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I have a pretty mint NA8 with the following specs (at least the ones you'd worry about related to heat):
specs
Forgive me for the Canadian units, it has 125xxx km's (77000miles) on the original engine and body. The turbo went on about 12,000 kms ago.
Tune is on the rich side, with minimal spark advance, and I'm capped at around 11.8 PSI.
On a day with outside temps around 25 C+ (77 F), I can only get 1 or 2 laps around a 1-2 minute per lap track. Speeds probably stay below 100 km/h (62 mph) most of the time with rev's around 4-7 rpm most of the time. At which point the temperature gauge begins to climb closer to 215-230 f. I've got a rev safety in the tune to drop the rev limiter when temps exceed 230 F (see pic below). I haven't seen it come up as an issue when doing spirited highway or mountain driving, but to be fair, I probably haven't done it on a day above 28 C (82 F). I should mention the thermostat is a Stant 45869 (195 F).
I've added water wetter and verified everything looks good. Did a coolant change. Oil changed, can't recall off hand what oil I'm running. Got a K24 filter.
What's next? Is that just the way it is with the turbo location? Maybe it's being a polished turbo, it's releasing more heat in the engine bay (or I'm way overthinking it). I just want to sort this out before the season starts again. I also want to properly dyno it, but I'd much rather do that when cooling is sorted out. I am running the stock plastic skid plate under the engine (for those who ask about air flow). One thing I noticed was my coolant overflow tank couldn't handle the corners so I added the vinyl tube to a water bottle. It basically creates a U shape to make the coolant have to go up again in order to spill out. It's been working well, just not sure if that's the wrong thing to do/puts pressure on the system.
*Trigger warning* I went past Chikara motorsports in Vancouver and someone there mentioned they don't like to turbo miatas specifically due to heat management. They suggested the best thing to do is change my bumper to one of the Japanese ones with the larger opening for air flow. I was a bit surprised by that, given the attached photo of my current area for air flow, and that the problem seems to happen at slower speeds. I can't recall if they said hood vents would help. I'm not against it, particularly above the turbo. I almost purchased their oil cooler kit, but we couldn't find a good spot to mount the radiator, and in the end figured it might just be covering up a problem. I was thinking to get an oil temperature sensor for my next step.
Really curious to hear your guys' thoughts on this. I'd love to push it a bit more this summer and tune it, knowing it's healthy going in. Kanadian Coolant Overflow Mod Front of car / air flow zone for reference. GTR for humility. showing engine bay layout
Last edited by Cowwalk; Feb 12, 2026 at 11:14 PM.
Reason: removed spoiler
Obviously track use is definitely more rigorous than street driving, but the first thing I noticed was mishimoto fans. They are junk. They let my stock car overheat with just the ac on idling. Your ducting looks pretty good, for a street and track use car, you still have the undertray and have minimal gaps between your mouth and first heat exchanger. How close are the intercooler and radiator/condenser? Having a large gap between those things without it ducted through will make air take the path of least resistance, being down under or around the heat exchangers behind it. Seriously get rid of the shittimoto fans, get some good fans, do some research on them if you're going to track the car a ton on hot days find what you think would work well. I dont track or autocross my car, but these spal fans keep my car cool very well, sitting at thermostat temp when theyre on. A maxxed out 2560 and ac and I have zero problems doing b2b pulls. Take this with a grain of salt because I dont track my car. But I have had overheating problems, and they all stemmed from airflow, specifically having mishimoto fans.
It would definitely not hurt to make sure you seal all the gaps between the heat exchangers, you want air to HAVE to go through them.
Obviously track use is definitely more rigorous than street driving, but the first thing I noticed was mishimoto fans. They are junk. They let my stock car overheat with just the ac on idling. Your ducting looks pretty good, for a street and track use car, you still have the undertray and have minimal gaps between your mouth and first heat exchanger. How close are the intercooler and radiator/condenser? Having a large gap between those things without it ducted through will make air take the path of least resistance, being down under or around the heat exchangers behind it. Seriously get rid of the shittimoto fans, get some good fans, do some research on them if you're going to track the car a ton on hot days find what you think would work well. I dont track or autocross my car, but these spal fans keep my car cool very well, sitting at thermostat temp when theyre on. A maxxed out 2560 and ac and I have zero problems doing b2b pulls. Take this with a grain of salt because I dont track my car. But I have had overheating problems, and they all stemmed from airflow, specifically having mishimoto fans.
It would definitely not hurt to make sure you seal all the gaps between the heat exchangers, you want air to HAVE to go through them.
Your car looks pretty nice overall
Thanks man, I havn't heard of that before. I'll look into it.
First step is to seal all the places the air can (ie does) bypass the intake duct/radiator face. IE the only way the air coming in can get out, is through the radiator. That includes sealing the front garnish.
Factory fan(s), factory fan shrouding. How old is the water pump? Fans only needed in traffic, low speed, and you don't want to obstruct the high volume of air coming through the radiator (you hope!) when at speed.
I have gone the opposite way to Bloopdog, I have opened up the space to allow air to bypass the IC and A/C condenser. First priority is cooling the car ... and I have not experienced any overheating on track yet, though I am about to start serious competition through the tail end of our summer - I will be watching that closely, particularly on 30*C plus days. I am looking at some bonnet ducts as the next step, but to now not needed.
Another thing that can help is have the fans stay on when engine off, to the point where the radiator is cold to the touch. Have set it on mine to about 70 celsius. This was enough for 10 minute sessions which is the max we get here. Then cooling down between sessions.
Pair this with an 82c thermostat.
This is not a solution but a patch.
Good luck.
Look at fast turbo track miatas for examples of a proper cooling stack and ducting. Most of them do not have the intercooler so far up front blocking the entire mouth forcing all air to go through it first. You mount the IC in such a way that air can bypass it and go through the radiator. You also want it to be further back from the mouth, I.E. not blocking the mouth, so that air can pocket in the mouth and build up pressure differential.
E.G.
This setup is 300+whp road course capable with ease.
First step is to seal all the places the air can (ie does) bypass the intake duct/radiator face. IE the only way the air coming in can get out, is through the radiator. That includes sealing the front garnish.
Factory fan(s), factory fan shrouding. How old is the water pump? Fans only needed in traffic, low speed, and you don't want to obstruct the high volume of air coming through the radiator (you hope!) when at speed.
I have gone the opposite way to Bloopdog, I have opened up the space to allow air to bypass the IC and A/C condenser. First priority is cooling the car ... and I have not experienced any overheating on track yet, though I am about to start serious competition through the tail end of our summer - I will be watching that closely, particularly on 30*C plus days. I am looking at some bonnet ducts as the next step, but to now not needed.
That's the exact thread I was looking for. Thanks! My search game is weak.
Another thing that can help is have the fans stay on when engine off, to the point where the radiator is cold to the touch. Have set it on mine to about 70 celsius. This was enough for 10 minute sessions which is the max we get here. Then cooling down between sessions.
Pair this with an 82c thermostat.
This is not a solution but a patch.
Good luck.
Look at fast turbo track miatas for examples of a proper cooling stack and ducting. Most of them do not have the intercooler so far up front blocking the entire mouth forcing all air to go through it first. You mount the IC in such a way that air can bypass it and go through the radiator. You also want it to be further back from the mouth, I.E. not blocking the mouth, so that air can pocket in the mouth and build up pressure differential.
E.G.
This setup is 300+whp road course capable with ease.
wow, do you have any drawings of what you've done? That's the cleanest setup i've seen. What radiator and intercooler is that? What fan are you running? Got a shot of it/the shroud? Any hood vents? What's the undertray look like where it attaches to the bumper?
I boxed it in in such a way that it's not reliant on a undertray or splitter for airflow. Also the bumper is still easily removed for service, my biggest complaint with my prior ducting was serviceability. The splitter attaches via quick release/pins and takes about 5m to put on/off and doesn't affect ducting.
Of course after this I went through a whole overcooling saga, so be careful!
I boxed it in in such a way that it's not reliant on a undertray or splitter for airflow. Also the bumper is still easily removed for service, my biggest complaint with my prior ducting was serviceability. The splitter attaches via quick release/pins and takes about 5m to put on/off and doesn't affect ducting.
Of course after this I went through a whole overcooling saga, so be careful!
Lol sounds intense. I was thinking to just add the Chikara oil cooler and do some minimal ducting. Keep in mind I don't have hood vents...
Also remove the turn signal intakes and go back to stock. They will pressurize the engine bay and reduce the amount of air that will pass through the heat exchangers.
Ricotta is correct, those TSI's are only hurting - not helping. They are cramming air underhood, making it harder for air to go through your radiator. Get rid of them ASAP.
Chikara motorsports is respected in the miata community, they seem like a good shop - but the comment about needing a larger mouth opening is just plain wrong. It has been proven that the mouth size is plenty large enough with proper ducting, even oversized! I narrowed mine down a bit even by blocking off either end of the "smile". They aren't wrong that turbo miatas require careful heat management, it's their Achiles heel - but there is a formula for it now days.
Without re-doing your whole setup, some basic ducting would do wonders. I'd suggest sealing up the bottom, between the bumper and the stock under tray. Also seal up the sides, around the intercooler. You need to force as much air as possible through the radiator. Air will always take the path of least resistance and go around the heat exchanger if it can. Think of it like water in a bucket, it's just going to spill out over the sides without any ducting there. Also tape the seam on your upper radiator panel to the rad, that helps.
Hood vents go a long way, and really are a requirement on a turbo track car. You don't want to vent over the turbo though, the vents should be right behind where the radiator ends. Example:
Proper vent location will vent the low pressure area of the hood, allowing air to escape from the radiator and keeping pressure from building up under the hood. Again, pressure differentials are your friend here and the key to keep air flowing through your heat exchangers.
Also remove the turn signal intakes and go back to stock. They will pressurize the engine bay and reduce the amount of air that will pass through the heat exchangers.
Originally Posted by Fireindc
Ricotta is correct, those TSI's are only hurting - not helping. They are cramming air underhood, making it harder for air to go through your radiator. Get rid of them ASAP.
Chikara motorsports is respected in the miata community, they seem like a good shop - but the comment about needing a larger mouth opening is just plain wrong. It has been proven that the mouth size is plenty large enough with proper ducting, even oversized! I narrowed mine down a bit even by blocking off either end of the "smile". They aren't wrong that turbo miatas require careful heat management, it's their Achiles heel - but there is a formula for it now days.
Without re-doing your whole setup, some basic ducting would do wonders. I'd suggest sealing up the bottom, between the bumper and the stock under tray. Also seal up the sides, around the intercooler. You need to force as much air as possible through the radiator. Air will always take the path of least resistance and go around the heat exchanger if it can. Think of it like water in a bucket, it's just going to spill out over the sides without any ducting there. Also tape the seam on your upper radiator panel to the rad, that helps.
Hood vents go a long way, and really are a requirement on a turbo track car. You don't want to vent over the turbo though, the vents should be right behind where the radiator ends. Example:
Proper vent location will vent the low pressure area of the hood, allowing air to escape from the radiator and keeping pressure from building up under the hood. Again, pressure differentials are your friend here and the key to keep air flowing through your heat exchangers.
I had not considered that. I love the look of them. Would adding mesh behind them help a bit Maybe I'll blank them off behind. I could use one of them if I add the oil cooler on one side now? That makes total sense on the pressurizing part. Do you guys know of some good CFD shots of the heat exchange at different air speeds? Would be very interesting to see that. I'd love to understand where the air is escaping once it's inside the engine bay (how much exits from the bottom vs. from the top by the windshield.
There's CFD data out there, for sure. The cowl area (top of the hood by the windshield) is high pressure, so no air actually escapes there. If anything air is forced in if not properly sealed. That's why the ricer "space the hood out" at the hinges **** doesn't work.
There's CFD data out there, for sure. The cowl area (top of the hood by the windshield) is high pressure, so no air actually escapes there. If anything air is forced in if not properly sealed. That's why the ricer "space the hood out" at the hinges **** doesn't work.
Yes, which makes a cowl intake a double whammy. Cold high(er) pressure intake air, and a great sound! I loved the one on my NB8A ...
I think supermiata has a picture of the miata hood with a grid on top showing which areas are low pressure and which are high pressure if you want to go digging for it. It would be a good reference for the proper hood vent locations. Fireindc is exactly correct you want to vent on a negative pressure spot to give air an easy escape from the bay. Don't bother with mesh on the turn signal intakes, just go back to stock and put your time into sealing up the radiator mouth. When you go back to stock fans, if one fan is enough to not overheat in traffic then consider removing the second fan, it will help more air pass through the heat exchangers at speed on the track.
I think supermiata has a picture of the miata hood with a grid on top showing which areas are low pressure and which are high pressure if you want to go digging for it. It would be a good reference for the proper hood vent locations. Fireindc is exactly correct you want to vent on a negative pressure spot to give air an easy escape from the bay. Don't bother with mesh on the turn signal intakes, just go back to stock and put your time into sealing up the radiator mouth. When you go back to stock fans, if one fan is enough to not overheat in traffic then consider removing the second fan, it will help more air pass through the heat exchangers at speed on the track.
That's good to hear. I'll start playing around. Sounds like my first step really is to get a oil temperature sensor to see what's actually happening with the oil temperature.
Overheating? Advice Needed NA8 Turbo
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