Ken and Ed Anderson.
Your info and advice is well recieved and
timely for me - I didn't know what to use, now at least I can
talk with some knowledge to suppliers.
One small question if I may - what is the
fuel rail pressure usually?
Thanks again!
George ( down under)
Hi Jerry and George,
The debate over the optimal injector size has been going on for
years. I personally plan to use 400cc/38 lb or 440cc/42 lb Ford
injectors. According to
http://www.maxcooper.com/rx7/how-to/fuel_system/calcs.html 38
lb injectors at 80% duty cycle / 43 lb / .5 BSFC pressure are good
for 242 HP. The 440cc/42 lb injecors are good for 267 HP.
Also check out RC Engineering which is the most accepted expert that
I know of (
http://www.rceng.com/technical.htm#WORKSHEET).
Using the same assumptions the 38 lb injectors are good for 242 HP and the
42 lb injectors are also good for 267 HP. Looks like these guys are
using the same formulas - good to see consistency from 2 different
sources.
Lastly, note that injectors should not be run continuously over 80%
duty cycle or they will overheat and fail. A smaller is better when
it comes to idle control. DO NOT forget this part of the
equation. Lastly, at cruise altitudes the injector cycle rate
decreases as the HP requirement decreases so at 8000 ft the duty cycle of
the injectors will only be 60 % which is very safe for sustained
operation. Call me if you want to discuss this. Go play with
the calculators posted above (which George has already
done).
Ken Powell
Bryant, Arkansas
501-847-4721