Overheating?

[dbr]

Davekmoore,
How much boost are you running in your SE?

[davekmoore]

Thankyou again for your reply.
I had read throught this thread but the specifics of which radiators work is not covered other than "over 40mm thick".
The performance of radiator varies even if the tube thickness and fin density are the same, depending on details such as the sharpness of the fin forming tool.
Without the oppertunity to test the radiators, the best indicator is the experience of other people with similiar cars.

The change due to the oil-air cooler is probably primarily due to the removal of the standard oil-water cooler that rejects its heat through the radiator. The oil-water cooler have the advantage of warming up the oil during cold start opperation, improving lubrication and fuel consumption (less pump drag). An alternative to improve the cooling for track days maybe to temporilly remove the cooling fans and shrouds. The fans provide air flow during low speed opperation but the shrouds restrict the amount of air that can flow through at high speeds. Use the cooldown lap to cool the turbo so that you don't need to idle to long in the pits.

All due respect and thanks to dbr but is this confusing only me or is much of it just the opposite of what other people have been saying to me?

[dbr]

One way to see who is right would be to try removing the fans next time you are at the track. It is a lot cheeper than buying an oil cooler kit.

[davekmoore]

One way to see who is right would be to try removing the fans next time you are at the track. It is a lot cheaper than buying an oil cooler kit.

Thanks but I've already invested in the oil cooler kit based upon heaps of advice from people who've done the same.

For what it's worth, and I'm not worried about who's "right", just whether my motor stays safe, another way would be for you to bring a turbo MX5 to Sandown in Feb without rad fans and we'll aim for similar times and compare our engine temps?

[bigdog]

Technically dbr is correct - a good radiator operating at high speed requires no fans to achieve optimum cooling, and the shrouds around the radiator are only effective at lower speeds. You wont find fans or rear shrouds on any open wheel race car or race built sports car. However your car needs to operate in traffic as well, and the fan/shroud arrangement is designed for this environment. The other variable is time spent idling on the start grid/dummy grid - plenty of race cars have cooked engines during delayed starts etc. My clubman racecar doesn't run a fan or shroud, and can idle on the start line for about 3 mins before I have to shut it down. So, in your case Dave, you could well improve your cooling on the track by removing the fans and shrouds and monitoring temps on a proper guage, but it is a fair bit of fiddle for a weekend warrior, and it sounds like the oil cooler is doing all you need anyway.

[davekmoore]

Technically dbr is correct - a good radiator operating at high speed requires no fans to achieve optimum cooling, and the shrouds around the radiator are only effective at lower speeds. You wont find fans or rear shrouds on any open wheel race car or race built sports car. However your car needs to operate in traffic as well, and the fan/shroud arrangement is designed for this environment. The other variable is time spent idling on the start grid/dummy grid - plenty of race cars have cooked engines during delayed starts etc. My clubman racecar doesn't run a fan or shroud, and can idle on the start line for about 3 mins before I have to shut it down. So, in your case Dave, you could well improve your cooling on the track by removing the fans and shrouds and monitoring temps on a proper guage, but it is a fair bit of fiddle for a weekend warrior, and it sounds like the oil cooler is doing all you need anyway.

Yes bigdog. I prefer to turn up at the track in the same car as I use on the road for 55,000+kms or more a year and just take out the contents of the boot, wind the Tiens fully hard instead of fully soft and pump the tyres up from 27psi to 40. End of. Although I also take your point about proper gauge(s) and this is on the agenda.

If I get more serious and find myself working the motor hard enough to challenge the existing cooling arrangements (I wish) I'll look at a coolant re-route then a bigger rad. And hey, I might even mess with setting the rear shockers a bit softer than the fronts. And/or putting my old wheels and worn out PP2s on. But that would be it. If I ever get the bug so hard that I need a car without fans or rad shrouds then that will probably still be BARMY but he'll be retired fom the road and I'll be using a Falcadore wagon or a campervan as my DD.

[davekmoore]

Oil filter relocation kit pics below. Along with Redline Water Wetter, an oil cooler, the extra oil volume because of the cooler and the relocation kit, and a high pressure radiator cap, this has proved to be a complete temp control solution. And all without jeopardising airflow to the over-size intercooler as the oil cooler is behind it.

Filter relocate small.jpg

Filter relocate small II.jpg

Just need to find another space for the airhorn now.

[deviant]

Where abouts and how is your oil cooler mounted?

[davekmoore]

Where abouts and how is your oil cooler mounted?

Low down between rad and IC. Not perfect but effective.

Forgot to mention that the rad was also thoroughly flushed while it was off.

[NitroDann]

Ive just read this entire thread and noticed that there isnt enough information to answer your question, so a lot of the answers are not going to be 100% relevant.

Things to remember,

Cooling while moving relies on a few things, you need to produce less heat than your cooling system can rid.

Heat production is based on a few things, how lean your running, how much timing, too little is a guaranteed overheat, how much power your producing (remember that is is the power the car is making at the time it overheats, not peak power, unless you overheating at full throttle)

Cooling relies on,
The efficiency of the heat exchanger surface to take heat from the liquid and give it to the air, this depends only on the material its made out of, ie aluminium or copper

The total surface area of the exterior has to match the total internal surface area, ie, if its twice as easy to transfer from water to radiator than it is from radiator to air it needs twice the internal surface area on the outside.
So basically this comes down to good design, and of course total size

Finally the last two are delta T, or difference in temperature, and actual airflow.
Delta T refers to the fact that a larger difference in temperature results in fater heat transfer, so cool air cools greater than hot air obviously.
Airflow relates to lots of things, frontal area helps, as it means more air hits it, then there is ducting to force all the air through it not just around it. and of course restrictions, including the thickness of the rad itself, the fans, the shrouds,

and lastly to get air through the radiator the air that has been throug needs a way to get out of the road, ie venting.

Fans ONLY help when your car is travelling at jogging pace or less.

Put your hand behind them when they are running and compare this airflow to what hits your hand when you put it out the window in a moving car, its ONLY to stop a stationary car from overheating.

Improving any of these will decrease engine temp, and doing things like adding a higher pressure rad cap or using glycol will increase the temp before actual boiling.

Dann

[MX5T]

Have you checked your boost map? Is your turbo running in it's efficient range? If not it'll make more heat than any radiator can get rid of - been there!

[NitroDann]

That wont affect him driving street speeds and street sensible as i believe this thread is about.

Dann

[davekmoore]

Thanks for the recent contributions to what is now quite an old thread.

The only issue I had was with a gurgling noise one very hot day when I parked BARMY nose down on quite a sloping drive. Although the "gauge" stayed dead centre I was a bit concerned about localised high temps in the system in this very rare combination of circumstances. Since then, a flush of the radiator, the addition of a high pressure rad cap, and a kit which includes an oil cooler, a filter relocation mount and the associated greater amount of oil being kept at a lower temperature, have together resulted in no more gurgling. And no sign of the gauge moving from dead centre under any circumstances.

[davekmoore]

Sorry if this is a near re-post of what I wrote earlier today. At the moment I think I pressed a wrong button and didn't post it. Anyway, I've now got better tyres and lowered the suspension and the driver might have get a bit quicker. All these together resulted in a tendency this week at Winton for the temp gauge to threaten to move off dead centre again.

Flushing the radiator, going to a high pressure rad cap and oil cooler plus a filter relocation, which means there is more oil doing more cooling, had previously dealt with any potential to get too hot.

So is the consensus (remembering that I'm not a spannerman and live in the depths of country Vic) that I should get along to my local radiator specialist for a bigger rad and the coolant re-route?

[NitroDann]

Depends where you are asking.

If you were on a large turbo mx5 only forum, the concensus would be reroute and ducting. Depending which model you have. Now im 99% sure your head gasket has eliminated the need for a reroute, but I would need an MSM expert to confirm that.

Dann