Shimmed oil pump, why?
So why would you want to get different shims on your oil pump?
Is there a reason not to get +35psi all the time? Under what situations would you want different shims? How does this work with the high volume pump? |
Stock pumps will produce the needed psi with the stock clearances in the crankshaft and connecting rods. Race motors often have much looser clearances, so to get the oil pressure to the correct level, you have to make an adjustment on the pump.
That is why you want to know what kind of clearances you will have in the bottom end before knowing exactly what kind of pump set up you will need. Also, I believe turbo oiling can rob some of that pressure as well, resulting in the need for an adjustment on the oil pump. |
I know about loose tolerances needing more flow, but that's why the high volume pump was produced, so that seems pointless to shim instead.
I can understand shimming for oil coolers and turbos, more lines and pressure loss, I'd forgotten about that when I posted, thanks for the reminder. But that wouldn't be more than 7psi, so I don't see the point of more. So: Loose engine = High flow pump. Turbo/oil cooler = one shim. What's the point of more? |
So far as I'm aware, "shimming" in this context is done to the plunger & spring which set the maximum oil pressure.
In the stock design, the bypass is supposed to open at around 60 PSI. So when the oil is very cold, this protects the system by setting a cap on the maximum pressure that will be generated. (Too much oil pressure and your oil filter bursts.) However, it's important to remember that this mechanism determines the maximum oil pressure. It should have no effect whatsoever on oil pressure below the bypass threshold. In other words, if you have only 10 PSI at idle, then you're going to have 10 PSI at idle no matter how stiffly you've shimmed the bypass spring. (Unless of course the whole reason you only have 10 PSI is because the bypass valve is sticking, though in that case the solution is simply to repair the plunger.) |
That's strange, I'd read the bypass was at 90psi when reading the original BE pump thread earlier today.
I assumed the shim set base pressure instead of maximum, that's good to know, thank you. It does seem to make shimming even more silly, though... (Responded to my post on m.net about the LS1 IAC, Joe.) |
I was easily seeing more than 60psi on my VVT motor for quite some time, on a quality solid state sensor.
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Joe that may be partially true. I was under the impression that oil is being recirculated all the time, and that it is fully open at 60 psi. From what I understood, shims would get your idle psi to a safe operating pressure when you have a loose motor. That is why there are so many options.
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1 Attachment(s)
Originally Posted by Nagase
(Post 696882)
That's strange, I'd read the bypass was at 90psi when reading the original BE pump thread earlier today.
Attachment 241320
Originally Posted by Reverant
(Post 696885)
I was easily seeing more than 60psi on my VVT motor for quite some time, on a quality solid state sensor.
Originally Posted by miata2fast
(Post 696886)
Joe that may be partially true. I was under the impression that oil is being recirculated all the time, and that it is fully open at 60 psi. From what I understood, shims would get your idle psi to a safe operating pressure when you have a loose motor. That is why there are so many options.
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Then why so many options?
I had a verbal conversation with the folks at Boundary, and they wanted to know what my final clearances were before they knew how to shim the pump. I do not recall the exact conversation, but that is how I remembered it. |
Originally Posted by miata2fast
(Post 696903)
Then why so many options?
Maybe if your engine is set up on the tight side, you want to increase the pressure beyond stock in order to achieve enough flow. That's a question for an experienced engine builder, of which I am not one. |
Yeah, I posted in this section rather than in a general one in the hope that someone from BE would show up and comment.
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Noticed Travis hadn't been on in a few days, shot off an email...
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Originally Posted by Joe Perez
(Post 696906)
I don't know.
Maybe if your engine is set up on the tight side, you want to increase the pressure beyond stock in order to achieve enough flow. That's a question for an experienced engine builder, of which I am not one. Ditto on my '92. If I really rev it on a cold morning, the stock OPG goes off-scale. I expect that we both have bypass valves which are sticking in their bores and failing to open when they should. ---- The only downside of running more pressure is that there is more power needed to drive the pump. There is a bit of an over limit situation where you can get bearing erosion by having too much pressure, but I wouldn't necessarily worry about it unless you are over 100 PSI all the time. |
If the shimming is for a tight engine, doesn't that make the high flow pump a bit useless?
I'm just not seeing the difference between a high flow pump and shims in that case, unless high flows are only for loose engines... but then why couldn't you just shim more for that? |
Oh no, there are actually physical limitations to the stock oils pumps. Some of the people on the boards here have used pre-VVT oil pumps with VVT engines and experienced no more then 40 PSI. Mazda sized the pumps extremely marginally for best fuel mileage and power. So if you change anything at all in the dynamics, raise the rev limit, or increase the boost pressure then you have changed the design operating condition of the bearing.
The main reason that we sell our assembled pumps in only high flow varieties is because we machine all the areas where the pump actually sits. This gets the most amount of flatness and concentric measurement out of the bore we can reasonably get. We want to produce the best product possible, and the as cast and machined surfaces aren't that great. This is especially true in used pumps were we've ween wear over .005 inches from the inside to the outside edge of the housing. |
my daddy was tellin me a story about his race cars one day.
and he told his friends he was putting motor X into his race car and they all said "those are oil starved with two pumps!" and he did some testing and determined that he was not having a pressure issue but he was having a flow issue so he ran four pumps and his motor did not starve and die. or something like that. |
Originally Posted by TravisR
(Post 697032)
Oh no, there are actually physical limitations to the stock oils pumps. Some of the people on the boards here have used pre-VVT oil pumps with VVT engines and experienced no more then 40 PSI. Mazda sized the pumps extremely marginally for best fuel mileage and power. So if you change anything at all in the dynamics, raise the rev limit, or increase the boost pressure then you have changed the design operating condition of the bearing.
The main reason that we sell our assembled pumps in only high flow varieties is because we machine all the areas where the pump actually sits. This gets the most amount of flatness and concentric measurement out of the bore we can reasonably get. We want to produce the best product possible, and the as cast and machined surfaces aren't that great. This is especially true in used pumps were we've ween wear over .005 inches from the inside to the outside edge of the housing. |
Originally Posted by Faeflora
(Post 697162)
Soooo... How much oil pressure do your VVT pumps generate when oil is hot? At idle? Max psi?
Jason was the guy on here who was having problems with pressure and his VVT motor. He made a post about it some months back. There was another instance posted before that, but I forgot the originators name. It is important to size the pump with the amount of oil flow that you need. Generally the street strip pump does it for everyone. If you're deleting oil squirters you can definitely use stock sizes. If you are going with a larger then normal clearances, have VVT, and keep the oil squirters you might want to consider a high flow. Best, Travis |
Random question:
I've already got a new set of your gears sitting on the shelf, and when I tore down the pump that came on my donor '99 engine, it seemed a bit worn. Not horrible, just "a bit." So I surf over to Rosenthal looking for new pump housings. They list two parts for 1999-2005 Miata. One is BP4W-14-100A "Through 2/28/1999 production" and the other is BP6D-14-100 "From 3/01/199 production." No mention is made of a change occurring in '01, which would have been VVT time. Moreover, the "old production" pump is $130, the "new production" pump is $250. The parts catalogs confirm this. A change happened in mid '99 (at VIN -9301) and this pump was used at least through the end of '02 production, which is the last catalog I have. Whiskey Tango Foxtrot? |
Originally Posted by Joe Perez
(Post 697342)
Random question:
I've already got a new set of your gears sitting on the shelf, and when I tore down the pump that came on my donor '99 engine, it seemed a bit worn. Not horrible, just "a bit." So I surf over to Rosenthal looking for new pump housings. They list two parts for 1999-2005 Miata. One is BP4W-14-100A "Through 2/28/1999 production" and the other is BP6D-14-100 "From 3/01/199 production." No mention is made of a change occurring in '01, which would have been VVT time. Moreover, the "old production" pump is $130, the "new production" pump is $250. The parts catalogs confirm this. A change happened in mid '99 (at VIN -9301) and this pump was used at least through the end of '02 production, which is the last catalog I have. Whiskey Tango Foxtrot? The gear thickness change has always been reported in 01. The complete pumps we sell fit on any block with a long nose crank though. We don't worry about it too much because most everyone who has a new housing and wants a billet set of gears has so much housing wear it won't work anyways. Thats not to say we don't exchange gear sets if they need the upgrade size. We have both in stock, we just have them send it back and then we exchange it. As far as why the catalog doesn't match that?? I don't know. The oil pump lineage I know about is as follows. So our motor line came from the protege, and the 1.6L used the original non-turbo protege pump and block. The upgrade to the 1.6L long nose crank also switched to the oil pump that the turbo protege (GTR or whatever) had. The pre 1.6L long nose blocks had a pump that was both smaller radially and axially. The long nose 1.6L pump was carried over to the 1.8L pump all the way up to 99 when they retooled the castings to a softer alloy. For what reason? I have no idea! In 01 when the VVT mechanism was added they also increased the oil pump size about 10% to accommodate for the increased volume demand. I also theorize that they increased the volume because of the high wear the pumps naturally went through due to the softer alloy. If my thinking is right we should see pumps wearing to the point where oil pressure is a problem in the next 2-3 years. This increase in pump size could delay the housing wear problem. Meh, the one thing I've learned about doing ignition systems in Miatas is that the progression is in no way linear. Quite frankly its pretty hackneyed! There is no telling what the actual reasons and when the actual changes occurred. |
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