Starting a BB Duster project

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I ran that nylon fan on my car for a while. I removed it at the track one day between passes, it was less than .10 from that fan to no fan at all. I never compared it to another fan.
 
I might check a couple of different fans next time I'm on the dyno. I can't see more than a few HP difference between fans. 30 hp doesn't seem believable. That would say that if you put one of those fans on a 30 hp electric motor that it would stall the motor. I doubt that it takes that much power to spin that nylon fan at 6000 rpm. It might require a couple of hp.
 
Ehhhhh, FWIW, you can tune into the engine masters and watch the fan episode. Take it for what it’s worth. Believe them or not, your call.
 
That is a pretty simple call. I don't believe them. That show is for entertainment, nothing else. I'm pretty sure a 5 hp electric motor will spin a nylon fan to 6000 rpm. If a 5 hp electric motor can spin it then how could it require 30 hp? The guys on engine masters either didn't double check their results or the messed up the test somehow.

Or think about a lawn mower engine that spins a big blade which also cuts grass. Lawn mowers are usually around 5hp and they spin a much larger blade than a nylon fan.
 
We used to have big industrial box fans where I worked. They were 42 inch diameter and something like 18,000 cfm. They had 1 hp electric motors on them.
 
as you say next time you're on the dyno if you have a few different fans to hand and time then it's worth a test. it doesn't take long to swap them out after all. i'd like to see an independent test myself to know if the engine masters show is bs.
neil.
 
jamesdart said:
I ran that nylon fan on my car for a while. I removed it at the track one day between passes, it was less than .10 from that fan to no fan at all. I never compared it to another fan.
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That to me says it takes alot more hp to go faster. Don't think 20hp would be much on an slip.
 
bluefish said:
Nice project and nice work. The fan in his pic eats a lot of power. If your going to use a mech. fan use this one. I just ordered the 19" to replace it as it will fit my 69 charger schoud that I used in my A body better.

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I have never seen a dyno study on this flexilite fan. There was a mag article some 18 yrs ago I read that said Andy's fan was the worst in the bunch of 8 or 10 fans dyno tested. The blades look to have a 90* bend. That's gonna catch alot of air. I would like to see Andy perform a dyno study on that fan just to see. Would be interesting.
 
Got to set up a radiator and shroud to simulate real world......just as Engine Masters did.
 
5.7 hemi said:
Got to set up a radiator and shroud to simulate real world......just as Engine Masters did.
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Weren`t they using a sbc for a test engine ? Torqueless little bastards unless u get into a bigger one. Our bigblocks probly handle the fan better, due to more torque to start with. I cant see 30 h.p. in a fan either, maybe 15 at the most on a small block. ???????
 
The dyno doesn’t lie. It’s a tool for measurement, the fans tested were done after a baseline was had without any fan. The 30 hp loss was from the addition of that particular fan. Is there a loss, certainly, and that engine on that dyno showed it took, at peak, 30 hp loss.
 
5.7 hemi said:
The dyno doesn’t lie. It’s a tool for measurement, the fans tested were done after a baseline was had without any fan. The 30 hp loss was from the addition of that particular fan. Is there a loss, certainly, and that engine on that dyno showed it took, at peak, 30 hp loss.
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People make errors all the time when running tests, especially if they think they know what the answer should be. It is called confirmation bias and it happens a lot. Even highly experienced engineers fall victim to confirmation bias. My guess is that the engine master guys wanted to see a big drop in power since that would give them something exciting for their video. They found a big number and were happy. They didn't bother to think that it might not be correct.

The best way to test fans would be to use an electric motor to spin the fan and measure the current required. That will tell you the power consumed without having to use a dyno. An engine dyno isn't a very good tool for measuring small power differences, it is more of a gross measurement tool. Kind of like a yardstick. There are lots and lots of things that can change from pull to pull which is why an engine dyno can have problems measuring this kind of stuff.
 
AndyF said:
The best way to test fans would be to use an electric motor to spin the fan and measure the current required. That will tell you the power consumed without having to use a dyno. An engine dyno isn't a very good tool for measuring small power differences, it is more of a gross measurement tool. Kind of like a yardstick. There are lots and lots of things that can change from pull to pull which is why an engine dyno can have problems measuring this kind of stuff.
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Coulnd't one mitigate any variability in the dyno tests by running multiple dyno runs under each scenario and averaging the results? Just thinking out loud here, since I didn't see any of the tests.
 
mopowers said:
Coulnd't one mitigate any variability in the dyno tests by running multiple dyno runs under each scenario and averaging the results? Just thinking out loud here, since I didn't see any of the tests.
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Yes, that is correct. The best way to do dyno testing is A-B-A testing where you run a baseline test, then test the new part, then re-run with the baseline. If the baseline repeats then you have some confidence that the test was valid. But hardly anyone ever does testing like this since it takes a long time and costs a bunch of money. I've run several hundred dyno tests over the past 20 years and I've never met a customer who was willing to pay double to go back and verify the baseline test. Once you install the new trick intake or carb and see the power increase nobody wants to put the stock parts back on to verify that the baseline hasn't moved.

I've done some baseline testing on my own engines and the results are usually mixed. I did a bunch of dyno testing last year with one of my 470 engines where we tested parts all day long and added power with every test. It felt great since everything we did made more power. Then the next morning the power was back to the same place as the previous morning. We never did figure it out for sure but it appears that the correction factors don't properly correct. So as the weather changed during the day the power changed. In our case we thought we were picking up power from the modifications but evidently it was just the correction factor changing. The next morning we were back in the same spot. I've run the same engine with zero modifications at different times during the day and have seen more than 20 hp difference. So that difference is due to the air changing even though the dyno numbers are "corrected". So when someone shows me a dyno test that "proves" something I know better. Proof is fairly elusive on an engine dyno unless you have a super expensive setup. I think some of the NASCAR boys have climate controlled rooms and that is probably what you need to have to see the little stuff. You also need some sort of big electric motor to spin the engine in order to measure friction. Not very many guys have access to that kind of test equipment.
 
famous bob said:
Tell that to prostock racer !
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A prostocker would not stop at 20hp gain. They constantly look for more like all other racers. I have test and tuned at the track a bunch gaining some mph, but not much in et. I stand by what I said earlier, it takes a lot of power to see anything on your et slip and the faster you are all the more it takes to go faster yet. With a car that 60's exceptionally well you may see more gain with 20hp. My car best 60's were 1.45, so et gains come slow in my program. That plastic fan has a few stories written about it as being the worst out there for costing hp. One of the reasons people use electric fans, free up power. If your not chasing et's and it cools good, i'd run it, who cares.
 
Out of curiosity was messing with one of those et hp calculators at my et, I added 30hp, and it was almost .3 gain.
 
jamesdart said:
Out of curiosity was messing with one of those et hp calculators at my et, I added 30hp, and it was almost .3 gain.
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Ryan Johnson used to say those are very accurate. Looks like the best dyno is the track and anyone wanting to have a cooling fan shoot out should do it at the track, but then again someone would say the weather must have changed. Never gonna win that type of debate.
 
bluefish said:
Ryan Johnson used to say those are very accurate. Looks like the best dyno is the track and anyone wanting to have a cooling fan shoot out should do it at the track, but then again someone would say the weather must have changed. Never gonna win that type of debate.
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I agree w/ most all this. But a prostock racer will almost kill for 20 h.p..
They are hunting for anything for an edge----------------
if Alan Johnson would have had an additional 20 h.p. on the top end , look where he would have been .
PROVIDING HE COULD PUT IT ON THE GROUND !!
 
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