clayne

kempo,

That sounds like a huge descrepancy. No o-ring failure or blockweld/cooling system fix was ever used with the Fluidyne installed?

Don't get me wrong, I'm all for the Koyo and have one myself, just 30C difference is huge.

cloud9

iTrader: (4)

I agree that is a huge difference, can you go more in depth on what caused such a huge difference

fd3s_rx7

iTrader: (13)

Koyo is better because everybody say so

rynberg

The Koyo doesn't necessarily cool better. It has the same amount of surface area, the only difference is that it is thicker. Thicker is not necessarily better, when it comes to heat exchanging.

Also, your numbers are bogus Kempo. The difference in cooling between the two radiators is minimal at best. There was something very wrong with your cooling system to hit 125C at the track. I tracked the car this summer at Buttonwillow at 13 psi in near 100F temps and was running max of 108C on the PFC (230F temps at the t-stat).

jspecracer7

125 C is borderline overheating the car...why would you push your engine that hard knowing your water temps were that high.

Also, I tracked my car about 2 years ago when I had the stock radiator....then again 2 weeks later when I had the Koyo. I saw NO DIFFERENCE IN WATER TEMPS. Maybe one or two at best.

kempo

iTrader: (2)

well i saw a huge difference in temp. and that was the only thing i replaceon the car. and no, no o-ring failure or blockweld/cooling system fix was ever done on the car. i also added pices of foam all arround the new koyo rad. to prevent air from by passing the rad. maybe that also helped my problem. at least thet was my personal expirience with the 2 units

DCrosby

I concur, I've only had my Koyo for 2 Weeks, but Temps when moving are 185 F and 220 F when standing still, now given that is during the winter in clifornia, and maybe I'll post on this again in the summer... but again I think anything is better than stock, and I don't have the money or the resources to compare them side by side for the benefit of an arguement...

rex u.k

Anyone got temps for the std. rad just to compare?
I just sold my stock rad, it really is a puny thing once the fans come off.
I bought the fluidyne.

David Beale

I doubt there's much difference between the two, overall. More coolant capacity can, however, help. Just linearize your temp. gauge and you will understand that the coolant temp. varies all over the place. More coolant will slow that variation down.

125C is ok as long as you have enough glycol in there. I run 50/50 glycol and distilled water. I saw 125C last summer, and it prompted me to check at what temp. it would boil - 135C or so. I am still running the stock rad. You should also note that the temps. people report from the Power FC are taken at the filler neck, not the temp. gauge sensor on the rotor housing. The temps. up there are often 10C lower than at the rotor housing.

My Koyo has been waiting in the basement for a while (was going to put it in summer before last, but the hoses I ordered didn't arrive in time so I'll do it this summer when I change the coolant). Running high temps. doesn't hurt anything, as long as it doesn't boil. If it boils you can have places without coolant (just gas) and they can get disasterously hot. As long as the whole engine heats up and cools down (effective coolant system) you shouldn't warp the iron parts and cause "O" ring failure.

DCrosby

True but rubber doesn't like heat, and the water jacket has rubber seals... so cooler -> better.... and coolant under pressure boils at a higher temp than coolant in a pot on the stove...

RotorMotor

iTrader: (5)

someone in this post mentioned using a KOYO for their ls1. im in the process of building a 20b FD and need to decide on a radiator now. im going with the koyo unless there is something larger out there.... anyone know if there is??? what are you high HP 13b guys using for a rad? anything above and beyond the KOYO?????? im also concerned w/ weight, so something bigger than the KOYO may not nessisarily be better.... -heath

SWAT81

iTrader: (14)

KOYO ALL THE WAY!!!! CHEAPER AND BIGGER WHAT MORE IS THERE TO ARGUE ABOUT????

clayne

PFC water-temp is taken from the water temperature sensor on the housing.

The one on the filler neck is a level sensor - has nothing to do with temperature readings. In addition any temperatures readings taken on the filler neck would be HIGHER than near the rotor housing as this is where coolant exits the system and enters the radiator.

speeddemon7

Boy.I opened up a can of worms ehh.LOL.
I guess its more of a personall preference.Although I would like to see some more concrete evidence on which one trully cools better.I mean if the fluydine one cools just the same then I would tend to agree with the fact that it is better for the simple fact that it doesnt take up as much space and also probably weighs less.
right now though I still think the koyo is probably the best bet.

wingsfan

That'd be me with the ls1. There are at least three of us running the Koyo with our LS1s. Two guys in Florida that you might want to ask about their experience with summer driving (1point3liter and tbielobocke here on the forum). I only recently got mine running, so no summer data yet. It works great so far though, my secondary fans are supposed to kick on by 220 and they haven't tripped yet. I don't see any reason why it wouldn't work for a 20B.

Of course, if you need bigger you can always go custom. John (LT1-7 here on the forum) has a very slick custom setup for his turbocharged LT1 swap that he had made for around $450 I think (not bad for custom)

RotorMotor

iTrader: (5)

hey hows it going? would you have any idea how much HP he is putting down (i guess that can be uesd as a very rough estimate of ones cooling needs, no?). $450 is not bad at all... only 100 more than the KOYO. id have one made in a heartbeat, except for the fact that im trying to avoid overkill. the 20b is heavier than i thought (i havent weighed mine yet, but other 20b folk are claiming 500lb for the long block w/ stock turbos), so im trying to make as many cuts in the weight department as is reasonably possible. BTW just for fun, do you have any idea how much your ls1 weighed? -heath

DCrosby

I know someone used a Chevy Rad, with some custum fitting, it's 1.3X as big as koyo, fans stay on for 12 seconds (Timed it) and then turn off for 5+ Minutes...
But it requred a FMIC, and Battery Relocation...

Lesson to be learned: Anything is possible... and more fluid = heavier, but more fluid = more heat displacement.

-DC

BTW my temp gauge (Defi) is plumbed in-between the rotor houseing and the water pump (In the water Jacket on the hot side of the thermostat, since what good does a 40 c reading in the rad do you if your thermometer is jammed and the coolant on the other side is 120 c ??

wingsfan

I know that John is shooting for around 700RWHP, but I'm not sure that it's a fair assesment of cooling needs. The fact that the LT1 is piston powered and the 20B obviously rotary would suggest that all other things being equal the rotary would produce more heat. Of coures he also has twice the displacement, so who knows?

If I were going with a 20B project I think I'd build everything overkill (weight be damend). i wouldn;t want to lose something that pricey because I skimped somewhere that I could have massively overdesigned.

As for the weight of my ls1, with all of the pulleys and accessories (power steering pump, ac, alternator, balancer, etc.) I'd estimate that it's in the 430-440lb range. The shipping invoice with my pallet said 680lbs, and that included a torque arm, the driveshaft, a pedal assembly, a spare clutch, and the transmission assembly. I know what the weights for everything else were, so assuming the pallet weight was accurate I come up with around 430#.

RotorMotor

iTrader: (5)

well i see that my 20b really IS a pig!! i love how the rotary guys rag on the ls1's but sometimes there is provoking by persons such as jimlab (not to name names hahaha)! i love the concept of the rotary so i chose to work with the 20b (even if it isnt the "best" choice of motors)... but to each his own eh? and as far as overbuilding i definatly agree to a certain extent. the only thing is that im am VERY concerned about maintaining the best charachteristic of the FD... its handling. i know im never going to get my 50/50 back but id like to come as close as possible. i cant remember off the top of my head how much the stock 13b weighed, but i think its was about 80 lbs less than the 20b (i may be mistaken... if thats right, that would put the 13b @ 420 which seems too high). anyway, back to radiators... the more weight i can save the better, but i do not want to risk overheating!

when i start adding the weight of all the extra parts i need in, it makes me very unsettled (FMIC, dual oil coolers, larger rad., etc.) and all that on top of the 20b makes me rethink the whole project.... but its really to late now. it seems that the consensus is that the KOYO is a damn good radiator (cheaper and larger than anything else) and that with proper ducting/sealing it may be all that is required for the FD under almost any circumstance. i think i will get one and see how it hangs in there.

anyone care to comment? thanks, heath

SleepR1

What about the Griffin radiator? Not sure if it's bigger than Koyo though?

David Beale

Clayne, no, the sensor on the rotor housing goes only to the meter. There is a sensor on the top of the motor that goes to the ECU (or Power FC). If you check out the wiring manual, you will see there is "Water Thermosensor" and "Water Thermosensor - meter". The second one is on the side of the engine and the first is on the top.

So I repeat - the temp the Power FC indicates is often 10C lower than that in the rotor housings.

clayne

4 cooling related sensors:

Pages E-14 to E-16:

1. Coolant level sensor is on the front of the filler neck.
2. Water thermo-SWITCH (it only changes resistance used to trigger fans in addition to other sensors!) is on the rear of the water-pump housing.

Page F-183:

3. Water thermo-SENSOR (variable resistance) also located on the back of the water-pump housing sends temperature to the ECU.

Page C1-19:

4. Water temperature gauge sender unit (sends temp to the gauge on the cluster).


The temperatures taken at the "filler-neck" will never be lower than at the housing unless your oil cooling system is having issues or have a localized hot-spot. The water coming from the thermostat and into the filler-neck housing is EXITING the engine - which means it contains the highest heat content.

The PFC commander is showing water-temp from the water thermo-sensor not the gauge sender.