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Half Radiator Questions

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dewoof01

15+ Year Contributor
160
0
Dec 22, 2005
Beaverton, Oregon
Ok so cant find much on this topic for the 420a. Doing a cooling system rebuild on my car getting most of the parts replaced or fixed. I am doing a Honda Half Radiator with a single slim fan. This is not my DD it is a garage queen that I just drive in the summer on the weekends maybe 500-1000 miles a year I put on. My questions is I noticed on Bullet's 2gnt write up he welded the cap hole on top of the radiator. My questions is for looks can i just run a second cap on there? I can't see why it would be an issue but just checking. Second question, napa only has available the 195 degree thermostat for our cars. Should I stick with that or look into going with a 180 degree since i'm having alot smaller radiator it might be better to have flow going at that lower temperature instead of waiting till its hot. I live in oregon so summers are 70-90 with maybe a week a year getting to 100 degrees.
 
I run a half rad with slim fans on my 4g63t . 2 caps is fine. Just T the over flow line I do not have a ac system tho. Track and weekend play car only. So far I have had no issues with cooling. Will be switching to water only with water wetter in the next week for summer. Just don't forget to swap it out for 50/50 coolant water before the cold months step in
 
I run a half rad with slim fans on my 4g63t . 2 caps is fine. Just T the over flow line I do not have a ac system tho. Track and weekend play car only. So far I have had no issues with cooling. Will be switching to water only with water wetter in the next week for summer. Just don't forget to swap it out for 50/50 coolant water before the cold months step in

Good to know but don't you 4g63 guys run 180* thermo's?
 
The t stat temp really don't matter. It's just the point it will open and release the hot water and draw in the cooled water It's if you can get air flow true the radiator to cool the hot back to cooler if you watch a scan tool u will see the water temp spike. Then start to drop. That is the t stat opening. When it dips to the lowest temp then starts to rise again it has closed
 
You water temps will all ways be withing 20° high or low of your t stat temp. Fuel injected engines run best when at close to tstat temps
 
This is why tstat temps are 170-190 to begin with. If there where not made to run best at this temp you would not need a t stat at all?
 
Yes I know all that what i'm saying is with a smaller rad and less capacity might it not be better for me to run a 180 t stat vs the stock or recommended 195 because in case i get into a situation where i'm exceeding the cooling capacity of the rad i'm averaging closer to the 180* vs. the 195*. Does that make sense? I just don't want to overheat the motor when running the 195 tstat because of the smaller rad when if i over heat running the 180 i'm still 15* cooler than with the 195 tstat. Make sense?
 
Yes. This has all been addressed before. Coolant capacity of a half rad is ruffly 1/2 to 3/4 of a gallon. Depending on if it's a 2 row or 3 row. The block will hold ruffly 3/4 of a gallon. So there is ample supply of cooler water to replace the hot water. Your climate location is not very hot to begin with. I'm in western ky and our summer months see upper 90's all season. I have no issue with a 2 row half rad I do not expect you to have any cooling issues. If you can get a lower t stat then do so. If not the stock 195 will work fine. You are nt anyways so not having a turbo keeps your underhand temps more manageable to begin with. You will need to run a second fan if you plan on retaining ac in the car tho. The condenser core will need to be able to get rid of heat for it to work
 
Yes. This has all been addressed before. Coolant capacity of a half rad is ruffly 1/2 to 3/4 of a gallon. Depending on if it's a 2 row or 3 row. The block will hold ruffly 3/4 of a gallon. So there is ample supply of cooler water to replace the hot water. Your climate location is not very hot to begin with. I'm in western ky and our summer months see upper 90's all season. I have no issue with a 2 row half rad I do not expect you to have any cooling issues. If you can get a lower t stat then do so. If not the stock 195 will work fine. You are nt anyways so not having a turbo keeps your underhand temps more manageable to begin with. You will need to run a second fan if you plan on retaining ac in the car tho. The condenser core will need to be able to get rid of heat for it to work
Ok good to know as i said the 4g63 guys have alot of info but na guys not much. I guess i will go single fan and 195 tstat and see if it goes hot under ac i will try 180 tstat first and if still bad add a second fan. U turbo guys can run ALOT hotter engine bays then us na guys
 
You will most Def need a second fan for the ac to work properly. That's why there are two fans. 1 is for the engine the other is for the ac. Under normal driving only the engine fan kick on and off with coolant temp. But when the ac is on both fans turn on high and will run constantly. freon pulls heat from the cab via the evaporator core making the air cool. The then hot pressurized freon moves to condenser core in front of the radiator and the fans pull air thru it to cool it down then the process begins again both fans must be running on high for the ac system to work correctly other wise the freon will get to hot and pressure will build till some this explodes. First thing is usually the condenser core. This is why the ac has a high pressure switch. If the freon pressure surpasses the switch pressure it will turn off the ac compressor before critical mass is achieved hahaha. But sometimes this fail safe does not always work in time. I've seen 3 systems explode before in my 15 years as a mechanic
 
If you plan on retaining ac. Use 2 fans 1 for the radiator the the other for the condenser core. Just like the stock system zip ties work best for mounting them thru a few fins. Do not run the ac without a second fan. Bad things can happen to your ac system. Ie. Critical mass. :)
 
Ok I'll grab another fan thanks for the tip makes sense on why.
Ok so last question still waiting on the last lower hose to arrive at Napa. I need to connect 2 rad hoses together bit the parts store didn't have a small enough exhaust pipe to seam the hoses together. In the write up bullet uses a cut off piece of water pipe but I dont have any. Any suggestions?
 
Y are you having to seam the hoses together. When I fitted mine. The lower hose worked fine. The upper hose needed a few inches cut off. My half rad is mounted on the pass side in front of the trans away from the turbo. Mounting wise I made a lower bracket that bolted up to the stock lower pass side. So I wouldn't have to cut up the car incase I ever decided to take it back to stock. The upper mount I used the stock support bracket but moved it to 1 of the pump stop holes for the hood. Bolted it down with a bolt 2 larger washers and a nut
 
It's a gvr4 but here's how I did mine. I also used new oem hoses and just cut alittle off and clamped them on. No leaks and my temps are perfect. Slim fan is from siliconeintakes.com and is wired into the stock harness. I'm also using a 180* oem thermostat and new Oem cap. Oh and I used both upper mounts, I used one up top, and drilled new holes and used 2 rivet nuts for 10mm bolts to bolt it down with ease. And simply bolted the second to my lower mount. I just bolted it to the driver side stock mount and it was perfect spacing for the half radiator to slide right in.
 

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