RB26 S13 – Custom Oversize GTR Sump

It took almost 50 hours to get this thing done and I’m pretty happy with the way it turned out.


Usually when you want to have an RB26 in a RWD car, at some point you need to wonder what to do with the sump. 99% of people will just grab an RB25 sump and bolt it on, which is initially what I had. But, I wanted something a little less ‘crap’ and something with a bit more strength in case it takes a hit.

Now, because the GTR sump is an AWD sump, it has a massive diff casing attached to the side of it. Obviously in a drift car that’s useless, but getting rid of it definitely isn’t an easy job.


The standard sumps are cast alloy, which is one major positive over the tin can sump of an RB25. One major negative though, the alloy is 6mm thick which means it takes forever to cut through it.


Because the sump would be so close to the ground, I needed to sacrifice a little bit of depth and try to make up for it in width.  Otherwise the bottom of the sump would have been 10mm off the ground which would mean the death of my oil pickup resulting in engine starvation.

So I measured a whole bunch of things and accounted for the engine lean (RB26 lean to the turbo side by a few degrees), then started cutting out what I didn’t need.


Goodbye standard sump.


Next things to get rid of were the diff casing and the axle hub on either side.


Both cuts worked out to be pretty clean considering I was using a reciprocating saw.


It took me two hours just to cut the diff casing off. Yes, TWO HOURS.

The only reason it was taking forever was because of how thick the casing is. One thing to remember if you try this, the cast alloy takes forever to cut!


So at this point I needed to do a bit more trimming to clean things up. I threw it in the mill and ran along the sump getting everything level and precise.


I wanted to get as many useless pieces off the sump as possible, so that meant both sides were in for a long run on the mill.

I spent about 11 hours straight going over the sides, doing 0.5mm runs manually. I could have gone faster and cut deeper each run, but that would mean possible vibrations and moving the sump putting everything at different heights and would end up giving me inaccurate cuts.


After a few final trims with the saw and another few hours shaping the base of the sump, I was done on the mill.

Next thing was to measure out where the plates for the new setup could fit. Since I was sacrificing depth, I needed to go out horizontally as far as possible.


I cut these out of some 3mm aluminium and had Andy bend them to shape.

He also made a new baffle and gate setup in the base to help keep as much oil as possible around the pickup.


We modified the pickup to suit the new depth, then pulled the motor out of the car to put it all together.


At the time of writing this, the motor has been in and out six times since the start of the year. I thought it was in for the final time last week but have since pulled it out again on monday morning so I can get the rack relocated, raise some mounting points, fit some things and make some more room for the gearbox.


New base and baffle setup ready to go.


Old sump off and new sump fitted!

As well as making a new base, we had to weld up the holes on both sides that the axle ran through. Then it was just a case of buzzing back to clean alloy, lining up the new base and welding it all together.


Also I had my Tomei oil pump fitted a couple weeks ago as well as getting a few other things checked over and sealed.

While the engine was out of the car for a while I had it compression tested, all six cylinders were over 185psi! I find that extremely reassuring considering most RB26 run perfectly fine on 160psi.

I’m pretty confident this thing is going to last me a while.


Looking forward to adding a few more colourful bits to make it a bit cleaner cosmetically.


Jacked the car up, lifted the engine off the table and put it back in the engine bay.


For such a big engine and such a small engine bay, it looks like I have a lot of room.


By the time I have the two turbos mounted and the cooler piping where it’s meant to be, I think the room will disappear pretty quick.

More happening this week as well as more parts turning up, I will update as often as I can.


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