Racing engine thermostats
Discussion
I was recently told that my Rover SD1 would be the only car on the grid with a thermostat. Unfortunately this info was received secondhand so I couldn't interrogate the originator. It sort of makes sense to me as the car is running at full whack for much of it's life and would therefore have the thermostat open and just causing an obstruction but surely there is still some value in speeding the warming up process etc. In case it makes any odd to the debate the engine is a 4.2 but otherwise pretty much standard as is the cooling system.
What thinks the group?
What thinks the group?
Evoluzione said:
If it's working ok then leave it in, only consider something else if it doesn't.
Since when has doing the same as everyone else ever won any races?
Sorry but this is... kinda... rubbish.Since when has doing the same as everyone else ever won any races?
as FWD racer said, you want a lower temperature for peak power. Most thermostats don't even begin to circulate coolant through the radiator until they reach 80 degrees plus, which is already too hot.
FWDRacer said:
65-70 degrees for peak power.
Too vague.F3 engines run about 55 degrees because they're massively knock limited.
F1 engines run about 125 degrees because they want power.
The hotter your engine the more power it will generate (assuming it is optimised for that temperature), but there are other compromises to take into account (coolant system pressurisation, engine tolerances, engine life etc)
It's a Rover V8- I'll wager that it does not want to be 90 degrees+ (which is where it will be if it's on track and the thermostat doesn't even begin to open until 80/85 deg+). Furthermore the 'stat will be causing a (admittedly very slight) restriction to water flow even when fully open.
I do not know the Rover V8, but it uses simular technology to my race car. My race car goes better at 70-80 than it does at 90 (rolling road varified). You also run a higher risk of detonation if the engine is too hot. You can run more ignition advance in a cooler engine which probably will increase power.
Finally- a 'stat, as well as being unecessary for the race engine, is just another potential failure item. I see no benefit in it being there at all except for faster warm-up, and there is the potential that the OP will be DNF'ing and skimming two cylinder heads should it fail.
I do not know the Rover V8, but it uses simular technology to my race car. My race car goes better at 70-80 than it does at 90 (rolling road varified). You also run a higher risk of detonation if the engine is too hot. You can run more ignition advance in a cooler engine which probably will increase power.
Finally- a 'stat, as well as being unecessary for the race engine, is just another potential failure item. I see no benefit in it being there at all except for faster warm-up, and there is the potential that the OP will be DNF'ing and skimming two cylinder heads should it fail.
Im not sure on the exact coolant lay out of your rover engine but a way in which to add much better control to your system temperature and also gain some extra horse power would be to lose your mechanical water pump and thermostat and replace it with an electric pump, water temp sensor and control system, thus still giving you control at low temperatures and also creating more power and response from your engine due to the reduction in drive of you mechanical water pump. 
ETA
Please do not conduct business on the forums.
ETA
Please do not conduct business on the forums.
Edited by Big Al. on Friday 10th August 20:24
terrybourne said:
Im not sure on the exact coolant lay out of your rover engine but a way in which to add much better control to your system temperature and also gain some extra horse power would be to lose your mechanical water pump and thermostat and replace it with an electric pump, water temp sensor and control system, thus still giving you control at low temperatures and also creating more power and response from your engine due to the reduction in drive of you mechanical water pump. Any queries you can contact me on here or at terryradbourne@bourneraceengines.com
Unless you use a smart alternator that only charges during negative torque transients, an electrical water pump with the same hydraulic power as the mechanical one actually reduces flywheel power (as an alternator is only typically 65% efficient). Most "electric" water pump systems however have such a low hydraulic power that they reduce the heat transfer characterstic and end up increasing metal temps and hence reducing power............Thanks for the thoughts people. I had a feeling it wasn't going to be quite the universally held view that it was billed as. I think I will leave it as is for the balance of the season and probably extract it as part of the over-winter works. My main reasoning being that it is not only a potential failure point in its own right but that it also makes bleeding the system more difficult which is easy to fail to do if in a hurry and can have very significant consequences on the RV8. I have a feeling any marginal difference either way in terms of the the efficiency of electrical v mechanical pumping will be less likely to pay dividends than spending the money on driver training.
this will all depend on how the engine was designed to run and what its calibrated to
as 70 °C coolant is great for keeping the heads cold for good vol eff but poor for piston clearance as this will be optimised at about 85° and if teh the car is on a production ECU then its likely that there will still be some extra fuel being added at 65°C which again you don't want if you're thrashing it
F1 engines only run at 125°C to keep the radiator sizes small, and the blocks are honed at temperature to help keep piston clearances down at this temperature - to the extent that the engines have to be pre-heated to 70°C before they can be fired up
as 70 °C coolant is great for keeping the heads cold for good vol eff but poor for piston clearance as this will be optimised at about 85° and if teh the car is on a production ECU then its likely that there will still be some extra fuel being added at 65°C which again you don't want if you're thrashing it
F1 engines only run at 125°C to keep the radiator sizes small, and the blocks are honed at temperature to help keep piston clearances down at this temperature - to the extent that the engines have to be pre-heated to 70°C before they can be fired up
Very old Fashioned and bound to be lambasted on here - but Drill the periphery of the Stat. A thermostats main use is to get the block up to temperature to help with heater cabin air-off temps on a production car. Not of any significance on a race car - the whole sytsme needs to be up to constant temp. Drilling a stat will allow a poprtion of it to be bypassed. Increases flow - roughly the same pressure drop across. Cost is a new stst gasket/replacement stat.
FWDRacer said:
Very old Fashioned and bound to be lambasted on here - but Drill the periphery of the Stat. A thermostats main use is to get the block up to temperature to help with heater cabin air-off temps on a production car. Not of any significance on a race car - the whole sytsme needs to be up to constant temp. Drilling a stat will allow a poprtion of it to be bypassed. Increases flow - roughly the same pressure drop across. Cost is a new stst gasket/replacement stat.
A thermostat is a temperature regulation device - it's primary purpose is to maintain the coolant temperature within a relatively small window. Without a thermostat, coolant temperature will vary in according to engine load, vehicle speed and ambient temperature.one eyed mick said:
Remove centre of the stat ,spring ,disc etc and just refit the outer disc ,this was used by BMC comps dep on hot 1275s works cars for rally use ,old school perhaps but so is the Buick /Rover !!
They used to sell a metal collar than did exactly the same thing. A proper Special Tuning part and everything.....most racing cars dont use a thermostat, for various reasons, but mainly as they are a point of failure.
engine temp is usualy set by blanking of the radiators, how much depends on the air temp, simple tape works best.
oil temp wants to be slightly over 100 deg c so that any moisture in the engine can evaperate off.
most good oils are happy to go this hot and even hotter.
coolant wants to be around the 90 deg c for most engines, however some use high pressure systems and have seen some go upto 120 deg c safely.
the most common engine failures are due to lack of heat not to much, in the old days of lemans, cars often failed around midnight, due to the lack of air temp causing engine failures until this was understood, often you will see teams altering radiator blanking in pit stops, when the comentator says that a team is cleaning out the radiators, what they are infact often doing is adding or removing blanking, now days more usualy done by changing bodywork as this can be quicker.
for club racing i would be tempted to leave a thermostat in, as without knowlage and accurate live data its not an easy thing to get temps right, and stats now are pretty reliable, the engine was designed to run with it so what makes you think you can do a better job?
and as to them not reacting quickly enough, well thats not true, they arent like a switch, ie open or shut, they will open as much or as little as needed. If your stats working properly and your still seeing high temps increace your air flow to your rads or even use bigger or better rads, most that started life as road rads are not that good, and they are often run at the incorrect angle to the air flow etc
engine temp is usualy set by blanking of the radiators, how much depends on the air temp, simple tape works best.
oil temp wants to be slightly over 100 deg c so that any moisture in the engine can evaperate off.
most good oils are happy to go this hot and even hotter.
coolant wants to be around the 90 deg c for most engines, however some use high pressure systems and have seen some go upto 120 deg c safely.
the most common engine failures are due to lack of heat not to much, in the old days of lemans, cars often failed around midnight, due to the lack of air temp causing engine failures until this was understood, often you will see teams altering radiator blanking in pit stops, when the comentator says that a team is cleaning out the radiators, what they are infact often doing is adding or removing blanking, now days more usualy done by changing bodywork as this can be quicker.
for club racing i would be tempted to leave a thermostat in, as without knowlage and accurate live data its not an easy thing to get temps right, and stats now are pretty reliable, the engine was designed to run with it so what makes you think you can do a better job?
and as to them not reacting quickly enough, well thats not true, they arent like a switch, ie open or shut, they will open as much or as little as needed. If your stats working properly and your still seeing high temps increace your air flow to your rads or even use bigger or better rads, most that started life as road rads are not that good, and they are often run at the incorrect angle to the air flow etc
Gassing Station | Engines & Drivetrain | Top of Page | What's New | My Stuff