Ian W - sorry bud - Rubbish - increasing the flow rate of the coolant by removing the stat is a BAD thing to do......if coolant flow is too fast it doesnt hang around in the radiatior long enough - and the engine overheats......fast flow is bad news........as a rule of thumb you need 1/3rd the engine power in L/min as an ideal coolant flow.......so for a 120bhp motor thats 40L/min.....this is well a proven method
Not so swift - This is the exact reason I was saying to use a thermostat - you need about 60-80psi pressure inside the block cooling jacket in order to resist the plate boiling effect created by the heat transfer of combustion.........if anyone is honestly telling me they think they should run 60-80psi in the rest of the cooling circuit - like in the rad and header tank on a hot summers race day race - by removing the thermostat - then sorry, but this is too high risk - even for semi-professional motorsport.
I have designed and converted engines for front running BTCC teams, WRC cars, Super 1600 rally cars and not to mention a few LeMans projects - and I currently design and develop what could be termed highly strung mid-range turbo-diesel engines, and we always run a thermostat......we have never run an engine without.....its too risky.....you are a brave man if you are telling your customer to run the entire cooling circuit at 60-80Psi........perhaps in F3 or F1, but deffo not on a clubbie or semi-pro job
The only engine I have worked on without a stat was an IRL V8 driven by a certain Mr T.Scheckter & co......needless to say they were expensive high-tech motors for US oval racing
yes the majority of bike engines run whats termed a bypass thermostat, if you remove this and dont re-plumb the system accordingly - engine failure awaits you in the not too distant future........bottom line - KEEP THE STAT
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Originally Posted by Notso Swift
I see your problem
Your engine id designed for a M-O-T-O-R-B-I-K-E and you drive a C-A-R!
Only kidding, I have been hanging to say that to someone, though.
Ian_w. I think the people who are advocating the use of a thermostat may be confusing is function as a restrictor, vs temperature regulation.
Could you confirm that while you do not use a thermostat, you still use a restrictor?
If so there would not necessarily be an increase on the stress on the top hose, unless the restrictor was after the hose. Otherwise is it a sealed system, where any increase in Temprature results in an increase in pressure?
For information of others – the pressure in the system at the radiator may be at a nominal figure of 15psi, however, in the block it is significantly higher as the water pump is trying to force more coolant through the system than can get back out again. That creates more pressure in the block, as has already been discussed, pressure helps prevent boiling. This is required as the coolant in the really hot parts of the motor, particularly the water jackets near the combustion chambers, will get to 140-160 deg C, and the increased pressure is required to prevent localised boiling. It can be a tight rope that you walk when you have to balance the coolant flow speed, the pressure in the block (as lower speed will invariably mean greater pressure it the rest of the installation is constant), versus the rate it absorbs heat in the motor, versus the rate it rejects heat from the radiator. I will be honest it is a bit hard for a club racer like me, and I use a thermostat as a result! This means the cooling system is not optimised, i.e. it is too big for normal operation, but at least it is safe during extreme conditions.
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