how to pick your radiator?

[DBrown]

I did a search to find some old info on how to select a radiator for what motor you wanted to run and didn't find the info I remember seeing.

I remember that Nobody had told me that the 2 core aluminum radiator from summit would work well with the motor I was planning to run, so the question of what I wanted to run is pretty much answered. BUT, I was wondering if y'all would like to post up some tech on how to select a radiator?

I'm sure most of us know what cross flow is, but I was looking for maybe some calculations or rule of thumb on number of core's and how much hose power it would be able to handle.

anyone?

[Nobody]

All I know is that X amount of HP requires Y amount of cooling. When I called Griffin about my radiator, they said it was good to about 400hp. I don't think there is a standard formula because radiators of different brands and construction are going to vary greatly.

A typical 2 core aluminum radiator is the same size as a typical 4 core copper. I believe the aluminum radiators cool better too. Aluminum seems to be cheaper too, unless you can find a junkyard app.

[OffroadBEAR]

to figure this out would take some involved thermodynamics, but common sense usually applies best. For an exact amount, you would have to know how much fuel is pumped into the cylinders, and how much heat they create to find out how much coolant you would need. I heard that the '85 bronco II radiator will work with a 302 'cause its 3 core, but if you already know what you want to run and that it will work with your engine, stick with that. Most aftermarket suppliers will supply you with the proper radiator, and aluminum works better than copper because it dissipates heat faster. As far as a junkyard application, if you can find a good radiator that was designed for your engine, just make sure it will fit in the front of your vehichle, or that you can make it fit.

[Nobody]

I've heard people claim the stock 3 core will cool 302 as well. I'd never recommend it though. At best it might be ok for a grocery getter, but for off idle wheelin, pulling long hills, traffic, or a warm summer day, no chance. The number one problem I see with most V8 conversions be it toyota, jeep, whatever, is overheating.

I see a lot of people try and make up for an undersize radiator with every type of fan imaginable, which at best is just a band-aid.

[OffroadBEAR]

Yeah, I'm gonna have to agree with nobody on that one, I just threw it out there.

[DBrown]

I know that alot of people complain about the EB's over heating and the stock radiator for an EB is a 3 core. but I have also talked to people about the stock passenger side water pump is not the best flowing thing either. I did have a buddy that put a 302 in a ranger and abused it on a daily basis and he ran the 2.8L radiator. it cooled fine.

I had remembered us talking about that it was a HP thing but I was thinking it might have something to do with coolent volume also.

[OffroadBEAR]

Coolant volume and volume flow. It might have something to do with HP, you could use that, but I think it has more to do with fuel flow and burn efficiency, and cylinder volume, since that determines the amount of heat put out by the cylinders, which determines how much coolant and its volume flow.

Paul

[DBrown]

well, here is what I am wanting to clear up. if the HP thing is the truth then an early 80's V8 sould be able to be cooled with a stock 2.9L radiator...

while I doubt that would work, the HP ratings are close. the thing I would expect to be different is the coolent volume and flow rate...does that make sence?

just wanting to clear up some myths...

[OffroadBEAR]

Well when the radiator shop said good for 400 hp, they are probably talking about aftermarket or hopped up engines of 8 cylinders, which are around the same in terms of heat output. They are probably calculating with a maximum heat output based on required fuel flow and combustion properties and an average coolant volume flow based on what kinds of water pumps would be required to support an engine of 400 hp. In terms of the 80 V8 and BII being able to be cooled by the BII radiator, that would be a big NO NO. The V8 will be close to twice the size of the BII's engine. While the HP numbers are the same, it will take more fuel to make X amount of HP in the bigger engine than making X amount of HP with a 2.9, the cylinders are much bigger and there are more of them, so the engine as a unit is going to put out more heat, which requires more coolant (even if you compare the 2.9 and the 4.9, the 4.9 has monster pistons and a large stroke, which requires way more effort to push up and down than the little pistons and short stroke of the 2.9, so it still produces more heat). Now the volume flow rate, too high a volume flow rate would just cause the coolant to get too hot and not cool the the engine due to not having enough time in the radiator, and too low would mean the engine would just overheat because coolant is not being cycled through fast enough to do anything. I would imagine that the volume flow rate in an 80s V8 would be a little higher than the 2.9s because it would need to move more coolant, but not by much.

If you tried to cool an early 80s V8 with a bronco II radiator, it would just melt because the BII radiator does not have enough coolant volume and not enough radiator surface area to sufficiently dissipate the heat from the coolant (the 2.9 has a 2 core rad and is very freakin small, a V8 rad is 2-4 core depending on engine displacement and is freakin big). My mom's police interceptor has a 350 and it has a freakin huge oversize radiator because cops drive the shit out of their cars, and leave them running for a good 8-10 hours a day (which is a very good thing, it makes sure all the internal engine parts are autoclaved in shape, and eliminates about 50-70% of engine wear due to eliminating heat temperature fluctuation and heat transfer of turning the engine on and off like a civillain vehichle, which is what causes most engine wear, cop engines can last up to 400k miles with regular maintenence because of this).

Bigger engine = More coolant = bigger radiator

[Nobody]

cop engines can last up to 400k miles with regular maintenence because of this).

I agree with OffroadBEAR. In the world of physics there is nothing "left over". We are just coverting energy from one form to another. Without some physics knowledge, it's sometimes hard to identify where/how engergy is being transfered/converted.

There is no way a 2.9L radiator is going to cool a V8 reliably. A gallon of gas stores a given amount of engery. A larger engine is typically able to convert that fuel into mechanical engery FASTER, therefore releasing more heat FASTER, which requires more cooling capacity.

That's why all these hybrid cars are pretty much bullshit. They are only making mileage gains in weight savings/reducing drag/picking up engergy from other sources(batteries), and creating the illusion that they are somehow converting engergy more efficiently. Fact is a gallon of gas can only move so much weight, so far, so fast. Diesels are more efficient at the cost of heavier duty parts = $$

Physics gurus can correct me here if I'm off track.

I think the whole HP thing is just more a rule of thumb that's easy for the consumer to understand.

[Nobody]

Here's an article on howstuffworks.com you might find interesting

http://auto.howstuffworks.com/cooling-system.htm

And another about creating more power

http://auto.howstuffworks.com/engine14.htm

Edit: And here's one on hybrid efficiency

http://auto.howstuffworks.com/hybrid-car8.htm

[OffroadBEAR]

yeah, the thing about cop engines is pretty amazing. My dad and his friend rebuilt the engine, then his friend drove it for a long time. He drove it a lot, so he just left it running all day for like 50k miles. The speedo broke years back with 180k on the odometer, and lord knows we have driven the shit out of that car and it still runs, only thing is valve seals leak, but it still runs good (better than my bronco, which still doesn't drive).

I agree with Nobody about the rule of thumb deal, its probably to make sure that they have product specs that make sense to the average consumer.

Hybrids are crap, I will never own one. If I need something to get great mileage, I will throw an old mercedes benz diesel into my bronco II and convert it to veggie oil (will justify a trip to MacDonalds). Besides the fact that fuel mileage ratings are measured in a lab, not in the real world, I refuse to drive anything that has an electric motor as motivation.

Paul

[Nobody]

I refuse to drive anything that has an electric motor as motivation.

Paul

I'll have to disagree with you there.....trains are electric Think of the gearing possibilitys when you can run your motor at 1 rpm with tons of available torque, and wheel speed when you need it. So much for aftermarket transfercases!

And we are officially off topic

[DBrown]

that was exactly the kind of answer I was looking for...

thanks

[OffroadBEAR]

You have a point Nobody. I don't ride on trains much but I think they are extremely impressive machines.

Its not that I think that electric motivation is totally crap, but I just don't trust cars with electric motivation at this point. Especially if it has a japanese manufacturer logo on it (sadly my blown trans is japanese, but my motor is german). I don't really like japanese cars and I don't really like electric cars at this point. I think people are jumping to the electric conclusion, that it is the answer to all the vehicular problems, but the IC engine still has a long life of development and refinement left, its just not marketable right now which is the reason it is being neglected. Besides, automakers keep mileage low so the oil companies can make money, then invest it into the automakers in one form or another (NOW we are off topic).

Anyway, I will probably not have any use for electric cars in my natural life.

Back to your radiator