road dyno??

4gotn · Post by **4gotn** » March 22nd, 2006, 1:54 pm

http://www.franklinracingproducts.com/roaddyno.html

never heard of an in car dyno...
does anyone think itd be worth the pitas id have to spend on it...
pluss it needs a labtop...i dont have one XD
just curious what some of the more exp moders think
theres only one dyno that ive found in my area so far and if there is only one im not sure if i can trust the condition of it so this would be a simple solution for me..if its worthwhile that is..

Legato626 · Post by **Legato626** » March 22nd, 2006, 1:58 pm

If your talking about the v tec units that stick on your window. I thought about it but I am not sure how accurate they are to a real dyno. I wouldnt mind purchasing one and then try it then go get it dynoed just to see how accurate it is.

Nd4SpdSe · Post by **Nd4SpdSe** » March 22nd, 2006, 2:43 pm

They are not really worth it IMO. The problem is too many factors to get an accurate result. On a regular dyno, your car isn't moving, so issues like weight and wind resistance isn't affecting the car's performance and can take into effect 100% of the car's acceleration/power capability and will give you the result in whp (wheel horse power). This will not give you how much power the engine itself is making, you need to pull the engine out of the car for that. Power loss though the drivetrain will give you a lower number than what the engine itself is making, but in the end, getting the power to the wheel is that really matters, bhp is just for marketting and bragging rights. Although the dyno itself creates resistance in the rollers, it is calibrated to compensate for itself.

The problem with any road/in-car/moving dyno, no matter how advanced it is, are literally stupid devices and will not give accurate results. Because your car is moving, thinks like weight and wind resistance come into effect. Less weight=less weight to move=more acceleration. Sure, you can get the car weighted, but things like the amount of fuel in the tank, how much the driver weights, if they had a big lunch or even how many layers of cloths the person is wearing add/remove weight from the car. You may or may not consider it negligable, but the fact that it varies can give inconsistant/inaccurate results. As well, the device doesn't know the aerodynamics of the car, if your driving a vehicle with the aerodynamics of a brick or a needle. Wind speed and direction as well.

This device however can be handy for figuring out 60-ft and 1/4 mile times because vehicle weight and wind resistance are factors for time/distance trials...however it must be accurately configured. The device needs to know of the exact wheel diameter and how fast it's rotating (this could probably be taken from the speedometer sensor) to know how much distance the car has actually travelled...but if you get any wheel spin/traction loss, this will also skew results, as you would not have travelled the actual distance that the unit thinks is it.

In the end, it would be a handy tool for personal testing and comparing each modifications to themselves reliatively, and even personal bests, but to measure actual vehicle performance, hell no. There's too much variables around the vehicle that the unit would not know about.

Cy · Post by Cy » March 22nd, 2006, 2:56 pm

wanna test it.. buy one and run it while on a dyno..then overlay the charts...

Yes obviously factors like head/tail wind will come into account(if you wanna get technical, what you had for lunch if not factored in will have a result)...but again... If you test on the same stretch of road going in both directions factors like that will work themselves out in the math..

I'd buy one..

4gotn · Post by **4gotn** » March 22nd, 2006, 3:07 pm

Nd4SpdSe
makes a stronger point
probly wont be worth it
i dont plan on testing and running all day
although i do live near a highway and when i pull out of my driveway its 55 and i could have a bit of fun with that...ie legal 0-60 time
i dont think its worth it in the long run
i could put a catback on my car or something for that
or 6 oil changes XD

Cy · Post by Cy » March 22nd, 2006, 3:19 pm

The package looks like a quick install... make the money back renting it to people for a day or 2 @ like 20$... a day...

Nd4SpdSe · Post by **Nd4SpdSe** » March 22nd, 2006, 3:49 pm

Cy wrote:wanna test it.. buy one and run it while on a dyno..then overlay the charts...

Wouldn't that defeat the purpose of getting one of these units if your already on a dyno

As well, you can do that, and take your car directly off the dyno and make a run on the road. Because the engine how has to now pull the weight of the car, as well, the car has to push against the wind, it'll take longer to get say, from ~0 to 7000rpms than it was on a dyno, so it will calculate less power cause it took you longer. Ya, the lunch thing is extreme, but it's still weight. Rule of thumb for weight reduction is apparently you gain 1/10 of a second per 100lbs lost....it may or may not be accurate, but those are things that do take into account when drag racing, but a standard dyno couldn't care less about.

Legato626 · Post by **Legato626** » March 22nd, 2006, 8:34 pm

G tech pro units I was thinking about getting one and testing it just to see if it does add up to it. If its just a little bit off thats freaking sweet if it is.

Typhoonk · Post by **Typhoonk** » March 23rd, 2006, 12:20 am

I got one of the little simple unit. Wasn't too accurate - probably +-5 or more hp but whatever. I got the unit for $20 of a friend (probably find em on ebay for that), and it's kinda fun to know how much hp you use when u are just driving normal...... Also measures some G's and stuff too

Hopefully I can hit a dyno this summer and see how accurate this thing is.

(anybody know a dyno near Oshawa?)

torpedan · Post by **torpedan** » March 23rd, 2006, 7:11 pm

I have had a G-tech before, and its a piece of crap. I have never used a G-tech Pro.

Now Road Dyno on the other hand...

Although there is a firm naysayer posting above me.. This product is actually fairly accurate. You need to dig up a good sum of information about your vehicle both including coeffiecnt of drag and Frontal area. It does have elevation and heat correction just be sure you dont decied to dyno your car on a windy day.

Finding a good flat surface is actually the hardest part about using this device. Even if you cant though using the same consistent strech will deliver the resutls you need. Although some people see dynos about bragging its more of a tool so you can compair before and after results from changes you have made to a motor.

The graphs are clear and its not hard to see where the modifications you have just done make a diffrence, this was actually really helpful in nailing the timing down on my old mx-3.

If my old laptop hard drive had not failed i would post some examples to show you what the software does and what it uses to calculate the vehicles horsepower. I have the CD around here somewhere though But i dont see myself geting off my a-- to find it.

All in all for the price i felt it was a good product

There is a link to a PDF at the bottom of thier page and if you read it there are good details about thier product.

edit:I suck at english.

Legato626 · Post by **Legato626** » March 23rd, 2006, 9:07 pm

I was always thinking about getting one just to see some changes and let people use it. But I would always use a really dyno after doing a big mod or something just to get a right reading.

torpedan · Post by **torpedan** » March 25th, 2006, 7:16 pm

Legato626 wrote:I was always thinking about getting one just to see some changes and let people use it. But I would always use a really dyno after doing a big mod or something just to get a right reading.

Just keep in mind right is always relative, you can dyno the same motor on diffrent 'real' dynos and get diffrent results each time. Sometimes the results are very far off from a prevoius run too.