| Author | Message | ||
     Dcmortalcoil |
In the RC51 forum (Speedzilla), some people argued that taking out the thermostat would make the engine run cooler. Others argued the opposite, due to the coolant flowing too quickly, which I believe is hogwash. It seems logical that taking out the thermostat would make the bike run cooler. The big question is by how much. I heard that running engine below the ideal temperature is also not good. What is the optimum coolant running temperature? Anyone try it with any bike? | ||
| Joshinga |
From what Iv seen my bike runs between 180-200 degrees. as for the thermostat if it is removed it really wont make the bike run cooler but it will make it take forever to warm up. all the thermostat does really is restricts the flow of coolant from going to the radiators till it reaches operating temp then opening and releasing it to the rest of the cooling system so the temp is maintained. if you remove it it will circulate threw the radiates right at start up. hope that helps (Message edited by joshinga on May 17, 2010) | ||
| Badlionsfan |
Well coolant flowing too fast isn't hogwash, other wise this product wouldn't be used in auto racing engines that don't use a thermostat. http://www.summitracing.com/parts/MOR-63440/ Keep the thermostat. If you wanna reduce coolant temps use a product like water wetter or something. | ||
| Froggy |
What he said. You will find that it takes longer to warm up and you will see the engine go back into cold state faster. The bike will maintain a constant temperature as best as it can. I typically see an average temp of 170°F. | ||
| Augustus74 |
Not recommended for the street and you would still need a restrictor like Badlions posted. | ||
| Dcmortalcoil |
If coolant flows faster, more coolant passes through the engine block. Wouldn't that cool the engine block that much faster, unless the coolant does not get cooled sufficiently through the radiator? | ||
| Dcmortalcoil |
My temperature at highways stays around 170-180 degrees. In local street riding, 190-200. Stuck in traffic 200+. | ||
| Stirz007 |
Maintaining constant temperature in a non-regulated (no thermostat)condition is difficult unless can you keep the inputs constant. By that, I mean for a constant engine heat output, constant speed (airflow through cooling surfaces), and air temperature, etc., the coolant temperature will be relatively stable within the limits of the cooling system. The system should provide lots of cooling capacity to handle maximum 'normal' operating conditions, but is oversized for cool temperatures and low engine effort - that's why it takes forever to warm up. You'll find in colder temperatures and lower engine effort, it will probably run like crap. The thermostat normally closes down to keep that comfy blanket of warm water around the engine - take it out, and you pull off the blanket. Most engines are designed to operate best within a relatively narrow temperature band - maybe 30 degrees. By taking the gizmo out that regulates that engine temperature, you affect the ability of cooling system to make the adjustments it needs to make as conditions change, especially in start-up and cool weather conditions. Dunno about bikes, because I've never tried it, but thermostats get pulled in some dirt track racers (4-wheeled kind), but they are running pretty much wide open flag to flag - they want all the cooling they can get. Bikes? maybe racing, but probably not worth it on the street IMO. Just two cents - Good question. | ||
| Dcmortalcoil |
I am not sure whether thermostat does anything once it opens at 160 degree. So in all instances of riding after warmup, it will stay open. | ||
| 1324 |
Buell/Rotax selected the thermostat they did to complement their fueling and emissions strategy. Remove the thermostat and it may never actually maintain the ideal temperature, unless you ride in the right climate with the right riding style; what those two variables are is a mystery. If the coolant temperature is too low, the bike will constantly run in the enriched condition (like a choke). You'll lose power and use more fuel. If the engine overheats, well, you know what happens... Leave it in place. If you really need to reduce excessive temps for some reason, I'd consider running straight water or some additive. But be forewarned, there is no free lunch. Running straight water with the system as-is might require a change of radiator caps to operate properly. I haven't heard of this issue on the 1125's, but it has occurred on other engines. I'm sure some racers/track day junkies can chime in with the water-only experiences. And of course, the obligatory geek alert: Running additives can work well, but you should try to match the fluid properties of the coolant you took out. Changing things like viscosity can pose issues later down the road on water pumps, seals, etc. Choose your additive carefully, as this is easier said than done. (Message edited by 1324 on May 18, 2010) | ||
| Ratbuell |
Just scanning because I'm almost late for work...but the other reason to leave the thermostat in is that without it, coolant moves through the engine too fast to soak up any heat. If the coolant doesn't soak in any heat, it can't carry it away like its designed to do. | ||
| Thefleshrocket |
Removing the thermostat will make the engine run cooler, to a point. My '03 Suzuki DR-Z400E is a 400cc single-cylinder dirt bike with a radiator on each side of the motor and no thermostat. It has a Veypor gauge cluster which shows exact the coolant temperature. Coolant temp is directly proportional to how much air is going through the radiators. For example, on a cool day when moving 30+mph, the coolant temp will usually be in the 130F range. On a hot day, it will probably be around 140-150F when cruising. When idling, the coolant temp keeps climbing until I get moving again. I've seen it get as high as 270F while stuck on a very slow portion of a trail, but as soon as I got up to 10mph, it dropped to the very low 200s range. If you remove the thermostat, the bike will probably run at about the same temp when idling or at slower speed, but it will probably run cooler when at cruising speeds. However, if the thermostat is a 160F unit as others have said, then you probably won't notice much of a reduction in temp. How often does your temp gauge read in the low 160s? When it's in the low 160s is probably the only time when removing the stat would cause the engine to run any cooler, because the stat is probably keeping the coolant from dropping below 160. | ||
| Joshinga |
one more purely selfish reason as others and I mentioned above removal of the the thermostat would make the bike warm up slower. And as you know when the engine is cold your red line is restricted do you really want to prolong the agony of having half throttle for longer than normal? plus having it randomly cooling down so much that it reverts back to the warm up rev limit. IMHO that would suck leave the light engines hot start banging through gears hit a long stretch engine cool and out of nowhere your rev limiter kicks in.  | ||
| Carbonbigfoot |
I believe I read somewhere that Buell tested the rotax running it at extended periods over 250F. Haven't heard of anyone melting one yet. My opinion, leave the stock system alone. Make sure it's full, but leave it alone. R | ||
| Kirb |
Faster flow rates don't impact the ability to remove heat as this is a pure heat transfer issue. What it does do is screw up the flow characteristics of the water. Faster water will flow more to the center of the passage while the water near the edge will slow. This causes a barrier to heat conduction. This will vary in different engines, so a blanket statement 'it won't work' is not true...to a point. | ||
| Psayton |
The thermostat does matter. Get and old Chevy with a small block in it and remove the thermostat. Drive it around town for awhile in the summer. You will overheat one of the best cooling engines made. I've done this before when I was young and the logic of running with no thermostat sounded good. What 1324 says is very true. I'm sure Erik and his crew didn't mess this up. Didn't Buell test their bikes in Mesa? Seems like that environment would be a very good one to see if your engine was cooling well. | ||
| Usanigel |
The ideal running temp is controlled by the thermostat. Take it out and you might as well be air cooled and leave the engine temp control to the gods. | ||
| Poppinsexz |
+1 for 1324. You can overcool without it, and also overheat(ie stop and go in town) | ||
| Thefleshrocket |
I have a really hard time believing that removing a thermostat will cause a vehicle to overheat at around-town speeds. At low speeds, the engine isn't turning a whole lot of RPM so the coolant isn't moving very fast, which bunks the "coolant moving too fast to cool the motor" idea. And the flow won't be THAT much more with the stat removed than if the thermostat was in place and open at those speeds. I'm not saying that it's impossible to overheat a vehicle by removing the thermostat, but I'd be really surprised to see it happen. (Message edited by thefleshrocket on May 18, 2010) | ||
| Bdutro |
I'm going to ignore a room full of engineers at Rotax and a room of engineers at Buell and go with what the guy on teh intarwebz said. *sigh* Machines have souls. Don't abuse them. | ||
| Poppinsexz |
All the while at low speed there is very low airflow across the radiator and engine. Heat transfer takes time, the coolant must be held in the radiator long enough for that transfer to take place. The thermostat divides the cooling system in two. There is a heating half and a cooling half. By removing the thermostat you have combined these two into one that has unrestricted flow. Time is lost for the heat transfer to take place. If enough airflow is maintained then the effects are mitigated. However with lesser airflow the coolant retains that heat for the next pass through the circuit. aw never mind. Just remove your thermostat and go drive through town with a bunch of stop and go. edited for clairity (Message edited by poppinsexz on May 18, 2010) | ||
| Stirz007 |
Fleshy - I tend to agree. Water/air heat exchangers (which is what the cooling system is) aren't designed to increase heat, thus 'causing" the motor to overheat when the thermostat is removed. My guess is that the overheat would have occurred regardless of whether the thermostat had been removed or not. In fact, the chances of overheat decrease with removal of the thermostat. Mortalcoil - keep in mind the thermostat is not a wide open/fully closed mechanism. Most thermostats have the ability to 'throttle' flow, depending on the temperature of the water flowing past. Wide open occurs at the high end of temperature scale, but the thermo can operate at a range of openings. So, once open, the thermostat can and will close while riding if it is cold enough outside. The whole idea that higher flow rates do not allow adequate heat transfer is not quite accurate, tempered by 1324's comments. Heat transfer is a function of temperature differential and mass flow rate. So a high flow rate with high difference in temperature will have the highest heat transfer rate, all other things constant (like turbulence and preferential flow paths). At low flow rates, the difference between the engine and water temperature within the cooling jacket will close quickly, eventually resulting in both engine and water temperatures elevating until boil away or engine seize. Poppin is right, there are two flow circuits in most auto/motor cooling systems. One circulates water around the jackets, picking up heat from the motor until the thermostat opens, allowing some of the hot water into the cooling circuit (radiator), while allowing some of the cooler water from the cooling circuit into the cooling jacket. This is how heat is bled from the motor. Without the control valve, the heat is wasted as quickly as it is generated until a balance is reached. Now add the effect of cooling fans, and this changes the equation again... And yes, I am an engineer, so I get all geeky about this stuff - - Sorry. | ||
| Bdutro |
This whole idea of the coolant moving too fast to cool is horse crap. Your coolant pump is designed to pump against a certain head pressure, remove that and you increase the chances of cavitation which a buffoon could improperly attribute to the water moving too fast, especially at higher engine speeds. *facepalm* Coolant flow removes energy from the metal, air flow removes energy from the coolant. I have never ever seen data that suggests that increasing flow or turbulence decreases the transfer of heat. These bikes don't have chokes on them like the old days, you've got a coolant temperature sensor. Run the coolant temp low and you'll trip the ECU into a cold-start fuel enrichment mode and then come back complaining of poor fuel economy. Continual operation in a cold-start mode (which is supposed to pour heat into the engine!) will not help you make power. | ||
| 1324 |
Wow, I just read what I posted at 7:19AM, and I apologize...I completely botched my explanation and ended up posting misinformation. My apologies...I've deleted the BS from the original post. What I meant to say, and failed to convey through the incorrect wording, was that cooling performance increases with increased flow rate. Simple physics. Funny how inadvertently slipping 'decreased' screws everything up. My bad. I won't even touch my half-assed explanation. I was clearly still asleep. Stirz and Bdutro are completely correct... But, the crux of my post still stands. Leave the thermostat in place. The engine will likely operate fine at any temperature above where the thermostat is fully open, but performance will absolutely suffer below that temperature. If you ride in cooler climates and/or ride with minimal stops or slow speed cruising, you'll fail to maintain operating temperature. I've done this both with cars and bikes...voluntary and involuntary. Never again. | ||
| Stevek1125r |
So remove the thermostat to gain what??? A thermostat is worth what these days... 15 hp? LMAO!!!!! I love the fact that some people absolutely feel the need to mess with their toys...to gain nothing! I mean really, a thermostat.... I never seen a thermostat advertised to make more power..... Yes i know cooler engine, blah blah more power, blah blah blah..... Gain what 2hp at the crank, so 3/4whp.... I don't know about ya'll but i didn't pay for the SUPER Sensitive butt dyno... i couldn't afford it... LOL now on my AutoX car, i run without a thermostat, but that car lives on the rev limiter for hours at a time..... You lose/gain more hp with intake charge temp difference more than coolant temp differences....seen that many times on the dyno..... | ||
| Poppinsexz |
Thats ok, I read your post and didn't catch it either, took it to be the opposite. Thats what I get for skimming  | ||
| Dcmortalcoil |
Who said anything about gaining horsepower? Just trying to stay cool. I just had wiring harness upgraded today for 1125CR. Must be the firmware upgrade, the engine temp is considerably higher than before. Outside temperature - wet and 57-60 degrees. Before harness upgrade: Coolant temperature at 164 degrees (highway) After harness upgrade: Coolant temperature at 176 degrees (highway) at stop and go 190-205 degrees The temperature never went that high before even when the outside temperature was over 90 degrees. I'll see how hot it will get soon enough when we hit 100 degrees. | ||
| Bdutro |
Have you seen those 'gauges' with blue and red edges and NORMAL in the middle 90% ? I think that should be your next mod. | ||
| Shags |
Taking out the thermostat is not a good thing it will cause hot spots in the engine.Its like rushing water in a river in the turns and bends it creates eddies were the coolant swirls.This was told to me by a 25 year diesel mechanic. | ||
| Aj2010 |
OK I just skimmed the last part so this comment may have already been made. Does the 1125 not use a bypass system (blocking thermostat)? If so then removing it would be a very bad idea as hot coolant would move through the rads (to be cooled) and the bypass back to the cylinders (not to be cooled) If this is the case then the engine would be running hotter as all of the coolant would not be circulating through the rads. ITEM DATA (info cut/pasted) from Buell manual Cooling system Cooling circuit by integrated water pump, thermostat controlled bypass Coolant Ethylene glycol, 50/50 mixture Normal operating temperature 140-220 °F 60-104 °C Overtemperature threshold (lamp lit) 230 °F 110 °C | ||
| Stirz007 |
OK Fine! This should explain it all clearly. http://www.youtube.com/watch?v=rLDgQg6bq7o&feature =related | ||
| S21125r |
In some situations coolant that is moving too slow can be a problem as well. The layer of coolant directly contacting the metal passages can form steam bubbles which act as an insulator. Kevin Cameron had on article on this some time ago and explained that some manufactures target certain hot areas with high flow coolant to help sweep that steam layer away. |
