Still have cooling woes. Thoughts on running K1100 without thermostat?
Turbo Mini Forums

Looking for input on this.

I don't know what it is with this block, but many years ago I never has a single issue with cooling. I used to brag about how my mini never overheated, was easy to control, all with a stock pump and super two core. Then I changed the block so I could retain my pistons - same water pump, crank, rods, rad, ECU, cranks sensor, everything - and immediately struggled to keep the thing cool.

Fast forward a few years, and I do the K1100 conversion, and figured that dry-decking the block would fix the issue - but no - it still runs hot. I'm now convinced that some blocks have a lousy core or something else that affect this; maybe reduced surface area or capacity compared to other blocks.

Anyways, I installed one of the bling alloy radiators, with a shroud and a new, much more powerful Spal fan (that could suck a bowling ball through a hose pipe), instead of the super-2 core and fiat fan I was running, and it's manageable, but the fan is still kicking in and out even under light cruise at 30mph with lots of airflow (on at 87 deg C off at 83 deg C) despite the thermostat being well open 10 degrees earlier.

I pulled the thermostat last night and checked it - it is opening at 72 deg C, and fully open by 76 deg C, and closes very similarly - a nice responsive thermostat. It already has three 5mm holes around the outside to allow for some circulation. I also have a small air-bleed tube (3mm bore) to vent to top (#4 end) of the head water jacket back into the top of the rad.

But as I'm typically dealing with weather that is usually no cooler than 30 and occasionally above 36, it isn't exactly like being in Manchester, so is a little more of a challenge.

I'm considering running without the thermostat to see how that goes, at least for the peak summer months, just wondering if anyone can think why this would not be beneficial?

Why do you think removing it would help? Personally never really get that theory.

I think that you are trying to run it too cool and don't have the temperature differential to get the heat transfer.

Personally, I would put a 85 Deg C Thermostat in and wind the fan settings up to 95 Deg C on.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Never remove a thermostat without replacing it with a sleeve or it messes up the circulation

Edited by TurboDave16V on 9th Jun, 2018.

Edited by TurboDave16V on 9th Jun, 2018.

Yes, differential to ambient.

Why do you try to run it so cool? Modern oils can run much hotter than the the old stuff.

Also a higher rating thermostat will slow down the water flow meaning that it has more time in the rad to cool. OK, the engine will have more time to heat the water but the lower water inlet temp will cover it.

Edited by Paul S on 9th Jun, 2018.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

I guess I'm trying to just keep it far away from the high temp zone, and give myself more of a buffer for when I do get "into it". Admittedly I've kept it below 12psi up to now, but 20+ is on the cards.

do you still have the mechanical fan?

Dave, sorry about the comment re thermo sleeve, you are right of course.

Terrible thing getting senile !!

Running it cooler would mean less chance of detonation wouldnt it?

..

Edited by Sprocket on 10th Jun, 2018.

It’s a trade off with higher cylinder wear rate. Unleaded fuels apparently burn better with engine tums nearer 90c but I have no evidence to this, but the wear is documented in several publications.

The theory that running an engine cool will increase performance as there is more fuel in the cylinder is a little flawed. The extra fuel is required to build up the fuel film in the engine surfaces. Most of the extra fuel exits the exhaust as hydrocarbons rather than carbon monoxide.

I don't run a stat in mine at all. usually runs at 85-90 deg during race conditions. Although a few weeks ago during a 45 min endurance race I did get to 105 deg, but it didn't chuck it's water out or complain at all

Team www.sheepspeed.com Racing