1. MY friends has a slightly modified 1993 MAZDA RX-7 (Touring Edition).
He has owned for some time but now for some reason whenever the car is driven for an excess of a couple of hours or if ran hard for half an hour it begins to heat up as much as 90 to 100celsius. Then when turned off the car can go up as much as 20celsius from there. Is this common in the third gen series? Car runs great other than this problem.
What could be the problem?

 

90 to 100 C is the norm for a stock rx7. the stock thermoswitch is supposed to kick in fans on high at about 105 so those are decent temps.

if he wants to get it lower get an FC thermoswitch which will lower the temp at which the fans turn on to about 95C.

or get a PFC and set it to whatever he wants.

it heats up after the car it turned off due to heat soak

 

90-100C is within spec and a localized engine block rise of 20C is also normal.

There are many threads on coolant temperature.

 

here, read this:

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/big-fat-fd3s-cooling-thread-571088/

 

so after running my car and then turning it off, it being at 115 celsius is normal?
this is rare when it actually gets this hot by the way

and what is is heat soak and how do i prevent it

 

heat soak is just heat being transferred from one medium to another, usually we used this term in reference to FMICs when they heat soak to the radiator.

you can't totally prevent it but you can minimize it by getting a vented hood and wrapping up some exhaust parts and your turbo

 

thx for info, link was helpful as well

 

BTW, tell your friend to get on the forums, he needs to know this stuff too

 

I had a cooling issue with my last fd a couple months back. maybe my thread might help your friend out. good luck.

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/cooling-issues-after-rebuild-need-advise-757613/

 

where is the temp sender located in your case?

 

its an apexi 1500 commander

 

When your temps run hot, turn on the AC and fans to full blast. This should make the radiator fans run at 100%. When I do this, my temps dip back to the mid to high 80s. Remember not to boost when your near your destination so as to minimize the heat.

 

interesting i will try that