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Old 04-17-2008, 10:36 PM   #1
Davenow
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Default 08 STI 11mm oil pump or JDM 12mm oil pump?

I figure since I am building the motor (100mm forged/coated CP pistons),and got all sorts of head/cam work done, and have a turbo to blow at high RPM, I would like to spin it to 7750 when at the drag strip. Lots of people (including myself) have spun bone stock EJ255s and 257s to 7500, so I think 7750 or maybe even 8k, only at the drag strip, is going to be safe.

But since I am a bone head and didnt get the rotating assembly 0 balanced or crank cross drilled, I figure I better hedge my bets with an upgraded oil pump. I figure even at 7500, the upgraded pump will give me that much more safety.


So, the 08 STI oil pump, which is 11mm, is a LOT cheaper than the JDM 12mm oil pump. Is the 12mm really needed or is the 11mm going to be enough of an upgrade.
I am figuring that the 11mm should be plenty since the OEM pump was working ok at 7500 right? Or is that idiot logic? The 12mm pump is almost twice as much as the 11mm, and I am running out of money on this build.



Thoughts? Opinions?
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Old 04-17-2008, 10:44 PM   #2
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I was thinking about this for my future build as well.
For me I'd go with the 12mm pump because it works. Also it's on the JDM ones because they rev HIGH. Our USDM STi only revs to 7krpms still, so it wouldn't need the 12mm pump. They upped it to the 11mm probably because it has AVCS on the exhaust side now.
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Old 04-17-2008, 10:58 PM   #3
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Right, but with me only having AVCS on the intake side, it should translate to more oil everywhere else.

Im just saying that if OEM was fine at 7500, and I am only looking for 7750(on occasion, will be 7500 normally) the extra flow from the 11mm should do shouldnt it?

*sigh*
I am just trying to determine if its a total waste to do the 11mm. I know the 12mm would do more. But the 11mm is going to do more than the OEM pump, do I really need the 12mm? its a lot more $$$

Last edited by Davenow; 04-17-2008 at 11:09 PM.
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Old 04-17-2008, 11:03 PM   #4
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Me I would choose the 11mm pump, it would suck to drain the pan at high rpm with the 12mm. Or over-aerate it and heat it up by running on the bypass all the time. On the other hand my cosworth 10mm pump seemed to handle 7800rpms with oem bearings and a stock un-drilled crank, bearings looked new after ~7k miles.
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Old 04-17-2008, 11:12 PM   #5
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Yeah I looked at the cosworth option, but the 11mm is cheaper and supposedly the cosworth doesnt flow as much. (somewhere in between the oem and 11mm I guess?)
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Old 04-17-2008, 11:37 PM   #6
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Quote:
Originally Posted by jays05 View Post
Me I would choose the 11mm pump, it would suck to drain the pan at high rpm with the 12mm.


yea but the 11mm pump flows more @ 6000RPM!!

Less pressure but flows more.
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Old 04-17-2008, 11:37 PM   #7
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Dave, the JDM pump isn't very much. Like $250 or something. That's what I'm running.
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Old 04-18-2008, 01:20 AM   #8
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my 12mm jdm pump was roughly $160.
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Old 04-18-2008, 01:34 AM   #9
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Wittmer 25 has the 12mm pump and we cleaned it up quite a bit. When the motor is cold it pegs the guage over 100 psi. at idle. When its warm it's about 35-40 at idle. His motor is a 04 sti with a gruppe s shortblock. I think the 12mm is too much volume unless you use an adjustable bypass. Without the external bypass it will aireate and heat the oil by continualy bypassing the oil in itself. Warm after the external bypass it's adjusted to 95 psi at 7k. Thats with 5w30 pennsoil. The external bypass is connected to a 3/8 steel line. The 12mm has that much extra volume. The chart shows 85 psi. Thats is wrong. Without an external bypass it makes 100psi by 5k easy. I like being able to adjust the pressure and also to have a oil cooler on the bypass circuit.
Charliew

Last edited by charliew; 04-18-2008 at 01:42 AM.
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Old 04-18-2008, 03:52 AM   #10
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Quote:
Originally Posted by texas05sti View Post
Dave, the JDM pump isn't very much. Like $250 or something. That's what I'm running.

But the 11mm USDM is like 125

Quote:
Originally Posted by n2oiroc View Post
my 12mm jdm pump was roughly $160.
From where?
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Old 04-18-2008, 04:54 AM   #11
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Here:
http://forums.nasioc.com/forums/show....php?t=1383866

They sell them for $159 shipped.
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Old 04-18-2008, 11:56 AM   #12
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I also got my 12mm pump for $159 from japanparts. I would opt. for the 11mm pump if I were you. My engine pegs my 100 psi oil pressure gauge at cold start idle and when the oil in oil pan warms up to 180-190 degrees F, the oil pressure at idle drops to around 25 psi. My car idles at 1000 rpm when warm. When my dino 5w30 oil is warmed up to around 180-190 degrees F, the oil pressure maxes at about 90 to 95 psi from around 3250ish rpm to redline. However I have an external by-pass valve (3/8" return line to oil fill tube) in a oil filter sandwich adapter that allows me to adjust my oil pressure without tearing down the engine:devil. By the way, my oil pressure sensor is measuring oil pressure just before orifice in the head (AVCS steel oil line). My 12mm pump is still by-passing oil at around 85-95 psi (2 washers under spring). I hope this info helps. I have an 04 sti.

Jonathon
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Old 04-18-2008, 12:17 PM   #13
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a close friend of mine has a built forged piston motor with cross drilled crank h beam rods, cams, ported heads 1mm over sized valves. spinning it to 8k he is running a shimmed 11mm pump with no il effects.
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Old 04-18-2008, 12:25 PM   #14
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Quote:
Originally Posted by jnorth85 View Post
a close friend of mine has a built forged piston motor with cross drilled crank h beam rods, cams, ported heads 1mm over sized valves. spinning it to 8k he is running a shimmed 11mm pump with no il effects.
Good to know, i am going to use a 11mm
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Old 04-18-2008, 07:01 PM   #15
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What is the correct part number for the 11mm pump??
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Old 04-18-2008, 09:42 PM   #16
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Quote:
Originally Posted by wittmer25 View Post
I also got my 12mm pump for $159 from japanparts. I would opt. for the 11mm pump if I were you. My engine pegs my 100 psi oil pressure gauge at cold start idle and when the oil in oil pan warms up to 180-190 degrees F, the oil pressure at idle drops to around 25 psi. My car idles at 1000 rpm when warm. When my dino 5w30 oil is warmed up to around 180-190 degrees F, the oil pressure maxes at about 90 to 95 psi from around 3250ish rpm to redline. However I have an external by-pass valve (3/8" return line to oil fill tube) in a oil filter sandwich adapter that allows me to adjust my oil pressure without tearing down the engine:devil. By the way, my oil pressure sensor is measuring oil pressure just before orifice in the head (AVCS steel oil line). My 12mm pump is still by-passing oil at around 85-95 psi (2 washers under spring). I hope this info helps. I have an 04 sti.

Jonathon
I'm wondering if it would be possible to see a few pics of your oil press. adj. setup!

Or your setup schematic.

Thx
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Old 04-18-2008, 09:59 PM   #17
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^^ yes sounds interesting..
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Old 04-18-2008, 11:58 PM   #18
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Yes.... Pics of the external by-pass setup would be usefull, planing on use in my hybrid build...
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Old 04-19-2008, 01:37 PM   #19
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The 12mm pump is a great pump.

Sucking a sump dry is a silly comment. Where is the oil going to go? Don't even say "in the heads". The rods and mains provide a very large oil demand and is also the fastest way to the sump. Plus the oil return passages in the heads are HUGE. I also find oil aeration to be a silly idea. The pump when operating won't have any air in it. It might for a few seconds, but that air will be carried out with the oil in the first few moments of operation. Where else is the air going to come from? Well some could come out of the oil on the suction side of the pump due to the low pressure. However, once the oil reaches the right temperature, all the entrained gases and fluids (water, fuel) should come out of solution and be carried out by the pcv system.

What pump should you choose? Depends on your demand. If you are running tight factory bearing tolerances, then there is no need for a 12mm pump. If you open up the tolerances to facilitate higher rpm and higher loads with thicker oil, then the 12mm pump is for you.

I am running the 12mm on a few built engines. Depending on the build in question here are the specs:
EJ257
Cross drilled crank and various block oil passage modifications, rod bearings set at .0017-.0019", Main clearance .0015" . Rods have built in piston oil squirters like the factory rods. Some aftermarket rods do not.

Running Mobil 1 15w-50

When cold the oil pressure is 95 psi (taken from the rear oil gallery plug). OMG!!! Well you know what? Good. Oil that is too cold shouldn't be driven on. If the pump bypasses during engine warmup, fine. It'll help warm the oil up to the proper temperature faster. Once the oil warms up, the pressure drops to around 40psi. Perfect. In fact, this is enough oil pressure that if I want to use my AVCS at idle, I can. And it helps tip in too.

At 7600rpm the car has 78psi of oil pressure (and still making HP).

So for ANYONE to recommend one pump over another without knowing the exact setup, down to the bearing tolerances, is an act of ignorance and should be disregarded.

So when someone asks: "What pump should I run?"
The response should be "Well that depends, tell me about your setup."
It shouldn't be "OMG, it's going to suck your sump dry!!"
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Old 04-19-2008, 01:54 PM   #20
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Oh, forgot to add something.

Shimming an oil pump.... does not do what a lot of people think it does.

It does NOT increase your RPM range.
Looking at the chart above, if you shimmed an 11mm pump, it WOULD NOT make it hold more than the 56.8psi at 6000 rpm. It is a positive displacement pump. It can only push so much oil. Shimming it does not change that.

Shimming a pump will increase your peak oil pressure IF you have enough flow to actually lift the relief. That's it.

Now according to that chart, shimming the 12mm pump would help it hold more than 85psi at 6000 rpm. That's because that chart shows that the 12mm pump is lifting it's relief at 6000 rpm because the demand was less than the supply rate.

The chart also makes you believe that the 11mm pump flows more than the 12mm pump at 6k rpm. That is only true if the demand is low enough to cause the pump to lift it's relief. If the demand is higher (and pressure is lower) then the relief will not lift and the 12mm pump will outflow the 11mm.
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Old 04-19-2008, 02:22 PM   #21
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Makes good sense. For high pressure with these types of pumps, you need flow and pressure adjustment.

I wonder about cavitation. Maybe this is what people were talking about when saying aeration. Maybe not. Hopefully, this sort of pump isn't susceptible to cavitation... which actually creates pockets of [not quite] vacuum in a liquid.

Russ
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Old 04-19-2008, 02:22 PM   #22
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seconding all this. this talk of sucking the sump dry is ridiculous.
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Old 04-19-2008, 02:22 PM   #23
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I am running a pretty tight setup. Cyl bores were machined a bit tighter, bearings are MINT so clearance is pretty much new factory tight.

I have settled on the 11mm. Simply because I can get it cheap and the 12mm is overkill for my fairly modest goals as far as RPM.
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Old 04-19-2008, 02:24 PM   #24
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Quote:
Originally Posted by nicad View Post
seconding all this. this talk of sucking the sump dry is ridiculous.

Agreed. I was thinking about it, and it occurs to me that OBVIOUSLY its not going to suck the pan dry or cause some sort of problem. ITS A FACTORY PUMP THAT COMES STOCK ON FACTORY CARS. As such, we know it isnt causing either of those problems.

Unless I am missing some big difference. I know there are differences in the motors, but I seriously doubt they are big enough to cause the issues people are talking about. The second AVCS setup doesnt use THAT much oil.
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Old 04-21-2008, 05:11 AM   #25
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Quote:
Originally Posted by Defiant Autospeed View Post
Agreed. I was thinking about it, and it occurs to me that OBVIOUSLY its not going to suck the pan dry or cause some sort of problem. ITS A FACTORY PUMP THAT COMES STOCK ON FACTORY CARS. As such, we know it isnt causing either of those problems.

Unless I am missing some big difference. I know there are differences in the motors, but I seriously doubt they are big enough to cause the issues people are talking about. The second AVCS setup doesnt use THAT much oil.
We've supplied quite a few of the 12mm Pumps with only ever one discussion of a failure ( the pump may/may not have been suspect in that failure )
One customer of ours in Europe who builds high revving Rally engines won't use anything else....

http://www.japanparts.com/db/partsli...=113-037-15010

113-037-15010 ( #31 is the 12mm Pump ) on Japanparts site

Forum rules won't let us post pricing, we give a 10% Discount off our website pricing for these to NASIOC members, which should translate to $160- ish on your doorstep at the current x-change rate

Graham Ware
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