eccentric shaft oil jet modification question
02-02-12, 12:40 AM
#1
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eccentric shaft oil jet modification question
Ive seen the oil jet plug modification with the weber jets inserted to replace the springs and ball. The mod is simple enough, but is this mod recommended for a daily driver? I have seen conflicting information on this point. Please clarify gurus!!!
02-02-12, 07:45 AM
#2
Waffles - hmmm good
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I am not a guru on engine mods at all but heres my 2 cents worth.
My understanding is that this mod is only required for extra lube/cooling capacity of the
rotors in very high rpm (>8K) applications and/or boosted applications. It will also
lower your oil pressure, especially at idle and will require other mods to compensate
for it.
My understanding is that this mod is only required for extra lube/cooling capacity of the
rotors in very high rpm (>8K) applications and/or boosted applications. It will also
lower your oil pressure, especially at idle and will require other mods to compensate
for it.
02-02-12, 10:03 AM
#3
The whole idea of the spring and ball arrangement is to raise intershaft pressure at the lower oil flow rates seen at low RPMs, which in turn increases available pressure and flow to the rotor bearings.
Using fixed jets increases oil flow into the rotor cavities to increase rotor cooling. But it does this by robbing available flow from the bearings.
All the mod references I've read over the years say that using fixed jets on the e-shaft is not appropriate for street cars, and is only really suited to high-RPM operations when using a high volume competition pump & high-pressure regulator.
Two direct citations that come to mind are Jim Downing's "How to Modify your RX-7" and the Mazdatrix web site.
Using fixed jets increases oil flow into the rotor cavities to increase rotor cooling. But it does this by robbing available flow from the bearings.
All the mod references I've read over the years say that using fixed jets on the e-shaft is not appropriate for street cars, and is only really suited to high-RPM operations when using a high volume competition pump & high-pressure regulator.
Two direct citations that come to mind are Jim Downing's "How to Modify your RX-7" and the Mazdatrix web site.
02-02-12, 10:29 AM
#4
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i've read a bunch of SAE papers, and having the rotors too cold is actually bad. so on a daily driver the ball and spring is probably better.
02-02-12, 12:16 PM
#5
R5 shafts came stock with full flow squirters. What was Mazda thinking?
I've got an engine here I built with an R5 shaft and S4 NA rotors. It only does about 14 psi at idle. The oil in the pan also gets nice and hot, obviously because the heat that's supposed to be in the rotors is down in the pan.
I have to do a quickie rebuild just to change to the checkball squirters.
I've got an engine here I built with an R5 shaft and S4 NA rotors. It only does about 14 psi at idle. The oil in the pan also gets nice and hot, obviously because the heat that's supposed to be in the rotors is down in the pan.
I have to do a quickie rebuild just to change to the checkball squirters.
02-02-12, 02:19 PM
#6
Jeff, help me out here; I'm familiar with R5 end-plates (SA's used em; "R5" cast into them as raised ID marks) but what's the model-range for R5 e-shafts, and how do you spot them?
Every R5 engine I've had or seen taken apart, and the year-specific e-shaft I bought new from Mazda one time years back, all came with spring-and-valve jets.
Every R5 engine I've had or seen taken apart, and the year-specific e-shaft I bought new from Mazda one time years back, all came with spring-and-valve jets.
02-02-12, 02:36 PM
#7
I have to disagree with this unless. E-shaft mod, factory oil pump and wacky modified ROPR. Over 50K miles of my engine as a DD and daily abuse, still runs strong. Now that you have my living proof, show me yours 
All the mod references I've read over the years say that using fixed jets on the e-shaft is not appropriate for street cars, and is only really suited to high-RPM operations when using a high volume competition pump & high-pressure regulator.
Two direct citations that come to mind are Jim Downing's "How to Modify your RX-7" and the Mazdatrix web site.
All the mod references I've read over the years say that using fixed jets on the e-shaft is not appropriate for street cars, and is only really suited to high-RPM operations when using a high volume competition pump & high-pressure regulator.
Two direct citations that come to mind are Jim Downing's "How to Modify your RX-7" and the Mazdatrix web site.
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02-02-12, 03:55 PM
#8
I am not a guru on engine mods at all but heres my 2 cents worth.
My understanding is that this mod is only required for extra lube/cooling capacity of the
rotors in very high rpm (>8K) applications and/or boosted applications. It will also
lower your oil pressure, especially at idle and will require other mods to compensate
for it.
My understanding is that this mod is only required for extra lube/cooling capacity of the
rotors in very high rpm (>8K) applications and/or boosted applications. It will also
lower your oil pressure, especially at idle and will require other mods to compensate
for it.
02-02-12, 08:57 PM
#10
Oh, sorry Divin, I should have specified every time I talk about an R5 engine, I'm refering to the J-spec 12As and 13Bs which all came stock with high volume oil pumps with full flow oil squirters and cat-type rotor housings which lack a thermal reactor air injection hole. This differentiates them from the US-spec SA engines which all had low volume oil pumps, checkball squirters and thermal reactor air holes in the housings.
The nitrided side plates and rotors/counterweights are the only similarities.
Here is a picture of an R5 full flow oil squirter available at Mazdatrix. They fit perfectly and are proven to work. No need to get a weber jet or whatever.
I can wait to rip these stupid things out and swap in a set of checkball squirters. I'll use the bigball type found in beehive 12As and all 13Bs 86 and up - not sure whether early 13Bs with low volume oil pumps used big checkballs or small. Gonna go big because I used S4 NA rotors which had big ***** in their shafts!
Incidentally, to keep the REPU on the road while I perform the rebuild, I'm thinking I'll just throw in the RBD for break in purposes. You know, the pony engine. It's just an idea. Don't hold me to it.
The nitrided side plates and rotors/counterweights are the only similarities.
Here is a picture of an R5 full flow oil squirter available at Mazdatrix. They fit perfectly and are proven to work. No need to get a weber jet or whatever.
I can wait to rip these stupid things out and swap in a set of checkball squirters. I'll use the bigball type found in beehive 12As and all 13Bs 86 and up - not sure whether early 13Bs with low volume oil pumps used big checkballs or small. Gonna go big because I used S4 NA rotors which had big ***** in their shafts!
Incidentally, to keep the REPU on the road while I perform the rebuild, I'm thinking I'll just throw in the RBD for break in purposes. You know, the pony engine. It's just an idea. Don't hold me to it.
02-03-12, 01:27 PM
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02-03-12, 10:03 PM
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Yeah, this is just what I mean. Seems there are two schools of thought on this. My thinking would be that if you are creating enough pressure the increased flow from the mod is better. BUT I don't even know how the oil flows through the e-shaft and rotors even though I have stared at that thing trying to picture it.
02-04-12, 12:30 PM
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Yeah, this is just what I mean. Seems there are two schools of thought on this. My thinking would be that if you are creating enough pressure the increased flow from the mod is better. BUT I don't even know how the oil flows through the e-shaft and rotors even though I have stared at that thing trying to picture it.
so on a race engine, that runs high rpm high horsepower, these are needed. on a street engine you don't need as much oil flow into the rotors, so the ball and spring works better.
there isn't a hard and fast rule for when to switch between the two.
the other issue, idle oil pressure, isn't important to road racers, generally anything under 4000rpm doesn't matter much, but a street car is UNDER 4000rpm about 80% of the time....
02-04-12, 07:23 PM
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02-06-12, 12:39 PM
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02-06-12, 12:39 PM
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02-06-12, 12:45 PM
#19
fixed jets are for track driven cars
ball and spring are for city driven cars and daily drivers
there is no realistic benefit to modifying the jets if you drive the car mainly on the street. i have done fixed jets and i will not again for anything i drive on the street.
ball and spring are for city driven cars and daily drivers
there is no realistic benefit to modifying the jets if you drive the car mainly on the street. i have done fixed jets and i will not again for anything i drive on the street.
02-06-12, 02:53 PM
#22
you could but isn't it easier to upgrade the oil cooler and lines than to rip apart the engine to tune the oiling system from the inside for the rare occasions that your rotors might be getting a little warm? i can see it more of an issue on turbo motors than naturally aspirated ones.
are the rotors getting so hot that the apex seal springs are flattening out or causing internal detonation to occur? if the answer is no then i try to leave sleeping dogs lie... on wacky's bbq.
are the rotors getting so hot that the apex seal springs are flattening out or causing internal detonation to occur? if the answer is no then i try to leave sleeping dogs lie... on wacky's bbq.