Electric Fans, double nothing

[kennythewelder]

Here is my write up on what I did in my 97, 5.7L. I have dual fans, and the alt does keep up but bearely. You will need to at least do the big 3 up grade. I go into detail in my post, just click the link.
https://www.gmt400.com/threads/electric-fan-swap-on-the-cheap.41756/

 

[L31MaxExpress]

I've been looking, so far I have found another BeCool sender that's off at 165, on at 195. The Vortecs (like many other engines) are designed to operate at 195 degrees. Love to find a switch that's off at 190-195, on at 200.

The Snap On link doesn't work?

They are not designed to run at 195 and run better running cooler than that. 195 is and was an emissions crutch.

 

[arrg]

So if my temp situation doesn't improve to my satiisfction I guess the logical step is electric fans.
Here's my thoughts******
They say a BBC needs over 4100 CFM, tall order to be sure right
One big 16 incher or 2 12" ??????
Shroud or not ????
Will I have to upgrade my alternator ??
Any other words of wisdom ????
Thanks
Bobby V

You should already have the big 17x34 inch radiator core with a BBC truck. If you do, you can fit the dual 16 inch fans from from a GMT800 or GMT900 with just a little trimming. And yes, you're going to want a better alternator if you go down that route.

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[alpinecrick]

They are not designed to run at 195 and run better running cooler than that. 195 is and was an emissions crutch.

L31,
What are the best coolant temps for a “modern” SBC?

 

[Schurkey]

I ran a 205 thermostat* in my truck for about two years. Maybe three.

I can hardly wait to hear your heads explode.

There's nothing wrong with a 195 thermostat in a street-driven vehicle. In the old days, the "HOT" light didn't come on until 240--265 degrees, depending on application.

In a perfect world, the intake manifold and cylinder head intake ports would be run relatively cool, the block, crank, pistons would run relatively hot. But it doesn't work that way in real life.





*Couldn't get the cab warm enough in the winter. Turned out, I had failed "foam" gaskets between the cowl and the HVAC blower fan compartment, leaking subzero air into the cab. Once I ripped the entire dash out to replace all the rotted "foam" gaskets, the truck was plenty warm with a plain ol' 195-degree thermostat.

 

[L31MaxExpress]

I run a 170°F thermostat in mine and have for years. It sits about 178-182°F year round. I have no problem getting heat quickly nor having enough heat to cook you out of the interior of a fullsize van. With the normal 195°F stat it runs in the 205-210°F range and the PCM is already pulling timing. It also causes more engine compartment heat which increases the IAT. Over 120°F IATs and the PCM pulls more timing.

The marine small blocks run a 140°F thermostat. The cooler you get the heads the more detonation resistant your engine is.

Gen2 engines cooled the heads first and run nearly a full point more compression as a result.

The stock Vortec tunes only give you about 24° total advance running cool and 18-20° in hot weather. There is room for improvement if you keep the engine cool. With a cool engine the old Hypertech tune had 31-32° total timing but required a 160°F stat for it. A fuel injected engine is not going to have cylinder bore wear even with the 140°F thermostat.

 

[L31MaxExpress]

When I had electric fans I ran without a thermostat. I used the restrictor washer you would run for a racecar. I experimented with various washer sizes and coolant temps. I used the ECT vs coolant temperature tables to allow more timing in the 120-170°F range. It made more power and got better mileage the cooler I ran it because it was able to tolerate full timing advance on 87 octane. When it got over 160°F I had to pull timing to keep it from knocking. The 170°F thermostat was a comprimise between a quicker warmup, stable operating temperature year round and minimal timing advance being pulled. 170F has also not given me any moisture buildup problems running E85. It is hot enough to vaporize water and fuel contamination out of the oil with my driving style. Most of my trips are 20+ miles each direction or more in the Express. It is rarely driven around town.

 

[Pinger]

When I had electric fans I ran without a thermostat. I used the restrictor washer you would run for a racecar. I experimented with various washer sizes and coolant temps. I used the ECT vs coolant temperature tables to allow more timing in the 120-170°F range. It made more power and got better mileage the cooler I ran it because it was able to tolerate full timing advance on 87 octane. When it got over 160°F I had to pull timing to keep it from knocking. The 170°F thermostat was a comprimise between a quicker warmup, stable operating temperature year round and minimal timing advance being pulled. 170F has also not given me any moisture buildup problems running E85. It is hot enough to vaporize water and fuel contamination out of the oil with my driving style. Most of my trips are 20+ miles each direction or more in the Express. It is rarely driven around town.

How do/did you know it was knocking? From scanner data and if so, live data or recorded?
I'm thinking of deleting my EGR (by simply disconnecting the electrical connection) after I've changed the inlet manifold gasket and cleaned the manifold.
I've read here that deleting EGR promotes detonation but my LPG has an octane # of 112 so some latitude there. But, if it detonates during driving - how do I know? Do I know?
In the old days before det sensors my ears would easily hear detonation. With my Vortec, won't it merely retard the timing and at worst all I can notice is a slight drop in torque/power?

Interesting reading this stuff. For a time - early 1990s - the obsession was running at around 230F (in Europe at least) the thinking being the lower temperature differential between the chamber and the coolant the less heat loss to the benefit of fuel efficiency. This seems to have been abandoned now and reading what you guys are writing re ignition timing I can see why (not least, as retarded timing leaves unused heat discarded into the exhaust and wasted).
Incidentally, Ricardo has some interesting observations on heat loss to coolant. He reckoned it was always overestimated as much of it occurred too late in the expansion stroke to be of any real use. He also made the point that a great deal of the heat going into the coolant occurred as the exhaust gas passed through the exhaust port - by which time there was nothing that could be done with that heat.

 

[PlayingWithTBI]

How do/did you know it was knocking? From scanner data and if so, live data or recorded?

You can see it in both scanner and/or data logs. You can also pull a spark plug and look for "pepper" looking spots on the porcelain.
https://www.dynamicefi.com/SparkPlug.php

 

[Pinger]

You can see it in both scanner and/or data logs. You can also pull a spark plug and look for "pepper" looking spots on the porcelain.
https://www.dynamicefi.com/SparkPlug.php

Doesn't the PCM just retard the timing as soon as detonation occurs (quicker than the human ear can hear it) and thus prevent any damage?

My smart - the engine of which has the notorious crap oil control rings - burned oil at 2-stroke levels (seriously!). The oil reduces the octane rating and the O2 sensor senses oil as fuel and reduces fueling and retards the timing to counter the detonation - which goes entirely unnoticed. The consequence of the late timing is burned exhaust valves. They all do it but never is detonation heard - only the misfire when the valves finally give up due to late timing. When stripped to remedy, there are never signs of detonation having occurred (despite how damaging prolonged detonation is).

The Vortec must surely contain detonation at safe (to itself) durations even if it does show up on data? What, BTW, does the data show - that the appropriate signal was received from the detonation sensor?