Do i need to upgrade radiator?

[peter møller]

As some of you know, I have this engine project in the works. To quickly sum things up, it will be a big bore redtop with 20V ITB´s, Schrick cams, forged pistons and different engine management (stand-alone) I am aiming at apprx. 180-190bhp.
Will it be a must to upgrade the thermostat and radiator for this.....what about oil-cooler?

[Aico]

I would go for the oil-cooler. But you're getting the gauges right? If the temp goes too high you know you need an oil cooler and/or a better radiator.

[JonT]

Most tuned engines fail beacause the oil cooler is not upgraded to compensate. Can't remember the rule of thumb for it but it was something like an extra row for every 20 hp (i'll try and find it again).

One useful radiator upgrade i heard of was using a deisel golf, as the inlet and outlets are in the correct place but it takes a 1/3 less room.

[Mux213]

Well that doesn't help you to much when you build up your car in winter and then find out the rad cant handle it in the summer

Peter, from what I understand these are the things you need to realize.

First off, running a car to cold is just as bad as running a car to hot. The thermostat does little more then regulate the amount of coolent from your radiator entering the engine and in that way it tries to keep the engine at a steady temparature. The more quickly your engine heat up, the more quickly the thermostat will open because its open temparature is reached earlier. but it is still the same temparature. It has nothing to do with the cooling capacity of your engine. The only thing you can regulate with a different thermostat is the target temparature of your engine. Now I'm sure noHachi can give a better explination of why you would want to lower (or raise) the temparature of your engine but generally speaking a different thermostat will not improve cooling at all, when your engine get hotter then it should be, thermostat will fully open bringing cooling to max, and if thats not enough to cool your engine, no brand of thermostat will rescue your engine.

Then there is the myth of getting bigger fans for your engine. You may think that having a big fan that blows lot of air will cool your engine better, but thats just a load of bullshit. Fans only are interested if you are going slower then 10kmph or going sideways (which makes them important to us drifters). Simply put, driving wind will always be loads stronger then what a fan pulls through. fans are just for cooling cars when they are not or hardly moving.

Then comes the radiator. The radiator is one heck of an important part of your cooling system. The bigger the radiator, the easier it is for the coolent to shed its temparature and thus remove heat from your engine. However just slamming a bigger radiator on your car doesn't automatically mean your car cools better. At some point other bits of your system become the restrictive part of the cooling system. Its just like with the brakes, when your brakes lock your tires, thats where it reaches the max, you can put bigger brakes on, but that wont improve braking at all.

Now here I must start admitting the amature in me surfaces The following is what I've understood from cooling (its ow so much more important in rotaries then in piston cars) from all the threads I've been appart from on the internet.

First off, the speed of coolent flow is important. Slow moving coolent means that by the time the coolent is halfway around your engine, its already heated up so much it doesn't obsorb any more heat. To fast moving coolent means the coolent doesn't get the chance to heat up and take away the heat from your engine (although I'm still puzzled about that last remark). The right watter pump is a must.

Then there is the size of coolent passages. Very simply put, there is a max cooling abillity of the passages in your engine. If you need more cooling, you need to enlarge these passages. Surface area is more important then temparature. Temparature energy flows just like so many other things, there is a maximum 'speed' at which temparature is exchanged between a hot body (engine) and a cold body (coolent) no matter how much colder the coolent gets.

Then there is the temparature of the coolent itself, now here I got totally confused myself. If the temparature of the coolent is to warm then offcourse it cant cool. But there was also an argument given that if the coolent is to cold, it doesn't cool well either. Something to do with heat transfer abillity of hot coolent versus cold coolent. It also had something to do with too large temparature differences within your engine could give negative effects. Again here the thermostat plays an important role making sure that ice cold coolent doesn't suddenly go circulating around in your engine, instead it will mix ice cold coolent from the radiator with hot coolent comming out of the engine.

How the oil cooler fits into the picture I am not entirely sure. But here overcooling becomes an even bigger issue. If you put a mega big oil cooler on your engine the oil entering into your engine will have cooled down so much that it looses its lubracating properties. Its like constantly running with a cold engine, we all knows what that does to an engine

[Widar]

If you're gonna change radiator i wanna buy your old one, mine is totally wasted.

Best Regards,

[JonT]

I recently bought a new radiator through a guy who had some new VALEO items. He still has a couple left, so i have let Widar know but there are a couple more, would be £35 each plus shipping to where ever.

[Mux213]

Jon, is it better then stock? any picture of it?

[JonT]

I'll get some pictures, still in discussions with the seller at present, trying to get the price down to secure his last three for forum members etc. They are a direct stock replacement buy the way

[Mux213]

Very nice

I dont need a new radiator but I could do with a visual upgrade

[Widar]

JonT Wrote:They are a direct stock replacement buy the way

Direct stock = less work for old Widar =