Dyno testing

ir3333 said
Watched a Dulcich / Friedberger video last night. They ran a warm 350 on the dyno with no fan and then added a fan. Total hp dropped 30 hp with a fan. That's quite a bit.
What would the total losses be if you add air cleaner, alternator, fuel pump and full exhaust?

Way too many variables to put a number on that.

Air cleaner: Depends on how carb is affected by using the air cleaner. We seldom test with out an air cleaner because nearly all applications we dyno run with an air cleaner. Different air cleaner setups (Filter base and lid) can make significant swings in air fuel ratio and power. It’s best if you plan on using an air cleaner to bring to the dyno what you plan on using. If you are open to different options then bring those also. We have seen both gains and losses going from air cleaner to air cleaner to no air cleaner.
Alternator: We did a little testing on a 602 crate motor with and without alternator. This was with a fully charged battery and a small alternator. Alternator manufacturer claimed big power with increased voltage to the ignition. I predicted it would loose a little power with the alternator. Result was less than 1 hp difference (within the margin of repeatability). 1. alternator no belt. 2. alternator with belt but wire unhooked. 3. alternator with belt and wire hooked up. Things that could change the results. The battery was fully charged and only the ignition was drawing on the battery so the alternator is not doing any work. Small alternator had little rotating mass so inertia play no significant part. With less than 6200 rpm and a good combustion chamber design and a properly working hei distributor no benefit is realized from a higher voltage. Change any of that and the results may be different.
Fuel pump: Sometimes we will initially run the motor with the dyno electric pump then switch to the mechanical pump that will be on the engine to make sure all is working properly. Can't recall ever seeing a loss in power with a properly working pump.
Full exhaust: That is a can of worms. Short version. Exhaust may or may not change things drastically.
Fans: We have tested a few fans. Generally the more air they move the more power it takes to turn them.