How do I drop my highway temp 8°?

[57vette]

Originally Posted by dhutton

With a 195 degree sensor the PWM controller is trying to control the temperature of the coolant exiting the radiator to 195 degrees afaik. If it enters the engine at 195 it seems reasonable that it would be 210-ish when it leaves the engine and enters the radiator.

Maybe try the 185 sensor if you want it to run cooler.

Don

I've tried 180° sensor and the 195° no real difference. Have also tried 160° and 180° thermostats, again, no difference in highway temp, fans are always on because once its warmed up its seems to stay at 200° which won't shut the fans down, and in traffic it goes to 220° and a little higher if its stopped and no airflow, just the fans.

Originally Posted by srode1

I don't think your fans do anything at highway speed, I agree turning them off with a switch wouldn't change the temperature. You can do the math to confirm if you want. Your set up doesn't look bad to me for an electric fan set up, but you are blocking some of the radiator with the shroud. A pusher fan isn't going to help things, it will block more air, don't do it. Around town bigger diameter fans would help probably, maybe some on the highway too. Do you know what your A/F mixture runs in those conditions? Maybe you are running too lean?

I kinda agree about the pusher concept. I don't know for sure what the A/F mixture is or the timing... gonna have to check that.

Originally Posted by Vegas69

On the highway that set up should run cooler than 200 in 85 degree weather. Not far from your t stat rating. I agree with looking at your air/fuel mixture and timing. A vaccum leak? Fatten up your idle circuit or throw some bigger jets in the primary side and see if it cools it down a bit. Does it surge under light throttle? Ping?

Hadn't thought of the vacuum leak possibility. No surging, no pinging, shuts off without any knocking or anything else.

While I'll admit that the article "Budget Cooling" drew me to these fans, plus the fact that they are shallow and many have used them for V8 engines including a 461 BBC although the El Camino has a bigger radiator than the Camaro I'm sure. Perhaps I have to look at a couple of more powerful 11'-12" fans that will fit without hitting the serpentine pulleys or belt.

Derale 16925 High Output Radiator Fan is a 12" that is rated at 2000 CFM at Zero static pressure, so maybe in real use it pulls 1500-1700 CFM? While they sell it separately as a Pusher, they offer it as a dual Puller 12" kit with a shroud and in the video demo they state it must be used with a custom shroud as a puller. I emailed them for more info and some better specs.



SPAL Automotive USA 30101522 is a 12" puller that's rated at 1328 CFM and I don't know if this one in tandem would be enough, although reviews say guys are using them with Big Blocks and they do the job. SPAL is supposedly the company that doesn't over rate their fans. These would probably fit well.

[dhutton]

Sensor won’t improve highway temperature. I proposed it since it should affect the slow moving and idle temperature which is 10 to 15 degrees higher than the highway temperature if I understood you correctly.

Highway temperature too high implies undersized radiator imho.

Don

[dhutton]

Suggestion to verify timing and AFR is an excellent one imho.

Based on what I know about you I know that you would enjoy logging and analyzing your AFR…

Don

[57vette]

Originally Posted by dhutton

Suggestion to verify timing and AFR is an excellent one imho.

Based on what I know about you I know that you would enjoy logging and analyzing your AFR…

Don

Don... I'm trying to get an appointment with a local tuner shop and have him take a look at everything (carb, ignition, timing, vacuum, and anything else that might affect cooling). Radiator is Cold Case's CHC11 which is their BBC model. The VA condenser is mounted according to VA's instructions, bolted to the front of the core support. The water pump is a high flow model that was included with the serpentine kit. The EMP/Stewart thermostat should rule out air trapped in the system, but we'll see. Here's a little video clip of a cold start showing coolant slowly moving, and of course it flies thru there when the motor is warmed up.

https://youtu.be/f9zE_8KdXWU

Someone had suggested moving the temp sensor away from the lower radiator hose neck, but I would think that's where the temp would be the coolest (?) once the car is warmed up and riding down the highway?

As far as fans go, with a 23" wide and 16" high core, the two 12" fans are about as big as I can go diameter wise, and because I'm extremely tight depth wise, I can't use a fan that's more than 3" deep from shroud flange to the rear edge of the motor housing. DeRale tech support emailed me last night and said the 16925 comes wired as a puller, is 12" and 3-1/8" deep and pulls 2000 CFM at zero static pressure. After I get some tuner info, I might buy one from Amazon and see if I can squeeze it in there, although the fans should not be a factor at 65mph. I haven't really explored the SPAL brushless 12" fans but I would guess they'd fit being even flatter. Don't know if you can even buy them without a shroud which I shouldn't need.

Mike

[dhutton]

If you move the temp sensor to a hotter location the fans will turn faster to drive that hotter location cooler. The net result should be lower coolant temperature as measured by your temperature gauge. This applies to idle and low speed driving, not highway driving.

Don

[57vette]

Originally Posted by dhutton

If you move the temp sensor to a hotter location the fans will turn faster to drive that hotter location cooler. The net result should be lower coolant temperature as measured by your temperature gauge. This applies to idle and low speed driving, not highway driving.

Don

I'm fine with 200° highway temp but I need to get that down to the mid to low 190's to turn the fans off. It'd be interesting to see if the fans were off on the highway at 65-70 (roughly 2200-2400 rpm) would the temp just stick at 200° or would it increase or decrease? When I had a 4-core radiator straight no clutch mechanical fan, I think... that fan would be pulling more air thru the radiator than dormant eFans right?

I guess I could move the sensor up higher on the side of the tank and see what happens, but am I missing something with regard to fan RPM? Carl's little PWM does a really nice job on the soft start of the two fans, and even when I shut the car down, its a slow ramp down for about a minute or so that the fans are powered but gradually reducing RPM until they stop. Moving the sensor to a hotter section of the radiator (closer to the top) would also probably keep the fans on at highway speed.

Yesterday I pulled off the bumper and grill because the RS grill's getting painted hopefully next week along with the endura bumper and a couple other items. Gonna take it for a ride and see what happens without a grill. I'm also thinking about building a lower close-out panel to help channel air thru the condenser and radiator. And I keep thinking about Mark Donahue's radiator ducting LOL.

[srode1]

Seems to me while working on air flow might lower your temperatures it's really not the root cause. Your set up doesn't look bad, I think there's something else going on that is getting your temps that high. Cruising down the highway just doesn't take that much horse power to do so you aren't making that much heat regardless of the engine size.

I'd be going after the basics first, it will be much cheaper and better for your engine longevity if mixture or advance is your problem and you address that.

[69hugger]

I'm going to suggest a very easy trial. I know many here will scoff at this... a few years ago I would have too.
But after I did this, my cooling issues vanished. It is simply see what happens if you remove the thermostat (gasp).
I have a '69 Camaro, 534" big block making 700 hp. My cooling system consists of the 1000 hp rated Be Cool rad w/ twin 11" Spals, and a Stewart water pump. The fans are ECM controlled to come on at 190, and shut off at 170.
When I ran a 160 deg. stat, it would run hot (210-220 +) only if stalled in traffic on a hot day, and take forever to cool down when I'd get moving again.
My very old school engine builder kept telling me to ditch the stat. I thought he was crazy. I'd cite every article ever about how doing so would speed up the coolant flow so the coolant was not removing enough heat from the engine, needing pressure in the block, etc. I was chasing all the stuff you are talking about here. Fan CFM, sealing air leakage cracks, water wetter, blah blah blah.
A few years ago, I was beating on the car pretty hard, and the cooling system blew. Coolant exploded everywhere. The engine bay was drenched. Only after detailed inspection did I discover what happened. With that flow restriction, the cooling system had created so much pressure the rear seal on the water pump had blown out.
I finally tried his suggestion. I have not run a stat since. And the car has not seen 200 degrees since. It normally runs almost exactly 100 deg. hotter than ambient. 80 degree days it runs 180. 50 degree day it runs 150. And makes no difference whether I'm on the highway or sitting in traffic with the A/C on.
I know it sounds crazy. I know the experts will scoff at this & cite why it won't work. And it probably won't work in every case. But in 1/2 hour you can try it. What do you have to lose?

[Vegas69]

A high flow t-stat may be a good compromise to none. If the coolant temp is 150, oil temp could be 150-170. Far from ideal. The moisture won’t burn off very efficiently and your oil pump will work harder. That can lead to distributor gear wear and failure. Lubrication is typically superior with reasonable oil temps. No stat will lead to a long warm up cycle too. A reasonably light synthetic would be my choice if you try it.

No stat in the summer is another option. I can see the benefit of the flow assuming the radiator can take advantage of the extra volume.

[Beechy]

Mike.
A few observations from my daily driven 68 Camaro, mild cam 350 auto, p/steer, no air, no oil cooler, stock brass radiator with trans cooler ports, some kind of Ford v8 electric fan with shroud and flaps, Davies Craig electric water pump with no thermostat. Travelled 120,000 miles so far, mild San Francisco type climate.

Maybe dumb luck with radiator sizing/water pump output (EWP80 running ALL THE TIME) but warm up times are normal despite NO thermostat, coolant temps always normal .....180 most days at all speeds, 200+ in stop/start.

Oil temps are mostly ALWAYS a few degrees cooler than coolant.
-Exception to this is starting quickly on cold morning and driving conservatively at freeway speeds, the oil can barely crack 120 = BAD. As soon as you get on the gas the oil temp will catch up.
-Also, getting on the gas at any time will see the oil HOTTER than coolant quite quickly, as much as 250, and take forever to come back down but will stay 5* hotter than coolant.

Oil has to be approx 180 to do its job, eliminate water and warm the crankcase......just like Todd said ^
Oil starts to break down 260+.

Every carb equipped car should have a 4-wire fuel/air meter, $200 will save you the first unnecessary tune up. Check timing at cruise rpm.
Normally a thicker radiator creates issues in traffic because fans struggle with heat soak but ok at speed because airflow, so not always a happy solution.

NEVER use a pusher fan, they're an expensive way to block airflow.

A/C condenser should be 3/4" clear of rad core.

You have done great with flaps and foam seals but fans for 200 h.p. does not compute.
I hope your first post is a typo where u say BBC with 1.25" rad outlets.....stock SBC is 1.5".

FYI.....Covid boredom got the best of me and I moved that stock radiator under the trunk and added an EWP130 under rear floor.
17 years ago I had built the trunk floor higher to accomodate the rad but never had time to do it.
Why? Because race car.....corner weights.
Outcome? NIGHTMARE....don't do it.
It runs cooler so far but spikes in cylinder head temps take a few miles to settle down