Are Rotary Engines that hot?
 

After i got back from work today I went inside for like an hour then came out to clean my oil cooler on my car, I popped the hood and it was still hot in there, so I got the rags wet and cleaned away anyways my finger touched the engine housing and it burnt me wtf? It has had an hour to coool down and is still hot enough to cause pain? Maybe im just a rotary noob but man is there anyway to keep the engine cooler?

I installed the electric fan and after i turn off the car it is still running and EVERYBODY comes up to me and says hey did you know your car is still running? It is kinda funny when they ask that cause we dont have it set to turn off when the car is off only when the engine reaches a certain temperature. Anyways does anyone know any thing to get to keep the car running cooler?

after i get home, i open the hood while its in the garage and it seems to cool down real quick.

Maybe im low on radiator fluid?

Maybe you shouldn't be sticking your fingers on a hot engine? I'll bet you are a teenager. Teenagers think everything should have happened like yesterday. When you turn off the car, it's not making heat anymore, so just forget about it, it will cool down in an hour or two (also, you might want to check the thermostat on that electric fan install, or go back to the stock fan, the way it's supposed to be). If the engine temp goes up while your driving around, give us another call.

Respectfully yours
Ray

The rotary exhaust gases are up to 250 degrees hotter than a piston engine. However the engine is adequately cooled to compensate for this. In particular the oil flow is a critical part of the cooling design.

Any rotary or piston engine takes time to cool down to external temperature after it is shut down. There is no advantage in speeding up the cooling period except possibly to turbos which need a timer while they spool down. Having a timer to an efan to the coolant radiator will have no measurable improvement to engine life and performance. In fact if you went to the extreme and ultra rapid cooling, there is a possibility of damage due to the different cooling characteristics of materials such as aluminium and steel.

If you have a cooling system problem and run too hot then there can be damage to the engine, but the damage will be done before it is turned off.

The moral is not to work on your engine until its not finger licking hot.

Damn, are you a hundred years old or what? I am only 21. I hate the snide comments on every question that 'oh you must be a teenager, you are dumb, and young, and I was never under thirty.' Grow the hell up. How about useful, intelligent information like he requested. Some thing like this...




Well, the exhaust is hotter than most piston engines, but the tempurature of the "block" or housings should be the same as an equivelent engine. 180-200 degrees aprox. You shouldn't worry about it unless on your guages it shows that you are running it hot. If it ever goes over one half on the temp guage, immediately shut off the engine and find the source of the problem.

Calvin, no offense, some of my best friends are teenagers, although as you suggest, I'm closer to 100. I think your suggestions for Erik are exactly right. Erik, forget my noise about electric fans and sticking your finger on a hot engine (you probably figured this one out already anyway), the important thing is to heed Calvin's advice:

"If it ever goes over one half on the temp guage, immediately shut off the engine and find the source of the problem"

Oh yeh, about rotary engines, they are definately very hot, that's why we love to drive them.

Ray

that is weird, i can touch any part of my engine while it is running besides the radiator and headers and they are only mildly hot. what kind of efan do you have on there. maybe it doesn't push enough air

Back when the first gen was fairly new, I took mine to a muffler shop to get an estimate. At that time, I already knew they ran hotter than a piston engine.

After the car was lifted in the bay, the muffler guy started to reach for the exhaust pipe to check for loose fittings and such.

As he reached up, I yelled, "hey, that gets real hot!"

He turned to me with an annoyed look on his face and said, "yea, I know kid, but I work with exhaust systems all the time, they aren't too hot for me."

Then he proceeded to grab the exhaust system with just a small rag in his hand.

You could hear him yelling and swearing for a long time as the exhaust piped burned his hand.

After he calmed down, I told him, it's a rotary engine, they run extremely hot.

thats good stuff right there. what kind of e-fan are you running? most ppl suggest around 2200-2500 cfm on a rx7. ive got mine on a thremostat like yours which keeps running after the car is shut down and ive gotten several comments about it.

I knew they ran hot, yes i am a teenager. Im just trying to learn more about my engine. I just figured after an hour it would be touchable. Here are some pictures of my E-fan setup.
http://img243.echo.cx/img243/9148/mi...13797pb.th.jpg

http://img243.echo.cx/img243/450/minidscf13804jt.th.jpg

On the temperature gauge the needle never even goes to the halfway mark or past it. So im guessing in runs cool. I just wanted to make sure I wasnt damaging my engine.

Cool Erik, take care of that puppy!

im getting my car painted right now and after i had it all taped up my friend had taped up my muffler which i didnt know so i drove into the booth and by the time i got to the booth which was mind you 20feet away i looked and the paper was burned away at the tips...lol

You can always pop a couple of vents on the hood to let out some of the heat

Is it hard to put those vents in the hood I noticed Kettlemans hood had vents in it and it looks pretty good. Thankyou Ray Green I really am trying to take care of this car and not abuse it. These things are rare and i wanna keep mine on the road!

You might also want to get a shroud of some sort, that way you are pulling air through the entire radiator and not just the center. Looks good though.

POST SOME MORE PICS!!!!

i will be doing this this month since i have a spare hood. i'll show you guys the results right after.

Please make a how to guide or show us with pics step by step so we can do the same without messing up our hoods.

actually... it will mess up the hood a bit.. lol

you will have get it repainted since welding marks will be left off and some bondo stuff as well.

i will also be removing some of the hood's under body pinnings to make it lighter. i don't mind since i will be using hood pins for the hood :)

what exactly are the exhaust temps of a rotary? from my experience i've heard more word-of-mouth people saying these engines run incredibly hot. however coolant temps seem fairly low. the exhaust temps out the back of my turbo flange on my supra can run upwards of 850c on 20psi of boost. this seems pretty high to me for a piston engine.

however, removing exhausts on Rx7s has to be the biggest pain in the ass ive ever encountered! :( not sure if its just the age difference or what, but christ, i've broken pretty much every bolt ive tried to remove on my SE

I do not think there is a problem. If the operating temperature is normal then your efan is the right size. An engine weighing say 300lbs operating at 200 degrees will take time to cool down.

As a teenager you will not remember pre-electric blanket days, but then a 3 pint hot water bottle placed in bed at 200 degrees was still warm to the touch six hours later.

Paradox an impact is your friend, best investment i've made in terms of a tool. :)

I have cut up, replaced, and staight piped 4 cars. I got one Nut to come off without breaking.

When your exhaust is hot enough to burn off engine paint designed for 1200*F then you know your exhaust is real hot. I have personal experience with this.

Surprisingly enough, I managed to remove my exhaust with only breaking 2 bolts.

got my exhaust off without ever breaking a bolt. If you go fast enough, a good oil leak will lubricate and rust proof the entire under carriage.

It may not be 'making' heat anymore, but it's also not circulating coolant to take the heat away. Engine surfaces tend to warm even more after shutdown, as the still-hot internals radiate the heat to the outside. It peaks about 20 minutes after the fact, then cools from there.

You should definately get a shroud around your e-fan. Looking at the gap between your fan and the rad, there's going to be a lot of air being pulled from the sides rather than through the rad itself. I'm in the middle of this mod myself. What I'm doing is modifying the stock shroud so that the fan bolts to the shroud and it's a perfect fit to the rad. It lays nice and flat as I have cut away all the extra material that used to cover the clutch fan.

I still have the old shroud i will try modifying it to fit around this. We would have use the plastic clips to make the fan hang on the radiator but after time these tend to sag and ruin the radiator. So we got some aluminum pieces and made a frame to bolt it on to.

Good point. It would help if an electric fan was coordinated with an electric water pump to circulate hot water from the engine to the radiator after the engine is shut down, but I've never heard of such a thing.

A rotary mechanic once told me that there is danger of the engine overheating at a place near the bottom of the engine after it is shutoff because the water is trapped and can go over the superheat temp of the pressurized system because it can't circulate.

F

In theory yes, but if you measure the surface temperatureoutside of the housing the actual variation is minor mainly caused by lack of air flow. The total heat of the engine will not increase. Thus, I cannot see how any damage will be caused to the engine. As I said earlier, the only possible exception would be the turbo with its high rpm needing lubrication on the spool down. This is the benefit of a turbo timer which keeps the engine running for a short period.

As for rotary temperatures, I suggest headers reach around 1500 degrees, mufflers around 600-700 degrees with the engine housings 180-200 degrees.

A rotary and modern high performance oils should easily handle normal temperatures. Loose the water pump and watch the engine destroy itself!

"It may not be 'making' heat anymore, but it's also not circulating coolant to take the heat away. Engine surfaces tend to warm even more after shutdown, as the still-hot internals radiate the heat to the outside. It peaks about 20 minutes after the fact, then cools from there."

Youch, teenagers beware! Don't move too fast!

Ray

Reviving a dead thread...!

Interesting idea... There are a couple electric waterpumps available...

Combined with a temp sensor... Plus a timer or low voltage sensor to make sure the battey doesn't drain...

Hmmm...

there was a controller available at one time that when the car was shut down it would toggle between the water pump and fan(run fan for set amount of time then run water pump). i looked but i wasnt able to find it now.
you could however run an electric water pump (or a universal remote mounted one) with an electric fan off of a thermostat(1 for both or 1 on each) hooked directly to the battery. this would allow the pump and the fan to run as long as the temp was above the set limit . to keep it from running the battery down you can run a battery buddy(device that disconnects the battery if voltage gets too low so you can still crank it) although i never had a problem with the fan killing the battery on my -se

Im 16, i dont go and sticking my fingers on hot housings, but they sure fit well in your womens pussy

Respectfully Pimpin' your wife
Bitch

That's pretty much what I was thinking...

Just a nice low setting, say half speed for both the fan and pump...

Hmm, mine only takes about an hour to cool down. . . . maybe stock exhaust vs manifold, for some strange reason that defies logic, has something to do with this?