Hey!

I have this Kit car which we have run and modded gently as things broke.. inc fitting a TD04 Turbo and what have you..

Trouble is, it's getting too hot on track. It is driven very hard, but the first thing to ring alarm bells is the temperatures - both Oil and Water.

So what do you think we should do about it?
Can you spot anything we have done wrong in the photos, or see anything which could be done better?













This is a shot from the back of the cylinder hear.. The CAS is on the top right to help get your bearings.. The front of the head is blocked off with the coolant re-route.

I wondered if the hot water from the Turbo sould A. Be here at all. And B. Is skewing the Temp readings - as it could be getting washed with the hot turbo water. Let me know your thoughts






Current thoughts are a thicker Radiator, and a bigger oil cooler sat upright between the Intercooler and Radiator - what do you think?

A Turbo blanket was in-use, and a malifold blanket even - until both burnt on the las track session

 

Are you getting actual boiling, or just high indications on the gauge? Water pump and thermostat ok?

Full undertray? if so are those vents the only exit for the post-radiator air? If so, those vents are too small, plus they need tabs on the front to lower the pressure over them and removal of the screens. The 'reverse NACA 'ducts I have heard are useless, dunno if that is true though, they need the tabs too. Check the fan is not running backwards, and can freewheel at speed with minimal restriction to air exiting the rad.

Can you separate the IC from the rad, and allow more mixing, or are they too tightly cowled by the nose cone? How much heat are you taking out via the IC, and is that overloading the rad? It looks like a big enough core, andI would not discount a bigger one - but you still need to get the hot air out of the engine bay.- and with a turbo that is a HOT engine bay.

To give you a general steer, the usual response to MX5 overheating is to ask 'have you installed the factory undertray?'. This cheap stock plastic thing is vital to facilitate the exit of the hot air from the engine bay - sure we talk about bonnet vents for the big hp turbo cars, but that assumes the basics (undertray, plugging gaps around the rad, etc) are in place. Search here on 'cooling megathread' for those basics.

 

Excellent reply, thanks Gee!

Not boiling no, just high temp readings on both Oil and Water

No undertray at all no. This could be made, maybe with rear facing vents.. the underside is the main way out for the air at the moment isn't it - not saying that's right.

Pleased to hear about tabs on the front, I have suggested this for an age but nobody thinks it'll do anything! I thought of swapping the mesh for rear facing louvers, with the front louver being the largest to create the vacuum. Also considered much bigger vents at the back of the engine bay to draw air out, again with louvers. Did think of making this just on the turbo side tbh, expel that hot air.





The fan does work properly and draws a lot of air through. Although the movement of the car would do that too. Gaps around the IC are closed to the nose cone yes, you can just see the thin rubber strips on the side of the IC which close the gap when the nose goes on. It has this all the way round btw.

Haven't monitored the temp difference IN - OUT of either the IC or Rad tbh. I did wonder if those stick on temperature strips would help view that.

The company which made the IC/Rad setup suggested moving the Oil cooler, even laying it flat. A fan could be added to this to ensure air is pulled through it. I'm thinking of a bigger, better quality Oil cooler too.

 

No undertray? I was expecting you to say it had a full undertray. As an experiment, I would suggest an undertray replicating the MX5 arrangement - starting under the radiator (to catch the hot air exiting, and going back say 1/3 of the way to the firewall, making sure no external air entering the hot plume.

I think the oil cooler is your canary. It suggests to me that you have fairly stagnant air there, if the fan is working as well as you suggest it should be pushing air through it, or the natural speed-related airflow should do the job.

Do you do datalogging from your ecu? It would be useful to wire in an extra IAT sensor, and position it around the back of the radiator, then move it to in front of and behind the oil cooler, and see wat the temperatures do - all in similar conditions, and/or correlate to CLT. A bit of shrouding to encourage airflow into that cooler might be a good idea too.

I'd also be talking to others running the same car, especially if you can find someone running your power output, there may be some templates for boosted cooling you can apply to yours.

I am also wondering if, while improvements can be made, the nose is simply too small for cooling a turbo car. Looking more closely, they seem pretty small up front, like most clubbies, but I have a mate who runs a compound boosted Locost clubbie and I haven't heard him talking about cooling issues.

 

if you don’t have an undertray then all the air rushing under the car stops the air coming out of the engine bay, meaning it won’t flow through the radiators properly.

The way undertrays work, is they promote the air to continue to flow along the bottom past the engine and drag out the engine bay air with it. You have high pressure in front of the radiator so you need to make the back side low pressure to pull the air through. The undertray helps achieve this as does the bonnet vents.

However the bonnet vents need to be in a low pressure area of the bonnet. I imagine totally different for your clubman, ,and may need wool tuft testing or similar to determine where the lows and highs are, but in a normal bonneted miata, the vents go just after the radiator as this is a low pressure zone. The further back they go the less effective they become, such that if you place them at the rear of the bonnet then at speed they will act as an inlet not an outlet..

Also having the raised lip on the first vane of the vent helps promote air to come up and out of the vent. Again you could prove this using wool tuft testing and videoing the tufts whilst moving with and without the front lip to show the difference.

 

Good input Rascal! I had tuft testing in my head when I started my reply, unfortunately it got lost in all the empty space up there , and never made it out.

Reason it was up there in the first place was I am, in the stinking hot weather we are having, wondering about the affect of my proposed bonnet vents on the air entering my cowl and thence the cabin. I was thinking of doing exactly that before I cut metal, put some tufts on the back of the bonnet and videoing it.

/thread drift.

 

Great replies - thanks guys!

I get the undertray idea. I just thought we get a lot of air into the engine bay, but the main way out had to be the underside as the other vents are both small, and slightly forward facing - not good either way ay! That's why I thought about the bigger louvered vent at the back by the turbo which I sketched above.

So, get an undertray on. Up to the front of the engine? So the hot air can be dragged out down the side of the engine? Many close the underside completely don't they and use vents on the bonnet to extract the air.

Gonna see if we can fit a slim oil cooler under the rad so it would face the fresh air too. It'd would be under the intercooler too so completely fresh air.

Haven't tried the wool tufting on the bonnet tbh. It's tricky as the car isn't road legal so driving it while not on a trackday is tricky.. I did try the wool on and around the oil cooler with the fan on and little air was pushed through the oil cooler tbh. Much of the air wanted to back up and exit through the gap at the top, between the oil cooler and fan. I tried a cardboard cap to that hole, in theory forcing air through the oil cooler. But you could hear the fan strain in a change of pitch. So I can't help but think the oil cooler is a bit crappy tbh.

 

Sick car! And to parrot the others, there's no way for your heat exchangers to work without ducting, I'm certain that will fix your issues. Ducting from the mouth so that 100% of air entering there is forced thru the heat exchangers. Lots of ways so do this, but you could whip up something pretty easily with Coloplast sheets.

 

Nah, seems there isn't enough room to run an Oil cooler under our rad like caterham do. We only have 40mm of space under the rad before it hits the nose cone. It is a smaller nose area on ours.

So back to the drawing board when it comes to oil cooler location.

Fireindc - cold air does hit the exchangers and is sealed around the nose cone. It seems making the area behind it a low pressure area to draw that warm air through and out is what we need.

 

OK, I missed where the heat exchangers were sealed to the nose cone When you say that, do you mean like fully sealed? Some kind of foam or something that keeps air from flowing around the exchangers? Air takes the path of least resistance so unless it's fully sealed that air is going to be escaping anywhere it can, especially the way your heat excahngers are double stacked.

And speaking of double stack, common theory is that air should be able to go around your IC and get to the rad directly. The way yours are stacked air must flow through the IC first before it even gets to the rad, there's a lot of resistance to get air flowing through both of those exchangers stacked like that. Your intercooler might be a bit oversized and part of the problem.

 

Yes, from the base of the radiator back. As Fire has said, sealing is critical, air will take the path of least resistance, and any gaps mean that a lot of air will force its way through them, not your radiator/IC/oil cooler. I am guessing because it is not what I am familiar with, but start with an undertray about 1/3 of the distance between the radiator and the base of the firewall. Be prepared to experiment. Remember, anything in front of the radiator is pre-heating the air before it even gets to the front of the radiator. That is not such an issue for the oil cooler, because both it and the radiator are directly cooling the engine, but you have limited/no choices so you have to do everything you can to make what you have work.

It is not so critical as the cold side, but try to seal the undertray it so it is just the hot air moving back, until it reaches the opening.

That is ok, just remember there is such a thing as over-cooling.

If you have space there, I be looking closely at getting that air up to the front of the radiator, including separating that IC from the radiator. If you can, just opening a gap at the bottom to allow more/colder air to enter the radiator face. ISTM coolant overheating is your first order problem, fix that, then look at what you need to do with the oil cooling.

So do it on track, either in competition, or a test/drive day. That has the advantage that it can be representative testing, repeatability is high, and it is either close to, or actually really IS, your worst case - extended high boost running. When starting out, I found that these days invaluable to be able to experiment. just go with a plan, write off the day as a fun day or a points-getter, and focus on getting the business done.

As for the oil cooler, it looks like a quality item, but that means nothing, it still needs air flowing through it. What oil temps are you reaching, and how does that relate to the max the mfr states?

 

The intercooler is the least important heat exchanger. Yours is arranged in a position of primacy. It looks good but perhaps it needs to be half as tall or an air gap could be created between it and the radiator to allow air to bypass the IC. :shrug:

Creating higher pressure in front of the radiator and lower behind it is critical. Preventing the air exiting the rad from being pulled back around and into the front of the radiator is important. Closing the engine compartment until behind the engine should help with creating a low pressure area, as mentioned. A small splitter, only as wide as the nosecone, is sometimes added to those cars to promote higher pressure in front of the radiator and to reduce front end aerodynamic lift, which is a known issue at higher speeds.

 

Gee Emm - Temps were 100 water - 115 Oil degrees C. I can't think what 'mfr states' is, sorry. We haven't data logged, just read the gauges as we drove.


Yes - Caterham cars have a much smaller intercooler mounted up at the top, which has a seperate air feed and exit. With a taller nose cone and vent higher up. It works for them.. perhaps its the best method for us too, but I'm hesitant to swap body panels and the entire cooling setup just yet.

Alu sheet on order to make the undertray.

Going to change the bonnet mesh to rear facing louvers too.

Should we add a cowl to the fan? I didn't think it was worth it given the fan almost covers the entire radiator. But perhaps it'd help with that sealing. I could seal the narrow gap between IC and Rad too, make sure the air is going through rather than dodging out the side.

We cant fit an oil cooler under the current Rad/intercooler setup, not enough space (this is how Catherham cars are setup btw, a shallow oil cooler sits under the rad and gets a cold air feed) So where do we mount ours? Considered mounting it a little further back, with it's own fan on. Which is still in the heated are, but hopefully that'll be drawn out better with the undertray..

Or, a complicated one, we mount the Oil cooler at the side of the engine (opposite to turbo) with side pods to allow air inlet and exhaust further back. Fear with this is it's really tight for space. Both making it fit and maintaining will be a knuckle buster.

 

Slight tangent.. but the Turbo nuts come loose.. what's the opinion on a solution to that?

I tried some, I think they were 'oval nuts' or something like that, which did work. But they were a wrestle to get off!

Considers a blob of weld.. Or lock wire perhaps - hmm

 

Does not seem too hot to me. Still, the remediation efforts won't hurt.

How much boost are you running on the TD04?

How much power are you making?

Are the nuts coming loose on Turbo, or are they stretching? Some form of inconel is often used when stretching (Stress Relaxation would be the proper term) is an issue.

DNM

 

The temp would carry on rising above those temps, we just back it off and allow it to cool at that point. We have broken engines in the past in NA form, so just trying to avoid doing that again.

Boost is 8-10psi. Power, not sure. Never got that reading from the dyno tbh, but perhaps 220-230 maybe. No big numbers, but we do push it hard.

Not sure how could you tell the difference between stretching and coming loose tbh. But it's come apart and blown the gasket anyway

 

Those temps are well under 'panic stations' levels, not that I am suggesting you are panicing, However we collectively have identified some issue that when addressed will help you cool more efficiently and give you more headroom for what we are here for - moah powa! Go for it!

 

Full Race sells inconel studs on their website but they aren't always where you'd expect on there, so you may need to hunt.

Some of us drilled and tapped the M8 stud holes out for M10 size and use inconel with no issues at over 300whp on track.

 

Increasing the space between the intercooler and radiator may help more cool air reach the radiator.

A fan shroud is a fantastic idea to eliminate reversion of warm air through the radiator. It made a bid difference for me.

A NACA duct in a place of laminar airflow can be made to feed the oil cooler by hose. The cooler can then be mounted anywhere. A small fan may additionally be employed to promote airflow. The NACA duct might be located in your new undertray, if that's convenient.

 

Something like this can be useful for directing air to the oil cooler