Oil Supply to Turbo
 

Finally getting to the finishing stages of installing a 99 engine and turbo in my 91. Basically had the oil feed plumbed from the right side feed I've seen most often, when my son asked why didn't I use the oil feed at the left rear of the head. Good question I said. A lot closer to turbo, shorter lines etc.

My question is, is there any downside to this? ie, the feed from the head comes after a restricter in the block. Is there enough oil there to feed cams, lifters AND the turbo? I never really thought about it, but how much oil does a turbo really use? This install is a small Garrett with sleeve bearings.

There are 2 or 3 threads just recently where we discussed this.
Search around.
Here's one of them:
https://www.miataturbo.net/diy-turbo...ey-plug-75112/

The conclusion is no one knows for sure, so attempt at your own risk.

By the way, I now have all tubes and fittings and plan to do my pressure testing that I promised tomorrow. Pressure vs RPM curve on that head port with no outflow, and with turbo.

I may use that plug as well...considering most turbos need some sort of restriction it may be an ideal solution.

YES PLEASE!!

That would be awesome.

Thanks

+Juan

Great - Thanks for that link. Seems a lot of us are in the same boat, ie, a bit skeptical about pulling oil from the head. That restrictor in the block has a dang small hole in it, but what I've seen was on older (pre 99) engines I've done. I haven't actually seen the restrictor in the block of the 99+ 1.8 to see if they've done anything different with the solid lifter cars.

Well, for now I guess I will stick with that port on the intake side. Like some, I was also concerned about the weight of stuff hanging off the tee - so I've got the pressure sensor mounted to the car on the end of a hose.

I know that the restrictor in the '99-'00 block is the same as in the '90-'97 block.

I cannot speak to the '01-'05, however I assume it's the same, since the VVT mechanism has its own dedicated feed.

What Joe says is what I was explaining to you the other day. 18psi linked you that thread I was discussing with you.

I say we go for it. It's not my head. :rofl:

HA HA - "WE" go for it!. You are quite right - its my head ;) We can do that if "we" put a turbo in your car. Meantime, I just can't see how enough oil can get there.

In the meantime, get well and I hope to see you at the shop in the morning.

its past "tomorrow"

any results?

Today is yesterday's tomorrow.

https://www.miataturbo.net/attachmen...1&d=1386555525

I posted the results and my comments in the thread where the promise was made:

https://www.miataturbo.net/diy-turbo...-supply-75631/

As expected, oil pressures are lower, and affected by flow. I am going to run head port for my TD04, and think that restricted flow to BB turbos would be OK as well.

Other research indicates that many other engines also use restrictors going to the heads, and factory turbos on those cars use the head ports for supply.

DNM

I am using this plug and a -3 line and havent had any problems.

I know the main discussion about this in the other thread, but I disagree with your comment if its being used as justification to pull from oil from the head.

A factory turbo car has an oil restrictor designed with turbos in mind. A non-factory turbo car did not however. What would be interest to see is what Mazda has done with the BP in turbo applications. I am pretty sure the oil feed for the mazdaspeed miata is from the block. Not sure about non US-market protege turbos that used the 1.8, the mazdaspeed protege, or any other application of the BP with a turbo from factory.

It would be cool if we could info on the restrictor used in those application and where mazda pulled the oil from.

In any case, I will take a look at your thread.

the MSM indeed does source from the block.

but then the MSM has a lot of really stupid things done to it as afterthoughts, so I'm not entirely convinced that proves anything.

In the 323GTX (both the B6 and BP versions, and regardless of market), the turbo oil supply was from the block, using the same port (near the flywheel on the exhaust side) that was preset in the early Miata engines.

The removal of this port from the Miata engine coincided with the discontinuation of the 6th gen Familia / 323 and, with it, the discontinuation of the last factory-turbocharged B engine of that era.

Joe can you comment on this:
https://www.miataturbo.net/diy-turbo...-supply-75631/

post 17 and on.

I know its like a limited production joint effort between aftermarket/mazda but mazda was still somewhat involved.

It keeps tempting me

well, the evidence there. I think people can pull their own conclusions. This is not like a coolant reroute for example, where Mazda had an original method, then tried a new configuration, then changed it multiple times in an effort to deal with a symptom.

It seems consistently Mazda has used the block port, not the head. Not saying that your engine will go boom if you diverge, but its probably the more "reliably safe" location to get oil for a turbo. It is also very possible the head port has enough tolerance to accommodate a turbo... *shrug* gotta try it out ;)

Yeah, I saw that, but I've already weighed in on a couple of the "which oil feed" threads this month, and I just didn't want to get into a pissing contest with an Aussie who was hell-bent on proving a point.


I don't have any empirical evidence to prove that taking oil from the head is a "bad" thing. All I can do is point out the fact that B engines run their cams directly in the head casting with no bearings, and that there's an oil restricter between the block and the head which I assume Mazda calibrated for the oiling demands of the head all by itself, with no turbo. Further, I read the fact that Mazda started drilling that hole in the block again on the MSM, after a 10 year hiatus, as evidence that they also felt that taking turbo oil from the block was potenially less risky / more reliable than taking it from the head.

I'm sure this isn't a binary deal, like "if you take turbo oil from the head, your engine will immediately explode." My guess is that, like forced induction in general, it's just a matter of degrees. Like if you take away 20% of the oil from the head, you will reduce the useful life of the [head / cams / followers] by xx%.

It only costs a few bucks extra in hose and fittings to source turbo oil from the block on a post-94 engine. And given that this is what both Mazda and the major US and Japan-based aftermarket suppliers (the ones who offer warranties on their kits) do, I will continue to recommend this practice.

But I'm not going to waste my time arguing about it with people who have something to prove.



That's exactly the correct way to look at problems such as this one; which solution presents the least chance of causing a problem.