F Hydro Questions

[Buddy Benedict]

I am venturing into uncharted territory and building an F Hydro for the Nats. It will be powered by a purple head 90 evo and based off of a JAE design.

Question #1: Should the tub be 4 or 5 inches wide?

Question #2: How much fuel does that motor need for the heat and a few extra laps?

Buddy

 

[Tom Foley]

18 - 20 OZ of fuel , 4 or 5 " will work .

 

[brad nichols]

I think 20 oz. at least but that depends on how thirsty your motor is. Tub width can be based on fuel capacity needed as an extra inch gives you a lot more fuel and also if you are using a 4 or 5" motor mount.

I built a 90-101 for an OPS 90 and it was 5" inside measurement and it needed fuel room. 4" will work with the CMB 90 if you have a custom fuel tank built with enough volume.

Brad

 

[sbowden21]

Were running 26-27oz tanks with the 101s... if i go in the water @ 2:15 im near dry by the end of the race...

 

[Danny King]

Were running 26-27oz tanks with the 101s... if i go in the water @ 2:15 im near dry by the end of the race...

Anywhere from 18 oz to ^^^ No exaggeration. All depends on what's done to the motors and most importantly how much nitro. Higher percentage uses more ounces per heat

 

[Tom Foley]

I think 20 oz. at least but that depends on how thirsty your motor is. Tub width can be based on fuel capacity needed as an extra inch gives you a lot more fuel and also if you are using a 4 or 5" motor mount.

I built a 90-101 for an OPS 90 and it was 5" inside measurement and it needed fuel room. 4" will work with the CMB 90 if you have a custom fuel tank built with enough volume.

Brad

Great points here !

 

[charles siler]

Ya OPS90 motors need the 4" tub minimum.

 

[Walt Barney]

Ya OPS90 motors need the 4" tub minimum.

Buddy,

Let me know what tub size you decide upon along with the width and height, and I will figure out the amount of fuel. Most tanks that I have built for a F boat come out to 19 -20 oz

Walt Barney

 

[charles siler]

These are 4" tubs.

 

[ALLAN YUEN]

the tub inside 4" and tank 22 oz Look to my Sell new JAE 60/90 with full hardware just need turn fin from Zipp kit Are you interesting?

 

[Terry Keeley]

20 oz is enough for my VAC 90 on 60%.

 

[dwilfong]

23 oz has worked for my 1.01 beast on 60%

 

[John Knight]

The EVO 90's are more fuel efficient than the RS 91 and 101's and the 90 VAC. They are not fuel hogs like the more current engines. Ran them for years and 18 -19 oz should be fine. Started the engine at the 2:15 mark, mill at 70% power and still had 3-4 oz left.

 

[Buddy Benedict]

the tub inside 4" and tank 22 oz Look to my Sell new JAE 60/90 with full hardware just need turn fin from Zipp kit Are you interesting?

I already have my kit and doing some changes to it. Thanks anyway

BTW: Allan, how long it the tub?

 

[Buddy Benedict]

Thanks for all the replies, I,ll have the 90's this weekend and I also have a 1 cube coming. I think I'll leave the tub at 5 inches, my fat fingers will fit into it easier

.

Buddy

 

[ALLAN YUEN]

the tub inside 4" and tank 22 oz Look to my Sell new JAE 60/90 with full hardware just need turn fin from Zipp kit Are you interesting?

I already have my kit and doing some changes to it. Thanks anyway

BTW: Allan, how long it the tub?

long 40.5" tub

 

[Buddy Benedict]

I need to order servos for this thing. What size do I need for steering?

Buddy

 

[sbowden21]

I need to order servos for this thing. What size do I need for steering?

Buddy

We're using hitech 7954sh... they have new servo out D-845wp has a lot more torque but is a little slow.

 

[Buddy Benedict]

Boats 3/4 done and I guess the next question is props. What should I start out with? The boat will be powered by a gold head 1 cube motor.

Buddy

 

[shoboat]

Buddy,

2719, 2817, 2819 should cover it all.

Thanks,

Mark Sholund