I have been thinking of trying this and am interested in your thoughts and experiences about installing 2 radiators for the purpose of "Extra Cooling".

If I would remove the AC radiator and install a 2nd Cooling radiator in its place, as long as the plumbong was correct, would it not help keep the engine even cooler.

What I am cooling is a 500+ chp 383. I miss my 170 - 180* temps and have been trying to figure out a way to get them back.

 

I use a BeCool radiator, with the fan temps coming on early. I know the LT1 is a little different, but one thing to remember is fan flow. The bigger radiators need more air flow when going slow or in stop and go traffic. If you have one fan, or two, get ahold of Spal fans and they cn hook you up . These fans are used in Lambo's, Ferraris etc, which definitely need allot of cooling, being mid engined motors.
When cruising down the highway with my 396LT1 my becool keeps me at around 170, with AC on about 180. In town it runs around 185-195. If I had Spal fans the extra cfm they pull would cool much better.

 

The fan that I just installed is a 3000CFM model. I thought about putting another fan in front, to push more air.

 

I think it's diminishing returns. In a 3 row radiator, for example, the last row does something like only 15% of the cooling, since the fins in front have already broken up the air stream and heated it up. I don't recall where I read up on this,.. but your 2nd radiator would not come close to doubling cooling capacity. And you'd have to customize your end tanks to route your coolant hoses. And you'd drop to 1/2 flow in each, which is gonna hurt your capacity in each by a small amount.

You'd get more cooling capacity for your trouble by installing an oil cooler and a high quality alum radiator.

Dual fans with a manual switch or low temp switch is a way better way to increase capacity... and put in an alternator cutout switch for the track, so all that juice drawn by the fans doesn't leave the alternator churning away hp on the 1/4 mile.

 

What kind of radiator do you have now? It would seem infinitely simpler to just install one of increased capacity.

 

I now have a Dewitt and find that it is quite adequate for my
stockish engine. If anything, the oil may now run colder than
I'd like. It fit into place like an OEM unit, if the coolant level
fitting had come pre-radiused/chamfered then the rad would
have been perfect. $495 direct.

Dewitt also offers a shroud with twin Spal fans to fit early
and late C4's.

However, for the man with serious mods there is this Ron Davis unit.

Ron Davis Radiators
1984-1989 C4 V8 All Part No. 1-16CV8389T
-Rated HP: 800*
-Automatic transmission (cooler fittings are GM 5/16" inverted flare),
Optional: Manual transmission order Part No. 1-16CV8389

 

Now that looks like it may do the job.

Thanks

 

Aye, for a while, anyway.

I've heard they need a bit of massaging in the shroud area
to get them in. I am not sure about the status of the rubber
mounts (OEM OK?, replacements included?)

I chose the Dewitt for its acknowledged drop-in fitment. It
can grow with my needs by adding better fans. Your needs
may call for more substantial measures.

Cheers.

.

 

I see these kinds of comments all the time and it makes me wonder why some people believe they are getting more by paying more. Ron Davis makes a fine product, but all of the aftermarket aluminum radiators are pretty much the same performance. Be-cool, Ron Davis, and our Direct Fit brand use two rows of 1" tubes, so the btu rating of all these radiators are the same.

So if the cooling performance is the same, why select one product over the other? How about the fit, price, delivery, and support? I feel we beat anyone in these areas. We are also a Corvette Forum sponsor, paying the light bill so this site can exist.

One of my dealers suggested that I create a whole different set of part numbers for a "racing series" and raise the prices about $200. He said "these guys will pay more for the same product if you tell them it's for racing". I responded "thats crazy". But that's exactly what you'd be doing with the other brands. Paying more for no more btu's.

I also have a comment on rating radiator on HP. I see that R/D rates this one at 800hp, but if you look at the whole catalog they have similar size cores that are only 450hp. Where did the 350 hp go? The answer is no where. These are not test results, they are estimates or guesses.

I no longer rate on HP because that doesn't mean anything. Radiators have a btu rating and testing is the only way to find this. Testing is expensive and most places will not do it, we did. If you download a pdf of our new 2006 catalog you will see each radiator has a btu rating. It is very similar to the system used when you purchase a barbeque. These have btu ratings that give you an idea of it's heating capacity. It never lists how many hot dogs you can cook. That's exactly what we are asking when someone says, "how many HP is that rated for"? Which is usually followed by "r/d rates thiers for 800hp". Whatever...

This is our version of the 84-89 and we include custom rubber cushion to make the install a snap.

Now for the original subject, two radiators.

Installing a double row radiator like the above is the same thing, only a lot easier.

 

This shows how everything must line up or it's a no go

 

From a weight distribution standpoint, It may be worth considering mounting two mid-sized or one large radiator in the back. user Baldturbofreak had some photos of his rear radiator setup on the forum in the past. Of course, full time electric fan use will be required. The extreme foward location of the front mount radiator makes that weight extra important.


Tom: What does one of your C4 vette radiators weigh, without and with the side tanks filled with water? I may seriously consider having you build two smaller units for me to put in the rear of the car, on either side of my center outlet exhaust.

 

Nice set up, when I need one I'll be looking your way

 

Thats a GREAT Photo! Heck I cut/modded my shroud with a stock GM rad just to make it easier to get the cooler lines and hoses off without having to take more stuff off.I cut the plastic on the drivers side so the top shroud can come off without taking the upper hose off when it wasnt needed when I had other mods to do.Didnt have to cut too much off.Looks about the same as what you have done there,minus the top part where the neck and cap stick through.

 

Well, as I recall there are factors whereby HP and BTU can be
related. Stated in various units they are something like:

• Btu /hr times 0.0003929 converts to horsepower-hrs
• Btu /min times 0.02356 converts to horsepower
• HP X 42.4 converts to BTU/minute

They may use two horizontal rows of 1" tubes, but that is far from the
whole story. There is also the number of vertical rows, fin count, wall
thickness, special wall finishes and so on.

Because of this, I don't think radiators from the different companies
are necessarily the same insofar as their Btu capacity.

Let's just look at number of vertical rows for a moment. Interestingly,
if the Ron Davis' catalog photo of the 800 HP rated 1984-1989 C4
p/n# 1-16CV8389T is accurate, then the Ron Davis rad has 2 fewer
vertical rows of tubes (35) than my Dewitts (37). All other things
being equal, this seems to indicate the Dewitts A84A 1984-89
Direct Fit® radiator is capable of supporting more than 800 HP,
using the RD method of determining such things.

However, what puzzles me is that using the rating of 5,051 Btu/min
that appears in the Dewitts catalog and the factors above for
conversion gives a result of 119 HP ? I don't have much HP but I have
more than that. Whatever the explanation about the rating, in
practical terms my Dewitts radiator is a huge improvement over
the OEM one it replaced.

Excellent points. I can say that Dewitts was outstanding on all counts.
[Well, maybe you got a little tired of me asking about a GP, delaying
the order to consider adding the Spal fans (but ultimately just getting
the rad) and then my writing to ask for shipping confirmation. But if
so, you were nice about it.]

However, another reason is suitability for purpose. In my earlier post
I only mentioned the other brand out of a belief that it was targeted
for more extreme applications than the Dewitts Direct Fit and thus
could provide more cooling capacity for 'Rich & Lisa_84' whom I
believe have some extensive modifications to accomodate. When I
post here I try to take into consideration what will work best for
someone, not just what products they can get from Supporting
Vendors. I feel I made adequately clear that I like my Dewitts but
that I thought they might need something beyond it.

I appreciate the support that vendors such as Dewitts contribute to
keeping the lights on in the forum, but it is a two-way street and the
vendors stand to benefit from the comments, pro and con, that
members make in the threads here.

I think the notion that the Dewitts is only an upgrade for stock vehicles
has been dispelled now by your remarks and by the observation about
the vertical tube count comparison.

However, maybe this all points out an opportunity for Dewitts to
adjust their marketing to blow the horn about how just because
the Direct Fit slips into place like an OEM doesn't mean that it
can't handle the needs of big displacement, nitrous and forced
induction applications. You'd have to be the judge about whether
to take the distributor's suggestion regarding pricing adjustments.

.

 

Tom, as an engineer, I like your post, it makes perfect sense. I love to see mistruths exposed.

Slalom, my first thoughts on your conversion to btu is that you should throw away the pencil and paper. The engine horsepower is not converted into btus. If your engine was enclosed in an adiabatic box, then ultimately, yes it does work that way. I'm sure there is some relationship between hp output and heat output, but it depends on many other factors. What % of that power output transforms to heat into the coolant, I don't know.

If a 800 hp motor runs wastes 65% of its power as heat, and 90% of that is handled by the cooling system, does that mean the radiator needs to handle 60% of the engines output? Is that 800 hp motor going to put out 800hp nonstop, or just on short drag runs? Is it racing in nascar at redline for an hour at a time?

I guess it's possible to rate in hp, using some standards for cfm and gpm through the rad, coolant ratio, air and water temperatures, engine duty cycle and heat efficiency, but if that isn't done, then as Tom said, it's just guesswork.

Rating a radiator for BTU output still requires performing tests at a standardized cfm or face velocity, and inlet water and air temp, and coolant ratio. In the HVAC industry, I think ARI (Air Conditioning and Research Institute) sets those standards.


I think another factor in comparing radiiators, is how (and how well) the fins are attached to the tubes. In my oem replacement, many of them aren't even connected. How is this process done? Is it dipped in something or just a friction fit? Are the tubes expanded to compress the fins inbetween? Does a midget tig each and every fin fold to the tubes?

 

Hmmm, where to begin ...

Unless the writings of Carnot, Clapeyron, Joule, Thomson and their
followers has been discredited or amended recently, then there is a
very clear relationship between work (expressed as HP) and heat
(expressed as Btu).

Energy is the capacity for doing work. With this we have the
'The Conservation of Energy Principal' (Energy can not be created
or destroyed). Then there is the First Law of Thermodynamics which
applies the CoE principal:

• Change in Internal Energy = Heat added - Work done

Heat engines like the Otto Cycle type we use in our Corvettes convert
energy stored in fuel into mechanical work and heat. A million years
ago, an autoshop teacher told me the following rule of thumb regarding
the energy released when fuel is burned: 1/3 gets turned into work
(HP), 1/3 goes out the exhaust and 1/3 has to be dissipated by a
cooling system of some sort. This rule of thumb still seems to be fairly
close for quick back-of-the-envelope estimates today.

James Watt originated the definition of HP. He did so in order
to come up with a way of rating the output of his steam engines.
He wanted to demonstrate that his engines converted the heat
released by the fuels of his day (cow chips, coal & wood) into
work more efficiently than engines of others. He pronounced
that 1 HP = 32,580 lbs-ft/min. (Interestingly, Mr Watt tested
with a breed of super horse from Krypton and few actual earthly
horses were ever found that could reproduce his results
consistently - but that's another story.)

The Btu describes the amount of heat required to raise the temperature
of 1 lb (avoirdupois) of water by 1ºF. Btu/h and Btu/m are units of
power. There are several factors for conversion of Btu to other units,
here are some relevent ones for our discussion:

• Btu/hr times 0.0003929 converts to HP/hrs
• Btu/min times 0.02356 converts to HP
• 1 HP is about 42.4 BTU/minute
• 1 HP is about 2540 BTU/hour

(Keep in mind that, unless otherwise stated, HP is a measure of work/minute.)

Just like engines, radiator performance is or can be quantified using
standards developed for this purpose. Typically the performance is
rated in Btu.

From there, it isn't too much of a leap to match an engine with a
radiator of sufficient capacity for the expected work the engine is
expected to perform. Measurements of power like HP and Btu/m take
into account the duration of the work. So the application (drag race,
off-shore event) is factored accordingly.

I acknowledge the point that different testing conditions will skew
results. If consumers don't read the fine print and educate themselves
about the meaning of it, then they'll lose in the long run and drag
down the vendors that don't play the game.



** ==== Afterthought ==== **

I just want to say that nothing I've written in this thread has been
intended to denigrate a product or a person. If something has come
across that way, I apologize unconditionally.

In good faith I stated I have product 'D' and like it but that product
'R' might suit Rich's needs. After looking at the points in a rebuttle
and studying photos of the two products, I saw physical signs that
led me to conclude maybe my 'D' unit actually has more Btu capacity
than the 'R' unit.

I tried doing the math using the criteria each vendor provided and
noted a discrepancy. I implied but didn't explicity suggest then that
the discrepancy might be a result of my own lack of knowledge, I
will do so now. If one of you can spell it out for me in a way that
jibes with what Lord Kelvin and his buddies laid out in their various
laws, principals and processes, I will be most grateful.

If there are going to be replies, let's do it in a new thread and link
there from here.

.

 

All good points, and comments. HP can be converted to btu/m and there is a relationship. If someone is cranking out some big HP's, hopefully most of that is going to the wheels and not heat generation.
I agree with the comment of different brands are not exactly the same. Brand "R" does in fact use a tighter fin density (18 fins per inch) 18fpi. The industry standard is typically between 10-14 fpi. The tighter fin density is specifically designed for high speed racing, where speeds are at or above 100 mph. Under those conditions, they might actually cool better. Even if ours has a couple extra rows. The problem is the majority of people do not drive at or above 100 mph and at cruising speeds of 30-40 mph, the air has trouble getting through this dense core design. I think our cores, with 14fpi is a nice middle point for both cruising and racing.

On how the fins get welded, there are no migets. The aluminum used to make radiators is called "cladded" material. This means the aluminum has an outer skin, with an alloy slightly lower in melting point. The cores are assembled and baked in special ovens, the clad material turns into a liquidous state and brazes the whole thing together.

 

The guy didn't ask for a physics lesson. I went with a Ron Davis and love it. Very little trimming involved. One reason I went with them is that they are local, have a great reputation, and was able to get it the same day. Nothing against BeCool or Dewitts - they may be just as good for a lower price.

 

I would say similar performance. Many factors besides #rows and width. How about tube height vs. fin space, fin design / density, internal turbulaters?

FYI my Griffin "racing" radiator has 2 x 1.25" rows and it was $50 more than the 2 x 1" version. But you need enough airflow!

The most important factor in keeping your C4 cool is getting air into the radiator and giving it a way out of the engine compartment!

Getting air from under the car just doesn't work well; I built a front airscoop and dropped temps from 245 to 215 in Phoenix on a 550hp motor.