Oil jet thermal pellet delete mod is stupid.
11-13-12, 07:13 PM
#1
Oil jet thermal pellet delete mod is stupid.
Yeah, I said it. 
This just seems like one of those mods where people have been doing it for so long that nobody can really remember why anymore. Is it that important to save $50? You can't even fill your tank with $50 now.
For those of you who have a fuzzy awareness of this mod, basically you delete the thermostat for the rotor cooling jets. It's typically performed during an engine rebuild or A rotary engine has cooling jets that spray oil into the back of the rotor, just like a piston engine with spray cooling jets.
The thermostat was introduced on 2nd generation Rx-7s. Its benefits include:
1) faster time for the vehicle to reach operating temperature, so you can have fun and enjoy driving sooner (rather than driving it very easy while its still cold).
2) faster time for the vehicle to reach operating temperature so you don't freeze your *** off in the winter so much while you wait for heat.
3) improved fuel consumption because less time is spent in a cold condition where the engine consumes more fuel
4) possibly reduced oil dilution because less time is spent in a cold condition where poorly-atomized fuel can end up in the crankcase
Yes they can fail. Any thermostat can fail, but I can't say there's a high rate of failure on original engines. This is probably a harsh thing to say (maybe even uncalled-for), but: Leave it to a rotary guy to take out a thermostat because everybody else told him too, because he's too lazy/cheap to buy another one, or because he doesn't fully understand its purpose.
Did you know that Audi uses computer-controlled oil spray jet thermostat on its twin turbo V8 now?
Now I'm sure that'll cost a gazillion dollars to fix. But a new eshaft thermostat for your rotary is like $50. Think about it on your next engine build.
This just seems like one of those mods where people have been doing it for so long that nobody can really remember why anymore. Is it that important to save $50? You can't even fill your tank with $50 now.
For those of you who have a fuzzy awareness of this mod, basically you delete the thermostat for the rotor cooling jets. It's typically performed during an engine rebuild or A rotary engine has cooling jets that spray oil into the back of the rotor, just like a piston engine with spray cooling jets.
The thermostat was introduced on 2nd generation Rx-7s. Its benefits include:
1) faster time for the vehicle to reach operating temperature, so you can have fun and enjoy driving sooner (rather than driving it very easy while its still cold).
2) faster time for the vehicle to reach operating temperature so you don't freeze your *** off in the winter so much while you wait for heat.
3) improved fuel consumption because less time is spent in a cold condition where the engine consumes more fuel
4) possibly reduced oil dilution because less time is spent in a cold condition where poorly-atomized fuel can end up in the crankcase
Yes they can fail. Any thermostat can fail, but I can't say there's a high rate of failure on original engines. This is probably a harsh thing to say (maybe even uncalled-for), but: Leave it to a rotary guy to take out a thermostat because everybody else told him too, because he's too lazy/cheap to buy another one, or because he doesn't fully understand its purpose.
Did you know that Audi uses computer-controlled oil spray jet thermostat on its twin turbo V8 now?
Now I'm sure that'll cost a gazillion dollars to fix. But a new eshaft thermostat for your rotary is like $50. Think about it on your next engine build.
11-14-12, 01:26 AM
#2
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Even a new one can fail..
Expecially since OEM quality isn't what is used to be 20+ years ago
Yes, it has a function, they put it there for a reason.
But building a reliable engine means taking out as much weak links as possible and over-engineering the entire setup.
If it means i have to sit in the cold longer and change the oil twice as much, so be it If that is what it takes to make my engine more reliable
The pro's of the thermostat do not weigh up to the consequences if it should fail.
THAT is the reason people delete it
Expecially since OEM quality isn't what is used to be 20+ years ago
Yes, it has a function, they put it there for a reason.
But building a reliable engine means taking out as much weak links as possible and over-engineering the entire setup.
If it means i have to sit in the cold longer and change the oil twice as much, so be it If that is what it takes to make my engine more reliable
The pro's of the thermostat do not weigh up to the consequences if it should fail.
THAT is the reason people delete it
11-14-12, 11:35 AM
#3
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the problem is that there isn't a symptom of a failed pellet except low oil pressure until the engine is cooked. the second symptom is high oil consumption, and then huge clouds of smoke.
i like to block it off, just because that way i don't have to worry about it again, although replacing the pellet is perfectly valid.
i have owned an FC with a bad pellet, it was bad when i bought the car in 1993 at 75,000miles, although i didn't know it at the time, by the time i sold it with 118k, it could give a smokescreen on command.
11-14-12, 11:54 AM
#4
i think the diagnosis of failed thermostats is grossly exaggerated. i have never seen one fail in a running engine. the ones that i pulled out that were failed were always when i had to heat the front main bolt to get the hub off that were fused together.
in virtually every case of low oil pressure the issue was a faulty front cover o-ring. in cases where the oil seals were cooked the engines had well over 100k miles and 20 years of use, the seals were hardened and cracked. that cannot be pinpointed to a front main shaft thermostat failure but i say just due to age, usually because the cars had sat dormant for many years with no constant run time.
i have never run into an issue even reusing the original pellets, so i'm calling BS on all the thermostat failure cases. i'm sure it does happen but due to other reasons, like an excessively overheated engine which other things will fail first anyhow.
on the other hand, the OEM oil seals are not the most durable material. i have used viton and have never seen it harden over time. screw OEM seals, they are also WAYYYY too ******* expensive for a simple o-ring. care to tell me why the dowel seals are $7 a piece? same as the oil filter pedestal o-rings? that is simply rediculous.
in virtually every case of low oil pressure the issue was a faulty front cover o-ring. in cases where the oil seals were cooked the engines had well over 100k miles and 20 years of use, the seals were hardened and cracked. that cannot be pinpointed to a front main shaft thermostat failure but i say just due to age, usually because the cars had sat dormant for many years with no constant run time.
i have never run into an issue even reusing the original pellets, so i'm calling BS on all the thermostat failure cases. i'm sure it does happen but due to other reasons, like an excessively overheated engine which other things will fail first anyhow.
on the other hand, the OEM oil seals are not the most durable material. i have used viton and have never seen it harden over time. screw OEM seals, they are also WAYYYY too ******* expensive for a simple o-ring. care to tell me why the dowel seals are $7 a piece? same as the oil filter pedestal o-rings? that is simply rediculous.
Last edited by RotaryEvolution; 11-14-12 at 12:02 PM.
11-14-12, 12:49 PM
#5
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Ok so it seems that there is over pricing on almost everything weather it's related to rotary engines or wheelbarrows . Bought a well known brand name dremel tool the other day to clean up the intake ports . as I have an old dremel I thought I would get just the flex extension The flex shaft was $50.45 separate . The whole tool dremel and kit with 100 pieces , plus flex shaft at the same store with case , same isle same flex shaft for $54.99 with a 5 year full warranty now what the hell is with that ??
Anyway I am just getting ready to order parts for my 13b and the new thermal pellet comes with the kit that I have decided to order . Should I( in the eyes of the more experienced rebuilders ) use the new or just clean up the old and reuse remember it is laying there anyway . just want some experienced imput for when assembly time comes
Thanks Gerald m.
Anyway I am just getting ready to order parts for my 13b and the new thermal pellet comes with the kit that I have decided to order . Should I( in the eyes of the more experienced rebuilders ) use the new or just clean up the old and reuse remember it is laying there anyway . just want some experienced imput for when assembly time comes
Thanks Gerald m.
11-14-12, 01:01 PM
#6
sorry i haven't gotten back to you yet Gerald.
the thermal pellet bypass is more of a performance modification IMO, most race engines aren't always up to full operating temp when you need them to be. in that event i would run the solid thermal pellet.
for street driven cars and not highly modified i would stick with the OEM, if it looks fine it probably is. you can pull the pin out and be sure the rubber seal is intact which will tell you the OEM pellet is still functional and usable. the other test works like any other thermostat test, boil some water and throw it in, the pin should push out of the pellet.
the thermal pellet bypass is more of a performance modification IMO, most race engines aren't always up to full operating temp when you need them to be. in that event i would run the solid thermal pellet.
for street driven cars and not highly modified i would stick with the OEM, if it looks fine it probably is. you can pull the pin out and be sure the rubber seal is intact which will tell you the OEM pellet is still functional and usable. the other test works like any other thermostat test, boil some water and throw it in, the pin should push out of the pellet.
11-14-12, 01:27 PM
#7
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That is pretty much what I thought you would say . actually just getting my thoughts together cleaning up intake runners and so on , Anytime . Thanks Karack . You might be rotary evolution to the rest of the world but you will always be Karack to me 
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11-14-12, 03:06 PM
#8
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re "not highly modified". what do you consider a coastal SouthCal ported TII, hybrid turbo, FMIC, open exhaust, 350+ whp potential, that sees 3K miles per year?
11-14-12, 03:52 PM
#9
what i consider highly modded is a car 500WHP and above, barely any street time. even then i have run the stock pellet and never had an issue. what i'm referring to is cars sitting in the pits that can't even fully warm up sitting there idling without an hour to spare. even then you have a warmup lap which usually does the trick. i've only installed maybe half a dozen thermal bypass pellets at customer request and i didn't want to spend an hour debating with the customer the why or why not's, i'm getting too old to babysit people who already have made up their minds.
berate me all you want, the pellets were all used/reused also. as i said, i have never seen one fail aside from the reason i gave above, i cooked them. even in 200,000 mile stock engines i have pulled them out and they looked and worked perfect.
i won't even argue the oil jet mod, that is for cars that are always revving past mid gauge.. otherwise it is an idiotic mod that results in stupid low oil pressures for marginal internal additional cooling. the pump needs to be overdriven or a sump installed to even provide adequate oil pressure. i did it once because i was curious about it when i first started doing engines on my car, i put another stock e-shaft in that engine the next open moment i had the engine back apart and never even brought it up again. i threw that shaft away because it was destroyed after working with the loctite and i could never get my jets back out.
some shops will sell you anything and call it an "upgrade", don't be fooled. there is plenty more important things to worry about with these engines than this particular failure. but honestly for the pellet i have no feeling on the subject either way, do it or don't, it isn't going to make a huge difference either way.
berate me all you want, the pellets were all used/reused also. as i said, i have never seen one fail aside from the reason i gave above, i cooked them. even in 200,000 mile stock engines i have pulled them out and they looked and worked perfect.
i won't even argue the oil jet mod, that is for cars that are always revving past mid gauge.. otherwise it is an idiotic mod that results in stupid low oil pressures for marginal internal additional cooling. the pump needs to be overdriven or a sump installed to even provide adequate oil pressure. i did it once because i was curious about it when i first started doing engines on my car, i put another stock e-shaft in that engine the next open moment i had the engine back apart and never even brought it up again. i threw that shaft away because it was destroyed after working with the loctite and i could never get my jets back out.
some shops will sell you anything and call it an "upgrade", don't be fooled. there is plenty more important things to worry about with these engines than this particular failure. but honestly for the pellet i have no feeling on the subject either way, do it or don't, it isn't going to make a huge difference either way.
Last edited by RotaryEvolution; 11-14-12 at 04:12 PM.
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05-10-13, 04:11 AM
#11
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I confirm this . I have fitted a Thermal pellet and the mazdaspeed Oil Jets (without ball and spring as preconised) because I make a lot of track day.
The problem is now, all the time the engine is cold, I consume a lot of oil because all the metal parts are not dilated and the oil pass every where. So my engine smoke a lot. As soon as it's hot, it doesn't smoke (only a little 2 stroke oil smoke because my OMP take 2 stroke oil in a seperate tank).
As soon as I use my car on the road, and after a long stop time, I create a enormous oil cloud.
The problem is now, all the time the engine is cold, I consume a lot of oil because all the metal parts are not dilated and the oil pass every where. So my engine smoke a lot. As soon as it's hot, it doesn't smoke (only a little 2 stroke oil smoke because my OMP take 2 stroke oil in a seperate tank).
As soon as I use my car on the road, and after a long stop time, I create a enormous oil cloud.
05-10-13, 11:36 AM
#12
I confirm this . I have fitted a Thermal pellet and the mazdaspeed Oil Jets (without ball and spring as preconised) because I make a lot of track day.
The problem is now, all the time the engine is cold, I consume a lot of oil because all the metal parts are not dilated and the oil pass every where. So my engine smoke a lot. As soon as it's hot, it doesn't smoke (only a little 2 stroke oil smoke because my OMP take 2 stroke oil in a seperate tank).
As soon as I use my car on the road, and after a long stop time, I create a enormous oil cloud.
The problem is now, all the time the engine is cold, I consume a lot of oil because all the metal parts are not dilated and the oil pass every where. So my engine smoke a lot. As soon as it's hot, it doesn't smoke (only a little 2 stroke oil smoke because my OMP take 2 stroke oil in a seperate tank).
As soon as I use my car on the road, and after a long stop time, I create a enormous oil cloud.
05-10-13, 09:10 PM
#13
Alright stupid question here but why not just use a solid thermal pellet. It allows oil to flow more constant from start up. Though warm up would be a bit longer wouldn't it add protection and reliability? Or am I missing the point completely. I understand that the stock thermal pellet acted as a sort of thermostat which was good in theory (guessing to keep oil pressure and to help reach operating temperature). But they can fail, OE quality is of question now days, and a solid pellet can't fail in theory). I'm not bashing either side I just want to understand why one wouldn't want to replace the OE pellet with a solid pellet?
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