Hmm no ac, no stereo, Just power the Holley, 1 radiator fan, 1 full time fuel pump and other pump when making a lot of boost, lights too.

 

ehhh. Well kinda not the same situation as myself and other people.

 

I'm of the opinion that the GM truck alternators are a different animal.
John has his double under driven and it still works, I know guys on here who way over spin theirs and have no issues with output at idle or high rpm (7,000rpm+).
I haven't been that lucky with alternators/batteries, so I just ponied up and bought an expensive alternator and battery because I was tired of dealing with it.
My last 4th gen F-body had a truck alternator with a 25% under drive crank pulley and it seemed to work fine shifting at 6,000-6,500rpm.

 

are you thinking the truck alternators are better? I know when my factory alternator went out, I replaced with a reman about 4 times until I paid the difference for a new delco alternator. Then it lasted much longer. I thought it was going out but then found out my wire to alternator was frayed and only hanging on by a few strands

 

I'm running a high output truck alternator, I want to say it's an Escalade.

 

100% better.
On my last car, a 02 Camaro SS I went through six reman alternators before I picked up a reman Escalade alternator and never had another issue, the car actually ran better too.
The truck case being larger than the smaller F-body case has more output at idle and in most cases will fit in the same location as the small F-body unit with a little massaging.
The JS truck case unit has the same diameter as the truck case but is a little longer so might be more challenging to package but well worth the extra power.
If you can fit a truck alternator in there, then that would be my move.

That's the one I used as well, worked excellent.
I was considering using one again but wanted output over a wide range and didn't want to pulley down and possibly lose output at idle or over spin it and it fail so I landed on a JS unit.

 

So on the order of the fans, my car is fairly quiet and the fans are a little loud because they are moving a bunch of air and I have the straight blades. I called Dennis over at proform and hes sending me a S style blade to try out and see if its quieter. I'll swap the blades out and let you guys know if theres a sound difference and since they are 100cfm less, if it makes any temp difference...which i suspect not.


EDIT: Dennis just text me and informed me the blades are not interchangeable. So hes sending me a complete s blade fan assembly. Still will keep you guys updated.

 

I'm also running an AD244 truck alternator with 10% under crank and 2.85" alt pulley. Output is a solid 14.4v at idle to 7k rpm

 

so I calculated the CFM for the fans

proform - 2087cfm
flexwave - 2031cfm
spal 16” 500w - 3511cfm

 

Found an ad for the Spal that says its rated at 2,450 total cfm.
Still higher than the others, maybe that's the installed flow versus open air?

 

Correct, the 2,450 cfm is rated at a restriction AKA installed (not open air). My numbers are based on the restriction of a dual 1" rad core. Maybe the pressure isn't high enough to reduce the airflow. The graph is in m3/h which they say converts 1m3/h is equal to 0.59 cfm. This puts me if At 4000m3/h thats the end of the graph your looking at only 2360cfm. The attached chart doesn't make any sense... I thought it was in CFM but its not apparently. Unless I'm reading this wrong... I assumed the green line is the Airflow but I guess it could be the efficency% is airflow except if you maxed out that table at 4000m3/h and convert that to CFM your at 2360cfm.

My brain says that if I'm getting 35mph through the same radiator that I was getting 19-22mph that the CFM doesnt just jump 400cfm going up 13-16mph. The 3,500 number feels right when you feel the air this thing is pulling that just doesn't make sense when SPAL rates them at 2,450.

 

Dude Dennis is cool AF. Is he sending them for free?

 

Dude Im stokeedddd! About to add a couple more pumps, so I def need the upgrade.

 

In case anyone wanted to know I got the spal 18” 800/850w fan today. Threw it on the rad core and did my tests. It’s not pulling 100% through the core without a shroud but wont have that for a while. This thing is big, heavy and eats a lot of juice. What’s weird is I think I might be maxing out my anemometer bc this thing pulled the high ft/min pretty quickly and then kinda peaked even though i could hear it spool up and the airflow increased. I might have to see if i can spin that thing up higher than 3100ft/min. I also think the air not coming into the fan from one direction prob lowered the number a bit. Basically pulling through the core will straighten the air out more.

this fan is negative PWM as fast is like 5-10% and slow is like 80%. What’s weird is I think around 85% at 100hz the fan stopped chugged and spun in the opposite direction becoming a pusher. Idk what’s up with that so I started at 80% and worked my way down to full speed.

Started out at 80% and that’s 2.5 amps/36w and 925ft/min

40% is 22amps/279w and 2243ft/min

10% is 73amps/842w and 3089ft/min which ends up at 4,447 CFM pulling through the core basically. The speed was 35.1mph which is basically the same as the 16” but given the 2” of extra blade and a slightly bigger hub the fan easily pulled 1000cfm more through a core.

 

Good info there. Your duty cycle results are not unexpected. These fans operate in a certain duty cycle range and outside of that range have different functions, as you discovered. Mine should be here this week.

Andrew

 

So you think that at 85% duty the fan switches mode to a pusher? that seems very odd. The Spal 16" didn't do that. I will say when the 18" Spal went into the pusher mode it chugged switching over but once it started pushing it was fine and spun up pretty quickly.

I know that Spal has certain frequency/duty cycles for testing and diagnostics but I've never heard of one switching directions before.

 

He is. The 12" and 16" were on the house. I offered to pay for them tho. The 16" S blade, I paid $15 shipping for it. lol. Even tho they were free, I'd let you guys know if there were any complaints. I have none. They are working quite well. The heat has been brutal here.

P.S. to be clear, I'm DD this car for the time being. This isn't just a run to the grocery store or the gym type of situation. I work almost 30 miles away and traffic is bumper to bumper most of my drive to and from. usually takes an hour to and hour and 20 mins to get home or to work. So in my opinion, they are being tested in pretty hard conditions.

 

what size proform and flexwave?> I forgot.

 

both are labeled as 16” and both are straight blade (flexwave has the wave blades). The flexwave is actually 15.5” and the proform are 15”.

 

ok, I had forgotten what size you had. Man it felt like the proform just smoked the flex a lite by a long shot. Maybe there’s a huge difference in the flex a lites? I had the 236 which is rated at 2660cfm.