Eric, I am unsure what the 4" dimension does. If someone uses a 4" duct, as you did on at least one of your systems, It seems that the hole to accommodate that would need to be larger than 4".

Also, for the oil cooler installations, at least for cars out our way that deal with 100+temps, we tend to install tall coolers mounted vertically behind the right front headlight, bumper, valance area. To get them in we are cutting the headlight bucket to make room for them to be mounted so this change does not work for that. Other than mounting them in the headlight area, I do not see much of an alternative. We can not mount them in front of our radiators. We all tried that and it caused the water temps to shoot up so we had to move them away from there.

My oil cooler is a Setrab and is about 7" wide and 12" long. Even with that, I run oil temps above 240 degrees in the heat so a smaller one would not work at all, at least in my case.

I think the oil cooler issue needs to be discussed in more detail before placing restrictions on them. While those that race in cooler parts of the country do not have issues with it, those of us that need them, need them, and restricting them will cause engine issues. As has been discussed, this is not a performance issue, it is an engine longevity issue.

Jim Foxx

I couldnt agree more Jim.
Most cars in California have large oil coolers. And we will need to have a good sized cut out to keep the air flow high for oil cooling.

Agreed, I have one of the smaller oil coolers in NorCal and still had to cut more than 4" hole to get direct airflow to the cooler.

I hear you guys. I hate last minute changes, as well, but I have been asked to specify this. I don't want to make the oil cooler ducting a huge deal, it just pains me to tacitly encourage people to cut foot wide holes in the unibody by specifying a big number. A lot of maximizing cooling efficiency is in ducting to force what air is coming in through the cooler, rather than setting it it open in the breeze. Small hole with ducting to seal in oil cooler > large hole with none. Holes in the unibody need not be the size of the entire oil cooler, but it sounds like that has been done a fair amount?

This is another area that regional experience comes into play. The guys out by me locate the oil coolers up front, as does Dirks, the engine builder I know the best. Mine is behind the right foglight opening. Few holes in the unibody around here . We seem to do fine up through the high 90's, but you guys see higher temps yet.

Give me your thoughts on what number we need here, or how to better balance things. I need to get this back to Will before he publishes it - so sooner is better.

My car is at the paint shop but my reccollection is that the opening for my oil cooler is about 5" x 8".
The hole for air box is 3 1/4" diameter.

I will measure my set up and try to get a picture or two but don't know how well a picture will show this in a tight space.

As for my oil cooler installation, I have a box attached to the front of the cooler and two ducts going into it to force all of the air through the cooler. One is from the fog light and one is from the turn signal opening. Even with this fully ducted system, I have real issues with oil temperature.

Another problem with this is the need to hold the oil cooler in front of the wheel well metal. Initially, my car had the cooler too far back and the air, as it was exiting the cooler, was "packing up" against the wheel well and oil temps were getting into the 260 plus range last summer. I had to refab the ducting in front of the cooler to allow it to move forward several inches. I also fabbed up a piece of sheetmetal that drops down below the oil cooler and into the air flow under the car in an attempt to get the air behind the cooler to get evacuated out and away to improve the airflow through the cooler. All of that helped but it is still higher than I would like.

I will also get the size of my cooler to post up. The bottom line is our high temps, out here, require substantial oil cooling and I do not want to put an oil cooler inside the car like NASCAR does. They have theirs behind the driver in a box that gets air from the 1/4 panel windows through NACA ducts and dump it out the bottom of the car. Having all of that hot oil inside the car is not something I want to contemplate. I like the idea of keeping it in the engine bay but we need to be able to cool it for the sake of our engines.

Jim Foxx