcal for tire/gear changes.

If these devices save points all along the RPM scale a simple computer program could be written to give you a graph or just like high school you could plot it. That's what a dyno is doing. It's a big calculator thats all.

One advantage the dyno has is the transducer that sniffs the tailpipe for ppm of fuel (A/F ratio) this can't be calculated and it tell you of rich or lean conditions.

An advantage to the in the car model would be your really moving and your ramair system is working.

The disadvantages or advantages depending on how you look at it is: wind resistance, drag, incline (not flat affecting speed), and weather but there is a formula for STD to SAE #'s you could log that number and be fine with varying weather just like the dyno does.

The biggest disadvantage is putting your car in 4th and pulling 2k to 6.5k like on a dyno. That's 140mph+.

Ok I guess I got a little out of my math and physics degrees I never really used

Shaker1 · 12-11-2003, 02:28 AM

Quote:

Originally posted by Joe91898
Here's the website for the Road Dyno
http://www.charm.net/~mchaney/roaddyno/

Looking at that picture of the device I would say it will be difficult to attach it to a plug wire given the 32V motor's coil-on-plug arrangement. That unit appears to have an inductance style clamp that requires access to a high voltage plug wire.

Joe91898 · 12-11-2003, 11:43 AM

Quote:

Originally posted by Shaker1
Looking at that picture of the device I would say it will be difficult to attach it to a plug wire given the 32V motor's coil-on-plug arrangement. That unit appears to have an inductance style clamp that requires access to a high voltage plug wire.

I have no clue about using it with this car. I didn't even know it didnt have wires

. I know so little about my car, yet I can break my bike motor down and do piston and cam work, go figure

I know my limitations, I'll never touch anything of importance under the hood of my Mach
You can also hook it to the coil(provided there are hook up points) with the aligator clips shown.
I've used ot both ways on my bike.
Thanks,
Joe

codymach · 12-11-2003, 11:43 AM

Other products like this one advertise that you simply plug it into the power supplu in your car, then attach to teh windshield...?

Joe91898 · 12-11-2003, 11:49 AM

Quote:

Originally posted by codymach
Other products like this one advertise that you simply plug it into the power supplu in your car, then attach to teh windshield...?

I think I've come across what you are refering to before but it is different from the RD. If you find any links could you post them? Might be something fun to get.
I use that RD on my Yamaha VStar 1100 and have also used it on my VMAX. It pretty acuurate but by the end of the run the speeds are excessive. A nice straight strecth of closed road and a lat top would be ideal.

Rooster · 12-16-2003, 11:21 PM

Check this site to verify HP and TQ Live Road DYNO.

http://www.smokemup.com/auto_math/pressure_ratio.php

Rooster · 12-16-2003, 11:22 PM

Post results ive done it with sevral big bore MC's. was within 10 prsent of actual dyno runs

H-TownMachI · 12-17-2003, 12:13 AM

Quote:

Originally posted by ttown
I'm sure with the weight of the car, a known distance recorded, a know speed recorded you could calculate your torque/hp. I'd have to breakout my physics books. I do remember :

Force=Mass X Distance

and there are formulas to determine HP, Force should be in ft/lbs of torque if I remember my physics from 20 years ago.

You could probally get within 5 percent but you'd only know your calculated HP/TQ. The dyno is an actual measurement and if calabrated correctly is much more accurate.

The dyno also gives you A/F reading and allows you to tune with out a dangerous tune for max HP/TQ.

ttown did you go to OU. What kind of physics did they teach.

Newtons 2nd law F=ma i.e. Force=mass x acceleration

Torque=Fd T=Force X distance

HP = Torque * RPM / 5,252

12-10-2003, 04:25 PM	#1
codymach Registered User Join Date: Jun 2003 Location: somewhere Posts: 2,840	Horse power readings from car computers? Thought I would re-do this thread the other was confusing. I have been reading advertisements where it is claimed you can get an accurate horse power reading from a "plug in computer" in your car. If this is true how would this work? Also has anyone actually bought one of these and did the Horse power reading come close to an actual dyno? I guess if these work the dyno might not be as necessary....I'd love to hear these actually are accurate. I was guessing I weigh my car then the computer determines speed and distance and you get Horse Power? I can weigh my mach here in town for $5.00 __________________ SUPPORTING MEMBER MODIFICATIONS: Bassani Mid-Length Ceramic Headers Bassani X-Pipe with cats SS Bassani Cat Back SS Meziere Electric water pump PHP Intake Spacer KN Filter Hurst Retro Shifter, T-handle Bullitt Fuel Door Bullitt Anthracite 18x9 wheels Goodrich g-force T/A KDW 265/40/18's Hurst Equipped Emblem Mach 1 I.D. Plate Shock tower covers Raised the shaker 2003 Mach 1 Torch Red 1965 Rambler Marlin 287 (Slowest car in the West!) 1951 Mercury (still in the field) 1966 Ford Galaxy 500, 352 cu. in. 4v 1994 F-150 4x4 2001 Focus

12-10-2003, 05:07 PM	#2
ttown Registered User Join Date: Jul 2003 Location: Oklahoma Posts: 844	I'm sure with the weight of the car, a known distance recorded, a know speed recorded you could calculate your torque/hp. I'd have to breakout my physics books. I do remember : Force=Mass X Distance and there are formulas to determine HP, Force should be in ft/lbs of torque if I remember my physics from 20 years ago. You could probally get within 5 percent but you'd only know your calculated HP/TQ. The dyno is an actual measurement and if calabrated correctly is much more accurate. The dyno also gives you A/F reading and allows you to tune with out a dangerous tune for max HP/TQ. __________________ 2003 Mach 1 Azure Blue 5 speed SAE-280RWHP 307RWTQ, A/F 13 Stock except K&N 2500miles DOB- 6/23/03 2004 Mach 1 Torch Red- Auto DOB - 4/14/04 Sold to son 2002 GT-Mineral Gray 5 speed UPR Blue Thunder Shifter Last edited by ttown; 12-10-2003 at 05:24 PM.

12-10-2003, 05:29 PM	#3
04Retro Registered User Join Date: Oct 2002 Location: Sacramento California Posts: 575	They can get you in the ballpark but that is all...too many factors that the computer does not take into consideration...True HP figures are taken at the crank-so just yank the engine. Next option is RWHP on the dyno but that is subject to all types of variables. Same car, same day 2 dynos across town and 2 different sets of numbers. As to the 'computer' the basic physics will tell you you need X hp to push X pounds at X speed...That will give you a basic min number but not the true number. You might have 400 crank hp but the physics will tell you only 350 as that was what was need to push the vehicle--the computer doesn't take into account how much hp was lost in the drive train-not all drive trains are alike...it also doesn't take into account the drag coefficient of the vehicle--less hp needed to push a corvette to 65mph then a flat nosed van......... __________________ David 04 Mach 1, Screaming Yellow, 5 sp, IUP 08 Bullitt Dark Highland Green

12-10-2003, 05:37 PM	#4
ttown Registered User Join Date: Jul 2003 Location: Oklahoma Posts: 844	Actually those number should be RWHP/RWTQ. Your moving in ft per second. So the calculation would be at the rear wheels not the crank. That said you would only get a ball park and I don't know what good it would do you. I guess you could buy a tuner and play be could end up blowing your engine with a lean condition. The dyno can be monitored real time and is used for tuning more than just finding out HP/TQ figures. Of course with temp/hum changes your numbers would vary, you would have to do an SAE # calcuation for those raw numbers to mean anything on a day to day basis. You dyno's have STD/SAE conversion calculations built into there program but you could do the formula with a calculator if you really wanted to. I could be wrong but that's the way I see it off the top of my head. __________________ 2003 Mach 1 Azure Blue 5 speed SAE-280RWHP 307RWTQ, A/F 13 Stock except K&N 2500miles DOB- 6/23/03 2004 Mach 1 Torch Red- Auto DOB - 4/14/04 Sold to son 2002 GT-Mineral Gray 5 speed UPR Blue Thunder Shifter Last edited by ttown; 12-10-2003 at 05:45 PM.

12-10-2003, 05:47 PM	#5
DSG2003Mach1 700 HP Mach Join Date: Nov 2003 Location: Orlando, FL Posts: 8,384	sounds like the new Gtech Pro and similar devices..I think those are mostly for people with no reasonable access to a dyno/track. Itll give you an idea if youre improving, or it a mod helped..just a guide really. Once youve made some 1/4 passes and compare the two, you can do some pretty accurate comparisons. I would think the same with the dyno...take the Gtech numbers compared to the dyno numbers and use it as a base...its no substitute for a dyno when it comes to tuning though __________________ 03 dsg mach1 - MPR built 9.5:1 motor, D1, cams, ported intake, full exhaust, magnum t56, built rear, E85 etc... '12 F150 FX2 Supercrew with Ecoboost daily beater

12-10-2003, 06:51 PM	#7
cammer Guest Join Date: Sep 2003 Location: El Dorado Hills, CA Posts: 27	I've been thinking about one of these too. Great info. It seems like it's better than seat of your pants, but not as good as a dyno or time slip.

12-10-2003, 06:53 PM	#8
Joe91898 Registered User Join Date: Jan 2003 Location: Mount Vernon, NY Posts: 402	Here's the website for the Road Dyno http://www.charm.net/~mchaney/roaddyno/ __________________ JJC SOLD '03 Mach1 Azure Blue

12-10-2003, 06:59 PM	#9
jrob350 Registered User Join Date: Nov 2003 Location: Columbus,IN Posts: 36	If you are refering to the GTech devices and other similar ones. They are fairly accurate. In true life they could be considered more accurate than a dyno because the dyno does not consider wind resistance, drag coefficient and other things. You will probably never get the same readings on these devices on different days, because air temp and weather have effects on horsepower and dyno runs will probably be more consistent since most are in a controlled environment. But the devices will probably give you a good reading plus or minus 3-4 HP __________________ 04 Mach 1 Azure Blue Born 10/03/03 Raised Shaker Removed Silencer K&N filter Pro 5.0 Shifter MAC Prochamber MAC 3" Catback

12-10-2003, 08:46 PM	#10
ttown Registered User Join Date: Jul 2003 Location: Oklahoma Posts: 844	A dyno uses the same math as one of these devices. The operator puts in known values of your car. I didn't pay much attention but I know the final gear ratio was one and probally tire size. The dynojet know the size of it's wheel (5ft I think) and with the size of your tires it can calculate your RPM's using of simple ration formula. It also solves using the same information you can get from the computer speedo that calculates distance. Your car is traveling on a big treadmill The analog speedo won't be accurate because of varying spring tensions through it's ranges, but the computers digital info should be very accurate. This is the same math and technoloy that allows you to buy a speedcal for tire/gear changes. If these devices save points all along the RPM scale a simple computer program could be written to give you a graph or just like high school you could plot it. That's what a dyno is doing. It's a big calculator thats all. One advantage the dyno has is the transducer that sniffs the tailpipe for ppm of fuel (A/F ratio) this can't be calculated and it tell you of rich or lean conditions. An advantage to the in the car model would be your really moving and your ramair system is working. The disadvantages or advantages depending on how you look at it is: wind resistance, drag, incline (not flat affecting speed), and weather but there is a formula for STD to SAE #'s you could log that number and be fine with varying weather just like the dyno does. The biggest disadvantage is putting your car in 4th and pulling 2k to 6.5k like on a dyno. That's 140mph+. Ok I guess I got a little out of my math and physics degrees I never really used __________________ 2003 Mach 1 Azure Blue 5 speed SAE-280RWHP 307RWTQ, A/F 13 Stock except K&N 2500miles DOB- 6/23/03 2004 Mach 1 Torch Red- Auto DOB - 4/14/04 Sold to son 2002 GT-Mineral Gray 5 speed UPR Blue Thunder Shifter Last edited by ttown; 12-10-2003 at 08:51 PM.

12-11-2003, 11:43 AM	#13
codymach Registered User Join Date: Jun 2003 Location: somewhere Posts: 2,840	Other products like this one advertise that you simply plug it into the power supplu in your car, then attach to teh windshield...? __________________ SUPPORTING MEMBER MODIFICATIONS: Bassani Mid-Length Ceramic Headers Bassani X-Pipe with cats SS Bassani Cat Back SS Meziere Electric water pump PHP Intake Spacer KN Filter Hurst Retro Shifter, T-handle Bullitt Fuel Door Bullitt Anthracite 18x9 wheels Goodrich g-force T/A KDW 265/40/18's Hurst Equipped Emblem Mach 1 I.D. Plate Shock tower covers Raised the shaker 2003 Mach 1 Torch Red 1965 Rambler Marlin 287 (Slowest car in the West!) 1951 Mercury (still in the field) 1966 Ford Galaxy 500, 352 cu. in. 4v 1994 F-150 4x4 2001 Focus

12-16-2003, 11:21 PM	#15
Rooster Registered User Join Date: Oct 2003 Location: Alamogordo Posts: 83	HP/TQ from road test calculations Check this site to verify HP and TQ Live Road DYNO. http://www.smokemup.com/auto_math/pressure_ratio.php

12-16-2003, 11:22 PM	#16
Rooster Registered User Join Date: Oct 2003 Location: Alamogordo Posts: 83	here ya go Post results ive done it with sevral big bore MC's. was within 10 prsent of actual dyno runs

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