ra12r
Zone Head
Posts: 919
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posted July 12, 2003 03:27 PM
NO Thermostat!!!
I am wondering if anyone has tried running the bike without the thermostat? If so, how did the bike temp react?!
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CrotchRocket
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posted July 12, 2003 04:27 PM
Never heard of anyone running a 12 without a thermostat...I dont think it will be good though!!!...It will mess up the operating temp of the motor and fan!!!...I would say that the fan may not comeon and the motor will get too hot in extreme heat as in driving in traffic...OR, it may run too cold and run like crap...Better off leaving it the way it is, unless you want to experiement and let us know what happens!!!
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12RPilot
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posted July 13, 2003 04:51 AM
I would never do it but I'm curious as to what the effect would actually be. It may be counterintuitive, but in our stock car we found that it's best to run something, if not a thermostat, then an orifice plate in it's place. I'm not going to get into why too much flow can be bad for cooling an engine, but it can be.
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ra12r
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posted July 13, 2003 05:18 AM
CR, the fan will still work because the fan switch is in the radiator,,,ie: manual fan switch connection.
Without the thermostat the motor would heat up slower. Plus a 180 thermostat stayswide open when a 210 thermostat is partially closed. The motor temp is still going to neutralize at some operating point but what that is is the question. When the fan comes on the thermostat is wide open and as soon as the bike starts moving it goes back to normal. I wonder just how much control our thermostat is doing?!
In my muscle cars I have always ran a 180 thermostat no problems. In our bikes i guareentee that the cylinder operating temp is 'HIGH ENOUGH" especially with the "EXTRA" heat that our compression makes. That is where the heat is coming from anyway the combustion of the gas. We can't control that. We are control the metal operating temp but even that with the tiny radiator is very limited.
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SprintZX12R
Parking Attendant
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posted July 13, 2003 08:42 AM
Remember, the water needs some time in the rad to allow for the heat to exchange. Without the stat, the flow rate is far too great and very little heat is exchanged. This ultimately leads to overheating. Per above, that's why when the stat was removed they needed to add a restrictor to slow the water flow thru the rad. The stat also allows for quick warm up, which is very important.
Why would you want to remove the stat anyway?????????
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ScaredyCat
Expert Class
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posted July 14, 2003 05:25 AM
As far as I'm aware the function of the stat is to restrict the flow to let the engine heat up quicker. It will also limit the minimum temperature after that (as if 12's needed that). If you want to run the engine colder, removing the stat will work, but it will happen all the time, not just when you need it. The fan will still start and stop at the same temperatues.
I'd stick with the thermostat installed.
Just a point - an increased rate of water flow won't decrease the heat transfer - it will change the temperature gradient across the exchanger. It will make the water pump work harder, but that won't noticeable given the power source!
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12RPilot
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posted July 14, 2003 06:27 AM
I wasn't going to get into fluid dynamics here but I can't go to bed for a while anyway. The problem with higher than designed flow rates is a build up of the boundry layer where flow is laminar. Lower flow may actually transfer more heat because the boundry layer (the layer of fluid against a surface that is stationary or moving very little) is thinner than in higher velocity fluid flow. Like I said, this applies mainly to areas where there is laminar flow. There are other factors that affect boundry layers and heat transfer. Turbulent flow can break up the boundry layer and help heat transfer. With all the nooks and crannies in an engine, there are many areas with turbulent flow. Some areas that promote laminar flow are along the outside of the cylinders themselves. Actually, for the best heat transfer, you want tiny steam bubbles to form on the surface you are cooling. Ideally, the coolant then strips the steam bubbles off the hot surface and the bubbles collapse in the coolant and transfer lots of heat energy. Unfortunately, that condition (called nucleate boiling) is right on the ragged edge and we can't operate an engine there because if conditions deteriorate, you get large steam bubbles that would then not strip away. Large steam bubbles clinging to a surface effectively insulate the engine surfaces you want to cool. So in a nutshell, high flow rates are great up to a point, but not necessarily ideal for all conditions.
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posted July 14, 2003 07:26 AM
If anything..simply remove the inner core of the Tstat...not the entire thing itself. This will provide similar flow when the Tstat is at max open (when its really hot). Removing the tstat would probably cause some odd heating issues given how small the radiator is.
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ra12r
Zone Head
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posted July 14, 2003 07:43 AM
What are our thermostats? 220,210 F or what? I do believe they are simple car thermostats, so a cooler one can be added.
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ScaredyCat
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posted July 14, 2003 08:20 AM
12R Pilot,
Excellent info, I'm learning here, thanks.
I agree that lower flow will transfer heat more efficiently, but that's given unlimited surface area (radiator size)? Nice, slow, water flow will allow the water to achieve exactly (or almost) air temperature.
There must be a curve where engine cooling is optimum though,:
0% Flow: No cooling:
x% flow: best cooling for the heat sink
500% flow: No cooling due to dynamic effects
It's sad I find this stuff interesting, but there you go. 12RPilot, can you explain this to me? Cheers my man.
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RAC4IT
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Bergie
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posted July 14, 2003 10:23 AM
you can carefully drill small holes in the stock thermostat to all bypass coolant to flow through before the thermostat opens to experiment
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ra12r
Zone Head
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posted July 14, 2003 10:43 AM
HMMMMMMM.............That would only affect the amount of time untill the thermostat opens....but not the end operating temp. My goal is to get the lowest operating temp possible. I believe the lowest operating temp is still going to be more than high enough. When the bike is running at 9'oclock that is great....but sit still in traffic or at the track and it goes up pretty fast. I believe the thermostat is responsible for this rise in temp so quickly. I even have the manual thermostat fan and turn it on in advance to sitting which helps.
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ScaredyCat
Expert Class
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posted July 14, 2003 12:58 PM
ra12r,
Nope, sorry, but your cooling capacity isn't much limited by your thermostat.
You can take it out and gain a small incremental cooling gain. It'll be the difference between a fuly open valve and a straight pipe. Not much.
It WILL keep your engine microscopicayy cooler, but you won't see a difference. You will find that your bike takes longer to warm up though.
Somebody shoot me down if this isn't true!
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Y2KZX12R
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posted July 14, 2003 02:01 PM
Theres some good points here. Also some very common myths.
About 2 years ago we did some tests reguarding waterpump speed and restrictor plate orfice size on the dyno. (DTS automotive engine dyno)
The test mule was a Big Block Chevy 454 engine that made typically 460 HP.
Basically the hotter the valves, pistons, combustion chamber walls etc. are, the lower the total heat transfer (loss) is because of the decrease in the temperature difference of the parts and the combustion. This alows more heat to be transfered to "work". This is one reason ceramic coatings make more power by reducing heat transfer and making more of the available BTUs transfer into power. A fully warmed up engine (and oil) will always make more power than a 140 degree engine.
Also the parts in the engine (piston, and rings) are designed to operate in a fairly narrow temperature range on modern engines. An old bike engine that doesnt have the tight tolerances that the zx12r engine has is less suseptable to these power losses. So untill the engine (pistons) are up to temp the engine can not make its max power. The rock of the piston is excessive. I've seen engines that were hammered hard cold break piston skirts off. This is less common on some of the advanced CAST pistons of today. But is still very true of forged (JE) pistons.
Lowering the thermostat temp will let you get away with more ignition timing in many cases. And this CAN but not always increase power in a given engine by bumping and moving the peak cylinder pressure.
In an adiobatic engine this whole issue is mute.
As far as coolant velocity, its takes far far longer for the heat transfer to occure around the valve bowls and cylinder walls than it does from the radiator to the air flowing thru the radiator. And its not even close.
What happens when you increase the velocity of the coolant thru the engine is that, the time it has to pickup the heat from the surface area in the engine is decreased. This reduces the overall BTU transfer. But the radiator can usually remove the heat fast enough to keep up with the increase of the coolant velocity so this may indicate a false lower operating temp on some engines depending on where the coolant sensor is located. Like I stated above, this isnt a bad thing in itself if the engine is designed to run in this window. Keeping the combustion heat transfer low into the parts like pistons, cylinder walls, and valves is good.
But when the parts start to operate outside of this window then engine failure is around the corner. Usually shows up in a sticking exhaust valve in a guide.
We found that slowing the waterpump down on an engine that sustains high rpms for a long time is not a bad thing. Because the waterpump is designed to provide enough cooling flow at idle. Most engines have a bypass of some kind for excessive water flow for this reason. The ones that do not can bennifit from a slower water pump speed providing they dont idle for long (on the street).
I'd keep it in there.
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12RPilot
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posted July 14, 2003 02:46 PM
Just checking in before going to work so I'll add more later. I'll leave you folks with one physical property to start with that is pretty much common sense: Heat transfer (BTUs) = (surface area) x (the difference in temps). Obviously, more surface area is better; and furthermore, hotter surfaces or cooler antifreeze gives more heat transfer. This science crap just all makes sense to us motorheads, don't it?
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CrotchRocket
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posted July 14, 2003 03:07 PM
Y2K...I recently bought a 2003 Chevy Express Van to haul around the 12...My previous 4 vehicles before the van have been Honda Accord/Civics and a Toyota Rav4...All those vehicles temp guages never moved whether I was sitting in bumper to bumper traffic, summer with A/C on, parked with A/C on for an hour never changing temp inside of vehicle...The Chevy Van temp guage moves all the time and in the heat with the A/C on the temp guage rises and the A/C turns warm, and if I am just sitting parked with van running the temp rises!!!...Why Cant GM make an efficient cooling system???...Do you have any suggestions as to what I can do to better the system!!!
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ra12r
Zone Head
Posts: 919
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posted July 14, 2003 04:03 PM
Okay,,,,i will leave it in, however i did check and on the thermostat is mark 60* C. The spring pressure isn't even close to a car thermostat so this thermostat is not a hot one anyway as my guessing conclusion. I just hate how the bike won't hold a steady temp and avoid getting hot when in traffic. My 2001 R6 never has a problem!!!
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Y2KZX12R
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posted July 15, 2003 05:10 AM
If the vehicle has electric fans, make shure that at least one fan is on all the time when the A/C is on "max". It sounds like the condenser is getting too hot.
Also you can try lowering the surface tension of the water with Water Wetter. It increases the heat transfer.
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dougmeyer
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moderated
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posted July 15, 2003 06:21 AM
During one "clean sheet of paper" engine design project I was on for 7 years, I did a great deal of cooling system testing and rather than repeat much that I learned here, Y2 is correct in all respects. But, keep in mind that the most important factor in any water/air cooling stystem is the AIR FLOW THROUGH THE RADIATOR (and radiator size). The thermostat is an important component. If you want a lower operatinmg temp, put in a "lower temp" thermostat. Crotch- The fact that your temp gauge moves proves taht your cooling system IS efficient!The thermostat is modulating the flow and the rad has the ability to lower the temp at will.
Doug
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CrotchRocket
Moderator
Bracket Racing with Betsy
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posted July 15, 2003 06:39 PM
Thanks Guys!!!
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Jason Miller StreetBike Seminars
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mrsantafe
Zone Head
Posts: 521
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posted July 17, 2003 08:41 AM
where can you get a lower degree thermostat? Carpenter runs his zx12's without thermostat. thx
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2006 ZX14 gone
2006 ZX10r (Wifes street bike)
2004 zx10r (her race bike)
2002 ZX12 (still kicking a--)
2007 gsxr 1k (race bike)
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