Temporary swings in underhood air temp don't have much of an influence on engine coolant temp. There's a long time lag to change the core temperature of 500 lbs of metal. The exception is if the engine is gulping hot air through the intake charge because that hot air goes straight to the cylinders and water jacket. Manage the manifold air temp & coolant temp and you'll pretty much be okay. Underhood air temp is really just extraneous IMO. Real hood extractors aren't for underhood air temp, it's to manage air flow with regards to under body pressure and aero.

Oil temp is another important indicator of what's happening inside your engine. It is mostly influenced by heat at bearing surfaces and is largely decoupled from coolant temps. You can have coolant temps at normal levels but the oil could be too cold or too hot. Hardly anybody has an oil temp gauge (I don't) but it's really important if you're pushing your car hard.

 

The Trans Am fender vent on the passenger side is functional. Seems ridiculous to me that the driver side vent isn't, but at least there's one path for the hot air to get out...

 

I know I'm late to the party with this question, but what's this "heat exchanger" that's always being mentioned? What's it for?...

 

The body Underhood has an opening for the wiring on the passenger side, whereas the drivers side is solid.
I think it's for his supercharger.

 

Really good work here Matt. Its especially good seeing how that radiator only has a -16 inlet and outlet.

 

Jeez that looks packed in there.

and I would guess oil temp is pretty close to coolant temp in the block

 

If you were right then oil coolers would be obsolete.

 

Matt - I was following most of this, but I think I may have gotten lost at some point - can you post up what your final configuration is? (fans, radiator, ducting, etc...) I think there is a lot of good troubleshooting that everyone did and I know you purchased some $$$ parts at some points.

I'm about to do the cooling system on my LS-swap and it'd be good to see where you ended up on this. A lot of great collective knowledge in this thread.

 

Matt, Im pretty sure there are 2 more side plastic pieces you can put on..or make them to seal up the rest of the ducting to the rad for better pulling of fresh air. Im ordering replacement panels as I have none of those pieces in place either. I like the addition of the foam with you installed your replacement rad. I still think the overall underhood temps are keeping things above where you want them to be and extracting some out will got you that 10* drop to feel more at ease. Making my T/A hood vents functional you can feel heat coming out of them even though its small opening.

 

Oil temp senders are cheap and just another sensor so they are on most cars today. Back in the 80s I only recall some built cars having them. They are, though, the better measure of engine temp aside from temperatures sensors on the metal itself.

 

Yea I’m missing the two side pieces with the X molded into them. I’ve been trying to find some but can only find them in a full set with the rest of the pieces.

 

Matt, any updates?

 

It's been hot where I live. Getting a good workout in hot weather out your way?

 

Matt,

I can report that adding the plastic shrouding to my car has dropped my temps around 15-20* keeping me around the 205* at idle now as opposed to 220*. Not that due to my intercooler size and location I was not able to use the side pieces. I plan to get some foam and cut to shape what i need and seal off as much a possible to funnel in air. I dont have a fan shroud on the rad and I think this might help while switching to slim fans. the only other thing Ive been contemplating is how well my waterpump is functioning which is the original from my 00 ls1 motor i started with. Might be time to change it out. Short of adding holes in the hood and coating my hotside piping to reduce heat..Im running out of options to run cooler temps

 

Been busy re-doing my fuel system so sorry for the lack of updates. The news is pretty good though. I drove the car down to the tuner a few weeks ago. Its an hour drive each way, most of it is highway. We hit some traffic along the way and we had the a/c blasting the entire trip. I took this screenshot the day of the tune. I’m happy to report that the coolant temp never passed 206 the entire day! Thats driving in the city, on the highway, and even in the crawling traffic we hit. Never turned the a/c off and never got hot. At highway speed it sat around 198, went to 206 in the stop and go traffic.


Now I was very pleased with this, but the following day was a little different. I took the car to a sonic drive in and sat there eating for about 25 minutes. Had the car idling with the a/c on the whole time. This day was a little warmer than the screenshot above, and the coolant temp SLOWLY made it to 217. I mean it was the slowest it ever climbed.. After leaving, the temp came back down to the normal 198-208 area. Now these were pretty extreme circumstances, and I was sitting there with the a/c on for way longer than I normally would. Regardless with the results from the day of tuning, I’m calling this pretty much fixed. I’m planning on sourcing the rest of the airdam I’m missing, so that may help a little more. I also ordered some more 5 inch piping to move my air filter out of the engine bay so that will help my iat’s a bit as well. I’m sure I can get it idling under 200 if I add some hood vents and wrap the headers, but honestly this is a massive improvement and I’m perfectly fine with it. Its literally running 30 degrees cooler.

 

That is great news. These engines make a lot of heat. Sitting and idling is pretty tough. The last thing I would think to try is put a lower cover from the radiator support to the crossmember to block recirculation of heated air from the engine bay.