NZConvertible

Like I said, it's been discussed many times before, usually when discussing why you shouldn't remove the coolant thermostat. A similar argument stands here. Basically the quicker an engine warms up the less fuel it uses, the less emissions it puts out and (most importantly) the less engine wear it suffers. Also you don't have to wait as long before using full power and revs.

Nope, the cat is heated by the exhaust temp, not the temp of the actual engine as such.

I'd never actually though of that, but it's not a silly idea.

But unlike the 3000rpm start, this is not causing enigne damage. Show me any evidence that it is. I've never seen any proof that using a thermal pellet does any damage to the engine.

Um, no it doesn't...

It isn't, but that's not what this does. What is does is disable the oil squirters that cool the insides of the rotors. Oil pressure to the rotor bearings is reduced, not stopped, but this only occurs during a time when the engine should only be experiencing low loads and low revs, so there is still plenty of lubrication for the rotors. If you're an idiot who romps on a cold motor then I guess you get what you deserve...

Probably not, but then the 787B was a racecar, so what it did or didn't have is completely irrelevant to this discussion. The circumstances of its useage to completely different.

The "won't fail" argument is pretty lightweight. As I said before, they fail due to old age and they last a damn long time. At this age a replacement thermal pellet will most likely outlast the car itself.

If you don't want to use one on your engine that fine by me. Just leave the dodgy engineering excuses behind and admit you're too cheap and/or lazy to buy a replacement.

RotaryEvolution

iTrader: (30)

we've been over all sides of the argument, i have yet to see anyone come here and say "my engine blew up because i removed the t-stat" or "my engine blew up since i put in a thermal pellet". they may very well reduce heat transfer but the cooling capability is still high enough that it is usually a tradeoff and no short or even long term harm is being done. i would much rather have more oil on parts than less... friction or heat? i will stick with heat, not friction..

some people have driven without t-stats for ages and had no problems, when i hear or see evidence that it is doing significant damage to the engine then i will believe it.

Rx7MPGUY84

eh, im convinced to get one

NZConvertible

Nobody has ever said that would cause an engine to "blow up".

You're making generalised statements about a very specific part of the engine's operation. In low-load, low-rpm situations (cold engine) far less oil is needed.

This statement makes no sense at all. The thermal pellet reduces cooling until the oil is warm, i.e. more heat. You're also assuming that the reduced oil flow causes more friction. When less oil is required, reducing oil flow does not cause more friction.

A significant percentage of the engine's overall wear takes place when the engine is cold. This has been known and understood since before you were born. It would be a little silly for you to say you didn't believe this...

This post is what exactly I meant by dodgy engineering excuses.

RotaryEvolution

iTrader: (30)

"A significant percentage of the engine's overall wear takes place when the engine is cold. This has been known and understood since before you were born. It would be a little silly for you to say you didn't believe this... "


i do believe this, it is what i am trying to convey. when an engine sits oil runs off of components, oiling them as soon as possible will reduce the friction and wear.


by removing the pellet it increases the flow rate which in turn reduces the ability of heat transfer to take place resulting in higher temps. i don't think it's all that confusing, i'm just replying to what was posted earlier.

NZConvertible

The oil supply to the bearing is not cut off, it is only reduced. There is still a sufficient amount of oil being supplied to the bearings from the moment oil pressure is created.

Either I'm misunderstanding you (sorry if I am) or you don't understand what the thermal pellet actually does. It only disables the cooling jets until the oil temp reaches 140degF. After that they operate normally until the engine shuts off and cools down. Putting in a solid pellet simply causes the cooling jets to work all the time. It does not change anything about how the engine operates once up to temp.

RotaryEvolution

iTrader: (30)

mmmf, i was thinking of a coolant thermostat which restricts flow... anyhow it just causes the rotors to take longer to heat up. in any case the t-stat can fail and provide less than adequate oiling for the rotors, a risk i would prefer to avoid, being my main concern here.

ddub

I'm not cheap, I just don't like the idea of oil being restricted in any way. Tell me why no prior 1986 rotary vehicles had this?

NZConvertible

Every part in your car can fail, but this one is proven to last ~15 years. If your only concern is that it might fail, why haven't you replaced it with a new one? You have no reason to expect it to not last this long.

Why is this remarkably simply concept so hard to understand? The bearings are getting enough oil. If they weren't, how come they've lasted the whole time from new until you removed the pellet? Do you have any genuine reasons to believe they're being damaged?

It's called progess. If you want I'll give you a long list of other things that pre-86 cars don't have.

The whole argument against the thermal bypass pellet seems to be based on the assumptions that (a) it's failure-prone and (b) it causes damage to the bearings due to lack of lubrication. Both of these points are completely untrue, and nobody has offered anything to prove otherwise.

ddub

Maybe, maybe not. I guess we can just leave it at you (and everyone else like you) have your beliefs about it, and we have ours.

I have read enough recommendations and blurbs about why this is a good mod by well respected rotary builders to believe what I do. I have also read all the other sides of it, and they all make good points too. I just came to this decision because I felt it was better.

Maybe I was right, maybe I wasn't, oh well

NZConvertible

If you have those beliefs, why can't you back them up with a solid engineering-based argument? So far nobody's actually refuted any of the technical info I've posted. All I see is "I don't like it".

I missed this bit earlier. Apart from the fact that both rotors are affected equally by the thermal bypass's operation, when an engine "blows", it's almost always due to apex seal failure. The only thing the thermal bypass can possibly effect is the rotor bearings, so there is absolutely no connection here. This is yet another example of dodgy engineering excuses. How can you argue against something when you don't understand what it does or how it works?

Aaron Cake

iTrader: (1)

That's certainly true, and like anything else, I'm sure that the part is not actually a flawed design. However, my only issues that that is no real way to tell that the pellet has failed other then a slight change in oil pressure (which the gauge may or may not show). A thermostat failure is easy to troubleshoot, but you could go for quite a while starving the rotors of oil cooling and some lubrication. One day you run up to high RPM, and then CLUNK!

Of course, it's opinion. I doubt that many engines have died due to failure of this part. I am, however, of the thought that I don't like hidden and difficult to troubleshoot failure points. Also, the solid pellets are cheaper then the thermal pellet.

91mazdarx7

from what i take from all this it isnt much of a worry about replacing it until you actually are rebuilding the engine does this sound right? so ill just let it how it is until i rebuild the engine then replace it but i am still undecided on getting a solid one or a thermal pellet what do you's prefer

Syonyk

It also affects the rotor surface temperatures, which are a known location for carbon buildup. I would tend to think that higher temperatures would leak to decreased carbon buildup, but this may or may not be true. At least for NAs, failure often occurs under not-so-heavily-loaded conditions where detonation shouldn't be a problem (plus NAs don't tend to die instantly from detonation anyway). My suspicion, looking at the carbon buildup on engines I've dismantled, is that a chunk of carbon breaks free from the rotor at some point and takes out an apex seal, which then takes out other apex seals. The rotor surface temperature would be a factor in this.

-=Russ=-

91mazdarx7

while we are on the subject about oil and eccentric shafts im about to change my oil what is a good oil to use in a s5 t2 and a s5 n/a

BlaCkPlaGUE

Well I'll stick with NZ on this topic. He knows his ****, he layed it all out for us, and I think the best idea is what he said.

Buy a brand new one, install it, and it will outlive the rest of the cars life. They don't fail, only after 10 years of driving do they have a chance to fail.

Someone should make a guide on how to replace it.

NZConvertible

True, the failure is not very obvious, although if you keep an eye on your gauges it should be apparent. The trick is whether you see it in time, but the same could also be said for any part of the cooling system too. If you don't look at the temp gauge regularly you won't notice you've overheated until you see the steam. IMO if you're worried about if failing because of age, just get a new one. The cost is pretty small compared to all the other stuff getting put on our cars, and would make little difference to the cost of a rebuild.

Have you read anything I posted about what the thermal bypass does? The thermal bypass does not make the rotors run any hotter or colder than a solid pellet would. It simply brings them up to normal operating temp quicker. Once the oil is warm, there is absolutely no difference between having an opeating thermal bypass or a solid pellet. Carbon build-up is in theory more likely without the bypass, since the engine takes longer to warm up, but any difference would be tiny.

91mazdarx7

thanks for all the help where would i get a new thermal bypass pellet there isn't any rotary shops around me that i know of i get all my parts online is there any web sites that sell them new also what would be a good motor oil to use on my s5 t2 and s5 n/a when i change the oil soon

Icemark

Actually I am sure of at least 3 engine failures related to this, where there was nothing else wrong other than a stuck thermo valve (that the owners did not think 10 psi low was anything to worry about).

In my opinion failure of the thermovalve will lead to apex seal failure through the rotor internally heating or bearing failure and the rotor shifting position against the worn bearings (chatter at high speed).

Syonyk

I personally would be inclined to believe that the rotor surface, being part of the combustion chamber, will reach operating temperature significantly faster than the oil, running through a cold engine, and having nearly 6 quarts to heat.

-=Russ=-

NZConvertible

Iron has a far higher thermal mass than oil, that is it needs to absorb a lot more heat energy to get the same temp increase. But that's not even the point. The rotor is supposed to be much hotter than the oil, that's just how engine's work. It's just silly to assume you understand the thermal workings of a rotary engine better than the engineers who designed it. Once again, the idea is to disable the cooling of the rotors when it's not needed.

RotaryEvolution

iTrader: (30)

technical engineers or emissions engineers? write a letter to mazda and ask them for the answer.

NZConvertible

"Emissions" is one of the most "technical" aspects of the engine, so your question doesn't make much sense. I don't know what you think a "technical engineer" is.

91mazdarx7

i got another question i dont need to rebuild my engine i only know the simple things like oil changing replacing some belts alternators exhaust ect the easy stuff i was wondering if i were to buy the video of the step by step rebuild video and watch it would i be able to gain alot of knowledge on the complete engine do you's think it would help me understand alot more then i do now

RotaryEvolution

iTrader: (30)

you're getting into this a little much, i'll let you win because you're just spinning in circles on the subject. i don't feel like arguing after a long week at work.