I think when I do the new ducting for the front I'm going to partially v-mount the intercooler...and separate the airflow so the rad gets some dedicated flow that doesn't go through the intercooler first. Intercoolers are really big heat sinks anyway...and I'd much rather have the cool air going to the rad

 

my 2nd rad is a 21x7.5 inches and 1 1/2 inches thick. Open fin design to allow good air flow with bigger that usual coolant flow tubes. 2 row.
By passing the thermostat is not a problem. As said --warm up is not an issue.
With the bypass system we have I too, was concerned that the 2nd rad would cool so much that it would take the primary coolant system to long to open. Thats one reason I placed a small hole in the thermostat.
Hear is my reasoning for what it is worth:
Adding a secondary rad may not allow the primary to warm enough to open the system in a timely fashion, or keep the system open consistantly--so by drilling the thermostat you allow a small amount of primary coolant to flow at all times. This reduces thermostat caused temp fluctuation (thermostat opening and closing), helps with preventing hotspots etc.
The bypass system in our cars is only present to shorten the warm up period-- drilling the therm does not seem to have made an impact on this. It takes me maybe one extra mile to reach warm up than it did before.
Warm needs to occur smoothly and gradulatly. Not getting warmer and warmer then ---wham!--- opening a valve and a bunch of cool coolant hitting everything. A drilled thermostat allows both radiators coolant to gradually warm and not cycle.
I would not advise adding a secondary radiator without doing this.
But what do I know? Just seems to work for me.
OD

 

what turbo setup do you currently have? i would eventually like to fab a minor v-mount on my greddy kit as well

 

Is there any specific reason RX-8's suffer from overheating? I have a crappy single Koyo as you say with dual 25 row oil coolers in my RX-7 running 20 pounds of boost making over 450 rwhp and my car runs max of 220*F on a hot summer day after 30 minutes sessions on the track. To note my EGT's preturbo are 1850*F.

thewird

 

who have tested that koyo is worse than OEM? and proves?

 

I honestly don't understand how an all aluminum bigger, higher flowing radiator can perform worse then OEM.

thewird

 

Flow

 

I just posted its higher flowing... so unless there was a test to specifically measure flow to prove the opposite I still cannot understand how it would perform worse.

thewird

 

Apparently it is not - in our application -
Having more fins is not always a plus and with our car moving air fast through the radiator is more important than fin count.
Maybe a koyo radiator would be ok for a race car with no engine bay obstruction of any form, just engine and ecu but for a daily driver it really heatsoaks everything in there and greatily reduces flow through the core and the engine bay

 

Um... radiator efficiency doesn't really matter daily driving lol. People have problems with cooling at the track, not on the street. Maybe instead of adding more radiators, has anyone thought of moving the A/C condensor instead?

thewird

 

radiator efficiency does matter when you put a bulky radiator in a daily driver and see higher temps than before... both in cruising and track. The koyo one heats everything behind it and reduces flow through the engine bay (so its own efficiency is reduced as well). Not always bigger is better, especially when it has to do with flow. speed\flow is something more important in our case.
BHR solved the problem with an improved flow through the core (less fins), Mazmart did it in a different way if i remember right but with comparable results.

 

There is nothing behind the radiator that needs to be cooled by any airflow. The only exception would be your intake. With radiators, bigger is always better as you have more surface area to dissipate heat. The only exception would be if you have too much cooling and the engine cannot reach operating temperature.

Has anyone thought of pointing the radiator down instead of up? Ducting would have to be done of course to force the air through the rad.

thewird

 

I'm sorry but i have to say that you're filling up the thread with false information.
While it is true that you do not need to cool anything with direct air flow it is true that without proper flow through the core you won't see any good results.
You should just search now and come back with some factual data and not just theory, for our application.

Giorgio

 

I'm just trying to get my head around a bigger, higher flowing all aluminum radiator cooling less then a smaller one. It just doesn't make sense. What are the circumstances behind the install? Does anything need to be removed when it is installed, which disturbes the airflow to the radiator? If there are bigger gaps around the radiator, the air would escape and go to the engine bay and not where it needs to be the radiator.

thewird

 

When you say "higher flowing" which mass flow are you talking about? If the Koyo has a higher fin count in a similar packaging profile, it would probably have less room to flow air. You could compensate for this with more powerful fans and adequate hot air evacuation on the backend. If the fans are stock and the engine bay evacuation poor, then the Koyo could become just a hot waterfilled barricade.

Does anyone know what percentage of the Koyo is air pathways versus the stock?

 

it doesnt have to make sense, just search through the old threads and see all the people who claimed INCREASE in temps... and also find the few who had data to back it up

 

you are running a turbo system--right?
No offense dude --but you do need to educate yourself much more.
many features to a radiator
fins per square inch
thickness
# of passes
coolant flow capacity
design of the end tanks
turbulance inside the coolant tubes
etc etc etc
take advantage of others beta testing--koyo doesnt work.

even the others only have a marginal affect for street driving

IT is all about the restricted airflow allowed to the radiator.
If the stock radiator was a straight up and down mount with full front air flow we would not have to do bandaids like this.
OD

 

If the problem is airflow, why hasn't anyone suggested attacking that problem specifically instead of adding more heat exchangers, adding more weight to the car unnecessarily? When I see people adding extra radiators, I'm honestly going w.t.f. You only need one solid unit and find a way to force the air through it.

Here's an example below...

All the air is forced through the radiator and intercooler, the engine bay gets the leftovers from the intercooler as the radiator shoots straight to the ground. I have made a custom diffuser with drilled holes for the radiator to vent through. Which you can sortof see in the last pic but not really. Anyway, I ran with an A/C condenser last year and the temps would only be a little bit higher but would still stabilize in a safe zone.

I have looked at an RX-8 with a turbo and there is room for a similar setup. However, I don't think you need to go this far to get proper cooling. Even a stock type setup, there are A LOT of open gaps for the air to escape as its coming in. With some proper ducting, you'll have better cooling then you'll know what to do with.









thewird

 

Apples and Oranges...you are making assumptions based on 2 different cars and setups.

Personally I think they are mostly valid...but until we try them we won't know for sure

I never fear the extra weight from a bit more coolant..and from larger rads and oil/coolers

I want a bombproof cooling system and I don't mind giving up a bit of weight to do it

My winter project is to re-do the entire front end ducting and intercooler placement...and figure out if I am going to drop the A/C from the car.....I really like it when it's hot...but I don't expect to drive it much on the street anymore...so it's kinda useless really

 

He's got a custom setup. Probably pushing well over 400 to the wheels.



Dan, any time, BBM me or call me if you need a hand with any of your ****, would be interesting. I'm avail every tues+thurs all day after 5 :D

Also, I need to take a ride in that monster, and check out your gauges.

 

i think our main problem with the turbo'ed rx8 is that we have the intercooler thats in front of everything and blocking all the way.

 

I wish Maybe when I'm done....

 

Hmm, if you were around 330 last year... After all you've done?? Must be going very conservatively!

 

dude ---to place the radiator more vertical, i lot would need to be done. The oem rad is too tall to place vertically unless you move it further back. It is sealed pretty good top and sides but to many people mess around with the foam sides and forget to re-install.
If the radiator is moved back some then air box and battery and overflow coolant tank would all have to be re done. Plus you are getting closer to the engine and coils. COils do not like heat fluctuation so that would also be a concern
You would also need all new custom cut coolant hoses.
THEN you would have to build the front air channel ducting because the stock shape doesnt allow good airflow in the top 1/3 of the space. It swirls--proven by smoke tests and the oem nose. When air swirls it doesnt penetrate very well.
I took the easy way out.
OD

 

I plan on V-mounting the intercooler not the RAD....don't see much sense in re-doing the rad placement...just too much work.

I'm hoping the intercooler can be turned without too much fabricating work