Sintered steel oil pump gears
 

What can be done with the oil pump gears to strengthen them? Cryo?

Yes, I know I can replace them with billet for $500. Thought I'd look for a low cost solution first.

He sells the gears themselves for 300 something, but you need to install them and get them machined to fit your oil pump exactly.

I still don't understand why horesepower supposedly kills oil pumps gears. I thought RPM was the culprit.

have people actually run into oil pump failures?

Ben, if you have an extra gear, cut it in half and we can do a hardness test on it to see if/what its treated to. Cause its a give and take. If you have an extra pump I could model it, then we water jet it (depending on thickness) out of a prehardened steel and voila oil pump.

Well, horsepower is a function of torque and RPM, after all...sounds logical to me.

Whereas 100lb-ft of torque at 8000 RPM might not kill an oil pump gear, 250lb-ft at 8000 RPM might.

I think someone really just needs to figure out a way to add cylinders to the B6/P so we can smooth out the power delivery...

sure, but how much of a load is an oil pump?

The load the fluid puts on the gear is constant (NA vs Boosted) and assuming the gears aren't misaligned and the shafts don't fail.

I don't have an 'extra' pump until I open up my block, as I'll be ordering a new one anyway.

We can get the off the shelf pair of replacement gears for $300 retail. I don't think we could make them for that. $500 includes a brand new pump, required machining to switch the gears out, and delivery.

Is this just for safe measure then?

Right. I don't see how load increases with more power. Oil is the same weight, and rpm is the same. I'm pretty sure that if oil pump gears really did fail at stock rpm, I would have killed them on my 16+ hours of track time post the 150k mile mark.

yeah the stock pump seems to be iffy >7500 rpm
Figured if sintered steel can be made stronger with shot peening or cryo or some other process I don't know about, it would be worthwhile.

It takes some combination of greater than stock power + high rpm. There are 2 gears and the outer gear seems to be the one that fails.

There is a guy on miata.net that lost 2 built motors in a row from oil pump gear failure. Granted, I believe he had a 400 hp drag car, but still.

Im wondering is thats just a freak of nature, but on a built motor i guess its good insurance.

The gears are made from powdered metalurgy, a form of sintering. The outside of the gears is very hard, tough, strong, etc. However, .050 below the surface of the gear, it's rather weak. Somewhere around 1/3 the strength of a true cast and machined gear of the same material. Often, since powdered metalurgy gears are made to reduce cost, they are not alloyed to be extra strong, so cryotreating will help, but not as much as it could, had the gears been made of other various alloys.

Crankshaft flex is what causes them to shatter, as they are quite brittle compared to a cast gear. It's not the power the pump takes to drive it that breaks the gear. There's not a whole lot you can do to strenghen them. If you knew what alloy they were made from, you could find out what cryo and hot/cold forming techniques would alter it's characteristics appropriately.

I've thought about doing this mod, but changed my mind because I didn't know crank flex was the issue.

Is 250whp enough reason to warrant one for a 99 motor?

Hustler-you'll probably be fine, as long as you don't make 250 whp @ 8K. I think for the cost and hassle of billet oil pump gears, I would either use and electric oil pump, or go all out with a dry sump setup.

yeah, because dry sump conversions are so affordable.

I have a buddy here that has broken two of them at 400 hp. If anyone wants a pump for testing, I have one in the garage, but it is stuck to my old crankshaft.. I cant get it off.

I'm seriously considering the billet oil pump gear pump for my build too. Course I also read somewhere in some thread that the ATI damper will reduce the crank issues that hurt oil pump gears. I'm not sure if that means one prevents need for the other or both is better than either or what.

I just know that when I add $500 here and $500 there it's a lot of damn coin.

cool. maybe throw it in your trunk for the next time you come up to DIY? I know a guy with a plasma torch that I've been dying to try :)

Then the next step is finding a place that can do the metalurgy. Loki or Pat, do you have a suggestion?

I got the billet gears for my motor. I'll pass on the pulley. I think as long as you get your bottom end balanced the need for the pulley is greatly reduced. My bottom end is balanced past 10k rpm.

I'm seriously getting tired of spending money on this fucking motor.

<7200 rpm rev limit & <275 whp neither the damper or gears matter

I'm planning on 7600 rpm rev limit, as I understand the 99-00 valves can get floaty after that.

a buddy of mine bent a valve at 8k a few months ago on a missed shift.

In a miata?
How does that happen with a non interference head? Is the head shaved or does he have a more aggressive cam, something along those lines?

I think it has stock cams. I don't know how it happens, but I assume the valve leaves the cam lobe. I was there when the head came off, and saw the slightly bent valve...bent just enough to not seal.

He must have over reved it or something. If you are sticking with the tock redline I don't think you need to worry about the gears. I'm gonna rev mine to the moon though.

I stated in that post that he bent the valve at 8k on a missed shift.

It depends on what you want done. There are a million different combos of heat treatment, let alone what metal to start with. First I would find what stock is and then figure out what you want.

Atlanta might be better suited for this. Assuming there is no impact loading I can help you. The equations are very simple and easy to follow. This weekend I will grab my books

The only thing that stopped me from getting them was the 2-3 week wait on them i was like WTF 2-3 weeks for a oil pump and it is 500$ nah

whoever is making these, ask him how he does it. I cant imagine he actually setup tooling for this.

unless has has a cnc machine

he has them made in sets there is a thread on m.net he gets billet blanks made then has them heat treated etc. it is a long proccess from what i see but after the first few sets i would think he would keep 2-3 sets on hand.

They really are nice :)

no doubt they are but it is'nt as if this is his first few sets of them he has been selling them for more than a year.

He doesn't just stock them though because its not like there is a huge demand for them either. Not many people pay out for the head work required to even support the revs it can handle. Send Bill an email and see if he has any if you want them.

http://forum.miata.net/vb/showthread...5&page=1&pp=25
explains the process, fairly involved. I'm sure they're top notch.

I have and did the last time i pulled the motor i was gonna need to wait a week for parts from trussville so i asked him and he gave me that so many weeks stuff. I thought hmm i send this guy 500$ for a oilpump they put good gears in and it will take a month for me to get them? he must have the gears already made so the main issue is the install on the oil pump from what i think. If it takes a week to lap in a set of gears that does not sound like a good deal. ya know.

That is an expensive process, I bet hes making lil' money on it. Wire EDM is amazing, we used it to make the splines on our Baja vehicle. Labor and time intensive (to set up) im surprised their EDM is open enough for him to make a few sets like hes done.

I bet we could make one cheaper, but probably not better for equal quality i would go with his. Cryo treating would be our only option, any heat treatment would lead to machining and then you are better off with his option.


Im thinking we look at options to improve the stock gears that will not require re machining.

He does not have the gear just sitting on a shelf..... They are made usually on a per order/group buy basis because of the large investment involved. I put mine into an ebay oil pump since I was measuring clearances anyway. I just needed to enlarge the smaller guide hole on the pump body by about 0.002", everything else checked out perfectly. The gears turn in the pump without and binding whatsoever.

As for the time it takes to get them made once the gears themselves are done, it is not entirely up to him. He has someone make the gears and someone install them in the pump. He is just to one that sets everything up. Basically a contractor if you want an analogy.

:rly:
Hmm, I thought that was the purpose of this thread... :)

I have access to a materials testing lab if you want hardness tests done.

I would like them done if we can get someone to donate a gear, we can't really decide on what to do if we dont have a baseline.

CJ--will the lab's report state metalurgy?

I'll look but im pretty sure I threw away the ebay oil pump gears, they should be close enough to stock quality.

:gtfo:

Get back in the HSV thread and forget about this gear pump shit. Use a straw and an ardvark. Problem solved.

Well if we know the metal and the hardness at different depths, and pictures if you got em onces its sliced we should be able to get a good idea of whats happening.

Personally, i dont care what they did to the original gear, i care what the gear ended up being.

Actually Im wrong. A carbon content would be nice, but we should be able to piece it together with some pictures and hardness tests

I can't find the gears....too bad, they were fun to play with.

That's cool. Maybe we can get stealth97's old oil pump gears. I think I'm closer to his car than he is, so I can hold hostages. :)

If you've seen my dyno run vid on youtube, his car is in front of mine, right side.

Not sure exactly what information they can provide. I do know they can do brinell hardness tests. Which would be possible on the outside of the gear and the inside. Not sure what the recommended method for cutting the gear would be though i'm sure they would know. I'm in metallurgy right now, only reason i know we have these labs. Hell we also have an SEM machine, electron microscopes are badass, tell you what.
They can also etch part of the piece and test the hardness of individual grains. Judging by the hardness of the inside and outside, i bet they would be able to tell what the base metal is as well as the heat treatment. Should be pretty simple stuff for the most part.

I've always wanted to hold a mazda rotor in the cylinder so i could spin it around the eppitrochoidal axis. Sure is a weird shape. Glad i never got into rotaries.

What are the causes of crankshaft flex? Weak main bearing/caps/fasteners?

Would not crankshaft flex be exacerbated by both RPM and torque, especially on in inline-4 cylinder with no extra balancing shafts?

we use EDM because it doesn't change the hardness when you cut it (it does slightly but nothing worth noting), water jet, i guess a band saw but its so uneven. Ask your machine guy, usually they have something worth while.

It definitely would, thats sorta why we all agree that your a dick... I mean that the oil pump needs some work done :dancegay:

you can always anneal and heat treat if you dont like the surface effects of the cutting method. i mean you're gonna do those anyway to get the final product.

well thats what ideally we would avoid.

Any of those would change the hardness of the metel and theres no point in doing a hardness test.

hey now, I offered the ones on my floor, not in, my car :nono:

I just need a hand getting the timing gear off. the whole crank with OP attached is laying on my floor. Even after torch work, and taking three chunks out of it with my prybar, I only got it to move just enough to pull the crank out. If anyone wants it for testing youre welcome to it.

sledge hammer? I doubt the gears need to be mint to get the testing you guys want done.

oil pump failure...
 

FYI - this is what the powerlist had to offer about oil pump failures (in 2005) ...
>
Out of the 469 PowerList members (and I would presume the highest per capita number of built motors in all of Miatadom) only 4 built motors have gone south. And all four were oil pump failures. And all four were using the OEM oil pump. And all four were far exceeding OEM design redline of 7,200rpms.

So, morale of the story may simply be: Don't over rev. the BP.

I ask the question originally to gauge the collective wisdom on how much boost a built motor can safely see. It sounds like RPMs (and oil pumps) should be more of a concern. Does anyone know of BP over-boost failure?

Jim in Tucson

#1
I destroyed 3 built engines. In all cases the Oil Pump shattered and smoked the
crank and bearings.. Never lost one due to boost, or tuning (I tune my own
engines and take a great deal of time) My highest hp was 489hp and that was
with Turbo and Nitrous on that motor. I hope to crack 500hp with my newest
engine revision. 9000rpm? I found that 8100rpm was the breaking point..
7800-8000 and I never broke one..
Marc

#2
my highest powered NA was 170 RWHP with a 8500 redline failed due to a
failed oil pump.
Greg

So eloquent; you've got a way with words...must really impress the ladies...

So, anyway, does anyone think this can be done for less than the $500 asking price of the M.net fella?