I have an exhaust tubing size question and how it relates to engine temps. Right now I have a 350TBI in a jeep and I can run it all day long in 100+ degree weather and it runs 190. However the temp climbs pretty fast when I drive up a long dirt road on a hill. It gets to 240ish and then I shut it down. After only a few minutes it’s back to 190 and I back on the trail to repeat the process. So my question is….will a larger diameter exhaust off of my headers get more of the heat out of the engine? I have read a bunch of stuff on other mods to lower temps but not this one.

1988 350TBI
19 x 26 aluminum cross flow rad
Flex-A-Lite 180 Black Magic X-treme Electric Fan
Inner fenders cut out
Holes in hood
AFI chip

Off the headers it is 2” and collects into a single 2.5” and then goes out the back through a muffler.

 

If the engine has to work against a (considerable) pressure to get rid of the exhaust then there will be more of a heat load on the cylinders and exhaust channels in the head. I can't say just how much this could amount to compared to the ordinary combustion heat, but improved breathing gets you more power for the same amount of fuel (I think, and increased efficiency means less heat. Although your exhaust dimensions seems a tad small (I'd step it up 1/2", depending on rpm's) I'd expect you'd get better results from going through your cooling system and tuning the mixture and ignition timing/ curves.

 

My rpm's are low...in the 1000 to 2500 range when driving on the dirt roads that I am having the heat issues with. I have been thinking a lot about the timing and the mixture. Is it posable to have a lean condition in the mid rpm range, not at low rpm, that would cause excessive heat buildup?

 

Ok, your exhaust doesn't pose any restriction at all up to 3500, and is useable up to 5000. Optimal timing and mixture requirements does vary throughout the rpm range. Late timing (& also wrong mixture) makes for a lazy & inefficient engine, & part of the gas consumption is wasted as extra heat. I would expect a good & healthy cooling system to be able to cope with some extra amount but I don't have enough experience with all these variables (and TBI + chips) to indicate exactly where your problem might be. One question that comes to mind is in what manner is the chip tuned to the engine?
BTW; the lack of response from the rest of the group might have something to do with the fact that your question is about a hill-climbing jeep, and this is a forum for third generation Camaros, Firebirds, & Trans-Am's you know..

 

The chip was tuned/burned by Affordable Fuel Injection. I told him what engine mods have been done and he burned the chip based on that. I know nothing about tuning so I have been reading to get up to speed on it.I understand that the application of the TBI is not the norm for this board. But the replies I did get point me in a direction worth checking out.
Thanks!