205 Turbo Overheating, ignition related?

[wicked 103 3 Cars]

If you have the coolant out, I would replace the thermostat as well, or check in some boiling water if it opens up completely. 

 

Up next I would take Peters advise to try some high octane fuel. 

[lahondal 17]

Already checked thermostat and seems to open fully. 

 

Will replace it anyway, as long as the waterpump and fit an HEPU unit althought seems in perfect working order and a reputed brand (SKF). 

 

I think i can see (not write) the ignition map we have at the ecumaster and post here if it will help in anything. 

[lahondal 17]

Other idea i had was to panneling the rear of the rad and only leave a hole for the fan (it is a 12" race unit 1800cfm capable), and run it always to see if the air is really passing throught the rad. 

 

I have seen this setup on various racecars and prototypes when rad is located in the rear or similar and seems to work fine.

[Thijs_Rallye 87 4 Cars]

Posting the ignition map wouldn't hurt no.

What I also am wondering about: if the engine has (almost) overheated, have you bled the system after that? What kind of power are you making with this engine?

 

Maybe it is point boiling somewhere.

[lahondal 17]

The coolant circuit was bled several times with every modification and part check with same results, its difficult to make the same mistake every time but  at this point with a lot of things tried can be a system design problem which avoid to properly bled the circuit, im open to all theories. 

 

I have some possibly useful info. 

 

-Return line from thermosthat to waterpump is direct along the back of the engine and near the exhaust manifold (the stock turbo return line was used and modified) and have a aprox 14mm ID pipe. Tried to restrict it with a pair of pliers on a race and didnt feel any difference at all. 

Can we make two 6mm holes in thermostat and blockoff this return line? 

 

-Coolant reservoir is maybe a little low on its position, with coolant at level it barely sits about 1cm above thermostat bled ports and 4cm above radiator top bled port.

 

-Waterpump was a SKF unit with blue plastic blades. Will be replaced by a HEPU with metal blades soon. 

 

-Thermostat is 82°C version, not modified. 

 

-Radiator is new, a BMW E36M Mishimoto unit. 

 

-Front of the rad is "panneled", i mean the rad fills the original rad hole, between headlights. I dont have either fiberglass skills and much space to make a shroud with the oil cooler and intercooler on the way. Worth place a flat sheet of aluminium over entire rad at aprox 3cm height and run a pair of big 4" or similar flexible pipes to a good place in front of balance? Or that will be a silly idea? 

 

Hope this info is useful. 

 

 

[lahondal 17]

16 hours ago, Thijs_Rallye said:

Posting the ignition map wouldn't hurt no.

What I also am wondering about: if the engine has (almost) overheated, have you bled the system after that? What kind of power are you making with this engine?

 

Maybe it is point boiling somewhere.

Sorry we are making only 230hp and 320nm at 1bar.

[Thijs_Rallye 87 4 Cars]

7 hours ago, lahondal said:

 

-Return line from thermosthat to waterpump is direct along the back of the engine and near the exhaust manifold (the stock turbo return line was used and modified) and have a aprox 14mm ID pipe. Tried to restrict it with a pair of pliers on a race and didnt feel any difference at all. 

Can we make two 6mm holes in thermostat and blockoff this return line?  

  

-Coolant reservoir is maybe a little low on its position, with coolant at level it barely sits about 1cm above thermostat bled ports and 4cm above radiator top bled port.

I could use some pics for clarification, since I never had the pleasure of owning a 2.0 tct lump. I do not know what return line you mean.

 

[Tom Fenton 1,542]

I think ignition timing could be the key here to be honest. Too retarded and its costing power and making heat.

[petert 588]

Post the ignition map.

[wicked 103 3 Cars]

15 hours ago, lahondal said:

 

-Return line from thermosthat to waterpump is direct along the back of the engine and near the exhaust manifold (the stock turbo return line was used and modified) and have a aprox 14mm ID pipe. Tried to restrict it with a pair of pliers on a race and didnt feel any difference at all. 

Can we make two 6mm holes in thermostat and blockoff this return line? 

 

 

 

Pls some pics... This sounds suspicious to me. My TCT does not have a return from thermostat to waterpump, except for the heater matrix and turbo cooling. These act as bypasses on the radiator, but have kind restriction inside that limit the flow. If you just bypassed the heater matrix or turbo with a piece of pipe, this could be your issue. 

If not used, you should block them completely to force the flow through the radiator. 

If the coolant can freely circulate from thermostat to waterpump, your radiator won't do much to cool the engine. 

 

The Mi16 has return from thermostat to waterpump, but that return is controlled by the thermostat, meaning this return is blocked when engine is on operating temperature. The outlet for the heater matrix is always open... 

On my Mi16 trackday car I blocked the outlet on the thermostat for the heater matrix completely and I have the impression that it improved the temperature stability/cooling capacity.

 

 

Edit:

These kind of blank are easy to use:

Hose cap

Edited September 21, 2022 by wicked

[lahondal 17]

5 hours ago, wicked said:

 

Pls some pics... This sounds suspicious to me. My TCT does not have a return from thermostat to waterpump, except for the heater matrix and turbo cooling. These act as bypasses on the radiator, but have kind restriction inside that limit the flow. If you just bypassed the heater matrix or turbo with a piece of pipe, this could be your issue. 

If not used, you should block them completely to force the flow through the radiator. 

If the coolant can freely circulate from thermostat to waterpump, your radiator won't do much to cool the engine. 

I think is indeed the heater matrix circuit, which thought it must be there to bypass the water when thermostat is closed. 

 

I leave a pair of old pics (dont have one at the moment) to explain from where to where is connected. 

 

It has no restriction at all. Tried to crush it with pliers last race but not full crushed as the driver dont know so much about engines and i was afraid he dont remember to free it when cold at the top of the hill. 

[lahondal 17]

12 hours ago, Tom Fenton said:

I think ignition timing could be the key here to be honest. Too retarded and its costing power and making heat.

Im looking forward to see the ign map.

[lahondal 17]

Sorry the pics. I have marked in red from and to where the pipe runs. 

[Tom Fenton 1,542]

That pipe is passing a lot of hot coolant round and round the engine. Block it off both ends, drill 2x 6mm holes in the thermostat rim then try again.

I’ve had those silicone caps come off so wouldn’t use them long term, but they are ok to use for a test.

[petert 588]

Definitely force all coolant through the engine. One entry in, one exit. Why do you need a heater matrix? It's a race car. I use the aluminium coolant entry, as it's easy to weld up unwanted holes.