ShopTalk Forums | Aircooled VW Tech & Restoration Help

I have been piecing together some info for rad sizing based on engine size .... Can you guys perhaps help me with some terminology and formula help ?

1. Basic rad sizing rule for engine size.
2. Aluminum vs, brass or regular car rads, can aluminum be small with same efficiency ?
3. What is the difference between # of cores, ie, 3 core rad means what ?

I'm just used to knowing that there is a rad in my watercooled cars and thats it

My size restriction will be able 12 high by 24 long for a Ford 2.3l stock motor ... want to figure out if it'll work ... what kind of rad I'll make sure cooling air gets to it .....

Mine isn't actually running yet, so I can't tell you weather my radiator choice was good or not. But one thing to keep in mind is the way that you pipe your radiator can also have a big effect. Mine is copper piping under the car. This adds a alot of surface area that will have air flowing across it = more cooling. Another thing to keep in mind is that a huge surface area isn't going to help that much if you are not getting natural flow to it, for this reason I put in a large scoop to force air up onto the radiator, and another one to keep air from flowing over the radiator. While a basic surface area per displacement number might be useful keep in mind some engines (rotary or turbo) will run hot for thir respective displacements. The best thing todo would be talk to other people running the 2.3L and see what has/hasn't worked for them. That is enough rambeling for me.

~Josh

could ask the 2.3 baja guys at vwbaja.net. Most of them run turbos on theirs. I'm putting one in mine but still don't have a rad. Getting one in the next two weeks though. three core is better than two. There are also high flow water pumps for these engines. about $70 on ebay.

Where the radiator is mounted so that it is square on to the direction of air flow (so that air flow is at 90° to the radiator in both the horizontal and vertical planes), a rough and ready rule of thumb for calculating the minimum required radiator core surface area in square inches is to take the cubic inches of the engine then add a further 50 (see http://www.4x4wire.com/jeep/tech/engine/cooling/ ).

A rule of thumb for calculating the minimum required grill opening is to have at least the same size as the surface area of the radiator core less the area of its fins and tubes. This equates to about 1/3 the total surface area of the radiator core (see Tech Tip #1 through #5 and Advanced Cooling System Basics at this web site http://www.stewartcomponents.com/Tech_Tips.htm ).

To check if your system is working correctly measure the inlet (upper hose) temperature and outlet (lower hose) temperature. The outlet temperature should be about 20 - 25% lower than the inlet.

Eureka, that's awesome info ! I/'ll take a peek through.....

So, for my 2.3l ( 230 Cu In plus 50 ), I'd need 280 cu in ...

My measuring was that a 12 high by 24 wide rad would be about the max, which is 288 > 280 min so that's great. Need to work on air flow, shrouding behind the rad and exiting air flow ......

What I have to be concerned with is air flow into the rad now. perhaps I'll need to buy that OEM mexican rad grille for the front of my bay window camper ... although I like what Wilma Busgo's friend did, adapt a fresh air grille from the front of a camper and graft into the bottom lip of the nose to allow air in, albeit only a small amt ( the grille is about 5 inch high ... )

metropoj wrote:Eureka, that's awesome info ! I/'ll take a peek through.....

So, for my 2.3l ( 230 Cu In plus 50 ), I'd need 280 cu in ...

)

careful 2.3 liters is not 230 cu inches. it's 140.35 cubic inches. so u'd need 190 square inches, which is 1225 square centimeters

Ah good point, not even thinking about that but 100% correct


140 Cu In plus 50 is the 190, so that means a smaller rad, that's good ...

So 11 X 18 inch rad should do the trick IF it's flowed properly .... this gives me some more options. I have the original rad from the Mustang that the 2.3l same out of. I am going to measure the core up to see what they put in for size ....

to convert cc to ci formula is cc div by 16.387 eg 2088cc div 16.387 = 127.42 ci kenendy eng then recommends if using a 3 core rad to take cubic inches times 1.5 to give you the usable square area for your rad have used this formula several times now and it has always worked out well for me

Cool, but what does three core or 2 core mean ? The thickness of the finned area ??

ya M you got it a3 core rad would have 3 rows of cross tube and finning

OK, I just measured up the old rad for the 2.3l in the Mustang. Now a 140 CID engine from what I can ascertain through this thread here should be 140 CID + 50 as a MINIMUM sizing, 190 Cu. In.

Now, the rad that was in the Mustang was 18.5 X 24 fin area, or 444 Cu. In. Why would the old rad be twice the size of what we're discussing here as a min. If they were close, I wouldn't really care about the difference, but they are very far apart in size.

I don't think Ford's rad size would mean that the rad was overcooling the motor ......

Any comments to help me figure this discrepancy out ?I also wonder about if I should take into consideration that the coolant has to flow a longer distance from front to back of my bus and may be a little slower due to the distance ...... ( probably need a hi po pump .... )

I have an older Kennedy Adapter catalog. He list minimum radiator sizes for 18 different engines from a Suby 1800 to a Nissan V6. The column that sizes the radiator for rear mounting averages 350 sq. inches. IMO, the main thing is bigger is better in this case. He calls for 325 sq in for a 2300 Ford Pinto '74+, rear mount.

Rear mounting rad ? I guess that's what they mean, I wonder if they overstate the size because of poor air flow to the rear of a vehicle ?

Interesting stuff, thanks for looking at up regis ! i'll havw to measure up and see what I can fit in that space .... yeah, bigger won't hurt as long as i can squeeze it in there ....

M if you look at these pictures http://frost.bbboy.net/vwengineconversi ... 4&thread=3 that rad is 13x18" which is 234 sq in but look how flat it is laying it cools my2088 cc motor very nicely so if you calulate 2088cc divide by 16.387(which will give you cubic inches ) =127.42x1.5(which is kennedys ruleof thumb)=191.13 sq in of rad area went just a little bigger because of the way the rad hangs in the roll cage one observation i can attest to is that having switched from a copper core rad to the custom built aluminum rad the alum runs somewhat cooler and seems to recover quicker by that i mean that when the cooling fan kicks in the rad gives off heat quicker
regards 2088bob

Bob, thank alot for the info. My calcs work out to 210 Cu Inches of rad area. The rad I'm looking at ( I beleive it is Aluminum ) is 19X17 from a 3.0 Mitsu V6 ( Early Caravan ) ..... so, I should be just fine .....

I think the rad looks a lot small than the later Caravan / Spirit / Acclaim Shadow, etc because in theses early cars, the condensor is beside the rad, whereas in later cars, it's in front, so they probably had to put a bigger rad in to compensate for air having to pass through consenser then to the rad .....