victor13b

the rx8 oem cooling fans come on at 206f (to hot) i se the mazport and rx8 perfomance kit value$100.00 plus.. i se in that kits use oem mod relays! somebody open the moded relay to se the mod in the relay. my plan to do is buy that
only 30.00 dollars and make the mod of relays !
or

9krpmrx8

iTrader: (46)

Mazsport, Mionds Eye Engineering, and rx8performance are the same person. And yeah there are many ways to accomplish this. Thanks for sharing.

victor13b

only ? is the relay mod. I think the mod to do is weld the wire from switch to ground terminal

UHATEIT

There is a fans on low mod that required you to tap into the connection of the relay and then ground the wire or run it through a switch. I was too lazy to put it on a switch so I just grounded it to the frame. It basically keeps the fans on low at all times.

This way your fans aren't waiting until 206 to come on like you said (low I assume) as I have no idea when the fans come on HIGH exactly as in what temp.

But with the fans on low it basically delays the inevitable on my car, yeah they are on from the time I flip on the key, but eventually the temps rise up to well over 206 anyways so it really doesn't do a whole lot except delay when exactly it will eventually reach the point at which fans turn on high.

p8ntman442

Does turning on the AC cause the radiator fan(s) to come on like in other cars? Typically when I need to cool a car down I just hit the AC button and the fans come on.

logalinipoo

yes it does, but it puts more load on the engine and more heat infront of the radiator so normally it makes the car run hotter not cooler.

lastphaseofthis

are you saying in general..? that info is WRONG

the a/c on keeps the fan on, and makes the thermostat do the job of maintaining temp. which is under 200.
this is with every car i've ever diagnosed an overheat problem on, the fan takes more heat out of the radiator then the A/c will put in..

the lower the blower motor fan speed, the less temp exchange to the evap core, and the less heat at the condenser.

rx8 specially, pretty sure the lowest my car stays at is when the a/c is going.

logalinipoo

My temps go up noticably with the ac on.

The ac system should not lower the temps at all. It might keep it a bit lower than it is when the fans are at low speed, but if you are not hot enough to need the high speed fans then you are not high enough to be concerned about the temps.

If you are already overheating then the fans should be on high. Turning the AC on then would only add heat to the system. Now if you are overheating and your fans are not on high for some reason then it might cool it off, but again that's just a bandaid for a bigger problem.

TeamRX8

iTrader: (25)

^^ truth

Not only higher load on the engine, but now you are heating the bumper inlet air before it enters the radiator with the AC condensor


.

p8ntman442

YUP, Its a bit difficult to find the right info out there but I did find this:


R134a compressors, the top limit for condensing temperature is 158 – 175°F (70 – 80°C) for air conditioning applications.


Source: http://www.mcc-hvac.com/CommonResour..._R134a_web.pdf


That means that your car condenser coil is likely between 100-140°F maybe higher when the ambient temperatures increase in hot climates.


The heat transfer across the radiator is calculated using an equation with flow rate and temperature difference at the same power level, so if you cut the temp difference in half (Rad out-ambient), then you need to double the air flow rate over the radiator. I would think the radiator fans are sized to compensate for the additional load of the condenser heat, as well as the engine load, but it sounds like logalinipoo does not experience that. This may be caused by dirty or bent fins on the radiator, or perhaps a previous overheat problem, that caused the car to boil over, then cooled and drew vacuum on the radiator causing the tubes to constrict and reduce total coolant flow through the radiator (had this happen myself, not on an 8).

p8ntman442

Can the fan turn on point not be modified in the PCM? Perhaps to come on at 195 rather than 206*F?

9krpmrx8

iTrader: (46)

Yes, it is common practice to do so. But you need a tuning solution to accomplish that.

UHATEIT

I guess then as far as the OP is suggesting, you can make this mod yourself with that thermostat mod off amazon for $25 and some wiring and then modifying stock relays. If anyone has cut apart the modified relay to see what was done inside, then he is trying to figure out what mods to make to it.

I'm all for your attempt to do this mod yourself man, if you can get it done post up! Looks like that Thermostat turns on at 180 and cools down to 165 thats pretty sweet actually.

With all the excess heat these RX8s have this should have been a setup from the factory. With my car at 82K miles now I don't know how much wear has beeen done ot it from the prior owners driving habits and I wish this was something they installed years ago to reduce the wear the engine has on it.

logalinipoo

Well you might want to take a look at what team wrote again. From my point of view he is agreeing with me.


But just to clarify, I'm driving a rebuilt engine with about 5K miles on it. All new hoses and a dual pass all aluminium CSF radiator with a custom Sheetmetal undertray that funnels all the air into the condenser/radiator instead of around it at all. I'm not talking foam I'm talking about a custom fit. On top of that I have a lowered thermostat and have programmed all the stock fans on by 190F.

With that out of the way. You are right it will run about 160F at 80 outside temps. If you're overheating at 80F then you have huge problems. Now you bump it up to 100F Ambient and your condenser pressure climbs to 300 PSI or so. it will climb another 10 degrees. If you look up a pressure temp chart then you can see definite numbers on the temps.

the stock fans are sized high enough to keep the engine from overheating when turning on the AC, but that does not mean the tempeture will drop. It will still raise. When you add the additional load and head of the ac running.

9krpmrx8

iTrader: (46)

I can easily see a 10-15F reduction in coolant temps when I turn off the AC this time of the year (100F+ daily) here in south Texas. This is driving hard of course, if I stay out of boost my temps stay close to 200F, but I have a bit of cooling mods.

TeamRX8

iTrader: (25)

and a big honking set of aftermarket fans, thanks for muddying the water tho ...

9krpmrx8

iTrader: (46)

Ah yes, I forgot. I love those fans,

UHATEIT

I understand the purpose of the bigger fans and also the fans on high mode from this mod. I am sure this is probably posted somewhere else, but are their any other negatives to having the fans on high at such a low temp of say 185-190?

Anytime my fans are on high there seems to be a lot of excess head coming back from the sides of the car. My wife noticed this last night when we pulled into the garage and the fans were on high, she got out and said holy **** its hot so I opened my door and there was a big amount of head under the car and blowing backwards down the side

Legot

iTrader: (1)

No, its just noisy.

UHATEIT

I am surprised how quiet it is actually. I can hardly hear the fans on high when they kick in and when they are on I have to roll the window down and be at a stop to hear them making any noise. But they do in fact work, they are just pretty quiet.

I was more concerned with excessive heat being pushed/forced towards other items that it could affect. I will need to wrap the AC lines with some insullation so that it covers any extra heat being put at it.