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performance upgrades, cooling system upgrades

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5 Min Read

Rotary Engine Upgrades | Temperatures too high?

The Rx7 turbo is a unique vehicle, in its stock form the cooling systems are pretty good.

Add in our high altitude and hot temperatures and you have a recipe for some higher than desired water / oil temperatures.

In the shop we have a S4 1987 turbocharged FC convertible. This is a fine automobile, with a needed boost of forced induction. This owner has owned this car since new, it is a wonderful driver.

We received an email / form from our website needing assistance with keeping temperatures in line for mountain driving. Who doesn't like to car up the canyons with a willing turbocharged rotary?

Having previously been to another shop getting the koyorad 53mm thick upgraded radiator installed with a dual stage (hi/low) fan and still having cooling issues as the temperatures tend to stack up with repeated high rpm driving. This sounds all too familiar for a solid rotary engine performance shop.

We got it on the rack (rotary lift of course), pulled off the under-tray and it is easy to see what the real issue is. The previous shop did a solid job replacing the radiator / cooling fan, we are ok with that. What we saw is a lot more than just replacing parts. We call this lazy follow-through.

All Cooling systems need to have proper ductwork to allow all of the radiators (water, oil, intercooler, AC) to have proper airflow to them to function properly.

Had this car been at sea level, it may never have this problem. I see so many shops depend on cooling coming from the fans. We do not have that luxury here in Colorado, details matter just as much as picking out the right parts.

Just because the fan comes on, it doesn't mean that air flow is going to be proper. Remember, air will always find the path of least resistance, add in hot air and you have even more reasons why the cooling system is going to have to work harder.

Screenshot 2024-07-08 at 8.42.22 AMHere we have the lower under-tray removed and one can see that the radiators are installed without concern for airflow. The air will always seek the path of least resistance, meaning only a portion of it will find its way through the coolers.

The current path has air going around (with some going thru) each and every cooler, efficiency is minimal, and with higher rpm's more boost, the cooling system temperature continues to stack higher and higher forcing the driver to get out of the throttle and reduce the fun factor to keep the engine from overheating. 

We will add in our proper directed / sealed ductwork to better get air to the radiators with upgrades to the oil coolers w/ fans to turn on when the ecu requires it. Anything less is just going to overwork the cooling system and lead to premature engine wear. 
Colorado's high altitude and hot temperatures require solid build parameters for the cooling system, add in the power of a turbo (or larger turbo) and you have to upgrade the system as a whole. Do it right, make solid reliable power.

Topics:   performance upgrades, cooling system upgrades

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