[Mikster]

Got a GTS-T race car with an RB26 twin turbo engine pushing 520bhp. Engine is new, almost stock and mapped with AEM. It runs really well, very responsive and has no fuelling issues, mixture is a bit rich too to keep it cool.

However it does get really hot after 7-8 laps. Water temps go over 120c and it boils over. Weater was hot though, 25c plus, but I had 2 electric 11inch fans switched on through out the race on the radiator. This is annoying as I have to slow down. The tracks here are short and bendy so you dont really get longish straights to provide lenghty spells of cool air through the radiator.

I have a Koyo radiator and large oil cooler. I will try to create a shroud for the radiator to focus airflow better and have ordered a cooling panel to help that too. Coolant is normal high quality stuff.

What are peoples experiences with RB26 engines and hard track work?

Btw - dont think its the headgasket, perhaps the thermostat is a little sluggish and the radiator lid is leaky. But is that enough to cause this?

I am running Catrol Motorsport 10w/60 oil which is possibly too thick, so will try and change to 5w/40 before the next outing. That might help too.

Appreciate your thoughts.

Cheers

 

[ru']

Out of interest, what were your oil temps when the water was 120C+ ?

 

[Mikster]

I think around 120c Oil temps.

 

[herman]

water temps

have you tried putting in a water addative that keeps the runnig temps lower?ive just bought some engine ice and ive been told to put distlled water in as will keep temps down to.as i havent run with it yet i cant cofirm if it works or not.

 

[Chris Wilson]

In my experience with these things anyone who genuinely nails one on a track will need to use the original type engine driven fan. If you think about it in basic terms, the engine fan, with the viscous fan clutch locked up fairly hard (clutch "feels" very hot air from rad and locks up more) takes about 4 BHP to drive it. If you had two electric motors driving fans with similar pitch and air flow capacity to the the stock fan the two, 2 HP electric motors would have to be ENORMOUS and driven off cable like battery cable. These small electric fans are fine until you get on track. Add a none stock FMIC that limits air flow, or fiddle with the stock fan ducting, remove it altogether, or even worse, remove the stock engine driven fan and duct, and you will see abnormal temps. These things need both forward motion air flow AND the engine fan with the stock sealed fan shroud (duct)

You will find keeping oil temps down with a big thermostatically controlled oil cooler, and removing or by passing the stock oil to water heat exchanger (under the stock filter) will take a BIG load off the water cooling rad. I used a 39 row cooler on my GTS-t with just a modded RB25 engine in it (that makes about 410 genuine BHP) When the install of the new RB26 engine is done I expect it to struggle and I may need to go bigger still on the oil cooler, depending on weather conditions.

If it's been mapped "safe", and you say it runs rich, it may also be mapped retarded. This can certainly raise temps. It may well pay to add some advance and run better fuel, if the timing is octane limited to a large extent.

Finally, GO NOT be tempted to try and get more heat out of the engine bay by raising the windscreen end of the bonnet up with hinge spacers. Where do makers put the heater air intake on cars? The base of the front screen! Why? Because it's an area of very high air pressure in motion. Why does raising the rear of the bonnet do harm, not good? Because this high air pressure actually goes into the under bonnet area to disrupt hot post radiator air flow from passing down the sides and atop the engine to exit down the transmission tunnel and out under the car. Any car post the early seventies will have have the air into and OUT of the heat exchangers carefully considered and managed, fiddle about at your peril. Leave the under engine bay shielding in place, too.

Hope something there may help.

There should be some photos of my oil cooler set up on my ftp site, have a poke about at ftp://ftp.chriswilson.tv under any Skyline_Stuff directory. It's disorganised, but you should be able to find them. BTW, you need big oil lines and fitings for these things, some of the kits I see fitted are barely worthy, flow wise, for an N/A 1 litre 4 cylinder race engine, let alone a modded twin turbo 2.6 six pot. Dash 12 is what you really need, hose and fittings wise, with a high flow adaptor filter adaptor plate. Remote oil filters are unnecessary and add plumbing length, unions (which by nature are ALWAYS restrictive to some degree) and complexity.

 

[Sub Boy]

Not being anywhere near as knowledgable (that doesn't look right...LOL!) as Chris Wilson on cars/engines....But my 2c,

I am running the same power as you, with a large radiator and a oil cooler (In prob not the best plase for it...in front of the Rad!) and run the car on my locar track that is small and tight, And still run the Vis-Fan from standard, and only get water temps as high as 90deg, and oil at 85deg with about the same laps.

hope this helps...

 

[Mikster]

Thanks for the feedback. I will have a look at your suggestions.