There is an easy way to figure how fast your truck is at top speed.

Draw two lines 100 feet apart. You'll need room on either side of the lines for braking and to reach your top speed. Do it on a nice level road. Then you'll need a stop watch and someone to time you. Get your truck up to operating temperature and do a run. You want your truck to be at top speed when you hit the first line and continue until you hit the second line. Get that someone to start the timer as soon as your truck starts to cross the first line. That someone will have to stop the timer as soon as your truck starts to cross the second line. Do it a few time. This will allow the time keeper to get some practice on the timing. Then, do it several time in both direction and record each time. Now, with your calculator, take 100 divide by your average time and multiply that by .68 and it will give you your speed in mph. So if your average time between lines is 1.8 seconds then it's 100/1.8x.68=37.77 mph.

Post your results here and include what your mods and hop ups are.

Oh, and try to be honest.

that doesnt make sense to me. how can a truck go 100ft in 1.8 seconds and only be doing 37 mph? it sounds good though your method. could you explain it a bit more, im a little slow

Remember, your truck should be at top speed during the 100' run.

wut he means is have your truck at full speed befor it hits the beggining of the track. its not a dead stop run.

1 mile = 5280 feet.

If it takes you 1 hour to drive 5280 feet, then you drove 1 mph.

1 hour = 60 minutes = 3600 seconds

3600 seconds / 5280 feet = .68181818181818

So, however many feet divided by however many seconds times .68 will give you MPH.

I suggest you do it over 100 feet for several reasons. The accuracy on the person timing the run for one thing. Anything less then 100 feet will be hard to time accurately. And anything over 100 feet, well, I would want to hold my throttle wide open that long.

How many feet equal a 1/8 scale quarter mile?
what would you do to figure that out? divide the number of feet in a 1/1 quarter mile by 1/8?.[sm=stupid.gif]

165 feet = 1/8 scale 1/4 mile 5280ft/4 / 8 /=divided

oh by the way these things go 280mph scale speed. about 35mph * 8 =280 thats pretty darn fast and weigh about 96 scale pounds

Hehehehe

1 tank holds 160 cc of fuel
1 Gallon = 3785.4118 cc
1 Gallon = 23.658823 tanks of fuel
1 Gallon = $26.00 (canadian)
$.90 = 1 tank of fuel
1 tank = 15 to 20 minutes
each minute = $.04 to $.06 of fuel.

Little pig this thing.

actually to find the scale weight of an rc vehicle you need to cube the scale of it. so if you want to find the scale weight of a 1/8 scale vehicle you need to multiply 8x8x8=512x12lbs=6,144lbs which is still light concidering a fullsize MT weighs like 12,000 to 15,000 lbs

why?[sm=confused.gif]

why what?

do u have to cube the scale?

if you think about it it will make sense.....i really suck at explaining things but trust me this is how its done.....immagine a cubic foot of water weighs 40 pounds and 1 cubic foot is 1/3 scale compared to a cubic yard, you would multiply 3x3x3 to get 27 (27 cubic feet in a cubic yard) then take 27 and multiply it by the weight of a cubic foot of water being 40lbs....so 27x40=1080....i hope this clears things up, like i said im really bad at explaining things

good idea but you have to many varibales. for example what if the person consistantly is slow in starting the watch. i mean like 3/10th of a second. that is such a small amount of time and it will mess up your whole top speed thing. what about buying like a bike spedometer and calibrating is correctly. also just ask a cop. everyone knows a cop

Perhaps that is why I suggested to do it a few times before recording to allow the time keeper to get some practice on the timing. I also suggested to do it several times in both direction and record each time. The times should be close. Lastly, I suggested you use your average time when doing the math. Sure there are some variables but there are way to minimize them. Go talk to a cop about the +/- of a radar gun. They can be 7 to 12 MPH + or -.

Besides, if the person is consistently slow in starting the watch, hopefully they are consistently slow in stopping the watch.

Oh, and your idea about the bike speedometer is great! Let me know when you hook it up to your savage. I would like to be there to watch you run next to your savage to try to read the speedometer!

Yes, I also think the idea of the bike speedometer is great, but what I thought I will do is to strap my little hand held GPS on the back of my SS 4.6 when I am finished with the break in and tuning. Then I will do it on an open parking lot and make sure I have at least 6 satelites or an accuracy of about 4m. With that I can do a few long runs and it will save the Max speed. I will reset it everytime and after about 10 of these runs just calculate the average to compensate for the accuracy.

Only downside is the weight of the GPS thats added to the total weight of the truck.

Chris

I was being sarcastic!

I also mentioned my way was an easy way to do it. Good luck Chris.

Stablock,
I agree your idee might be an easy way, but you need someone to help you.
Have you seen the small ones that actually connect to inline skates as well?
And as with the GPS you don't need to run next to the Savage to read the speedo, haha, they also save the max speed, average speed, time etc. and you can reset it and check it AFTER the run.

Chris

like what u just about the bike thing their easy as hell to work all u have to do as rapp that little magnet to the inside of your rims and other reciving part to somewhere on your truck but place it near the inside of the rim then just calibrate it for the rim size mount the panel on your truck and drive, then get your truck and read the pannel and it will tell u top speed. i might work it might not but im gunna tare my dads off his bike and tell u if it works

yes but if they are consistantly slow in starting in (ie have a slow reaction time) but then on time stopping it then your calcs will be off. im not bashing your idea but just use a radar gun. man if they radar guns are 7 to 12 mph off then people in court who argue tickets would consistantly win. they are not very acurate. the cops have the best toys. also, you can hook up a bike speedo. it may not be the best idea but it will be very close. you can buy some that log the top speeds so you run it for 100ft and then it will hit top speed and then drive it back and look at the speedo to see how fast it got going.

No, you're not bashing the idea. You only commented on how bad it is and suggested several other options to achieve the same results. Whatever...

You know, it's not that hard to do. It's very easy to start and stop the time when the front wheels touch the line. If your friend is that bad at it, let them drive the truck and time it yourself. Or better yet, hang out with smarter friends!

What I was suggesting is a method that is a fast and easy to do. It will not cost you any money, you don't have to do any mods, mount gadgets, glue magnets to your rims, be a mathematician, calibrate anything, or try to befriend a cop. Pretty easy, huh?

I think I'll go play with my truck now!

Enjoy all.

or go get an rc speedo on the bay for 20 bucks!!!!!!!!!!!!!!!!!!!!

If they have a slow reaction time, they wouldn't be on time stopping it either. Their reaction time applies to both events.
If they are consistant on the time it takes to hit the button after it crosses a line, then the calcs will be accurate. The more consistent your timer is, the more accurate the calcs.

It doesn't really matter if the timers reaction time is slow, as long as it is consistant.

Discussion of reaction time is pretty much moot anyway since the timer can anticipate it crossing the line. It's not like you have to respond to a sudden event like a light coming on. You can see the truck approaching, then crossing the line. Hitting the stopwatch button as it crosses should be pretty simple to do consistantly. The timer should also be able to tell you if he got it right, or missed by a bit and should discard the run time.

As long as the lines are accurately measured, and the guy with the stopwatch has a clear view of both lines, you should get numbers as accurate as any radar. Probably better.