Whipple A980 Nozzle Area Calcs.

Hey guys, firstly thank you to everyone on here for the great source of information.
It has helped me to run our very low budget aussie k boat racing team with very few issues and i am very greatful for your help.
With our 16/71 hh i have been using the .36 x boost number method of determining nozzle area and have found this a very safe calculation to use. I have actually found .33 closer for what we need but i think that is due to the lower compression (9 to 1)on our endurance type application.
We are now in the process of switching to a Whipple and aiming for 25 to 28 pounds of boost.
My question is would i be safe to assume this .36 x boost calc is still the one to use, or is it too lean?
Thanks in advance and once again for all the great advice that you guys post.
Cheers Jamie.

 

Thanks Mike will continue to use the formula.
Cheers Jamie

 

Its been handy for me too over a variety of combinations.
Also would i be correct in assuming a whipple at a relatively lower overdrive (around 30 to 35%) that we will run is going to be more efficient than a rootes pretty much everywhere and apart from the appropriate loop (on a 990) i was not looking to be running a high speed in the system?
Thanks for the replies.

 

The port nozzle stagger is likely different

 

when I went from hi helix to whipple I basically flipped the fuel system. 2 went to 7 say flipped front to rear and side to side. It worked as good starting point. Whipple is way more efficient piece. Off base tuneup and I was 5.60 to 5.70's out the gate and this was in 1996 so way back when.LOL

 

We are going from a 16 HH to the screw i was about 8 nozzle sizes smaller at the back. I guess the front of the whipple gets a lot more fuel than the back?

 

Re read his post. Your small # 7 becomes front # 2. The screw discharges to the rear doesn't it ?

 

Yes it does but after 25 years of doing the opposite i have to be told twice lol
Cheers guys

 

Can you please explain the .36 x boost rule for working out nozzle area?

 

The formula of .36 x boost figure is a gpm starting point for the motor.
Example .36 x 50 pounds = 18 gpm required to motor