Maximum Operating temp! Engine Gurus please!
11-11-16, 04:11 PM
#26
Full Member
Thread Starter
from the other thread.
it would appear that Mazda has done what every piston engine has also done, and revised the coolant flow so that the engine is more evenly heated. i would imagine this lets them run the new engine, either at the same temp with better efficiency, or more probably at higher temps without problems.
it would appear that Mazda has done what every piston engine has also done, and revised the coolant flow so that the engine is more evenly heated. i would imagine this lets them run the new engine, either at the same temp with better efficiency, or more probably at higher temps without problems.
When NASA was ******* with the rotary engine, they found something stupid like 30% more efficiency when they "insulated" the cumbustion chamber. Thats ******* crazy interms of internal cumbustion engines. Wankel's have a brutal surface area to volume ratio. A good way to stop heat transfer, is to raise the system temperature to combat the transfer of energy. Less combustion heat is lost to the cooling system. This becomes even more important when using cooler burning fuels, like Ethanol. (ill be testing with e98 at some Point)
So besides designing a system that can stay stable in all conditions, im going to try to raise the efficiency of my Engine by insulating the Huge Combustion chamber with a revised Cooling system that absorbs less heat from the cumbustion process. and this is just one of the benifits of what im going to try to do.
I know some of you are looking at me like a ******* tard, but its because the "other" guys... hint... industry insiders... hint. dont talk about these subjects very often. Alot of current knowledge in the modified world is still tied to 1950's technology... like lower temp thermostate's. lol.
Im just trying to get some current data on the subject before i jump in head first.
11-11-16, 07:35 PM
#27
Moderator
iTrader: (3)
Join Date: Mar 2001
Location: https://www2.mazda.com/en/100th/
Posts: 30,770
Received 2,561 Likes
on
1,822 Posts
So besides designing a system that can stay stable in all conditions, im going to try to raise the efficiency of my Engine by insulating the Huge Combustion chamber with a revised Cooling system that absorbs less heat from the cumbustion process. and this is just one of the benifits of what im going to try to do.
I know some of you are looking at me like a ******* tard, but its because the "other" guys... hint... industry insiders... hint. dont talk about these subjects very often. Alot of current knowledge in the modified world is still tied to 1950's technology... like lower temp thermostate's. lol.
Im just trying to get some current data on the subject before i jump in head first.
I know some of you are looking at me like a ******* tard, but its because the "other" guys... hint... industry insiders... hint. dont talk about these subjects very often. Alot of current knowledge in the modified world is still tied to 1950's technology... like lower temp thermostate's. lol.
Im just trying to get some current data on the subject before i jump in head first.
the only real caveat is that the rotary isn't a small block chevy, its its own unique beast. so you need to pay attention to what the engine is telling you.
11-11-16, 09:23 PM
#28
Banned. I got OWNED!!!
I was only copying what you had said. Are you saying 45psi absolute? Therefore it's 45-14.7 = 30.3psi (GAGE!) which is nowhere near your 22psi cap.
11-12-16, 11:11 AM
#29
Old [Sch|F]ool
I am thinking that if you bleed off coolant from the bottom half of the engine before it gets to the thermostat, and cool IT off, you'll be removing heat from the hottest part of the engine (what you want to do) and the upper half doesn't absorb as much heat from the coolant, it would be stagnant until the thermostat NEEDED to open. And if you were cooling the hot part of the engine separately, you could install a much colder thermostat. Or none at all, just a restrictor.
If you can keep the top half of the engine cool, you wouldn't get the high temp power loss problem. What we need is a rotary McDLT, keep the hot part hot and the cool part cool. (And now I am dating myself with this reference!)
Where you measure coolant temp is also critical! Mazda put the temp gauge's bulb near the hottest part of the engine. They also put the EFI computer's temp sender in the water pump housing where the coolant temp is "generic". Watching both the gauge on the dash and the computer data, it is fascinating to see how the two different positions vary. I've seen "overheat" on the gauge while the water neck was happily showing 175F.
Last edited by peejay; 11-12-16 at 11:17 AM.
11-12-16, 05:51 PM
#30
Banned. I got OWNED!!!
Call me crazy, call me a fool, but I think the opposite of this and this is part of why I want to try the secondary cooling circuit that pulls off of the heater core nipple. That point is the hottest point of coolant in the engine, everywhere "downstream" of that the coolant is heating the engine.
I am thinking that if you bleed off coolant from the bottom half of the engine before it gets to the thermostat, and cool IT off, you'll be removing heat from the hottest part of the engine (what you want to do) and the upper half doesn't absorb as much heat from the coolant, it would be stagnant until the thermostat NEEDED to open. And if you were cooling the hot part of the engine separately, you could install a much colder thermostat. Or none at all, just a restrictor.
If you can keep the top half of the engine cool, you wouldn't get the high temp power loss problem. What we need is a rotary McDLT, keep the hot part hot and the cool part cool. (And now I am dating myself with this reference!)
Where you measure coolant temp is also critical! Mazda put the temp gauge's bulb near the hottest part of the engine. They also put the EFI computer's temp sender in the water pump housing where the coolant temp is "generic". Watching both the gauge on the dash and the computer data, it is fascinating to see how the two different positions vary. I've seen "overheat" on the gauge while the water neck was happily showing 175F.
I am thinking that if you bleed off coolant from the bottom half of the engine before it gets to the thermostat, and cool IT off, you'll be removing heat from the hottest part of the engine (what you want to do) and the upper half doesn't absorb as much heat from the coolant, it would be stagnant until the thermostat NEEDED to open. And if you were cooling the hot part of the engine separately, you could install a much colder thermostat. Or none at all, just a restrictor.
If you can keep the top half of the engine cool, you wouldn't get the high temp power loss problem. What we need is a rotary McDLT, keep the hot part hot and the cool part cool. (And now I am dating myself with this reference!)
Where you measure coolant temp is also critical! Mazda put the temp gauge's bulb near the hottest part of the engine. They also put the EFI computer's temp sender in the water pump housing where the coolant temp is "generic". Watching both the gauge on the dash and the computer data, it is fascinating to see how the two different positions vary. I've seen "overheat" on the gauge while the water neck was happily showing 175F.
11-12-16, 06:32 PM
#31
Old [Sch|F]ool
I'm unconcerned. Follow Mazda torque specs with Mazda tension bolts (no studs, no massively overtightening them) and be happy.
I've torqued every rotary I have built to 23ft-lb and I will use WOT at low RPM when cold (only way to get good drivability with a cold engine!) and so far no problems, except for when I used cheap 18 gauge wire and tried to drive the car when it was 5 degrees outside. Then it burnt through the seals and I had to rebuild it. With Viton cord, which isn't much more expensive than electrical wire.
I've torqued every rotary I have built to 23ft-lb and I will use WOT at low RPM when cold (only way to get good drivability with a cold engine!) and so far no problems, except for when I used cheap 18 gauge wire and tried to drive the car when it was 5 degrees outside. Then it burnt through the seals and I had to rebuild it. With Viton cord, which isn't much more expensive than electrical wire.
Last edited by peejay; 11-12-16 at 06:35 PM.
11-18-16, 12:51 PM
#32
I'm a heat transfer engineer and ive also successfully built a national championship winning rotary powered race car.
I'll leave alone the impression i get from the OP's posts and instead give my real world experience.
Running a rotary engine above 220deg water temp (in the engine) for any extended period of time will cause failure and destruction of parts, often catastrophic. The block assembly is not designed to have it's various parts expand to that operating temp, further even the best water seals in the world will be very short lived at 240deg. I've blown one engine in the 6 years we've been racing this car, it was directly attributable with running the car in an enduo at average water temps of 235deg (at the rear iron). The water seals failed about 45min in which imediatly spiked the engine temp and destoryed the center iron (a huge chunk litterally cracked off).
I've never heard of anyone running that kind of temp for an extended period of time. Sure drag cars might see that for a few seconds, but not road race cars.
I'll leave alone the impression i get from the OP's posts and instead give my real world experience.
Running a rotary engine above 220deg water temp (in the engine) for any extended period of time will cause failure and destruction of parts, often catastrophic. The block assembly is not designed to have it's various parts expand to that operating temp, further even the best water seals in the world will be very short lived at 240deg. I've blown one engine in the 6 years we've been racing this car, it was directly attributable with running the car in an enduo at average water temps of 235deg (at the rear iron). The water seals failed about 45min in which imediatly spiked the engine temp and destoryed the center iron (a huge chunk litterally cracked off).
I've never heard of anyone running that kind of temp for an extended period of time. Sure drag cars might see that for a few seconds, but not road race cars.
Last edited by RockLobster; 11-18-16 at 01:04 PM.
11-18-16, 01:03 PM
#33
from the other thread.
it would appear that Mazda has done what every piston engine has also done, and revised the coolant flow so that the engine is more evenly heated. i would imagine this lets them run the new engine, either at the same temp with better efficiency, or more probably at higher temps without problems.
it would appear that Mazda has done what every piston engine has also done, and revised the coolant flow so that the engine is more evenly heated. i would imagine this lets them run the new engine, either at the same temp with better efficiency, or more probably at higher temps without problems.
I think any rotary in a full output environment (racing) would need drastic redesign in not just tolerances/clearances but materials to survive those kinds of temps. 240+F water temp.
11-18-16, 01:15 PM
#34
Old [Sch|F]ool
Some piston engined race cars are built and run hot (like the nascar example) simply out of necessity, smaller radiator opening = better aero, so run it as hot as we can so we reduce the amount of heat transfer surface needed to transfer the same amount of heat.
As one engine department head put it, (paraphrased) "We are using 2600hp worth of fuel energy to get 900hp. That means there are up to 1700hp worth of gains to be had in thermal efficiency, with the engines we have today, so that is where we are focused"
Part of getting that missing 1700hp is losing less heat to the cooling system, and one way to do that is to reduce the temp delta from combustion to the cooling system.
There are aero benefits too, of course, but no action should have only one objective...
11-18-16, 07:30 PM
#35
Good point. But fuel economy and emissions go hand in hand. 
Less fuel you burn, the less emissions you have. I get that it will raise some of the nasty ones like NOx etc...
The hotter the exhaust too the better the catalyst works (to a point).
It's an interesting point but one that may not translate to a rotary like it does with pistons? I mean power output, not fuel efficiency.
Less fuel you burn, the less emissions you have. I get that it will raise some of the nasty ones like NOx etc...The hotter the exhaust too the better the catalyst works (to a point).
It's an interesting point but one that may not translate to a rotary like it does with pistons? I mean power output, not fuel efficiency.
Last edited by RockLobster; 11-18-16 at 07:49 PM.
11-18-16, 07:44 PM
#36
To further relay my experience. I've been told by more than one engine builder that the OEM seals melt above 220 deg coolant temp. "Heavy Duty" water seals likewise fail above that temp but, it just takes longer.
If you run an engine above that water temp you are on borrowed time.
Like PeeJay says where you measure coolant temp paints a drastically different picture as to what the coolant seals are seeing on the hot side of the motor. My reference point has always been at the OEM gauge sensor point (rear iron).
If you run an engine above that water temp you are on borrowed time.
Like PeeJay says where you measure coolant temp paints a drastically different picture as to what the coolant seals are seeing on the hot side of the motor. My reference point has always been at the OEM gauge sensor point (rear iron).
Last edited by RockLobster; 11-18-16 at 07:51 PM.
11-19-16, 05:11 PM
#37
Banned. I got OWNED!!!
To further relay my experience. I've been told by more than one engine builder that the OEM seals melt above 220 deg coolant temp. "Heavy Duty" water seals likewise fail above that temp but, it just takes longer.
If you run an engine above that water temp you are on borrowed time.
Like PeeJay says where you measure coolant temp paints a drastically different picture as to what the coolant seals are seeing on the hot side of the motor. My reference point has always been at the OEM gauge sensor point (rear iron).
If you run an engine above that water temp you are on borrowed time.
Like PeeJay says where you measure coolant temp paints a drastically different picture as to what the coolant seals are seeing on the hot side of the motor. My reference point has always been at the OEM gauge sensor point (rear iron).
11-19-16, 07:56 PM
#38
Old [Sch|F]ool
Depending on the engine loadings, 220F coolant temp might be 230F temp at the inner seals or it might be 300F. Somewhere is a topo map style chart of the rotor housing at a certain BMEP/RPM and the rotor housings were around 450F near the plugs and I forget where at the sides. (And people wonder why Evans NPG has had such a following in the FD world!)
Make the cooling system work more evenly, and you can run hotter coolant.
Make the cooling system work more evenly, and you can run hotter coolant.
11-20-16, 07:18 AM
#39
"Elusive, not deceptive!”
If it were possible to make the large figure eight...... we used a silver plated copper tubular oring that had nitrogen pressure in it on turbines in high temp areas.
And I think this is the chart that peejay was referring to.
And I think this is the chart that peejay was referring to.
11-29-16, 02:59 AM
#41
Banned. I got OWNED!!!
12-01-16, 07:22 PM
#42
Old [Sch|F]ool
I have over four years and don't know how many tens of thousands of miles or how many overheats on Viton cord coolant seals, engine is still sealed up.
12-02-16, 10:04 AM
#44
Banned. I got OWNED!!!
12-02-16, 10:58 PM
#45
Moderator
iTrader: (3)
Join Date: Mar 2001
Location: https://www2.mazda.com/en/100th/
Posts: 30,770
Received 2,561 Likes
on
1,822 Posts
i want the new engine to have an MLS gasket, like a piston engine head gasket. just because i'm tired of scraping
12-12-16, 09:12 AM
#46
I ran my 20b for a year with consistent 250-260 degree temperatures on track after 5-10 minutes at full bore running Evans coolant and had no issues. The engine loses power though at anything over 170-180 degrees so I don't understand the point in wanting to run your engine intentionally hotter then it should be.
thewird
thewird
12-14-16, 03:05 AM
#50
Banned. I got OWNED!!!
