avenge

What would be the min size of tank for a 21 motor ?? Space is limited, so i was thinking 6 oz main and 1 oz hopper ... Any input would be great ....

ob nut

My Feedback: (1)

On my .21 OB, a 6 oz with 1oz hopper will run the full 02:30 milling plus the 6 + laps during a race. K&B motor that is... My MAC .21 will need around 10 oz..

coriolan

6 Oz isn't much for a piped .21 if you start early and have to do the full milling time on a NAMBA circuit. Have seen many boats end up DNF on the last 1/2 lap for lack of fuel [8D]

Hydro Junkie

You asked the same question in another forum and in neither case did you say what boat you are dealing with. Hull type will make a difference, as you were told in that other forum. Are we talking a hydro, rigger, deep vee, cat or tunnel. I based my answer in the other forum on what a sport hydro would most likely require

Ron Olson

My Feedback: (1)

I've used up 6 oz. in a .21 mono during a heat and I start when they say I'm on the clock. It does depend a lot on the powerplant like Mark (pick one) said. Some sip the fuel and others like MAC's and CMB's are thirsty. Save fuel during mill time if you're worried by driving slower. 'Riggers run pretty much WOT all the time so they'll use more.

avenge

The hull is a phil thomas ssp 20 and going to use a cmb 21 .. The boat was set up with an 8oz tank but the tank rubs up against the carb ....

Dan S

That looks like Terry's old SSP and he had enough fuel with his 8oz tank for every race and milling.

I ran my SSP with Terry, I had a Nova Rossi LS, a 6oz main and 1oz hopper tank, that gave me enough for approx 1 min 15 of milling and the race.
Don't recall ever seeing a problem with his tank rubbing on the carb.
Ask Terry how he had the tank mounted and secured.

Dan.

avenge

Yes .... I picked it up from him this summer ... And the tank included was an 8oz, and it was rubbing up against the carb .... He was using shogoo to keep the tank in place but it was still up against the carb ... I just wanted one that wouldnt rub up against the carb ... I tried moving the tank forward but the cowl would not close ... Just thinking on ways not to have it rub .... It was suggested that i get a metal tank for it .....

kgibson4

My Feedback: (4)

You could try using a heat gun to re-form the tank where it interferes with the cowl when you move it forward. The heat gun work is best done outside of the boat.

Dan S

Thanks avenge,
I didn't know that it was rubbing before, Terry never told me he had a problem.
I believe like kg said, that you can use heat to reform a sullivan tank. You could form a small indentation so that it does not touch the carb.

I know I posted a pic of mine on your other thread, unfortunately the location of my tanks wont help you much, my SSP hull is the next design with a hole in each sponsons (each side of engine) to put the tanks in.
maybe you could modify yours to do the same.

Dan.

avenge

I was planning to do that if I can not find the right size tanks ... I ran the boat a few times this summer and it ran very well ..... No issues really other than the tank rubbing ... I will try and reshape the tank, or try the main tank with the hopper if that dont work .... Thanx for all the input ...