Cooling system quandry, need help.
 

Hey guys, I have been doing alot of reading on the cooling systems and the different upgrades available for the FD. The obvious upgrades to cooling down the motor are an upgraded rad, better oil cooler, ast, and maybe a vented hood. I have noticed in some photos however an air separator tank in place of the thermostat housing , such as the one listed here at RHD japan.

http://www.rhdjapan.com/revoultion-r...fd3s-13b-14459

I am uncertain as to if this deletes the thermostat completely , or what exactly it is accomplishing aside from the basic ast characteristics and cleaning up the engine bay. Could someone please shed some light on this topic.

never seen that before...looks like it does completely replace the housing. Not sure I would do this and delete the thermostat...interesting.

It doesn't replace the t-stat. The stock jdm housing does not have a two-piece filler neck so deleting the stock ast using the FC filler neck isn't possible. I THINK that's why it was developed. And also why you don't see them here in north america....we don't need them.

As for cooling improvements don't forget the FC thermoswitch, plugging open spaces around the radiator with foam, using as much water to coolant as you can, AI systems etc.

FWIW, here's a picture of a late-model JDM engine. Notice the one-piece filler neck:

http://i1126.photobucket.com/albums/...illterneck.jpg

I think it does a good job of lightening your wallet. Beyond that, I don't see a relevant improvement to anything by using that product.

Pardon the noob question, but on RHD in the "FD3S RX-7 Collector, Overflow & Catch Tanks" section, I am somewhat confused. Looking at the products, I wonder, are there different names for the AST? Such as "Carbing Reservoir Tank Type", "Radiator Separator Tank" "Radiator Breather Tank", or are these actually different products all together?

Thanks

Not sure about "Carbing Reservoir Tank Type"....but suspect "Radiator Seperator Tank" and "Radiator Breather Tank" both refer to what WE in North America call the "Air Separation Tank"

[QUOTE=Sgtblue;10529856]It doesn't replace the t-stat. The stock jdm housing does not have a two-piece filler neck so deleting the stock ast using the FC filler neck isn't possible. I THINK that's why it was developed. And also why you don't see them here in north america....we don't need them.

As for cooling improvements don't forget the FC thermoswitch, plugging open spaces around the radiator with foam, using as much water to coolant as you can, AI systems etc.[/QUOT

I dont understand all the FC references as I am referring to an FD, unless I am missing something. The photo clearly shows the entire thermo housing removed. So I would like to know if the piece I am looking at is merely an AST, or what ? Where does the thermostat go if that piece is installed, I am confused. I have seen this on alot of racecars, it certainly cleans up the engine bay as well, but I want to know exactly what this piece is and what role it plays in improving the cooling system. Anybody ?

Here is a link to a photo where it is installed.

https://www.rx7club.com/showthread.p...&highlight=ast

I figured it out, that particular AST has a larger resovior, cleans up the the engine bay and simply replaces the stock housing, it still retains the thermostat. Thanks for everyones input.

Sorry, I missed this^ earlier. If your not already clear....
The North American cars all had a two-piece filler neck. This allowed you to replace the bolt-on section of the filler neck with a piece from the FC's filler neck that had a nipple to connect directly to the coolant overflow. Doing so produced a small empty chamber that functions for the AST and allows you to delete the traditional AST.
See black filler neck extention picture below with the small hose attached:

http://i1126.photobucket.com/albums/...e002Medium.jpg

As mentioned and pictured earlier, the later JDM engines did not come with a filler neck that had the "bolt-on" extention, so replacing it with the FC piece wasn't possible. Hence, they replaced the ENTIRE t-stat housing with the piece you were asking about. And it's only really useful if you wish to remove the standard AST and have a late model JDM t-stat housing. Not sure if that housing would be compatible with all aftermarket SMICs either.