Should I drill a hole in my engine block?
 

I'm in the process of building my motor now. It has been discussed about how to vent the gasses from the block under boost. I was looking at the vent hole that is raised and located at the back on the passenger side. It appears that port and the one ahead of it connect together along the side of the block right where the BP lettering is and then goes down to a very large casting hole, you can see it when you look inside the block. Has anybody drilled a block vent hole there? It's high enough in the block that G-forces on the oil wouldn't be a factor there. 3/8" NPT with a 90 pointing up would ensure any stray oil would drain back. Has anybody else thought of this? Downside?

https://www.miataturbo.net/attachmen...ine=1351826252
https://www.miataturbo.net/attachmen...ine=1351826252
https://www.miataturbo.net/attachmen...ine=1351826252
https://www.miataturbo.net/attachmen...ine=1351826252

or just run ALLOFIT and let the block vent itself

AIDSthread.

why?
you can weld a single -12AN bung to your valve cover and not have any blow-by issues with a single catch can.

So how much boost are you running?

80psi?

No.

VTA block FTL.

yes

Drill a bigger hole, make it a 5 cylinder.

I was looking at the catch can thread and it seemed that BBundy was trying to come up with a solution for this.If I recall, you cot all the oil draining back down and its competeng with gasses that are trying to get to the valve cover. I've done the improvements to the valve cover. Boost will be in the low 20's down the road. (What's max psi a 2560 can be used at?) I just if seemed like a logical location then drill and tap it, install a plug, then down the road it could be of benefit later.

lol 20psi on a 2560

Vlad, OK, maybe I phrased that wrong. The question was what is the safe maximum operating pressure for the 2560. This spring I will be looking at an upgrade.
Sav, you say no, Bob was looking for a solution. I thought there was research to support that block venting was a good thing?

Just run a dry sump with a vacuuum pump. That is what the cool kids are doing now

Probably no more than 18 max and even then it will probably taper.
But even if you do upgrade later, unless you run something sized like FAIRYFLOWERS BORGWARNER S366 I just don't see the need for anything fancy. And drilling block for vents just seems like an insanely crazy idea.

Only one hole? Weaksauce...

Can we be constructive and support someone trying something new for a change? I want to see how this turns out. Do we know what that boss is there for and whats behind it? Its obviously an intentional casting boss either there just as a surface for the machinist to pick up on later or as a potential spot to drill for something.

I have been running with a hole drilled in my block for a breather port for a couple years now. It works and was an improvement I believe.

I drilled up by the oil filter just behind the #1 squirter though. This is the same location that Mazda cast in a block breather port on 1.6l B6-T and early 1.6l Miata blocks but they never used it on cars imported to the US they just put a rubber cap over the nipple. They removed the port from the casting for the 1.8l blocks.

I Drilled and tapped to a ½” NPT to -10 an and JB welded the fitting in the block. Runs up to a T with a line coming from the Exhaust side valve cover vent then to a catch can with oil separator. Intake side PCV port is blocked off.

I have the catch can setup where I can vent it to atmosphere or to a slash cut that has the exhaust flow pull a small vacuum on it. It works better and makes less mess to have the exhaust flow sucking the blow-by gas out the tailpipe though technically not legal pre SCCA GCR.

Bob

low testosterone post.

It takes someone with Balls to drill a hole in there block.

we already have Fae for that:fael:

He said drill not blow.

Sarah Palin's got your back

https://www.miataturbo.net/attachmen...ine=1351878745

If you've got the stones to maybe ruin a block, go for it. I however will not be pioneering this technique.

Alternately: who has a broke ass BP block to cut up and show us whats inside?

All I can say is my current system is the best I have come up with yet at solving the breather issues with a 350+ HP track Miata that turns righteously quick lap times in a somewhat reliable and repeated manner. It has a hole drilled in the block to aid the breather system.

Would you happen to have pics?

I didn't know that you were running a slash cut. Do you ever have smokey exhaust because of the slash cut? I do occasionally :(

And by "technically not legal" you mean "explicitly banned in its own rule", right? :party:

When I ran the vent line from the intake side PCV port it was a disaster after hard left hand turns. Blocked that off and it was fine. I know there is still some oil getting sucked out the tailpipe because of the residue that collects in the hose going back to the exhaust but I don’t have oil smoke clouds following me around. Smoke problems I have had after this install were from failed o2 and running too rich. I safety wise or environmentally don’t see the difference between vent to atmosphere and vent to atmosphere out the tailpipe. For some reason the people making competition rules don’t like it though.

Hose shown going to the pcv port is blocked off now. Dont use that thing.

Hey Bob, I don't mean to be "that guy" but are there 3 spacers under your oil filter? Looks like filter > mocal thermostat spacer > gauge and turbo feed spacer > OEM heat exchanger > block

Mazda originally designed the B6-T with a Breather port in the block I have talked to some European Rally guys who ran the cars in factory support trim and said they came with a breather system with an oil separator that drained back into the bottom of the oil pan. I have never seen the system installed myself but if you had a US spec GTX it came with the breather and the return port blocked off as shown below.
https://www.miataturbo.net/attachmen...p1010dt004-jpg

Factory oil to water heat exchanger
Accusump feed block
Mocal themostat for oil cooler
filter.

Christ, I knew that, thanks man. I think you told me about the Accusump mounting the last time I saw you at Laguna :facepalm: :loser:

The guys road racing older GT-Rs with RB26's use a large diameter hose between the top end of the block and the back of the head to allow the gasses from blowby and pumping pulses to pass more readily to the valve cover area. The oil draining back to the pan is fighting the gasses coming upward from the other direction through the same small area and at high RPMs and high boost there is a lot of both. Increasing the flow area between the top and bottom of the engine reduces the speed of the gasses and creates less oil vapor as the two pass each other. Everything gets where it is going with less impediments.

Damn, you beat me to it. I was gonna run out and snap a picture of those fittings on my b6t.

i feel like maybe "you" shouldn't drill a hole in your block, id personally weld a bung to the valve cover if your intention is to avoid blow by... but realistically if u really need to in order to run 20+PSI id avoid DIY

I run 40psi and two -12 fittings do the trick well enough.

Hondas/evos etc that run high boost frequently have 4x -8 fittings...

How much boost will you run?

A single -12 was fine for me at 25psi.

I'm not as familiar with miatas, but id never intend on drilling a hole in a block, build vehicles so you can remove modifications without preeminently damaging your car.

if u ever wanna pull your turbo id prefer to just swap a stock valve cover instead

If you turbo as well as you grammar, you are already preeminently damaging your car.

There is always a point of no return. For me it was the third heater core that leaked. Now, my car will never return to a stock coolant system. That's just one example on my personal car.

troll :facepalm:
well i guess it reflects the fact that i never have 'turbo'ed" a car. hence NOOBIZM...

It all depends how far your willing to go, what i do know is simplicity in turn has always brought reliability. If you decide to drill into your block id recommend having a machine shop handle it.

just stop posting

You don't really need to do that, just swiss cheese the valve cover. All the Spec Miata folks do it.

TOO LATE ............

I have two BP blocks. The stock block that I bent the rods in and the built block. For this the stock block was used. Started with a smalish bit and worked my way up. There's at least 1/2" of space behind the hole. Tapping the threads went fine. So Just after I get done Lordrigamus (Jeff) stopped by and wasn't looking an it more than 30 seconds and said "I don't think the starter's gonna fit where ya drilled the hole". Completely forgot about the starter. (nobody else thought of it either) It's right there where the BP is. SO, I drilled another hole above where the P is on the slant of the casting. This is actually a much better place. Even more room in this part of the casting. Clears the starter, no problemo. The old hole gets a plug. The new hole is at the perfect angle to vent gasses without any engine oil getting into it. Also win is this part of the engine block is a non stressed area and I don't have to worry about the first hole creating any stress cracks. I will post some pics tomorrow. :party:

Fuck you and your lack of picturrrrrrrrrs!

(not that I'ma do this at any point in the future)

Lol'd pretty hard here.

For reals just get a catch can setup and be done with it.

I tried several versions of valve cover weld on bungs. They all ended up with oveflowing the catch can with oil. but it only ever did it on a race track. never driving it around on the street for testing.

FWIW I also now run with the ceramic coated pistons and the oil squirters blocked off.

Bob

OK, pics. As you know the first hole was fail, in the way of the starter. It will get a plug with JB weld on the threads. The second hole above the "P" also makes more sense. This is where it will go on the built block. Even with two vacuum cleaners going it was still a PITA to clean and ideally should be done at the beginning of a build. This would be impossible with the pan on. You couldn't flush all the shavings out the oil hole.

https://www.miataturbo.net/attachmen...ine=1352076495
https://www.miataturbo.net/attachmen...ine=1352076495
Here's the fail with the starter in place. :vash:
https://www.miataturbo.net/attachmen...ine=1352076495
Some clean up stuff.
https://www.miataturbo.net/attachmen...ine=1352076495
https://www.miataturbo.net/attachmen...ine=1352076495
And finally the correct location.
Before:
https://www.miataturbo.net/attachmen...ine=1352076495
And after:
https://www.miataturbo.net/attachmen...ine=1352076495
https://www.miataturbo.net/attachmen...ine=1352076495

damn the block looks thin. And the pics of you drilling it made my weinis twitch

I wonder why that web and pocket are there to begin with? It certainly does not seem structural.

https://www.miataturbo.net/attachmen...1&d=1352138009

Where does this plug go, into that cavity?

Keep us updated on how this works when you have it up and running. This is just down from the drain back through the block from the right rear corner of the head. Same area of the head that the PCV breather picks up in that and based on my experience the drain back doesn’t work fast enough to keep liquid oil from filling up the PCV baffles. I wonder if putting the breather where you are putting it will allow the back right corner of the head to drain back faster instead of pooling oil in the head.

agreed, i was kinda shocked looks really thin.

EO2K, I believe that's where Mazda machined the oil galley. You can see the bump in the block running past the oil filter. So it kinda makes sense that they would have to move the drain/vent out of the way.
Bob, theoretically yes. Both the vent and the drain hole converge in this same area, this would give the gasses a better path of least resistance.
If you have a 4qt system, how many quarts do you think are up in the motor trying to drain back?

That plug caps off the main oil galley, carrying the pressurized oil exiting the filter out to the main bearings. The passage which goes up into the head intersects with it.

https://www.miataturbo.net/attachmen...1&d=1352168706

Awesome, thanks guys. With the main oil channel there and the block drain above, that makes a lot more sense.

I didn't think this was that much of an issue with the BP. Its not like a FE series Ford V8 where you have to put an extra 1-1.5qts in the sump if you plan on running on the highway for any length of time. It makes sense though, blowby heading up and oil heading down, add to that boost, high RPM and high volume oil pump and you are probably outside the factory design envelope for drain operation.

As long as "we" are drilling holes in things, I wonder if its possible to open up the drain on the head/block/head gasket to improve the issue? Anyone tried it? I understand its a completely different application, but it seems to help the FE boys :dunno:

In for results.

My guess is it could go as high as a couple quart sitting in the top of the head at times. Both driving the piss out of it and hard cornering reduce the ability for it to find its way down the drain back holes to the pan. I never could reproduce the serious breather issues on the street.

Also adding more and bigger breathers in the valve cover reduce crank case pressure from blow by but increasing the gas flow running back up the drain back holes to the head to find their way out the valve cover breathers tends to impede the drain back action. Imagine trying to poor oil through a funnel with somebody blowing on the bottom of it.

Nm, ignore this post.

So, does it blend?

Seems to be the same concept that is found of the Ford 2.3 SOHC

Hole in block > baffel can> Hose> PCV Valve> Hose> Intake ( Behind the TB)

This set up is used on both Turbo and NA, carb and FI

Sorry, not sure what blend means. Motor is almost done. The plan is to run this vent separately to atmosphere via a clear hose and clear container to see if it's playing nice with the rest of the motor. Next step would be clear hose to the rest of the catch can system and see how that works, then black hose.

In your defense, I should have said "So, will it blend?"

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But I was really just fishing for an update :)