Just throwing this out there, e85 drastically lowered my egt’s especially at idle, thus lowered my under hood temps. My IAT and coolant temps were always pretty decent as I have a good FMIC and good condition cooling system. But, when I switched to e85 my egt gauge is considerably lower than on 93. I was around 1000 degrees and now I’m down to around 800. I also noticed my fan doesn’t cycle as much (which makes dialing in your idle a lot easier!)

99dsmer4g63 said:

Yeah if your car is running really lean it will definitely make it run hotter. I’m no tuner by any means but from experience a lean idle or cruise mixture seems to raise the temps.

-Daniel

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Gotcha, it doesn't appear to be running very idle from my logs and I don't have it running past stock boost despite the bigger turbo, but I'll check it again to see if it is the case. Thanks.

All the information in this thread has been solid. All I hope to do is narrow down your search for a solution.

If your car has issues with overheating at idle, you should focus on the things that will help when the car is not moving. I have found that the most important things to focus on are air through the radiator at idle. People typically suggest stock fans and that is absolutely a great answer. The more correct answer is to have proper ducting that forces all the air the fans are drawing through the radiator. The next thing to focus on are CFM numbers. Unfortunately you CAN NOT trust claimed CFM. You must verify the numbers.

On the inside of the engine, some things to consider are the aforementioned head-gasket issues. Can you verify if the cooling system has zero air in the radiator cap area? It may be as simple as just doing a proper bleed or the radiator cap sealing surface cleaned up. It may be as complicated as a new HG, deck surface, cylinder head decked. You mentioned OEM thermostat and rad cap, so good on you. Next up is coolant flow through the motor at idle. I have yet to test this one but some claim that the fin style water pumps like OEM work better than the wheel type used by some aftermarket manufacturers. I'll have data on that one in 4-6 months.

Ever since going 16G, 3" core FMIC on a 2gb Talon bumper and a moderate tune, the car has lived in the 95C-103C* range on a daily basis. She warms up super quick and stays hot no matter hwat. Also running a 1.1 bar cap, a good water-coolant mixture and AC fan set to come on if I push the AC switch (AC has been deleted, no condenser radiator between intercooler and water rad.).

I have learned that no matter what I did, no matter how much I played around with all these things, such as coolant offset, water ratio, caps, ducts,... nothing helped. This setup and the tune I have simply make her run the way she does. The downside is I'm always about 1* of knock retard due to coolant being over 95*, but the upsides are that when oil gets to 100C and slightly above, it actually starts to boil the water away. And as we all know, water in oil is bad. Modern cars are all set up to purposefully keep their oil temps at 100C and slightly over just for this reason, to boil out the water.

So I've stopped worrying about it. My oil is great, clean, coolant is crystal clear. The tune is solid, and I haven't melted or detonated a piston top for the past few years. I shudder more when people rave how their car runs at 79*C compared to the industry standard 91-95C for that era and 100+ for nowadays. Oil needs to get to a certain temp to really do its job and too low can be just as much of a problem as too high. I know this is a topic about water temp but technically water and oil temps are always linked at the core of the motor, so it's worth discussing both.

I think those giving experiences should include if they are still running AC or not as it makes a massive difference. But since you have your condenser removed you should be getting enough airflow. What are you AFRs like at idle and cruise? If they are too rich or lean it will run hot

2GB GSX, 14B setup with all the stock heatshielding, eBay aluminum radiator, OEM cooling fans, working A/C system, and VRSF FMIC. No ducting, nothing custom at all, and 94*+ North Carolina days while using the A/C and temps never got above 190*. Even at the hottest.


Was tuned at 21lbs, Pump 93. Never touched E85 on that car.


Hope this helps. Gotta be some other problem.

Will Kellermann said:

I'm definitely planning on cutting off the black part on the top of that bumper. I used Valvoline Zerex Asian Vehicle coolant in my system, if that is ok. When I replaced the thermostat, I didn't see any rust on that part of the system. It also has a new Gates Water Pump that's been on there for about 4000 miles and didn't see any rust there either. Is there a different area I should inspect that tends to accumulate rust? Also, do you think the VRSF has better passage for air to the radiator, seems like quite a few people run the punishment china-special FMIC ok, but some have reported airflow issues with it.

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I normally run the traditional Prestone 50/50 mix and had never had any issues. My cooling system is pretty much stock aside from just a higher pressure radiator cap (1.3 bar if I remember correctly) and some redline water wetter which I decided to add just because.

As for the VRSF FMIC having better air passages vs others, I do not know the answer to that myself but I do recall it being a "replica" of a name brand FMIC (cant remember the name) which was known to be pretty efficient when compared to others, and by efficient I'm mostly talking about its capabilities of it being able to cool down the hot air coming from the Turbo as well as not having a bad pressure loss.

BTW if you turn on your car with the radiator cap off, after you reach operation temperature and your thermostat opens up; do you see your water move? I once met a guy that for the life of him could not figure out what the issue with his cooling system was no matter what he did and it turned out to be that his water pump wheel had broken off which was causing his radiator fluid not to flow thru the radiator and so on. If you haven't done this give it a try, will also help with burping the system as others have stated here.

red_devil said:

I think those giving experiences should include if they are still running AC or not as it makes a massive difference. But since you have your condenser removed you should be getting enough airflow. What are you AFRs like at idle and cruise? If they are too rich or lean it will run hot

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You are right, Running AC here.

red_devil said:

I think those giving experiences should include if they are still running AC or not as it makes a massive difference. But since you have your condenser removed you should be getting enough airflow. What are you AFRs like at idle and cruise? If they are too rich or lean it will run hot

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When I had a/c and now that I don’t have a/c made an absolutely no difference on my car. Im currently on 93 pump but won’t be much longer either. We also already touched on his a/f ratio and he claims that are not that far off to cause his problems.

I personally know that if my car started to run hotter than I think it should be I would question something in my coolant system or the health of the motor or the oil system. Once again I’ve never had a car/truck running hotter than it should and thought I need to add fans and or make some air ducts to get more airflow. Take that as you will.

-Daniel

99dsmer4g63 said:

When I had a/c and now that I don’t have a/c made an absolutely no difference on my car. Im currently on 93 pump but won’t be much longer either. We also already touched on his a/f ratio and he claims that are not that far off to cause his problems.

I personally know that if my car started to run hotter than I think it should be I would question something in my coolant system or the health of the motor or the oil system. Once again I’ve never had a car/truck running hotter than it should and thought I need to add fans and or make some air ducts to get more airflow. Take that as you will.

-Daniel

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That all depends on the outside temperature and if you were running AC or not. In Florida my car would run fine with the AC off but as soon as AC was on the temp would rise to 225F. These cars have very little surface area to get air in and even then it's not very efficient.

I've ran into similar issues with an FMIC on 2gb GSX's. The thing that has been the most successful for me is adding ducting between the intercooler all the way to the radiator, as others have mentioned. I've done this with AC in place and it instantly resolved the issues I'd have with overheating at highway/cruising speeds. I've added pieces of foam pipe insulation between the radiator and AC condenser and then made some metal pieces to guide the air from the FMIC to the AC condenser.

Have you checked if your water pump is still good? As in, you're not missing blades on the impeller and it's not gummed up? Temps should rise a bit in a pull but not that much. I think you need to post a log, you might have a mechanical or gasket issue.

Remove the bumper to see if ducting will help. If youre still overheating without a front bumper then dont bother wasting time with ducting

We must start back with the fact that The factory cooling system is more than adequate for the vehicle.

When we introduce variables, thicker radiators, non original fans, we add more possible problems

What we do know is that some people can run intercoolers and big radiators without issues, so that likely means that your cooling system is the problem and not the intercooler.

It is my opinion that the dual core radiator has a higher tendency to heat soak, and it is a fact that the fans are less effective drawing air through a thicker radiator, so once that thick radiator gets too hot the fans will not cool it back down

Im not saying a factory radiator will solve the problem, but you can find them on ebay for $68.

Also a few months ago a guy posted that he was using a 2gnt factory radiator fan in the condensor fan slot. That seems like a great upgrade that will flow better than the oem condensor fan

Your problem seems pretty drastic, overheating after a pull to me is a sign of a heat pocket in the head caused by a warped head or bad headgasket

red_devil said:

That all depends on the outside temperature and if you were running AC or not. In Florida my car would run fine with the AC off but as soon as AC was on the temp would rise to 225F. These cars have very little surface area to get air in and even then it's not very efficient.

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Just wanted to clear this up. I have never seen temps in the 225 range. Honestly if I did I would probably pull over and shut the car down. When I drive my car I usually have no purpose in my mind other than maybe getting fuel or grabbing some cigarettes at the store. I’m just looking to enjoy driving it.

If the ac was on and it was a hot day I still never seen any thing over what I would say is normal. Not trying to say people in here haven’t but once again I would suspect something else to be at play at that time.

Also at the time I had a/c still with the factory radiator the car was still my daily driver. So sitting in traffic with the a/c in the summer was something that car would have seen.

-Daniel