Was out at Buttonwillow this weekend for the 1st time since by rebuild and it was ridiculously hot. Ambient was over 100 F most of Sunday and close to that on Saturday. One constant issue I had throughout the weekend was overheating. On my out laps car would come up to around 210 F and if I pushed it for a lap it would come up to around 225-230 F. (not comfortable with that) Needless to say, I did a lot of cool down laps in putting it around. The temps would always climb slowly and very with how long I was in boost throughout the lap. If I hammered it all the way down the front straight, temps would climb 5-10*F in that one pass. Cooling down would take forever on the slow laps (heat soak?)

Details of my current setup below. I may be forgetting some items but this is the bulk.

• 1.6 M45 motor (Fresh rebuild) with Ebay A/A Intercooler blocking approx half the radiator opening.
• 37mm Koyo Aluminum Radiator
• M-tuned reroute
• 180* Tstat
• Fresh water + water wetter
• Ducted radiator opening (Home Depot Special)
• Hood central vent and side louvers
• Water temp reading taken at rear block outlet
• Heater core bypassed with 1/4" restrictor in hose
• Only 1 fan on driver's side
• Factory undertray in place

So from this point I have run out of ideas for overheating caused by a failure or not having part of the equation not setup properly. My thinking is that I just didn't have enough radiator there with the intercooler to keep the car cool. Do you guys agree? Is that another root cause?

My thinking is improve venting from hood by added lips to the current vent and enlarging the vent all together (think it's too small) and upgrade to a thicker/larger radiator. If I upgrade the radiator, do I need to move all the way up to something like the TSE unit? Or will a 55mm Koyo/Mishimoto/Etc. do for my under 200whp levels?

 

Little ------ AIDS radiator is the problem. Get a bigger one, TSE if you have the cheddar.

 

Sounds like you have taken all the usual steps. I would have thought the 37 would be enough for an M45 1.6 but maybe H man is right, time for a 55mm Koyo or TSE's cross flow. I assume your we'll under 200whp?

Also, if you have any "cooling or intake openings in the front of the car that allow air to enter the engine bay without going through the rad core first, plug them. Little things like TSI's. sloppy rad ducting, holes in the bumper skin, etc, can undo all the hard work getting the cooling system to reject heat by not letting the core get enough airflow.

 

Pics of vents?

 

I was able to keep my 250whp car cool with a 55mm radiator, ducting, hood vent, and an FMIC blocking 90% of the "mouth".

 

The easy solution is just to buy the best radiator on the market - ours.

 

Where are you pulling the air intake for the heaton? Getting the filter for it out of the engine bay and into cold air will increase your compressor efficiency and lower the heat overall and should help engine temps (this goes for any compressor in the intake but double for roots[technically not a compressor ******* bite me]). Also more fuel and more timing advance will help as well if you want to get another hot track day in before you get proper cooling mods done. Or switching to e85 or race gas with methanol in it will make a big difference as well. Heatons heat the car up fast. In sub-freezing temps I'd have my old car up to the thermo temp in under a 1/4 mile of 25mph driving just getting to the main road. So the fact that only a little m45 on a 1.6 is getting it cooking is not surprising.

 

Car is making 170whp. No other openings on the front of the car except the hood vent and louvers as previously mentioned. During the weekend I also had an on track collision so the drivers side headlight and turn signal were taped up with Gorilla tape, seemed to hold fine so I didn't think that was an issue. Was running real hot before the collision too.

Will post shortly. Think I just have a crappy cell phone picture but it will do. The center vent is located center on the hood and just in front of the valve cover. The side louvers are copies of the FM louvers. They are located at cylinders 1 & 2 over the wheel wells.

This was my thinking too. Save up to buy one. I really don't want to spend the time, money and energy to buy a 55mm that only saves me $100-200 and still may not be the answer. A lot more expensive to throw away a track weekend due to overheating.

 

Intake is located right behind the drivers headlight like most other NA cold air intakes I've seen. Nothing done to isolate the filter. Thought process is that if the intercooler is doing it's job, the air should cool down enough before getting into the motor. Don't know what my AIT's got up to. Is there a way to read that off the MS after the fact?

Also, don't see a way I would route the intake to a cooler place in the engine bay. Cowl intake just wasn't going to work room wise.

 

How it was taped up and one side of the vent/louver


Shakey but shows what you need

 

Looks OK. I would maybe extend the hood vent a bit forward but that's not the cause of the overheating.

Maybe pressure test the cap. I like the 1.3bar Koyo cap which raises the boiling point a bit past the stock 1.1bar cap. I've seen caps with slightly damaged gaskets burn up engines more than once. As the engine heats and cools, it fails to draw a vacuum and pull overflow coolant into the system. The low pressure also allows hot spots in the head.

 

Emilio, can you explain how TSI's reduce the air flow through the radiator?

 

Any hole in the front of the car that allows air into the engine bay is adding pressure to it. What pushes air through the rad is a pressure differential. Vehicle speed increase pressure in front of the rad. More pressure in front of rad, less pressure behind it in the engine bay. Add more pressure behind the rad by adding holes to the front of the car and the pressure differential across the rad is lowered. Thus, less airflow through rad. TSI's don't hurt rad flow if they are completely sealed from the engine bay, only feeding into the induction system of the engine.

There are many detailed threads here regarding the Miata cooling system. comradefks has clearly read all of them and taken all the typical steps to inprove cooling in an F/I track Miata. Something is being missed though so we're kida brainstorming to try to figure out what it is. On paper at least, it shouldn't be overheating really.

 

I wouldnt think it was a weak rad cap. If you have a weak rad cap and the temp gauge shows your over heating the car is already toast because at that point its reading the temperature of the head and not the coolant.

 

Maybe a stupid question - but did you check for air in the system? The long M-tuned return can have a tendancy to trap air. Didn't see it mentioned, so thought I'd ask... I would 'assume' this was checked.

 

Haven't tested the cap previously but it as aftermarket, don't know the exact brand. Will put in on the list to replace if for nothing but to cross it off the list.

Drained the system and bled it after Saturday up at the track. Seemed to bleed out all the air (bubbles). Water was flowing cleanly at the radiator fill.

Just to confirm, we do not have a block coolant drain location right? Only the drain plug on the radiator correct?

 

How much "heat soak" in the engine bay is normal? When I come in off track everything in the engine bay is untouchable. That includes supercharger, valve cover, anything near the radiator, even the intake manifold is noticeably hot. I'm wondering if the louvers I installed are doing anything or maybe hurting me.

Also, I am starting to get more and more OK with just biting the bullet and going for a TSE unit before the next weekend out there. Gotta fit that in with planning for my wedding somehow....eep

 

If you don't have an oil cooler (supercharger owners, lol) then you have ~300*f+ engine oil in there so yeah, everything is going to be fire hot.

The vent in my hood makes everything surprisingly cool, but I can provide any specific data due to the confidentiality agreements with my race team, McLaren.

 

Yes on only having the drain on the radiator.

How are you bleeding the system?

 

Oil temps at the drain plug sensor got up to about 250F over the weekend. Don't know what the delta between that location and an oil cooler sandwich plate or the other locations for a reading are.

As far as bleeding, I fill the radiator with the nose of the car jacked up then run it until it's up to temp at idle. Keep filling radiator as needed. Then hold that car at between 2k and 3k in revs as it continues to purge out air. Basically stop when I stop seeing bubbles come out of the fill. Let the car cool down and top off the radiator/overflow as needed at the point.