Thermoswitch and Pettit fan switch, is it the same?
 

I was planning to install a FC thermoswitch. That was untill I came upon this, a Pettit fan switch here http://pettitracing.com/rx7/index_cooling.htm. The fans are supposed to come on at 185f. Is this fan switch basically the same thing as the FC thermoswitch which activates the fans at 210f? If so, would it be better the keep the temps at a consistant 185f rather than 210f?

Thanks,
Liem.

Disregard.

Next time I won't be so lazy and do a search. :)

At 185 degrees, a stock ECU will not allow the engine to run full power at high rpm. Coolant temps need to be closer to 200 for the ECU to allow full power at high rpm.

Thanks, I didn't know that. I'm running a Pettit Unlimited ECU, will this allow me to run full power at high rpms regardless of temps assuming it's over 180f of course?

Thanks Adam, the cheap bastard intake fits like a glove and theres definitely more power. How do I know, let just say I had back to back friendly runs. Two cars faster to 130 infact. :)

The Pettit ECU may be a stock ECU that has had the fuel maps changed to accomodate higher boost. Most likely, it will not give full power at 180 degrees.

I placed an order for FC thermoswitch but I can change my order for Pettit Fan Switch if the claims above are not true.

I asked Pettit about this issue and here is their answer:

"From our experience installing and shipping nearly 1000 fan switches world wide, and using a infrared pyrometer to measure actual temp at the thermostat housing the double throttle control usually opens around 175f, but with the 180 t stat & 185 f switch, the cars do seem to take longer to come up to temp.
also it is a well known industry fact that cooler operating temperatures usually provide the best performance and longevity for any vehicle. On the US spec RX7 FD the cooling fan thermo switch and thermostat are factory set to maintain a minimum operating temperature of 92C / 197.6 F and often higher, then with age, use and heat cycles these parts slowly degrade requiring higher and higher temperatures to trigger the fans and open the thermostat, as a result it is not uncommon to see operating temperatures of 104C / 220F and higher. Another commonly overlooked fact is that the engine temperature gauge reads normal (basically in the middle) from 71C / 160F all the way up to 113C / 235F the factory does this so owners won’t complain or question the gauge variations due to weather changes. Installing our 82C / 180F thermostat and 85C / 185F fan switch can reduce operating temperatures 30C / 40F, a simple cure that every RX7 needs, reducing operating temperatures will maximize performance and longevity for not only the engine but all the under hood components and accessories, thus adding reliability and extending usable life."

Can someone clarify this for me please, cause I'd prefer the Pettit fan switch since it has lower temps and they seem to be similar price with FC thermoswitch.

^This sounds wrong. The OEM thermoswitch is set for 108 C. (226 F.) and the Series 5 FC thermoswitch is set for 95 C. (203 F.)

That's not important though, I just want to know if installing a Pettit fan switch will have any cons like car not making full power like Adam C mentioned or not.

Pettit doesn't seem to think so and they have great experience with rotary engines. On the other hand this is a very old thread and nobody disagreed with Adam C.

I just installed pettit fan switch. frankly I have no notice of low power at high rpm. maybe I'm not driving passionate enough. The only thing happened was: it killed my alternator & battery because the fan stays on longer after engine off.

overall I'm very happy with the switch. the engine is cooler = longevity.

IMO, there is no reason to have the fans set to come on at 185F. I do agree with Pettit that there shouldn't be any real problems in doing so; however, you will run the fans more often so they will ultimately fail sooner (i.e. they don't last forever).

The FC thermoswitch setting falls roughly half-way between those of the FD thermoswitch and Pettit's. You'll still get a significant safety margin over OEM but without the downsides. And if you have a PFC or considering one in the future, adjustments can be made there.

I was about to buy the Pettit switch. Can anybody tell me a good place to get the FC switch?

Will this lower temp fan switch change anything with my cooling fan mod? I have the switch on the center console.

A few things need to be cleared up here.

1. the "power loss" people are talking about is the double throttle system. That turns off at 80 C.

https://www.rx7club.com/attachment.p...1&d=1259702369

2. You can see also that the factory FD thermostat is a 180 degree F thermostat. It cracks open at about 82 C and opens fully at 95 C, the same temperature as the FC thermoswitch everybody uses. There's nothing wrong with the factory thermostat. Mazda has been using these thermostat temps for 40 years, since at least the Rx-2:

https://www.rx7club.com/attachment.p...1&d=1259702369

3. the thermoswitch is used as part of the logic that triggers the aftercool function when the car shuts off

FC Thermoswitch + OEM thermostat for me then ;) Thanks Arghx :icon_tup:

Is there a recommended place to buy an FC thermoswitch?

I checked Mazdatrix, RX-7.com, Pettit, Racing Beat

I bought mine from Ray @ Malloy Mazda, he seems to be a popular guy around here and so far my initial impressions are very positive :icon_tup:

^ +1 Ray is awesome! I buy from him whenever I get the chance.

Recommended pettit 185° degree fan switch in Ecu aftermarket (microtech, adaptronic, etc)?

It all depends if you want the fans to turn on low speed at 185 deg. with the Pettit switch or 203 deg. with the FC switch. Personally I think 203 is a little late.

How about it. They aren't THAT expensive to buy brand new, but I would test it first before installing.

And why are you shouting? And in magenta? :scratch: