Better AC with different size pulley?

[Vettepilot]

Forgot to post this one. That is a GMT400 pusher fan with the shorter bracket flipped upside down and the longer mount legs bent to hold the fan in the desired location. They work fairly well.

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You earlier cited the cop cars as an example:

“It's not impossible; the cop cars idle for days without a ‘China Syndrome’!!”

yet you don’t like their method:





Ok then, show us the cooling fan solution(s) you craft that finally satisfy your objective. I’m interested.


On the topic of blower motors:



Measuring the voltage and current is easy-peasy, multiply them and their product is the applied power; it doesn’t tell the tale?

“Tach it” - do you need the RPM? Can do, with a ‘scope.

Hiya, me again.

Yes, I have thought of adding a pusher fan to my direct drive setup. Who makes the one shown? Was it effective?

No. Nobody involved with performance work likes today's factory high temps, and one of the first mods you see is to get those temps down. I fully agree with this as an engine builder and enthusiast.

Yes, motor rpms. Motors have a "KV" rating, which simplistically, is how many rpms per volt they turn. The higher the KV, the faster they will turn at a given voltage, but will draw more amps. As to a measure of "work", then amps times volts equals watts, a measure of force or work.

So again, if we work out the rpms of our current fan motors, we could then search for a higher KV motor. Of course, it would then be on us to determine if our relays, resistor packs, and wiring are up to the task of supplying the higher amp draw. There's no free lunch; not with motors, engines, nor women...

;~)

Vettepilot

 

[Vettepilot]

I will re-phrase one of my earlier questions.

Does anyone know of any tests showing how much having a too small diameter fan in a shroud hurts?

I shopped around for an aggressive reverse rotation fan, but as it turns out, it is a bit small for the shroud. I could probably go two inches larger to fit the shroud better. I am curious as to how much this is hurting me. Clearly, I have an idle airflow problem, because as soon as it's underway, it cools right down.

Another thing. I would very definitely raise the idle rpm a bit, but that's not so simple with EFI.

Vettepilot

 

[GoToGuy]

You want the maximum cooling radiator available in a 400 series. Get the 3500 HD series big block radiator. Full width, full depth of tanks, 3 rows cooling tubes and it's 19 1/2 inches tall. It 2 3/16 inches deep. As this Spectra CU1696. Along with the larger radiator shroud. You have seen cop vehicles, but if actually look at the LEO option there's no magic. As for the 160 , that's unrealistic in so many ways. The ecm doesn't work with that condition. The engine oil operating range is 180 to 245 depending on additives/ mineral or synthetic. The btu transfer rate has limitations.
It's the laws of physics.
Add more exits for under hood heat to escape, results in lower temps.
Your going on about how hot your engine is operating, is futile.
If added a new different style radiator fan, is it positioned correctly, what is gap between blades and shroud. The fan is a type of " ducted fan " to be most efficient, position / blade clearance matters.
Unless you install a radiator out of a " Cat D9 " the math doesn't work. *** temp / btu transfer / outside air temp = temperature reduction point.

 

[Vettepilot]

I won't debate it any further. There's dozens of reasons to strive for lower temps, and many of us do so. This truck runs, and runs exactly how I want with the larger/better radiator I have installed. Just not at idle because I have an airflow problem when static/idling that I am trouble shooting. It does indeed stay at 160 to 180 once underway, so your theory that that is impossible is just not true.

Our opinions on optimum engine temps differ. I could waste time quoting my engineering reasons, but it's pointless to argue about it. You choose to accept running your engine(s) at high temps, and that is fine, but rest assured that over 55 years of actual engine building and racing, you will never convince me it is ok.

Vettepilot

 

[L31MaxExpress]

180F for an iron head engine and 195F an aluminum head engine is perfect. I am running the L31 in the 87 G20 a bit warmer with a 195F thermostat. The junk Proflow 4 ECM is just happier running at that temperature.

 

[L31MaxExpress]

I am running 91+ octane, 10.25:1 compression, 190-195 psi cranking compression and 34* total at 3,200 rpm and 12.6:1 AFR at WOT. Plugs look perfect. In 103F heat today, running 194F at the time. A/C was on and the a/c pusher fan was doing its thing. A/C was holding mid 40s at the center vent at idle.

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[Vettepilot]

Looks like you're all dialed in. Fuel pressure a touch low though??

Vettepilot

 

[L31MaxExpress]

Looks like you're all dialed in. Fuel pressure a touch low though??

Vettepilot

It is vacuum referenced using Edelbrocks fuel rail mounted LT1 style regulator kit, 43.5 psi key on, engine off. Vacuum refrenced regulators drop about 1/2 psi for every 1 in/hg vacuum applied to the regulator. The injector is flowing the same as it would with no vacuum and full pressure as the differential pressure across it is the same.

 

[JohnZ71]

If your truck is a Vortec with a spin on fan clutch should be relatively easy to use the Duramax blade. GM 1580690 on the Hayden 2851 clutch. I ended up having to trim a bit of the blade length to fit in the fan shroud of my Express van. It has not been a problem. I followed the contour of the blade, marked the distance I needed to trim, IIRC it was 5/8" or so, then trimmed the first blade. I used the trimmed off piece as a templete to mark the rest of the blades. A sharp pair of scissors or tin snips will go right through the plastic blade. Even with the blades trimmed a bit, the Duramax fan has a lot more surface area and pitch than the 11-bladed tow package fan.

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The Hayden clutch says it’s reverse rotation…is that correct?

 

[1998_K1500_Sub]

The Hayden clutch says it’s reverse rotation…is that correct?

Does that clutch "engage" at a temperature that's usable for you?

If you're shooting for 160F engine temps like @Vettepilot, I'm guessing "not", but it'll be interesting to know.

@L31MaxExpress has experimented with an electrically-actuated clutch retrofit on the GMT400s. It would enable engagement and disengagement, e.g., at any engine temp or vehicle speed, provided that one can provide an appropriate ON/OFF signal to the clutch (e.g., from the ECU or other means).