Project Z06: Continuing Fabrication on Our Dry Sump System

Update by J.G. Pasterjak to the Chevrolet Corvette Z06 project car
Feb 28, 2020

In a previous update on our C5 Corvette Z06 project car, we laid out the basic function of our dry sump system, and now it’s time to start physically laying out pieces. So let’s talk a bit about what components need to be in place on a proper dry sump and where they need to (or can) be located.

First, you’ll need a sump tank, since the engine-mounted pan is no longer the repository for the oil. This tank mounts in a vertical orientation and has one line attached near the bottom feeding the oil pump with fresh oil, and one (or possibly more in some applications) line attached at the top receiving oil coming back from the pan. The tank will also need provision for a vent line, and a drain line.

From the tank, the oil is sucked to the pump, then from the pump it gets pressurized and sent to a remote filter. Once it gets through the filter, it flows into the block via an adapter plate attached where the stock filter was originally located. After flowing through the engine and draining into the pan, two ports in the pan allow the oil to be sucked out into the pump, then returned to the remote sump, completing the circuit. 

Additionally, there are a few considerations when physically locating some of these components primarily the vertical relationship of the sump tank and the pump. While a quality oil pump like our three-stage Aviaid unit could easily create enough vacuum to draw the oil “uphill” from the tank to the inlet, each time the engine was shut off you would run the risk of the oil draining back and the pump losing its prime. So each startup could pose a risk of briefly running the engine dry before the pump picked up enough oil to properly supply it.

So vertical orientation of the tank and the pump is critical. Ideally you’ll want the outlet of the tank to be vertically higher than the pump inlet, so the supply hose has an aggregate downhill run from tank to pump. Also, you’ll not want any part of the supply hose to be above the level of the oil in the tank. 

Likewise the oil filter. While the pressurized oil can easily be pushed uphill from the pump, why make extra work for it? Still, we’re not going to make a final call on a location for our filter until the engine is back in the car and we know what we’re working around. Once that happens, we’ll endeavor to keep the lines short and the vertical changes minimal.

In our case, we had a couple options for tank mounting. Most C5 dry sump installs use either the space vacated by the battery under the hood, or the rear trunk of the car for the tank. Using the battery space requires cutting off the fuse box mounting flange from the frame, and doing some trimming to the inner fender liner, but it keeps your tank close to the pump. We chose the other option, which was the trunk, however. For us, this came with a couple advantages. First, there was no frame or fender modifications to fool with, we weren’t using the trunk anyway, and the roll bar mounting points made for a nice beefy spot to locate a bracket. Plus the longer lines give us an additional quart or so of total oil capacity.

Our mount was a simple arrangement welded out of 1-inch-square tubing and bolted between the rear roll bar mounts. Some ¼-20 nutserts hold the tank bracket to the frame, and we’ve got plenty of room to run whatever lines we need wherever we need them to go. Best of all, the vertical location means a bare minimum of “uphill” travel of the feed hose, and no risk of the feed hose ever going higher than the oil level in the tank, keeping our pump inlet nice and wet.

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Dr. Hess
Dr. Hess MegaDork
2/28/20 10:00 a.m.

Billzilla made a dry sump pump by hooking two SBC oil pumps together, adding a pulley and driving them off an accessory belt.

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