Hi TJ, post a new Topic for your question. Unless it has something to do with high RPM water pump modifications it should be a new Topic.

my 140y was overheating yesterday, above the high mark of the car, not sure wats causing it, as the radiator is full off water, had my radiator recorded about 2 months ago to a 3 core, taking my water capacity up from just over 2 litres to over 4 litres, surely there is enough water, almost half gets lost, i see no leaks, I believe my thermostat has been removed also, I'm thinking its the waterpump that has the problem. Also when I filled the water up and ran the engine, bubbles appeared big ones and also small ones making a bit of a frothy look. Any ideas?

I dont have any heating problems with my L20 setup but if it ever start getting a problem you guys have given me a bit to think about. Thanx!

I am using my 160f thermostat gutted as a restrictor.

Rezlo, i agree that the info i am providing isnt applicable to all but the top HP engines. But please dont discount it.
Im not a HVAC engeneer, But after owning a radiator buisness for several years i have learned a bit.

We do agree on most things:)

I regards to your questions, systems with pre pump themostats? any increase in pressure will still be due to a restriction somewhere. it may well still be the thermostat. after all it is a loop. The system itself will have a slight restriction all the way round. Even an open thermostat is a restriction that will give a block pressure increase at any decent RPM.

It is usualy a "washer" that is put in place of the thermostat when using an electric waterpump, you change the ID of the "washer" to get your correct flow rate, best measured by checking actual flow as well as the differential temp between engine in and engine out at WOT. It is not uncommon to use restrictors in more than one place.

how do you put a restrictor in?

Being an HVAC engineer at one of the largest automotive OEMS, on most every car I have ever tested, the pressure in the block has never been 2-3psi higher than radiator with the thermostat open (obviously closed is a different story, but how often is it closed in race conditions?) If you think the block is magicaly presurised by the thermostat then how do cars that run pre pump thermostats also generate slightly elivated block pressures?


Your biggest problem with removing the thermostat besides for the mechanical clearances is actualy flow not pressure, to much flow = not enough time to absorb the heat, this is why systems are are open loop use restrictors to slow the flow in key area's.

Again, 95% of above info is totaly pointless in the A-series unless your aiming for 180+hp

Sikyne's on the money.

Many don't realise this is an important part of how the cooling system works. Block pressure created between the pump and thermostat (or restricter) is what greatly assists the coolant picking up heat (then taking it to the radiator to be dissipated).

This is why you should never run an engine with no thermostat - the water temp reading may come down but that's simply because its not collecting heat from the engine.

The stock system may well be making 20psi block presure. Ive never measured an "A" series system. This is the presure between the waterpump and the thermostat or restrictor. You dont have to have high presure in the radiator to have high block presure. The presure the pump makes in the block is over and above the cap presure.

Eg. Cap presure 13psi, Pump presure 7 psi to the thermostat/restrictor= 20psi block presure....
The most the radiator sees is 13psi.

I was suggesting the high presure caps when using an electric pump instead of the standard pump on race applications.