External Oil Line/Line Loop Oil Modification
 

Hey everyone, I've been hunting around, trying to find the information needed to do the external oil line modification. It's the one where oil is routed in/out the side galleys of the front iron and bypasses the front cover and the dowel pin running between the oil filter pedestal and the front stationary gear. I generally have a good idea of how to accomplish this now, but I haven't found much about sizing of the -AN fittings. A lot of the pictures in threads detailing how it's done are also missing, so it's hard to even ballpark them. I've seen someone mention (probably Banzai Racing) that they put -8AN fittings in the center iron of a 20B, but looking at my S4T2, that looks a bit large for the side oil galleys in the front iron. What size fittings did you all use for this modification?

I used 6an and a pineapple racing oil pedestal adapter.

https://farm2.staticflickr.com/1667/...71a1a51c_h.jpgIMG_1561 by thomas telesco, on Flickr

2 of these:

http://www.ebay.com/itm/141866558757?_trksid=p2060353.m2749.l2648&ssPageName=STRK%3AMEBIDX%3AIT
1 ft of this:

http://www.ebay.com/itm/141866565248?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
2 of these:

http://www.ebay.com/itm/311516410177?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
And the pedestal:

Oil Pedestal Adapter, all except RX8

You will also need a 1/4" npt tap, and the associated drill bit.

I have -6AN as well.

I would not use pipe fitting bends (tight radius bend) since you are specifically doing this mod to decrease the pressure drop of the oil going to the front bearing.

Straight off the oil filter pedestal adapter, between the oil dipstick tube and the housing and down to the front oil plug galley and then a 90 deg hose end fitting (longer radius mandrel bend).

Tap the side housing with straight threads (instead of tapered pipe threads) and seal with a crush washer so you don't crack the cast iron.

Digging this up again. My question is more on the actual line routing. My plan is to plug the front cover feed and use solid dowels. I've looked at pics of only one line in front cover and also two. I can't find a definite answer on routing tho and all threads the pics are gone. I am planning on front oil pump out iron to cooler, cooler out to remote filter mount, filter mount to rear iron, then a oil filter adapter of some sort feeding front bearing through front iron and also adapter feeding turbo. Does that sound like proper routing? Thanks

Two lines in the front side housing.

-6an oil into the front bearing and -10an oil out to the oil cooler.

If you see one with one line they are using the (convoluted) front cover's oil cooler outlet still.

If you block oil flow to the front cover you lose your cold start oil pressure relief valve, oil to the CAS gear and oil to the oil metering pump.

I used a hollow dowel between the front cover and stock oil pump outlet to keep the o-ring in place (it kept popping out) and just blocked front cover oil cooler outlet.


https://cimg9.ibsrv.net/gimg/www.rx7...1b58c89fcf.gif


I almost feel like I shouldn't tell anyone how it is done because if one can't reason out the system they probably shouldn't be doing the modifications...

Doesn't a metal front cover gasket eliminate the
Téflon o-ring ?

And also,
I'm no expert by if the oil pressure doesn't go to the front cover (if installed) isn't it enough for the teflon o-ring to NOT to fall , since pressure is by-pass.

What diagram is that for, BLUE_TII? It looks EFI, but has a distributor. IIRC, FCs have an oil thermostat in the oil cooler and the front pressure regulator bypasses straight into the pan, not through the bottom of the engine to rear pressure regulator. Early euro 13B, or GSL-SE engine?

And to be fair to siguy2k, I had troubles figuring out this modification until I actually cracked open a 13B. It's a bit hard to understand when there's no pictures left anywhere. When I asked this question, I hadn't ever seen the inside of a 13B until now, and didn't really have the means of doing so (I didn't have irons to spare lying around). Now that I have, I could go back into the threads without pictures and actually understand what they're saying.

Also, to 7krayziboi, the metal front cover gasket is all inclusive. If you use it, you won't need to worry about the teflon ring or the o-ring, and since they're built into the gasket, they won't fall out (unless the gasket falls down too, but then you have other problems to worry about as well). I'm not sure what you mean, with the whole pressure bypass preventing the o-ring from falling. The hollow dowel comment was just to keep a means of preventing the o-ring from falling without blocking oil flow.

The hollow dowel comment was just to keep a means of preventing the o-ring from falling without blocking oil flow.

Keeping the o-ring in place and also leaking less than o-ring or metal gasket when the oil pressure does push the front cover away from the front side housing.

Mazda just missed putting a boss and bolt there next to the oil pump outlet when they designed the engine. In the '60s they must not have imagined how high they would jack the pressure up on the 13B-REW.

Holy crap, that's new to me

Double post

https://cimg2.ibsrv.net/gimg/www.rx7...69c47f575c.jpg
I did it this way to keep the power steering and AC brackethttps://cimg9.ibsrv.net/gimg/www.rx7...3ebec1830d.jpg

Part of the external mod is to do away with the sharp 90s in the front iron.

this is the none turbo:

https://www.rx7club.com/attachments/...rbo-ii-omp.jpg

this would be the T2

https://www.rx7club.com/attachments/...s-oil-flow.jpg

Here is pics on a 13b-rew
The AC bracket needs to be modified to be able to use PS.

Little FIY,
I haven't attach the AC but I have a good feeling it won't fit.

Attachment 595733

Here's the 13B-REW iron I got from some big time drag racers in PR. Identical irons from the builder have been low 7s in the 1/4 .
It looks like they slipped a piece of tubing into the galley and ground it flush. This way, if the dowel casting broke, you wouldn't lose oil pressure and could finish the pass.
If anyone's interested, this iron is for sale :?

https://cimg2.ibsrv.net/gimg/www.rx7...73ba3c5e2a.jpg

https://cimg3.ibsrv.net/gimg/www.rx7...5942400170.jpg

https://cimg4.ibsrv.net/gimg/www.rx7...fbd7620e80.jpg

What size fitting are you running in the front iron?

As for using the compressor, You have to either use a sharp 90 bend fittings straight in the front iron or space out the AC compressor last time I checked.

I used -06 Boss to -06 for the oil feed
And -06 Boss to -10 for the return IIRC.

I haven't attached the oil lines yet but
In regard of the 90" degree fitting.

I pretty sure there is enough space to put an 90hose end to it, it might be a little tight on the return because of the PS line bracket.

As other stated, probably a banjo on the return will solve fitment problems.

But eh,I'll see when I cross that bridge .

Sorry for the poor quality pics but here is how I did mine. all -6 size and an NPT to AN adapter into the front housing. Also if your going this far, I would suggest port matching the opening in the stationary gear to the opening in the iron. I'm no scientist but during my research for oil modifications I found that walls in the system are bad and most of the ports in the oiling system don't match up very well.

https://cimg9.ibsrv.net/gimg/www.rx7...14af5e6e8c.jpg

https://cimg2.ibsrv.net/gimg/www.rx7...dd09136fc6.jpg

Your engine bay looks sweet. I'll check on the port alignment when I get to that hurdle.

I'm going to try a steel M16x1.5 to -8AN fitting with a crush washer, to see if I can't squeeze a larger fitting in there than the usual -6AN. -8AN ORB looks too scary for the lower front iron passage.

Bringing an old thread back to life. I understand the concept and the idea behind it. I understand reasoning behind it (Due to running a solid one piece dowel in the upper dowel location.) Just have one question for it. You end up using the oil galley passage in the front iron lower section to supply oil from the rear of the engine via a pedestal. On the Turbo, you supply oil to the turbo via the front iron top port, with the solid dowel is this location blocked as well or does it still function? I'm no fluid dynamics person, but even looking at the oem flow path, I don't see how well it would work in the first place as it has to flow backwards and up. Any input from people who have done it?

The dowel sits in the front iron before the turbo passage .

So the oil feed passage is unblocked, correct?

Correct , the flow change direction from the top of the front iron (blocked by solid dowel) to the center of it where the new oil feed is.

The main direction of the oil coming from the pedestal will be to the front bearing as it's now in a straight path to it , (compare to the 2 extra 90• angle the OEM system use).

On the OEM setup , the oil has to go up the front iron (just a little) to feed the the turbo through the oil galley from the rear iron.

This mods basically eliminates 3 90•angle in the the OEM oil system (or 5 if use straight Feed/Return fitting)

Attachment 731824

But the loop line mod was not created to make the oiling system work with solid dowels (though it does work for that purpose) it was created to increase and balance oil flow into the front and rear of the eccentric shaft for the rotor bearing and rotor cooling.

The factory eccentric has some efforts to balance the flow by having just one oil entry hole in the rear main bearing journal while providing two oil entries on the front main bearing journal (to make up for all the oil pressure and flow loss from the convoluted oil path to the front main bearing.

The loop line mod is to make a smooth passage for oil directly into the front main bearing area for the highest possible pressure and flow.

Then you can go ahead and add the second oil entry onto the rear main bearing journal.

Balance is important because the oil flow will follow the path of least resistance. Too much flow in the rear and you could starve the front (and vice versa).

Another trick you can do to increase oil flow into and out of the eccentric shaft to feed the rotor bearing and rotor cooling jets is to relive the entry and exit holes.
https://cimg4.ibsrv.net/gimg/www.rx7...ea8ce5e1f9.jpg

Another way you can increase oil flow to the rotor bearings is to limit oil cooling flow by putting in the Mazdacomp restricted oil cooling jets or the Webber jet mod to restrict flow.
Stock
https://cimg7.ibsrv.net/gimg/www.rx7...2e7799951e.jpg
Restricted
https://cimg8.ibsrv.net/gimg/www.rx7...d50ffbe477.jpg

Thank you both for the information. These are both things I haven't been able to find using google searches. I understood the loopline mod being needed for the solid dowel to be able to feed the front rotor as you blocked the path when installing both solid dowels. I did not know that there was added benefits for doing it without the solid dowels, as I am sitting here doing research for the next build and attempting to make a motor that will outlast the turbo for that time when I decide my current setup is not enough.

So, if you where to solid dowel it in both locations with the loopline mod, would it be necessary to add the additional inlet to the rear main bearing as you had mentioned?

I have no experience with solid dowels. You would have to take the localized oil pressure readings before and after adding the loop line mod to find out. You also have the variable of what size and shape AN fittings/hose you use for the loop line. -8AN is the norm and usually there are two 90 deg mandrel bend AN hose ends used, but it could be done with bigger hose and straight AN fittings with a big loop in the hose.

In my mind dowels with some give would be "stronger" than solid dowels. If the engine is detonating and the rotor housings are deforming and wrenching the side housings through the dowel pin I would rather have a dowel pin with give to dampen the shock loads. I would drill out the side housings and put in a soft metal bushing for the dowel pin to ride in to help prevent cracking of the side housings under detonation hammering before I would make the dowel pins more rigid. Or better, machine the dowels down so a soft metal sleeve fits over the ends that will be in the side housings.

I guess the drag idea is to finish the pass with the cracked side housing and without oiling down your rear tires, so solid dowels is like a couple second bandaid.

I have block the oem oil filter position (I have relocate my oil filter).
Can I use a line(an 8 fitting) from the relocation filter adaptor to front iron?

what size npt fitting did you use to attach the an line to the block

try reading the list again:

Any chance the photos can be restored, interesting thread

What cant you see? I can see all posted pics.

don't know whats going on, cant see any of the pictures from the start of the thread, am using my phone, might try a lap top

Are these the Mazda Competition oil cooling jets you were talking about? If so what size are the normal cooling jets?

https://mazdatrix.com/product/ecc-sh...ition-200-jet/
https://cimg7.ibsrv.net/gimg/www.rx7...513bfabb9.jpeg

@InZaneX3651 might want to tag him. Type @ and then start type blue tii and his user name will pop up

@BlueTII

I dont have a great way to measure for you, so I stuck the shanks of drill bits into the stock and Mazda Comp rotor cooling jets.

Stock jet was ~2.5mm or 0.098"

Mazda Comp jet 8553-11-411 was ~2mm or 0.079"

The Mazda Comp jet 2mm corresponds to Weber 200 jet recommended by Racing Beat for pressing into the rear of stock 2.5mm jets for NA race cars and Racing Beat recommends 220 Weber jets (2.2mm) for Turbo race applications.

I also looked over old threads by rotary guru Lynn E. Hannover and my measurements correspond exactly to what he wrote then.

I have no idea where the 0.200 size comes from in Mazda Trix description. Who measures in 10ths of MMs? Who doesnt include units with measurements? They do include the Mazda SKU now so you dont have to reconfigure the MazdaTrix part numbers anymore.

too much assuming; just a number without any measurement reference like mm or “/inches

it’s likely just referencing the Weber part #/size


I’d assume a 2.5mm is the same initial part number with .250 on the end.
​​​​​​​.

However the MazdaTrix part is the Mazda Competition oil jet, nothing to do with Weber.
https://cimg3.ibsrv.net/gimg/www.rx7...7d6d2610db.jpg

when it’s said and done both accomplish the exact same thing

it’s just a reference number, nothing to get hung up on, but if you want to make a big deal about it then call Mazdatrix and let ‘er rip …

otherwise the old school guys have been around a long time and they don’t hung up and scrappy on this kind of minutia like you youngsters do :tonque:

straight off the Adkins site; selling Motorsport part and referencing the Weber jet

hope this helps you sleep well tonight :suspect:


https://cimg2.ibsrv.net/gimg/www.rx7...bdf793c6f.jpeg

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My humor = your big deal.

We've been at this impass many times.

and I thought my humor sucked … :suspect:
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its not funny, but worth pointing out that the stock jet is bigger, but doesn't flow as much because its got a check ball and spring.
so the competition mod is essentially to get rid of that, but 2.5 mm is too big, so they went smaller.

the ball and spring keep it from oiling the rotor at low RPM, which is why the race stuff isn't recommended in a street car, your idle oil pressure will be really low

No, the stock jet is bigger and flows more oil into the rotor.

The oil flows through the square openings around the check ball with no restriction when the check balls are extended by centripedal force.

The whole point of the Mazda Comp rotor jets is to LIMIT oil flow out into the rotors so there is more oil pressure for the rotor bearings.

Eliminating the check balls is just a race reliability mod like locking the distributor and will have some benefit in regards to heatsoaking rotors in the pits.

The Mazda Comp jets do flow more oil than the stock jets with the check balls closed off at low rpm- that is why oil pressure is lower at idle with Mazda Comp jets.
______________


Lynn E. Hanover , 05-03-2004 08:47 PM
Fabricator
Quote:
Originally Posted by BDC' date='Feb 8 2004, 03:46 PM
The outlet on the stock jet is larger by about 1.5 to 2 times. I think just removing the ball and spring and using the jet alone would make the oil pressure at idle drop to nearly zip. That's my theory on it, atleast.



B
The stock jet hole is in excess of .100" the 200 weber jet is smaller than that. So the recomendation in the Racing Beat book is suggesting that you reduce oil flow to the rotors for high power applications. It is not well explained in the Racing Beat book.



However,



This is a racing only change that will get you poor oil pressure at idle and just off idle. The object is to control the amount of oil going to the rotors at high speed.

If you add the 115 pound pressure relief valve for racing, once the oil is hot, you will be adding oil to the rotors in buckets per second quantities, with the stock setup. For turbo cars, rotor temperature is a bigger problem, but even then if you are not running flat out across Nevada at night with all of your ECM gear running, then what is your problem?



The added amounts of oil is of no value at all to the rotors, and you want a bunch more of that oil to be going to the bearings to move out superheated oil lest the bearings start to loose overlay. Rotor cooling in turbos is to prevent detonation.

Not a problem in NA engines (OK if you climb Pikes Peak in 5th gear it's a problem)

but for the most part not a problem.



So why do that?



If you have the good pump, and shim the front relief so it cannot open, and add the 115 pound rear relief then your full throttle oil pressure will be 115 pounds hot. You could squirt hot oil through the stock jet (over .100") over your house. And there are two of those holes in your oil system. The weber jets cut down these two (leaks) to something reasonable, like enough to cool 4 rotors. But it ain't for the street. At 60 to 80 pounds of oil pressure the flow through the stock jet (the hole in the screw) is much reduced. And therefore ideal for street use.



The oil hole in the rotor bearing throw has a slight centrifugal force advantage over the oil jet, so in theory, the pressure at the rotor bearing is higher even though the is no restriction at all in front of the cooling jet hole.



At any rate (pun) the ball and spring offer no restriction to oil flow, because the oil goes through the square opening behind the spring.



If you want to do this anyway, you can braze the stock jet shut and redrill it to match a .200 Weber jet.



So there you have it. The jets restrict oil flow to the rotors when high oil pressure is used. Weber main jets fit the taper at the bottom of the jet well better than the Weber air correctors, but it matters not what you use. If you do this you need more than stock oil pressure. There is no need to glue the jet into the holder. It cannot go anywhere, and if the jet screw comes out, the jet will definitely not be your problem. They used to take a three corner punch, and stake a bit of crank material into the screw driver slot in addition to the Locktite or simular on the threads.



If you have done this and have not added the high pressure relief valve, there is no shame in that. There is also not much oil pressure at idle. If you don't run it real hard, it won't matter, and the oil pressure comes up with RPM, so it won't hurt you there. But don't add the high pressure relief valve thinking that it will cure the low idle oil pressure. It will not. Those oil holes are now open all of the time, and at idle there is just not much oil flow, thus no oil pressure.



On the other hand, the bearings are huge and just need a few drops of oil at idle to survive. So tape over the bottom of the range on the gage and forget about it.



Lynn E. Hanover
Reply

so just bumping this, and without going into the details on the why part of it, which is inconsequential to the inquiry.

If someone wanted to physically seal or block off the oil galley flow to the dowel position in the REW front iron, is it feasible to simply press or drill/tap/thread a plug there from the dowel hole opening side?


https://cimg8.ibsrv.net/gimg/www.rx7...f5bbebb63.jpeg
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that is what the NA cars have... if you were testing stuff or needed to move a turbo car with out the turbo, a non banjo bolt would also work

maybe it’s not clear what I’m asking; I’m referring to internally blocking the oil galley to the dowel pin. Most people using a solid dowel would just rely on the dowel and O-ring there to block it. I actually want to physically block off the oil galley there rather than rely on the dowel/O-ring. If nobody has the answer then I’ll likely have it myself tomorrow when the new front iron arrives. Likely nobody else ever cared enough to bother with it and just let the solid dowel serve that purpose instead.
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it's still going to be pressurized if blocking the front, the flow comes from the oil filter down into the galley, why not block it at the rear iron instead?

don’t ass-u-me us, bro 😎

that end is easily addressed. So no need to either mention or discuss it. :)

However, I inspected and assessed a new front iron today. There’s only maybe 1/4” between the dowel opening end-stop and the oil galley diameter going to the front stationary bearing. Thats not a lot of meat to work with, but we only need to stop flow and the pressure relative to the area won’t require much thickness to hold against the resulting force upon it.


https://cimg5.ibsrv.net/gimg/www.rx7...b603b6465.jpeg
looking in the dowel hole from the rotor housing side.

It appears that if it was tapped and a threaded plug with thread sealer was used there, that the opening going straight through to the stationary bearing can be expanded in the other directions to provide an equivalent flow entrance area if the plug protruded through some to block the side into the dowel entrance. Or that the plug face itself could be ground into the main galley opening shape, but that’s going to depend on how deep the allen hex hole is relative to the thickness.

Otherwise it may require either using a thicker plug and machining down the excess on the dowel side to be flush with the dowel opening end-stop, or applying the same process using a plug that has an external hex/square protrusion for tightening it down. My assessment is that it can be accomplished by a reasonably skilled machinist.

ps: I love the smell of fresh cosmoline in the morning :suspect:

https://cimg5.ibsrv.net/gimg/www.rx7...72cffc64d.jpeg
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i.e. recently manufactured irons arriving from Japan.
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bumping this to ask if anyones knows or can verify the solid 1pc dowel length for a 13B REW?

just measuring the total length on the oil galley dowel position with machined ends, I’m coming up with 234mm (12mm+80mm+50mm+80mm+12mm) as the total available length. The other galley-less dowel position without the machined ends seems to accept a longer total length.

As far as I’m aware, everyone is using the same single dowel length in both ends though. I’m just not sure what that length is though. Ran a bunch of searches and haven’t found it mentioned or discussed.

Obviously 12A, 20B, 26B etc. are different lengths, but haven’t found any lengths ever listed. Kind of like looking for the proverbial needle in the haystack given how old this forum is. Assuming anyone ever did list them.

TIA.
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Used my sketchy POS 12" calipers on a set of Pineapple 1-piece solid dowels I have, so the result is a little questionable. With the fudge factor, I think it's made to a nominal dimension of 230mm in length.

that makes sense, thank you.
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