High temps in summer heat.....suggestions please.

[maxgus]

Hey Guys,

I supercharged (rotrex) my car about 4 months ago and have been loving it. So far haven't really had any issues other than a vacuum leak coming from an injector due to old seals being re used. Now I totally understood that the temps were going to get higher once the s/c was installed so I upgraded to a 32mm core koyo alum radiator. Everything was fine until the full brunt of summer kicked in.

The issue I have is that if you turn the A/C on the temps rise pretty quickly reaching the 3/4 mark on the temp gauge. Not overheating as such but hotter than I would like it to run. It had a major service before the charger was installed so the thermostat was changed as was the coolant. I have since flushed the system out twice and refilled with new coolant. I have replaced the radiator cap and recently installed after market fans and shroud as well. Have spoken to the guys at Mx5 plus regarding coolant re route but they advised that this probably wont help my situation. Have also spoken to red devil radiators and they are not really sure either other than to drop it in for a look. Pretty sure relocating the oil cooler would be a positive......painful job though.

Ok so the set up is as such. Of course there is an intercooler out front that will block some of the airflow and on top of that the oil cooler for the S/C is mounted directly in front of the A/C condenser. I totally understand that this is all contributing to the issue. Runs fine without the A/C on or in the cooler months with the A/C on. I have all the factory plastics in place to keep as much of the airflow to the radiator as possible. This issue happens both around town and on the highway.

Has anybody else had this issue or can anyone throw ideas at me. I might have to look at venting in order to reduce under bonnet temps. I am looking at installing water and oil temp gauge very soon. Any advice would be appreciated.

Thanks
Angus

[Magpie]

Is the OEM undertray installed, i noticed you have said that all the plastics are in place, but just checking.

What you may need now is to seal around the radiator with foam from Clark Rubber to ensure that all the air is going through the radiator. By the time air hits the radiator it will already be hot so the key is getting more air through.

Are your fans running the right way?

[maxgus]

magpie pmd you by mistake.

[maxgus]

Yes the undertray is in place and I have sealed the top but not the sides and bottom. Next job on the list. Have just thrown a higher pressure rated rad cap on. Probably wont help but cant hurt. Looking at radiator cooling panel as well.

[hks_kansei]

Get the system pressure tested, there's no point in having a high pressure cap if it's got a pinhole leak somewhere.

Also look at things like the water pump.

I'd also look into having the radiator flushed properly (the stuff you pour in can only really get rid of smallish scale and gunk, heavier sh*t needs a proper flush where the end tanks are removed and the core is blasted clear)

[davekmoore]

You should be worried if the gauge gets above 1/2.

This is one of many threads on the interweb about potential solutions: http://www.miataturbo.net/race-prep-75/ ... ead-79930/

[maxgus]

Hks - Radiator is a few years old so might need a proper clean out. I was thinking about getting a pressure test and will try to get it done tomorrow. Had its 200k service done and water pump was replaced so I imagine its fine. Thanks

Dave - Yeah I'm a bit worried. Thanks for the link.

[cookie]

Fwiw, mine starts to get warm on traxk, but never in the city. Stock radiator and spal slimline fan to replace stock ac fan, both fans wired in parallel. Mayne try that as a cheap idea, tales two seconds. My ac gets overpowered now there's an intercooler in the way be radiator handles it fine, even with hard driving in traffic in mid 30's.

[Danny]

Get rid of the anti-freeze. Try this http://www.nulon.com.au/products/Coolin ... .VJNiu7AQ0.

You could do a drain, flush and fill with distilled water to see if it's going to be cooler. Should be as water is the most efficient. If so add the Nulon for it's corrosion protection and keep away from the snow.

[trader]

I'm running a rotrex on my 1.6. It is a stock kit using the stock ecu but it uses a different fuel regulator than the 1.8 kit unless you have a tuned ecu. The big plus with the rotrex is it runs cool so you should not be having overheating problems especially with intercooler. I've had mine out on hot days with A/C on and it never goes over halfway.
I run with no 'plastics' or undertray but do have coolant re route. I put that on at the same time as the rotrex so not sure if that improved things although it certainly delays the initial warmup time. I also have a Koyo radiator.
If its happening around town (when the rotrex is just spinning) and on the highway I think it would point to some other issue.

[davekmoore]

My reroute speeds up warm up - a lot. There must be different types.

[rascal]

My reroute speeds up warm up - a lot. There must be different types.

Agree with Davek here.

The reroute means the water going back to the radiator passes all cylinders rather than just the front couple so it would absorb more heat and so warm up quicker..
Did you fit the bigger radiator at the same time also?

[Magpie]

Bigger is not always better in radiators. A thicker radiator relies upon greater surface area, however this also increases the resistance of the air moving through it. As resistance increases the capcity for the air flowing through to absorb heat is decreased.

What a thicker radiator is good at is having a larger volume of coolant in the system. There have been recent posts of 1/2 size radiators being more than effective at the track. Further Danny's MX5 20BPP radiator was too efficent and it needed to be slowed down to allow heat to build up in the system. Both of these systems had small fans but relied upon the air flowing through to produce the cooling. In fact Danny notes that the fan is only there for when stopped.

You need to consider what is the pressure on both sides of the radiator. To get more flow you either need to increase the pressure on the outside of the radiator or decrease the pressue in the engine bay.

Also consider the post about getting rid of the anti-freeze especially if you are not in a very cold environment. Even look at http://www.evanscoolants.com.au/.

[trader]

If you read the 949 racing website it agrees with comments made here. In my case though the re route definitely takes longer to heat up (I run two NA's and have monitored them closely). My view is that the coolant re route has improved my system to a degree that I have no overheating -I have a thermostat that has two weep holes in it though...

[maxgus]

Thanks for the help guys I appreciate it. I am as we speak dumping the coolant (again) and replacing with redline water wetter and demineralised water. I will see if that makes any changes and go from there.