multiflow radiators
 

I'm going to buy a new Koyo aluminum rad for the '89 vert and they have a "triple pass" model vs single pass ... sounds like it should be better with 2 extra trips around the rad, but is it really worth the extra $50 ??

any thoughts ?

I think it will keep the radiator more cool and if the radiator is cool then it will work more better which will keep your engine cool so yea its worth it to me you should get it

We use dual pass rad's on the race cars. All it does is split the rad top to bottom so water goes across the top half through the end tank and across the bottom half. For a triple it would be cut into three sections. I don't know how they would do a triple and keep the outlets on the same side though.

On the street it wouldn't be worth it unless you are pushing big HP numbers. Every pass through the rad actually costs some HP. You wouldn't notice the HP loss on the street but racing is another can of worms, it shows up on the dyno.

Tu Shay Tu Shay!!!! Thats Very Ture If Its Just Going To Be A Daily Driver Then I Would Go With The Aluminum Single Rad

Another thing about the multi-pass radiators on the street that most people don't think about is warm-up time. My multi-pass Griffin takes FOREVER (like 15+ minutes, longer if moving) to get the car to operating temperature here in snowy Rochester. This is a big problem for 2 reasons: 1) no heat til the car is warm, which means no defrost 2) kills fuel mileage since the car spends a long time on the cold map before switching over

just some food for thought, I wish someone had mentioned it to me before I got mine

thats a big help ......... the car will be in winnipeg starting next spring , and even though its only driven april to november , that would suck in the spring and fall in the morning...... winnipeg is rochester inside a fridge

sounds like the single pass is the way to go for a cool climate, DD, street car .

that long warm up time in cooler temperatures issue won't be a problem with a single pass aluminum vs stock rad will it ?

in light of my hot runner and living in the desert i may need to get a dual pass or triple pass.

Its the change in volume that does it the most, my car holds over a gallon more coolant with the griffin. iirc, the koyos still have fairly small endtanks so i doubt it will be as big of deal

The thermostat should regulate the coolant flow so that the car takes no longer to warm up. It *should* be the same no matter what rad you've got.

Yep, what Black91n/a said. And an aftermarket rad with, say, 4 cores will hold more fluid but the increased cooling comes from spreading the fluid into more tubes as the air goes by. Its all about surface area of the tubes and fins.

Each pass through the rad actually gives you less cooling power than the previous pass. It has to do with difference in temperatures of the air and coolant. As the coolant cools the rad can do less for you because the air and coolant temps are closer to being the same.

So, unless you are pushing your turbo hard all the time(if you have one) or you live in Death Valley you don't need one. Even in Death Valley the stock one should be fine for a mildly modified car. Save your dough for somehing that will make your car more fun.

It takes longer to warm up (for me anyway) simply becuase there is more fluid to warm up. The thermostat can be working just fine, but more net work is needed to heat the coolant cuz there is more of it. More coolant = more work. Driving it makes it worse since you start getting airflow over it which cools it down (esp in Rochester lol).

jgrewe - you are right, it does get less efficient with each pass, good point to bring up, esp on a street car

The thermostat only regulates what is in the engine.


So if the engine gets the liquid warmed up, it opens, and colder liquid comes in. As soo as colder coolant hits the thermostat it closes. The hot coolant goes through three passes, cools way down, and has to start all over again. At the same time the engine is being cooled by cold coolant, which is then cooled down after it reaches the radiator.


So there is a definite increase in the amount of time before the coolant reaches its "warm" temp because of the increased cooling capacity of the radiator. All the coolant doesnt reach 180* at the same time. It goes in spurts as the thermo opens and closes based on what the temp of the coolant at the thermostat is at.


BC

But the thermostat isolates the increased coolant volume (in the rad) from the engine. There's no flow through the rad untill the thermostat opens, so it shouldn't take any longer to get to the rad opening temp, afterwards it will take a little longer, but it should get warm pretty quick.

I've always wondered if the t-stat is like an on/off switch or a constantly variable control. We use blanking plates on the race cars with different size holes for different ambiant temps so the $5 moving part doesn't take us out of a race. I would guess that it opens until it gets the fresh water that has only gone though the engine once and then closes up a bit when that temp is lower. Then it only slows things down a little.

I know when you run an engine and watch the flow through the rad cap hole you can tell when it opens. If it keeps taking 'sips' of cooler water while driving I can see how it would take longer to warm up the whole volume of coolant.

We don't have that problem down here too much, women put on fur coats if it gets below 55F. So the car never has to warm up from sub zero temps.

I did grow up in Ohio though so I feel your pain!

No matter how the thing works (and now I really want to know), there is still more volume to heat up, and its gonna take longer. My in-block temp sensor (stock location) tends to not fluctuate, so I gotta think that it just slows the flow down instead of completely blocking it... I wonder if I have a bad thermostat? I never had any problem warming up with the stock rad. hmmm

Its not an on/off switch. Take one and throw it in to a pot and put the pot on the stove. When it reaches near the "open" temp it starts to open. it reaches full open at 180*, or whatever temp thermo you buy. Thats why it can take longer to get all the coolant to operating temp. You have to get it all heated up. The coolant in the block reaches temp just as fast, but then it is replaced by cold coolant as soon as the thermo opens.


BC

thermostats should start opening within a couple degress within its rating. and be fully open BY or before 20 degrees hotter than its rating.

Yea, I've tested them in a pot of water before and I've seen how slow they open. I was just thinking out loud about how fast they might 'cycle' or react. Most of the time that I can think of they are controlling the water as it leaves the engine. So that water that comes in and only runs through the engine once before it gets to the t-stat has to cause it to close up a bit. I just think it does that partial open position until all the water that hits it is in its range. So, since that rad is busy cooling the water as you drive it will take longer to get it all up to temp with a larger volume of coolant and better rad.

meh my heater core is bad anyway LOL.

Double pass radiators require 16x more pressure to flow the same volume of coolant through them, as compared to a single pass radiator. Triple pass radiators require 64x more pressure to maintain the same volume. Automotive water pumps are a centrifugal design, not positive displacement, so with a double pass radiator, the pressure is doubled and flow is reduced by approximately 33%. Modern radiator designs, using wide/thin cross sections tubes, seldom benefit from multiple pass configurations. The decrease in flow caused by multiple passes offsets any benefits of a high-flow water pump.


http://www.stewartcomponents.com/tec...ech_Tips_5.htm
These guys know their stuff.

ok well the multi pass takes too long to warm up but wont the engine last longer bcs of the the lower temps?

Not necessarily. The engine was designed to run at certain temperatures. The stock components were put on there to keep it at the temperature. Running too cold can actually hurt your engine.

Ok ...... put all that in a blender and what comes out ? ............ I'd say the single pass Koyo is the choice .

:bigthumb: