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One of the first things I noticed about my 80,000-mile Civic Type R was how sluggish and laggy it felt in the Southern California heat. Even with an upgraded intercooler and 2020 CTR grille for more airflow, something about the high ambient temperatures really decreased power on my car. So I dug in and set about battling heat with research and some choice mods.
Heat management is one of the most well-documented issues with the CTR, but it’s usually related to coolant temperature. The truth is that any turbo car will have issues handling heat compared to a naturally aspirated car. By design, turbochargers use wasted exhaust energy (which is heat and airflow) to increase the power output of the engine. Thus, you have a glowing ball of blazing cast iron right in the middle of the engine bay. It’s going to get warm under the hood.
The Overheating Issue
In the specific case of the CTR, the packaging of the exhaust and induction system is slightly peculiar, though not abnormal. The CTR is powered by a unique variant of Honda’s K-series engine called the K20C1. It shares very little with the Ks of the past, and this is evidenced by the reversal of the intake and exhaust locations. On previous K20s, the intake was at the front near the radiator and the exhaust was at the back of the engine bay. The CTR is reversed, meaning the turbocharger is at the front of the engine, closer to the radiator. And the packaging is tight.
Though high coolant temperatures on track aren’t explicitly pinned on this packaging. In fact, the car can cool itself extraordinarily well during spirited street driving and coolant temps stay low in traffic on hot days. The issue of coolant temperatures getting high during track driving is down to a question of radiator cooling capacity and airflow. My issue with heat soak around town is all down to the routing of the intake system over the hot turbocharger as well as the unique engine calibration strategies of the car.
The primary issue I see with the CTR is the usage of heavy cast aluminum pieces in the intake system. The turbo inlet tube is a hulking piece of metal that travels directly over the turbo and the intercooler outlet charge pipe is the same story. The issue with using metal, especially metal with weight, is that it retains heat much more readily and for much longer than plastic parts. The Civic Si uses plastic parts, so there must be some reason for cast aluminum on the higher-performance car but I haven’t figured out what the upside is yet. When I reached out to Honda for an answer, company spokesperson Carl Pulley told me that the 10th gen Civic Type R development team “disbanded when it completed its task and went on to other things” so we might not be able to get an official answer. Perhaps a third-party engineer will be able to give us insights on that in the future.
How the Car Responds to Temperature
Another other issue is that the MAF (mass air-flow) and first IAT (intake air temperature) sensor live at the airbox, before the intake system crosses over the turbo, so unmeasured heat is introduced into the intake system. This matters because of two things: The cooler the air going into the intercooler, the cooler it’ll be coming out. And the car bases its calculation on data that might not be true if the temperature gain is substantial.
The ECU definitely uses the sensor at the intake manifold as a primary data point, but it also seems to use the pre-turbo IAT sensor to determine the efficiency of the turbo. The correlation with tuning is unclear but I think it’s worth chasing down. I have two mods planned for this: using reflective tape on the cast aluminum turbo inlet tube and installing something called a turbo blanket.
Repelling the Heat
Heat-reflecting tape should be relatively self-explanatory. Wrapping the turbo inlet in it should help repel heat away from the precious intake air. The turbo blanket is a lot more interesting. It’s a combination of silicone fiberglass and a special calcium magnesium silicate wool that wraps around the turbo, like a blanket. As mentioned earlier, turbos thrive with heat. The turbo blanket helps keep heat in the hot side of the turbo, keeping that exhaust energy in while acting as a serious heat shield for the rest of the engine bay. This will be the mod that should make the biggest difference in underhood temperature and turbo lag.
Yes, turbo lag. The company I bought the blanket from, PTP Turbo Blankets, claims that the blanket effectively reduces spool time. It’s been tested and backed up by many trusted sources. What I’m most curious about is how it will affect heat management on the CTR. In the case of my install, the standard heatshield (complete with classic Honda do-not-touch-hands logo) fit over the blanket with zero problems, except that one bolt on the front no longer fit. Snaking the blanket with wire and encasing the turbo in it was tedious but not bad once I removed the core support.
I went out for a test run to get a temperature and response baseline before the mods using the Hondata data logging function on my phone. I hoped to get some info on intake air temperatures before and after—quantifying exact turbo lag numbers would take more precise equipment like a dyno.
My initial runs showed a 10-degree Fahrenheit difference between the MAF IAT and the intake manifold charge air while cruising. The MAF IAT was around 100 degrees while the intake manifold would be around 110 degrees on an 80-degree ambient temperature day. That tells us another thing about the underhood temperatures if the airbox air temps are 20 degrees higher than ambient. The MAF IAT also rose quickly at stop lights to 50 degrees above ambient.
Doing the mods themselves wasn’t simple. In fact, it was a little time-consuming; taking about four hours to do the inlet pipe and the turbo blanket. This was because the engine bay is tightly packaged against the radiator core support. I tried to resist outright removing the support for a few hours but once I put the car into its service position with no support, everything fell into place. This is a word of caution for anyone modding their CTR: just remove the support. It’s easier that way.
With the mods installed and the car back together, I went for testing on a warmer 92-degree day. The difference was somewhat startling in the data and very interesting on a subjective driving feel level. Now the MAF IAT and the intake manifold are the exact same temperature and lived around 110-115 degrees. The data is imperfect because of the warmer day, and temperature is a nonlinear relationship when it comes to cooling. But what was interesting was that the MAF IAT resisted rising above 125 degrees, which is a reduction of 15 degrees at the airbox. That’s not nothing.
Closing out with the subjective feel of the mods, I’ll say that the difference is substantial but not night and day. Turbo lag is better mitigated for sure but in an interesting way. Where it has improved in a blindingly clear way is the response from off-throttle to about 5 psi of boost. The turbo wakes up much more quickly and gives the car wonderful driveability when transitioning onto the throttle. It has more torque in no- and low-boost situations. Most importantly, it felt much happier on a 92-degree day than it did on an 80-degree day. It shed the heat-soaked feel pretty strongly, and that’s what I really wanted. Though a later mod revealed something important about why my car made boost sluggishly. That’s for another blog.
For the $200 the turbo blanket cost, this mod feels like a no-brainer to me. It’ll be put to the real test at the next track day. Until then, it’s suspension time for my Type R and also finding the real issue behind my turbo lag.