khkim0102

Hi!

My Thunder Cat 31 is still in the stock set-up, and it has been running only about 5-6 galons. A little while ago, I measured the full speed of my TC 31 with a Bushnell Radar Gun.

Even though I tried all kinds of adjustments, it hit only 30 mph (I used 20 % nitro fuel). I expected over 35 mph, but it was slower than I expected.

What is "the normal MAXIMUM SPEED" of TC 31 with the stock set-up?

In addition, my place is close to the ocean, so that the elevation is not high.
Isn't there any way to increase speed with the stock motor? Chaging the prop?

Thanks!

yannicksjh

Hi, well if you have time on your hands, here is a very long thread on the Thundercat 31 and all its possible mods. I can't tell you from experience because my TC 31 is still on its way in the mail but i'm halfway through reading the 104 pages. Here's the link: http://www.rcuniverse.com/forum/m_40...tm.htm#4095782

wave waker

we love to see pics man,,post it,,ur not too far, high 30's to low 40's for stock tc31.

i use 20% nitro if just for playin around but if i want to test the speed i go 40-65% nitro.

what prop are u using? how does the boat behave on topspeed?

ww

TCHedOff

Just an FYI (if you didnt already know), to get the ost accurate reading w/your Bushnell you'll want the boat to be coming straight at you or going straight away from you.... Every degree off from this affects your accuracy.... if you werent measuring this way, you may be faster than you think. Our club uses a Bushnell and has a speed run (the 1st meet of the yr). My boat was faster than my driving ability at the time, so I was afraid to drive towards the dock very much.... the result was 38 or 39mph.... I got a call from Geraghty the following day, saying that boat was running 50 all day.... I can tell just by looking at it. Then I stopwatched the video from bouy 6 to bouy 1 - turned out it was running 50 mph on the nuts!

malicent

Not to get to far off topic TCH but what formula did you use to get the speed from the measurements? My math skills are failing me at the monent lmao

amax

If You are using The Stock Prop It's Not balanced and Sharpened, It Must be B&S or it will Destroy The Strut and Prop Shaft and will Greatly Reduce Top Speeds. Upping the Nitro % is also a Good Way to Increase Speed\Power, the DYN. 32 will take 50% All Day Long when Tunned Properly. When Increasing Nitro Content Proper Tunning Becomes Much More Critical.

khkim0102

Hi, guys! Thank you for your response!

I will post the pictures of my TC 31 within a few days, becuase I took it apart. I will put them back together within a few days, and then I will take pictures, posting them.

Amax, you said that the strut and prop shaft recuce the speed. How do they recuce the speed? Then, isn't there any way to prevent it?

Thanks again, guys!

toyotatruckin

I believe he was saying the reduced speed would come from the non balanced/sharpened prop and above is correct the radar gun is an unreliable way to check speed, the smaller boats next to impossible the larger boats needs to be directly coming at you, we tested this a long time back using a stalker radar gun, again the gas boats we checked got ok readings but you had to set-up for the pass..

TC31 should expect 30-37 stock depending on set-up

asmund

My TC 31 hits 47 miles on my Bushnell gun, but it has all the mods in that loooong thread done to it and then some (lots of work inside the engine and header too). First of loose the stock prather 215 prop and get an Octura M445, that will get you some more miles. Like the rest says more nitro, I use 45% because I can`t get 60% around here.

amax

You Need to Balance and Sharpen the Prop, a sharpened prop cuts into the water a Dull Prop Slaps the water, an Unbalenced Prop Will Shake and Literally Break the Strut off and your prop and drive shaft will be at The Bottom of The Pond,,,,Been there Done That,,[:@]

TCHedOff

Malicent, I did a speed chart last summer for those who run on the same sized course as ours. All you need is a stopwatch. See here:
http://www.rcuniverse.com/forum/m_87...tm.htm#8745370

khkim0102

Hi, guys!

I do apologize for so late posting the pictures! I tried to post a few times, but it didn't work. I think there was a problem on my computer or the server.

Here are the pictures!

rcguy1411

if you want more speed change the prop cut 1/2 to 3/4 inch of the bottom of the rudder and port match the exhaust (header) these few thing should get you 1 to 3 mph if you realoly wan t to go fast read the thread its a long one but has every mod to make the tc31 a quick boat

amax

You need a Balanced and Sharpened Prop, or read the thread on doing your own prop, and do that prop.

khkim0102

Thank you for your responses!

It takes a little too long for My TC 31 to plane. When giving half-throttle, it doesn't cavitate much, but it takes too long to plane. When giving almost full throttle, it cavitates a lot, also it tooks a little too long to plane.

I tried a little bit down angle of the prop shaft, and then it gets a little better, but the boat becomes slower at the full throttle.

Any ideas for this? Thank you again!

amax

You need a Balanced and Sharpened Prop, or read the thread on doing your own prop, and do that prop.