Are the SI’s overheating on track?

Love my CTR but after all the mods in the book I cannot keep it cool for more than 1-2 laps depending on track and temp. Interested in just selling/ trading for a SI coupe if they stay cool.

Tried to search but brought up endless CTR posts. Anyone road racing their SI and how’s it doing?

Stock I never had a problem, even on the hottest days going wot. I added a ktuner with the tsp1 tune. Did my first track day with it last weekend. Base tune no problem. Map 2 it got hot but was manageable. Map 3 it I would get 3 laps in and I have to do a cool down lap. Went one session like that and went back to map 2. I'm gonna add a koyo radiator and oil cooler next. See if that helps on map 3. At least keep map 2 under half on the temp gauge.

Nice that’s good to hear. Even with an oil cooler, open grill, water wetter, wrapped downpipe/ front pipe and a bunch of gold tape I can’t keep temps down on Hondata tune for mine.

Is that at thunderhill?

Streets of willow at willow springs raceway. I'm sure the extra boost on the map3 just made the car way too hot. It's still a mostly stock si. Just suspension work and now a ktuner.

No overheating, but had to upgrade brake pads. If you drive it to its potential, the pads will fade a few laps into a session. It will feel slow coming out of turns, but it carries quite a bit of momentum.

I know there is a lot of variables that go into this but overall, Im guessing its safe to say our civics (CTR's and SI's) were dialed in to the max, when it comes to boost?
Im starting to notice a common trend that once boost is added or even just bolt ons, heaps of issues start to arise. Clutch being the main one for the SI's and heat being the next which logically speaking makes sense. More power, hotter engine bay. As of now Just focusing on handling mods, but i do plan on getting ktuner from TSP and want to avoid any heating issues. Not sure if OP has this already but wouldnt a bigger FMIC solve this heating issue? @Chief lazy leaf @.grimace im new to understanding how the mechanics work and shit so go easy on me lol

On the Si the turbo is tiny and can flow at max in the middle of the RPM range with the hottest reflashes. You're pushing a lot of hot air if you ask too much from them... and all that hot air may be at a high pressure, but the actual mass of air won't really be much more.

You can rough math it as I don't have a great chart... but figure...

(atmospheric pressure + boost)/atmospheric pressure = pressure ratio

TSP Stage 1 map 3 is 24.5# so...

(14.7+24.5)/14.7=2.67

From MHI...


It'd appear that that's the bleeding edge of what the turbo can do and well beyond what it can do efficiently. This compressor map *sucks* but usually the most efficient spot is around the middle... and that's probably at a boost pressure closer to ~1 atm (a PR of 2) or ~15#. It *can* do more but at making IATs progressively hotter and hotter. You're trying to push so much air at as high of a pressure as it can muster and it just can't keep up. My first couple turbo cars didn't even have intercoolers. They were larger turbos than these, but only pushed 6.7#... so their operating PR was less than 1.5. With operating very efficiently an intercooler wasn't required.

As to heat... I have never used water wetter but I have run 30/70 since I live in a hot climate. Cheaper due to using less coolant and water has a higher specific heat capacity and transfer coefficient. You still have acceptable freeze protection so long as you don't live in regions with very hard freezes. Still good corrosion protection. Still a higher boiling point... though technically nucleate boiling is good... it's bulk boiling that's bad (very). Water wetter actually have a decent product sheet that has the data to compare 100/0 50/50 and 0/100. You can estimate the 30/70 as probably being a ~5% cooling improvement. Always use distilled water. You don't want minerals playing out or chlorides in the water that'll plate up and reduce the heat transfer in the radiator or promote corrosion.

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.redlineoil.com/Content/files/tech/WaterWetter%20Tech%20Info.pdf&ved=2ahUKEwjY0MKagZrkAhVLc98KHdTLB_oQFjAAegQIAxAB&usg=AOvVaw2xq_KYodmdLInLuAKlYB_7

It'll make 0 difference unless you're overwhelming your cooling system. Once that happens, and your thermostat is as open as it'll go... you'd have a bit more cooling capacity and the ability to transfer heat a little better... within the abilities if the radiator... fan and whatever ambients you have to work with. You can modify/replace your grill to allow more airflow at the expense of extra wind resistance.

I don't know much about doing anything with oil other than adding an oil cooler and ensuring you're on the high end of the allowed capacity. More oil = more oil to be able to contain heat... so you'd heat up slightly slower... but your also cool off a bit slower most likely. On the older K series engines... you ran with your oil higher to ensure you didn't get starvation under hard cornering. Baffles were made to help prevent this as well. (DO NOT overfill your oil)

If your chasing lower IATs... a better intercooler helps but it's really just a band-aid to try to fix running a turbocharger at too high a pressure and, thus, making too much heat. Running a larger turbocharger that'll flow more air at a lower pressure fixes the problem, but is going to shift your power and to the right.

It was an interesting compromise to stick such a small turbo on the car... as they really sacrificed the top end for torque in the low/midrange. That is, however, where most folks probably wanted it and where they use it for normal daily driving.

Yonder said:

As of now Just focusing on handling mods, but i do plan on getting ktuner from TSP and want to avoid any heating issues. Not sure if OP has this already but wouldnt a bigger FMIC solve this heating issue? @Chief lazy leaf @.grimace im new to understanding how the mechanics work and shit so go easy on me lol

Click to expand...

A lot of people misunderstand FMIC. The charge air temperature will be lower, resulting in denser air, but the larger intercooler can add a slight amount of drag which can somewhat negate any power gains. ... To put it simply: no, a larger intercooler will not really add any horsepower to your car. However, that’s not the fill picture, another factor is piping, some people install large metal intercooler piping (which results in higher temperatures in the engine bay and the air feeding the engine negating any benefit from the FMIC). The next issue is over heating which is rarely caused by high charge air temperatures. The biggest issue is fluid temperatures on the track, ie coolant, oil, etc... A huge FMIC has a massive design flaw, it is located directly in front of the radiator. The FMIC blocks airflow to the radiator reducing its functionality. This can be resolved by installing or creating a SMIC instead, this leaves maximum air flow to the radiator allowing the system to keep coolant temperatures at low levels. Updating the oil cooler is the next best option, like the radiator, a larger, free flowing system will reduce oil temperatures. So an FMIC is a great idea in theory, but it really has limitations (especially city and daily operations).

Chief lazy leaf said:

Stock I never had a problem, even on the hottest days going wot. I added a ktuner with the tsp1 tune. Did my first track day with it last weekend. Base tune no problem. Map 2 it got hot but was manageable. Map 3 it I would get 3 laps in and I have to do a cool down lap. Went one session like that and went back to map 2. I'm gonna add a koyo radiator and oil cooler next. See if that helps on map 3. At least keep map 2 under half on the temp gauge.

Click to expand...

I have the same tune and same experience with map 3. So I use map 2 on the track. I got a turbo blanket, thinking that might be a cheap fix, but the install isn't going to be easy, so I haven't done it.

kingbudd said:

A lot of people misunderstand FMIC. The charge air temperature will be lower, resulting in denser air, but the larger intercooler can add a slight amount of drag which can somewhat negate any power gains. ... To put it simply: no, a larger intercooler will not really add any horsepower to your car. However, that’s not the fill picture, another factor is piping, some people install large metal intercooler piping (which results in higher temperatures in the engine bay and the air feeding the engine negating any benefit from the FMIC). The next issue is over heating which is rarely caused by high charge air temperatures. The biggest issue is fluid temperatures on the track, ie coolant, oil, etc... A huge FMIC has a massive design flaw, it is located directly in front of the radiator. The FMIC blocks airflow to the radiator reducing its functionality. This can be resolved by installing or creating a SMIC instead, this leaves maximum air flow to the radiator allowing the system to keep coolant temperatures at low levels. Updating the oil cooler is the next best option, like the radiator, a larger, free flowing system will reduce oil temperatures. So an FMIC is a great idea in theory, but it really has limitations (especially city and daily operations).

Click to expand...

Yup most people talk about a FMIC like it’s a cooling mod when it’s not. Luckily the CTR oil cooler goes on the side vents where I notice the SI ones just block the radiator wtf? Weird design choice for sure

Yeah... when I see Z guys go from this...

to this...

...it makes me laugh.

Especially if they're still running stock or smallish turbos.

@kingbudd
Hell yeah haha thanks for that knowledge bomb “The more you knoooow!” Haha

EDIT: This has me wondering why isn't there more SMIC on the market if they seem to be the smarter option?

@charleswrivers
I see the STI guys do that pretty often as well. I believe their intercoolers are directly on top of the engine where the hood scoop is?

Yonder said:

@charleswrivers
I see the STI guys do that pretty often as well. I believe their intercoolers are directly on top of the engine where the hood scoop is?

Click to expand...

Yep... pretty sure they're right under the duct on the hood.

All the Z32s had SMICs. The Z31s had no intercooler for their stock 6.7# boost level. Still... the SMICs didn't affect cooling based on being completely out of the way of the radiator. The condenser was sort of near the radiator... but it was so small, the effect was minimal.

If you go stacking a FMIC... an oil cooler... a ATF/MTF cooler and the the condenser all in front of the radiator... it was really blocks it up.

If the problem is coolant temps though... I'd definitely do a small drain and top off with distilled water and consider either modifying the existing grill or changing them... as I think the piano black 'grill' aftermarkets are cheap. Remember... coolant still does a job of raising boiling point, providing corrosion protection on top of it's anti-freeze duty. It *isn't* as good of a coolant as pure water... but you should still have coolant. I've never used less than 30/70. That's good down to about 10F. 40/60 is good to about -10F. 50/50 is good to -30F. Here in SE GA and back when I was in FL... I'd do 30/70 w/no fear. In WA or NY... I was always doing 50/50. You have to ensure your ratio is proper for your living conditions. 50/50 is a good safe amount as it covers you pretty much anywhere in the US. I've heard of people doing 30/70 in very cold climates... but you'd actually hurt cooling performance... but because you're in such a cold climate, the cold ambients cover you.

Grills on passenger vehicles actually are pretty restrictive, with many of the 'ducts' being false to improve aerodynamics and make the best drag coefficients possible for improved fuel economy while sacrificing outright cooling ability. So far as bang for the buck, I'd try those tricks before messing with the radiator itself. You can see the flipside of folks blocking airflow to improve aerodynamics over at ecomodder for vehicles that can give up some cooling to try and squeeze ever last MPG out of their cars. The other effect it to improve warmup, as engines are inefficient when cold.

The manufacturer already compromised on cooling for us for efficiency. There's certainly some to be won back. You can upgrade fans and radiators... but if you've got ducts that are actually blanks... you're not getting your money's worth.

Admittedly, I've got much more experience with trying to make the most out of computer cases than cars... but when you're using air to cool... one need only look at the design if the front end to realize that a great deal if cooling ability was sacrificed for aerodynamics. Some of my greatest success hasn't been with adjusting CPU voltages/frequencies... messing with fans or heatsinks... but in making alterations to cases to minimize restriction... or to direct airflow.

Did anyone noticed any change of ECT drops by lowering the fan engagement threshold and or by removing the metal undertray, so the air as actully somewhere to flow?