Thread: How Much Cooling Is Enough

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How do you size and design a cooling system (rad/fan/etc)?

Here is the vehicle: a 90 Jeep Wrangler with a 305 chevy 4bbl, stock, cast iron manifolds (in and ex), 700R4.

the motor i am in the process of pulling (same specs as the one above that is goin in) is munched. Not sure why (yet), but no oil pressure is part of it.

Pulled the rad and fan (and other parts) today - the rad is NOT the jeep rad (this one has the trans cooler built in, the jeep was originally a 5 speed). The rad is a top and bottom tank, trans cooler at the bottom, not very big in any dimension, brass. The fan is a GM clutched unit, with 5 a-symetrical blades that are the shortest blades i have ever seen - 4 or 5" long MAX! No A/C.

This vehicle was driven this way...but i have no way of knowing how hot it ran or how they drove it, etc.

So, how does one figure out how much cooling a given motor needs?

I would like to do an elec fan...must the temp sensor go in the rad or can it go in the gooseneck? The rad has no holes for it, the gooseneck (and intake) do.

I need to know if i will have enough cooling if i am crawling through the woods at 2500 rpm as well as rush hour traffic. I care not to munch a motor!

Thanks!

Two problems with the 'use the donor vehicle cooling system' -

a) no donor vehicle, as the Jeep came this way (to me).
b)the space available in a wrangler is much narrower than in a camaro.

Other (side) issues:
the camaro that is donating the replacement 305 is getting a 400HP 350, so it needs to retain a cooling system - since the stock 305 was about 180HP, we may need to improve the cooling system on the camaro as well.

There must be a formula for this stuff...
X HP = Y BTU per RPM or Hour or...

X sq in of rad at Y CFM airflow = Z BTU dispersal

The GM engineers, etc, all went to school to do the math, so the math must exist someplace....must search more.


Streets - the XJ (llke the comanche i had) has a rad about 30" wide. The Wrangler (YJ or TJ) has maybe more vertical space but much much less horizontal space so dual elec fans (my preference) won't physically fit. Well, 8" ones might

Originally posted by screamer63_1979

How Much Cooling Is Enough

When you get frost build up on the intake..................... youv'e gone toooooooo far.

Originally posted by Streets
Sorry Chris.. ALL I know about jeeps are, is that they get 500 feet farther into the mudbogs here, before they bury themselves to the frame.. I use a '78 Fairmont verticle flow 4-core rad on my Pail to cool the Blown 383 and it ran right around 220° normal temps.. It is 16½"x16½" Core and I run a 16" Chevy Citation electric fan on it.. Works for me...

How do you have the fan wired? I have to check my rad, number of cores wise. I want an elec fan...not sure on how to wire it. Would llke to stick a temp sensor in the gooseneck and run that to a relay that runs the fan, with a switch for over riding for an always on if i want, all wired to the batt so it can run with car off.

How'd you do it?

Ive got an 87 YJ with a 350 in it. Was having cooling issues from the git go. Electric fans are not cheep and im the type of guy that likes to tinkersooo. From a jeep forum I got the info that an elctric fan from a crown vic. cop car is the best e/f on the market. You can get the wiring kit and sensor from summitt. It cools my YJ at an idle all day to no more then 160 degrees. 180 to 190 down the road or even creeping or crawlng hills. Also Think about some hood vents along the sides and in the middle of your hood just behind the carb.

I would hope the originator of this post has figured the cooling sytem out in 3yrs and two months.

Don't you just hate it when someone does something to fix a problem, then never come back and tell you what they did? Or how it worked out?