Don't quote me on this but i've heard 2/10's with running down the track with the fan switched on versus running with it off. Depends on a lot of variables though - too hard to accurately gauge.
Even the biggest electric fans will only put a 1 to 1.5 HP drain on the motor through the alternator - most are less than that. There's VERY little to be gained with it switched on or off, although if you have a choice, clearly leave it off. The big gain comes from replacing the stock mechanical fan - which can consume 5 to 15HP depending on type, condition of clutch, rpm, etc.
Don't forget to upgrade your charging system to handle extra load of the fan. Also a DCControler will help keep things running smooth.
Beat you to it Mike! LoL
I gained nothing when I switched. Granted I ran on different days, they were quite similar weather wise and my time slips were almost identical throughout the length of the 1320'.
I have heard of some people picking up a few h/p from it, but unless your stock fan clutch is binding, the gain will probably me minimal.
Dont let it discourage you from upgrading though. It is a worthiwhile mod to do for sure .
It's definitely a worthwhile investment. But I still believe in the inability to recreate something perfectly. The weather can be different, humidity, track conditions, grip, reaction time, engine temps - like I said too many, but the gains are there.
I gained 1hp, and lost 3tq on the dyno, which, corrects for atmosphere, has no tractions issues at my power level, and R/T doesn't factor.
At the track, in as close as you're gonna get weather, with 60's varrying in the 100ths ET's showed no gains/losses what-so-ever.
Should be noted, R/T has no bearing on ET's.
I'm glad to be rid of the propellor noise... outside of that...