Quote:
Originally Posted by AdamIsAdam
As for vacuum at highway speed, I never got out to measure  |
Tape a gauge to the windshield, route a hose to the manifold. Depending on the vacuum generated by the engine UNDER LOAD, you may not have anywhere near the timing advance you think you have. In other words, have you lost all your vacuum advance on the highway? Is the timing now not advanced enough so that it create heat issues?
Quote:
Originally Posted by AdamIsAdam
I was watching an episode of Engine Masters where they tested various fans and shrouds. They found that a clutch fan robbed the least amount of HP over fixed, flex, etc. And then for kicks, they compared the clutch fan setup with and without a shroud and found that removing the shroud increased HP by 8HP. So I was convinced to go without.
https://youtu.be/ZXdLgaFXZzs?t=14m18s
As for the Severe duty issue, well, it works so I'll just leave well enough alone at this point. |
Yup, I'm surprised that removing the shroud makes an 8 HP difference on the fan that dragged the most. I wasn't expecting that. In fact, I think it's outright suspicious. They're claiming that the fan takes as much as 30 horsepower. Again, suspicious. I don't think the belt will transmit that much power. I wonder how much power was upset due to turbulent air flow over the open carb due to fan blast. They never showed so much as an air cleaner on the carb, and I would have expected some sort of dyno-velocity-stack-airflow-measurement-device.
Of course the clutch fan used less horsepower--the radiator was dry (not heated) so the clutch stayed disengaged. Re-run that test with a hot radiator and see what happens!
I'd like to have had noise measurements included in that test. Guess: The loudest fan robbed the most power.
Note that they claim it's an "OE" (original equipment) style fan clutch. You aren't using an OE fan clutch, you're using an "extreme duty" (Hayden calls them "Severe Duty") AND you've modified it so that it drags EVEN MORE. That fan clutch is practically locked-up. 'Course, I can't tell for sure from here. Only you know.