How do I drop my highway temp 8°?

[67-ls1]

The fact that it won’t cool on the highway leads me to believe it’s airflow related. Or lack of…
How is the airflow OUT of the engine compartment?
Do you have a front spoiler? A front spoiler can lower the pressure under the car and allow more engine compartment air to escape under the car.

[57vette]

Originally Posted by 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?

Originally Posted by 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

Originally Posted by Musclerodz

Make sure your not collapsing your lower hose at higher rpms.

Originally Posted by SuperB70

Here is my .02, been building custom cooling systems years. I think 8 now.

Core: its not about rows anymore, thats old scool when there only was one type of tube.

Nowdays tubes comes in many width and height. Even with inside tube fins. Most important is fpi (fin per inch), talking about airflow fins between the tubes. That is industrial scale of efficiency.
Ofcourse adding rows can make a difference means of coolant capasity.
But usually I can get by with 66mm core to first 1000hp at street car.
I choose to build horizontal flow cores, dual-pass. Not a big fan of original style vertical single pass cores. With dual pass design, I can control coolant flow better vs fan/-s.


Fan sensor: I go to local partstore and search/buy oem sensor with right turn on and turn off values.
In here (Finland) I use sensor for Volvo, has little lower turn off temp than on temp. There is two kind of sensors, ones that close the circuit and ones that earth it. I use mainly one that earth it. That controls a relay for the fan/-s or a controller. I can also connect a on/off switch to by pass the sensor if I want to run the fans what ever reasom.
LS and other modern cases ECU will control that.
I've come up a wirins system that uses 1 earthing sensor, 1x 4 pin relay, 1 or 2x5pin relays and a on/off switch. Then fan/-s can be contolled by temp sensor ( even when car is parked, ign. off) ECU or switch.

Fan sensor location: near upper hose or at least first 1/3 of the rad core height. If the sensor is lower down the line, the hole core get hot and takes longer to cool it. Can even be at intake manifold. Never in lower radhose, when thats hot, your rad has already soked the heat and you are

Fans: you cant go wrong with SPAL. If you want, you can get motorsport models, huge cfm but not Amps. With brushless motors. Not the cheapest, but there aint never cheap and good in same package. WRC rallycars, rallycross cars, track cars use them. Many high end supercars use them.

Fanshrout: I dont use those airflaps, not sure why anybody would use them. Fan opening is enough, just 3/4 off the core, seal it with rubber seal and fan/-s sucking hole area of the core. If one is running without the other. There need to be a blocking wall inside the shroud. Othervice the running fan suck the air from other fans opening and not through the core. Again first 1/3 of the heigth of the core is most critical, thats where the most heat is. I always try to amount AC and/or supercharger heat exchangers lower portion just because of that.

Thermostat: if you run without one, replace it with nascar-style restriction plate, just stainless steel "washer" with 3/4" opening. I use that even with electric pumps. And for those I use german-made Piersburgs out of BMW, cheap and flow the same as Davies but better pressure. PWM controlled either by ECU or stand alone controller.
Running with out any restriction means that coolant flows too fast and heat tranfer dosent happen. You gauge reads cool but engine can be boiling hot.

Coolant pressure: that is another friend of yours. Rises the boiling point, raise the pressure and boiling point rises with it. Make sure your core can handel that. You dont want that to turn in to football (american style, not soccer)

Expansion tank: if you have just a line from under the cap to ground. WRONG! You need to install a breatable tank with incoming from rad has inner tube going almost to the bottom. 1/2 or 3/4"short is fine. When the cap releases the pressure the coolant goes, like the name says expansion tank. When the coolant system cool after engine been shoot off, vacuum will refill the coolant system from the tank. How clever is that! Dont need to be refilling that 1"- 1 1/2" that is missing from rad.

Coolant: there is "new" style coolant in the market, no water, boiling point .Evans waterless coolant. Boiling point is 375'f

Oilcooler: Engine oil temp goes hand in hand with coolant temp. If oil temp is always up, you dont get coolant temp down. Hot engine is hot engine.
Good, powerful oil cooler with thermostat is good investment.

Airflow: you are in right track. There needs to be high pressure area in front of the radiator. Air needs to be forced through the core. When you need more cooling power, more fpi (fin per inch) you will need and that develops restriction to the air flow. You need to win that restriction. High pressure is you friend on that. If you have holes in radiator support, if air can go past the rad, no high pressure and you need to use fan/-s to make up for that.

Engine rpm: it plays a import role. Even in highway driving when throttle is at minimun if engine is turning rpm lets say above 3000 you will build alot of heat. That just is how gas engine work. Diesel needs fuel to make heat.

Originally Posted by 67-ls1

The fact that it won’t cool on the highway leads me to believe it’s airflow related. Or lack of…
How is the airflow OUT of the engine compartment?
Do you have a front spoiler? A front spoiler can lower the pressure under the car and allow more engine compartment air to escape under the car.

Thanks for all the great feedback. I'm possibly looking at two possible problem issues; highway driving (with no eFans running), and very slow or stopped driving with eFans running. I've talked to others who have used these exact fans on both BBCs and SBCs with no issues so I'm not giving up on them yet. Absolutely nothing has changed as far as the engine tune goes. With the old 180° ordinary thermostat and a 4 core copper BBC radiator she ran just fine at 175°-180° on any hot day as long as I was moving at more than 30 mph. But now its a new radiator, Vintage Air, Serpentine belt setup with reverse high flow water pump. Couple of comments regarding your punchlist ideas:

· Radiator is a BBC spec Cold Case with a core size of 23" wide, 16" high, and 3" thick. Its a two-tube core and the tubes are 1-1/4", the coolant hose IN/OUT are standard chevy sizes. There's no room for a bigger radiator unless I have a custom core support built... which seems like a waste since so many people run BBCs in 69 Camaros.

· Lower radiator hose has a coil inside to prevent collapsing.

· Running without a thermostat is something I hear every now and then. I feel I have to try a few other things before doing that... as easy as it is to do. I'm currently running a EMP/Stewart high-flow 180° thermostat and this model has three (3) 1/8" holes drilled into it to ensure there's no air bubbles and that regardless of temp some coolant is always flowing so it can't get stuck shut.

· My shroud inside depth is just a tiny bit under 1" between the core and the inside of the shroud.

· The Vintage Air Condenser is mounted correctly with VA components and is about 3/4" forward of the core.

· The two Ford 12" fans are pullers, not pushers. While I realize they were originally used in a roughly 200 HP Ford Contour SVT, this dual fan setup has been used in numerous V8 applications including off road vehicles.

· I'm using Carl Casanova's PWM to control the fans, and per Carl's instructions the 195° sensor is mounted on the lower PS of the radiator tank just ahead of the return hose that goes to the water pump. At Don Hutton's suggestion I have rewired the PWM so that the POS/NEG wires are both 8AWG and connected directly to the battery terminals bc I wasn't getting full voltage to the fans.

· With regard to airflow, I designed and built a sheetmetal lower closeout panel to prevent a large portion of the grill air from spilling out through the lower valance opening. I actually ran this by some gear heads in the Physics Forum who agreed that blocking the main escape route would increase pressure to the condenser core to flow through them. And I do have an upper closeout panel on the car. Here's some pictures.









· Unfortunately, my interior is being redone over the winter and because the shop owner got COVID while on vacation, he could not return to the USA until he was re-tested twice so he lost 3 weeks and then he lost an employee so he's scrambling all alone now to try and catch up. Hopefully by the end of next week he might be done and I can get back on the road for more testing.

· As far as a wide-band goes... I might look into that. I had a AEM wide-band on my supercharged Lightning and I thought it was a great gauge. Once I get on the road I can go get a bung welded onto my exhaust system. On the Lightning my bung was welded on the down pipe from the header collector. Here's a picture of my headers, where would the best spot be to mount a bung?





Again... thanks for the feedback. Hoping to solve this mystery.-Mike

[srode1]

Hey quick question Mike, did your car ever run cool on the highway? If so what did you change? Is this a new to you engine? Maybe I missed it, but I dont' see any background reading back through the thread. Getting the car to run cool on the highway just shouldn't be this challenging and certainly shouldn't need any fancy modifications.