Overheating on load - Larger aftermarket alloy radiator?

[uzz320]

I have been having some issues with overheating when the engine is at high load for greater than normal periods (such as long steep hill climbs, gymkhana, repeated 0-100 runs) ever since I have had the car. Driving around town or on the highway I never see a rise in temperatures, there have been a few times on very hot days where it has crept slightly but never inexplicably (i.e. there is always either high ambient temp, or I am stressing the engine).

If the car was only driven like most cars are (e.g. your average camry), this would probably not be an issue - the problem is that I want to do at least hillclimbs and gymkhanas in it, and also to be able to go for a spirited drive in the hills without having to watch the temp guage and temper my throttle accordingly (defeating the purpose of the car really). I have read all the threads that I can find RE overheating, alloy radiators etc but I have yet to see any direct comparisons between the stock radiator and the aftermarket (thicker) alloy radiators. I will come back to this, now to my options:

I have seen that a few on here have the Golpher (Gopher?) brand alloy radiators (http://www.ebay.com.au/itm/MITSUBIS...=AU_Car_Parts_Accessories&hash=item3f20a3ce74) and have seen no real negative feedback. They have a 40mm core, and will allow me to retain the current plumbing of my auto trans cooler lines.

The other option I have found is from Winner Racing (http://www.ebay.com.au/itm/aluminum...r_Truck_Parts_Accessories&hash=item20bc5821e1). Has anyone had experience with one of these? I have no idea of the quality, or the fit unlike the Golpher. The only reason that I would even consider it is that the core thickness is 56mm. Does anyone have any opinions (or even better, facts) as to the benefit of the extra thickness on cooling potential, or the potential problems with making it fit?

Are there any other options out there that I have missed?

Back to earlier, has anyone got any temperature comparisons for stock v alloy (engine temp over the same steep hill on similar days, temp drop across the cores etc). I am working on getting Evoscan running to log some temperatures, so I should be able to answer that in the future - can anyone confirm the correction needed to the temp value displayed in Evoscan? I think i reads 8 degrees too high...

I am intending to keep the stock fans as I have never had a problem at low speed, and am also looking at making some sort of front shroud to direct all the air from the grill opening through the intercooler, condenser then radiator rather than have some of it disappear into the wheel arches. Any input with regards to that would be appreciated

Thanks in advance,
Martin

 

[Guest]

I have a very similar looking Radiator in my evo 7, also chinese, I believe winner racing sell the same Alloy radiator ad I bought from Asi_Performane on ebay so I would hazard a guess it would be the same quality, most likely from the same manufacturer (just speculating by looking at it and what else they sell)

Mine was $150, looked very similar, performs and fit perfectly and had a lot of solid reviews from people in big power and track Evo's, so I have all the faith in the world in it. I would take a gamble on personally.

 

[uzz320]

I have a very similar looking Radiator in my evo 7, also chinese, I believe winner racing sell the same Alloy radiator ad I bought from Asi_Performane on ebay so I would hazard a guess it would be the same quality, most likely from the same manufacturer (just speculating by looking at it and what else they sell)

Mine was $150, looked very similar, performs and fit perfectly and had a lot of solid reviews from people in big power and track Evo's, so I have all the faith in the world in it. I would take a gamble on personally.

I guess the next question then is whether or not it will fit with the stock fans (will definitely need some massaging, as the golpher does).

 

[Guest]

Mine barely fit the fans in without the shroud touching the radiator hose (about 8-10mm clearance) because the top tank is a lot wider ad thicker than the factory plastic one. Fan bolted on perfectly though.

 

[fieldy107]

it will fit with the stock fans, but only just. mine also has a 40mm core and it just touched the front turbos heat shield so I had to give it a bit of a push to get it in.

 

[jungle]

Golpher is fitted to many cars now, zero neg feedback, plus it'll allow you to run transcoder if you get the auto version.
Be careful going much thicker than 40mm for street car, the aircharge will have a harder time getting through that after going through you aircon core, intercooler and finally your radiator.
You will need to trim some of the plastic on your oem fans shroud, but that's easy as.

Experience. Well my track car (6 cylinder turbo) uses a 40mm core, no issues. A mate runs a 55mm PWR core on his street car, even with the God of electric fans, a 3000cfm SPAL, we had to install another pusher on the front to keep it cool on the street. So you decide.

Thicker isn't always better......THAT'S WHAT SHE SAID

 

[uzz320]

I suspect that the 56mm may need too much of the fan shroud ground away, and I was thinking along the lines of what jungle has said regarding the thickness being a problem with low airflow. Does the 40mm keep the VR4 cool enough? (I assume your track car is not the Legnum) With the stock radiator, the temperature is managable but I can't be on the power as much as I would like. From what I can gather, this is fairly normal for the stock radiator (from what TME_Steve said whilst on the dyno and on the 40 min drive to the airport - got warm on dyno, was perfectly fine in traffic). Has anyone had any heat issues whilst running the Golpher?

 

[AKKO]

Have you checked out the Koyorad Spec-R offerings for comparison?
Mines being fitted next week...

Refer - http://ozvr4.com/forums/showthread....adiator-and-Gopher-Radiator-Any-other-Options

 

[uzz320]

Have you checked out the Koyorad Spec-R offerings for comparison?
Mines being fitted next week...

Refer - http://ozvr4.com/forums/showthread....adiator-and-Gopher-Radiator-Any-other-Options

Where are they available from, and at what cost?

 

[AKKO]

^ see page two...

 

[uzz320]

Thanks

Does it definitely fit with the OEM fans? if so, can you please take some photos of the clearances once fitted so that I can guage whether a 56mm will likely fit? (I know thats only a few mm extra, but I suspect it to be tight) I have no doubt the koyo it is a great radiator, but I can't quite justify the price - well I probably could if I tried hard enough. Any data on performance?

 

[TME_Steve]

Hi Martin, I can't give you data of car a with different radiators but I can tell if a car has a stock radiator without looking while its on the dyno. The stock radiators will go to a higher temp than the bigger rads after 1or2 runs. After a few runs even cooling down between each the temps will be consistently higher at the end of each run with a stock rad.

as for thickness, I too would be careful of that, WRX intercoolers are a classic example of this (and more prone to the problem being perpendicular to natural airflow) but the really thick cores generally perform worse than the marginally thicker than stock cores due to lack of airflow.

Remember too that you have already increased resistance with a bigger intercooler in front of the radiator.

The other thing you well probably have to do is black the areas around the radiator so air is forced through it more. And copper cores transfer heat better than aluminium cores but obviously weigh more, your call

 

[uzz320]

Hi Martin, I can't give you data of car a with different radiators but I can tell if a car has a stock radiator without looking while its on the dyno. The stock radiators will go to a higher temp than the bigger rads after 1or2 runs. After a few runs even cooling down between each the temps will be consistently higher at the end of each run with a stock rad.

as for thickness, I too would be careful of that, WRX intercoolers are a classic example of this (and more prone to the problem being perpendicular to natural airflow) but the really thick cores generally perform worse than the marginally thicker than stock cores due to lack of airflow.

Remember too that you have already increased resistance with a bigger intercooler in front of the radiator.

The other thing you well probably have to do is black the areas around the radiator so air is forced through it more. And copper cores transfer heat better than aluminium cores but obviously weigh more, your call

Thanks Steve,

How many degrees difference are we talking roughly? (at the end of dyno pulls - stock v thicker alloy)

I definitely intend to block the gaps around the radiator, and I think it should make a fair difference too. Has anyone done this and put some photos anywhere, I would love to see how they blocked it, mounting points etc.

 

[TME_Steve]

Say 102 vs 96.... (Evoscan reads 6 degrees above that)

Bradc blocked his off, don't know if there are pics

 

[ersanalamin]

Hi Martin, I can't give you data of car a with different radiators but I can tell if a car has a stock radiator without looking while its on the dyno. The stock radiators will go to a higher temp than the bigger rads after 1or2 runs. After a few runs even cooling down between each the temps will be consistently higher at the end of each run with a stock rad.

as for thickness, I too would be careful of that, WRX intercoolers are a classic example of this (and more prone to the problem being perpendicular to natural airflow) but the really thick cores generally perform worse than the marginally thicker than stock cores due to lack of airflow.

Remember too that you have already increased resistance with a bigger intercooler in front of the radiator.

The other thing you well probably have to do is black the areas around the radiator so air is forced through it more. And copper cores transfer heat better than aluminium cores but obviously weigh more, your call

so which one is better to fight the heat, copper radiator or alloy radiator?

 

[uzz320]

Copper has roughly double the thermal conductivity of Aluminium alloy, however the alloy radiators are normally more effective. This is because copper cores are normally made of brass tubes with copper fins, which are attached together with solder. The solder has poor thermal conductivity which effectively negates the benefits of the copper fins. With radiator design, it all comes down to the small details. External and internal surface area, design of the fins and internals to create turbulence and the effect this all has on the flow rate of the coolant and air have a greater effect than the material does. In fact a radiator with smaller dimensions, but more fins, can be more effective than a larger unit.

In reality, a good brand (which has been well engineered) copper radiator would likely be better than a poorly designed alloy radiator. In the copper radiators, the only options always seem to be well regarded brands - this may be why they have a reputation for better performance, rather than the inherent benefits of their construction material.

 

[uzz320]

I am going to add to that. Assuming you did have a fully copper radiator, copper is not as strong as aluminium alloy and is prone to bursting under pressure (well it will deform more easily when heated anyway). The tube wall thickness therefore needs to be increased, normally it is double that of an alloy radiator. As wall thickness (t) has the same degree of effect (although inverse) as thermal conductivity (k) on the overall energy transfer, the doubled t value offsets the doubled k value of the copper core. This means that in practice, copper and aluminium alloy will perform the same.

 

[rbrtpalin]

Interesting issues and info guys.
I too experienced the overheating issue on the track after 4-5 laps. When driving hard for extended periods, the temp increased right up.

I have not been back to the track, but have since installed a Gopher radiator with no issues.

Would love to know if there are any other common issues that can cause the overheating problem at consistent load - thermostat etc etc.

Cheers
Rob

 

[uzz320]

Interesting issues and info guys.
I too experienced the overheating issue on the track after 4-5 laps. When driving hard for extended periods, the temp increased right up.

I have not been back to the track, but have since installed a Gopher radiator with no issues.

Would love to know if there are any other common issues that can cause the overheating problem at consistent load - thermostat etc etc.

Cheers
Rob

Yes there are a few . I would be very keen to see the difference the new radiator made for you - which is hard to accurately measure unfortunately.

There are a number of factors that impact on the ability of the cooling system to cope with the amount of heat the engine produces on consistant load. The more obvious and serious are a stuck thermostat and a blocked radiator. If a thermostat sticks shut, it will be very easy to notice there is something wrong - normal driving will not be possible without seeing temps skyrocket. The more common problem is thermostats not fully opening due to corrosion etc; this is more difficult to diagnose as there will be coolant flow, but not enough to be working at 100%. Thermostats often fail after being overheated, so if you have any problems the best first step is to change the thermostat and coolant. When the thermostat opens, it also blocks a bypass channel in the block which allows coolant circulation through the engine while the thermostat is closed. If the wrong thermostat is fitted, or there is a problem with this part of the thermostat for some reason, coolant will not circulate the radiator at the full flow rate as some of the coolant will be going through this byass and recirculating the engine. The coolant itself can also play a huge role, specifically the ratio of water to antifreeze. Antifreeze, ethelyne glycol, both lowers the freezing point and raises the boling point of the coolant mixture; it also has additives to help prevent corosion. Its effect on freezing point is of no concern to most in Australia, however the effects on boiling point are helpful:

Most people tend to run a 50/50 mix which bumps the boiling temp up by around 8 degrees C. The side effect of this is what happens to the specific heat of the coolant mixture; specific heat being, in the following graph, the amount of energy required to heat up 1 pound by 1 degree farenheit. It is essentially the ability of the coolant to absorb energy, as once the coolant reaches the same temperature as the engine there is no longer any energy transfer; the same deal goes with the air passing through the radiator.

Based on this, water is the most effective coolant when only cooling ability is considered. As you increase the % of antifreeze you will notice a higher temperature when really pushing the car. By running 100% water at the track, you are getting a free 15% increase in the cooling systems capacity to remove heat. If you put too much anifreeze in for street driving (very common) you will be reducing cooling ability.

The other problem that many of us create is the modification of air flow through the radiator. The fitting of an aftermarket intercooler, trans cooler or power steering cooler all reduce the effectiveness of airflow through the radiator. This is due to their impact on air pressure (as flow is dictated by pressure differential across the core) and the fact that they raise the temperature of the air before it gets to the radiator.

There are so many factors at play in the cooling system of cars, most of which are ignored - I will go into more detail one day Hope this has been helpful to someone...

 

[TME_Steve]

Remember too that the boiling point is different under pressure (higher), that's why if your cap fails water will boil out etc etc.

Nice graphs Martin.