If the engine is at RPM and you are nearly stationary, a flex fan is the wrong fan for the application. Saw somebody put one of those on a stationary 350 on a generator and kept wondering why it overheated under load. You want a fixed blade fan for maximum airflow.Originally Posted by kidsandjeep
Agree with fixed fan, no fan clutch for max airflow, but most power loss.
I think you are on the right track with the 3300 CFM electric setup, if it is an airflow issue. Had a mostly stock 75 Corvette in the shop that we wound up with a dual fan, one 14" and one 12" with properly modified shroud because of fitment issues, to finally keep it cool when extended idling, in gear, with A/C on. Calculated airflow was 4200 CFM.
I never ran a flex fan with a clutch, bolt directly to water pump with only enough spacer to clear fan belts, etc. Make sure you have proper spacing to shroud, if applicable. I have had best results with this type
https://www.amazon.com/Derale-17018-...s%2C139&sr=8-5
Short style water pump gets you an extra 1/2" clearance if you have a long style.
Last edited by MO LS Noobie; 11-10-2023 at 03:56 PM.
I have run 6,000 cfm of electric with a 454 34 x 17 x 2" core radiator and it would not keep a 350 under load cool.
KidsandJeeps, I think you are fighting a tuning issues (timing and AF ratio) for climbing mountains, not an air flow thru rad.
You stated "The trails I ran in the summer at Moab were slow speeds, high outdoor temperatures." you said speeds slower then going up (25mph) mountain. I am thinking your speeds were 15mph or less in 90's+ heat and it doesn't run hot. Thus I am thinking it has to do with thin air. Moab is at 4000' and Colorado is at 6000' and from there you start to go higher. Also the air gets colder the higher you go.
I think, I would start with a data log driving up the mountain to see if you can see a point of where she start to get warm related to elevation, from there I would look at Air Fuel Ratio and timing.
My quick thought was you need more timing and less fuel, so a quick google look up found these post.
https://www.google.com/search?q=effe...t=gws-wiz-serp
Hope this helps
Screen captures from a data log: fuel rich / lean and spark advance.
Spark Advance.JPG
Near Idle.jpg
Off Idle.jpg
If you are running antifreeze/coolant you may want to go to straight distilled water. Antifreeze/coolant raises the boiling point and freezing point of water but it's the water that cools the engine.
Dave W what do them jpgs reference? are they from a tune you did for a high altitude? or are them a starting point for Jeepsandkids based on your experience?
Also Jeepsandkids, I noticed something in the jpegs Dave W posted, all the titles or headers call out a wide band O2 sensor. The point being if you don't have an wide band O2 installed you should install one. If i have learned anything on this site it is a wide band is ALMOST a must have to start.
I find a wideband mostly irrelevant myself except for tuning transition fuel. I have very seldom used them in 20 years. I find the fueling right where it needs to be when I tune using narrowbands alone. I hook a wideband up and the tuning based on narrowbands is right where it needs to be. The wideband is helpful to me in one place, because it is quicker responding for transitions though. I can use 02 sensor voltage to get the fueling as close as any wideband at WOT and fuel trims to get the part-throttle fueling done. Start with idle amd part-throttle tuning using fuel trims, get the VE table where it needs to be and the WOT falls into place pretty easily. There is very little power difference between 11:1 and 13:1. I shoot for 12:1 at peak torque and 12.5:1 at peak HP. It is safe and it works. Stay a bit on the rich side with the narrowbands at 880+ mv at peak HP and 920+ at peak torque. Staying on the rich side helps keep the combustion chambers and spark plugs cooler, basically eliminating pre-ignition.
Last edited by Fast355; 11-14-2023 at 08:43 PM.
I did some data analysis AFR vs. BLM. Using the Myth Busters way of collecting data the "Control Vehicle" was data logged while being driven to and from work for 5 weekdays. All 10 data logs (.CSV files) were combined into ONE very large file.
I'm of the opinion, Good Data will provide a Good Tune. It's debatable AFR vs. BLM. Sometimes the computer will lock the BLM's at 128, which provides the ultimate tuning frustrations.
All things considered, the Smiles per Mile favors AFR.
BLM - Near Idle.jpg
Near Idle.jpg
BLM - Off Idle.jpg
Off Idle.jpg
PE Active.jpg
Injector Duty Cycle.jpg
Spark Advance.JPG
Last edited by dave w; 11-15-2023 at 07:53 PM.
I would agree that data collection is helpful. I would be confirming BARO updates when increasing altitude. BARO is determined at key on / engine off and during some WOT operation. BARO represents barometric pressure where the engine is operating. If BARO is off, other values calculated using BARO will be incorrect.
Tuning options can include adding fuel and reducing timing as the engine gets hotter. These tricks usually help reduce engine temperature at the expense of fuel economy. In tuning everything is a balance of one kind or another.
Engine oil temperature can be used to help determine whether or not spark advance is correct. As spark advance increases, so does engine oil temp. And oil temp increases faster than coolant temp. Start your run with engine at operating temp and keep an eye on oil temp. If you see rapid increase in oil temp before a change in coolant temp, it may indicate too much spark advance.
Luckily, the old SBC uses a moveable distributor. There's nothing that says you can't try moving the distributor 2-4 degrees retarded before going up the hill. If the cooling problem inproves then you might benefit from a tune that removes some spark advance.
What octane fuel are you running? At 3500 - 4000 feet in MT I found that pulling timing a couple of degrees helped a bunch of engines. GM said it wouldn't but dang if the rancher's trucks didn't run a bit cooler. We had 85.5 octane fuel as the base level, then 87 and 89.
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