Oil Pan Clearance

Hello! 

I am currently in the process of swapping a 2.0 Ford Ecoboost into my NA Miata. I am using a 2.3 Ranger oil pan that hangs about  1 inch below the front subframe. With the front suspension raised, im at about 2 3/4 inches of ground clearance. This car is built to mainly be a fast street car that will be competitive at autocross and fun on the track. Im curious if I should look into having this pan made shallower, or just make some kind of skid plate? I feel like a shallower pan would be against what I would want as i would want as mush oil in the sump as possible. Raising the engine is not an option unfortunately due to good clearance. The rack mounts will hold the back of the front splitter, so that should help with saving that. (Yes, i am going to cut the bolts down) Thanks!

A steel skid plate connected to the subframe should keep it safe enough. You might want to think carefully about driving a car with 2.75" ground clearance on the street though, anything below 4" gets really impractical really fast, for production cars you only see track-day specials with less than 4" clearance. That's the height of a standard speedbump and a lot of speedbumps are taller than standard.

In reply to GameboyRMH :

Thankfully the roads around me are pretty good, and the car will get trailered to any events it attends. I will probably go the skid plate route, as remaking these motor mounts is not something I will really be able to do this late into the project. I presume I should have plenty of clearance for the track. I appreciate the input!

Either a skid plate or, if it were me, I would try really hard to find/but/build a pan that was shallower and wider so I could have more clearance while maintaining the same oil volume.  

Might be a candidate for dry sumping - cots a few bucks but with the minimal ground clearance you are talking about it might cost less than fixing what is there now if you go pogo-sticking with it.

For on street protection, I'd agree with a skid plate, but that will take away even more ground clearance.  If you just want protection for track/autox use, could you bolt/weld a piece of metal to the bottom of the subframe that is just a smidge lower than the oil pan?  That way, it takes the hit if your suspension is fully compressed and you hit a small bump.

Too low for me. But you do you.

eastsideTim said:

but that will take away even more ground clearance.

I think this shouldn't be un-noticed. You'll need a very strong plate which means having ribs, beads, or something like that. You'll also want clearance; a plate that presses against the pan will not be a huge help. Some help from abrasion, but it wouldn't be great. So now you are talking losing another precious inch at least. 

If dry sump isn't viable, what about something like an Accu-sump? I have no firsthand experience with them, so this is not an endorsement of them. Just a leaping-off point. 

I wonder if a pan from a Focus with an underslung air conditioning compressor would be shallower, but still clear the subframe.

Nope Nope Nope.

Looks like it would hit the deck at full suspension travel, let alone a crown in the road or some debris or a speed bump or something.  

That's not really streetable. Of all the things to be the lowest point on the car, that's a bad one. If you can't afford the loss of ground clearance from a skid plate, I'd put an impact bar in front of it that was the same depth as the pad. I'd also put sliders that hang 1/4" below the pan so you ground out on them instead of the pan itself. Put some UHMW plastic on the bottom of the sliders.

Something like this - these are from my own car.

You can see here how this one prevented damage to the cats which still kissed the surface but didn't get crushed.

A similar set of sliders for the exhaust and diff. This is post-rally so you can see that it really worked.

Here's my under-pan skid plate. I think it's 3/16" alloy. It took some serious hits while rallying and never deflected.

IIRC 7000-series alloys are the ones you want for a tight clearance skidplate because they don't really bend.  Downside is, they don't really bend, meaning they crack if you need to bend it to form something skidplate shaped.

I really like that design, I assume it only bolts in at the rear and just sort of hooks over the subframe up front.  Seems pretty service-friendly.

In reply to Pete. (l33t FS) :

Yup, that's exactly it. Two bolts to remove. Might be a little harder to manage with a stock(ish) subframe. 

It's better than a certain V6 swap kit that has the oil pan hang down in front of the subfame. But I would at the very least use an impact bar like Keith's, and if this were mine I would be searching for a shallower but wider pan.

Is the 2.0 Ecoboost block the same as the MZR block in an NC Miata, or am I mixing engine families?

In reply to DeadSkunk (Warren) :

It is similar but IIRC is based on the taller 2.3 block.

The Ecoboost is basically an evolution of the MZR. We've used Ford's engineering to inform our NC turbo system :)

In reply to MadScientistMatt :

sadly, they do not exist. I have spoken with the fellows at JEM Sport who make a whole ton of Ecoboost swap components. From their research, the only pan out there that is shallow enough in the front to clear the subframe and still have some oil pan sump is the Ranger Duratec as shown here. I raised the front end to get it to about 3 inches off the ground at the lowest point. I'll look into making some kind of skid plate like Keith had sent. Thanks everyone for the input. 

Part of the issue is the location of the oil pump, the pan can only be so shallow there.

IIRC the Rangers did not have balance shafts, the other engines incorporated the balance shafts into the oil pump assembly and this is why the other pans are deeper.  They extend a lot further forward.

In reply to Pete. (l33t FS) :

Exactly. I have the balance shaft deleted in mine, and the oil pump is not too low on the front of the engine. The pan is about as thin as it could be where it is above the crossmember. I would raise the engine, however I would be out of the hood if I did that.

Let me know if I can provide any more useful pics.

FYI, this is a slider and not an impact bar. I wasn't clear about that. The black pad is the UHMW plastic. 

This is an impact bar I put on another build to protect an oil pan that was 1" below the subframe and had 3.5" of ground clearance to the pan.

In reply to Keith Tanner :

I see what you have done here, and I really appreciate the detailed pictures. I will try to replicate this as best as I can, as I like the idea of being able to protect it without sacrificing ground clearance. Ill just have to keep my eyes peeled for high crowns and pot holes haha. Thanks again! 

In reply to c_allen :

From experience doing TSD rallies in an '85 RX-7 with typically tired springs and with a full load of gear in the car because my navigator was a hyperdork that way*, you will hear things graunching on high crowned roads as a reminder to drive on the crowns and not in the gullies.  With that in mind it might not be a bad idea to "ramp" the stop, or have a second lower skid behind the oil pan as a kind of depth gauge, so you don't do any kind of concussive full-stop on anything in the road.

* We didn't have a rally odometer/computer in his car, but aside from tools and triangles and road flares he had a big book with time/speed/distance charts and would mark every turn in the route book to the second, so all we really had to do was not get lost and mind how many seconds off we were at each step.  We got a lot of zero scores that way.

Though this thread seems done, one more data point. Midlana had 4" of ground clearance, based on the thinking that the biggest thing to encounter on most roads would be tire tread or maybe a section of 4x4 wood. The latter is 3.75", so it would clear. Regardless what the design-to height is, that's only true at rest. I did scrape the chassis (the oil pan is above the frame rails) on the street one time, hitting a dip at speed due to the combination of spring rate, shock valving, and tire deflection.