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DIY Accusump for Extra Engine Survivability

Submitted by shredjesse on Tue, 11/25/2025 - 13:04

This article is currently being actively developed during the winter of 2025 into 2026. If everything goes to plan, it'll be thoroughly track tested through the 2026 season.

I've put this article out in advance as some folks have requested the ability to follow along, so I apologize in advance that this is a work in progress and some pictures may be missing, descriptions may be lacking, and some things may even change. For the most up to date information, reach out to me on any of the various corvette places like the facebook groups or Corvette forum!

Article Sections:

  1. Backstory
  2. Why Get An Accusump?
  3. Development process
  4. Parts List and Installation Steps
  5. Track Testing & Data Driven Results

Backstory

If you've been reading this blog for a bit now you may remember that my original article on doing a DIY oil cooler setup on your C5 Corvette included plans for putting in an Accusump. I was adding the oil cooler to help keep the car alive for as long as possible, and an accusump seemed like a fairly adjacent part to add even more safety margin to the setup while I was already in there. I had plans to mount where the windshield washer fluid reservoir was (see picture above), and hoped that somebody with a 3D printer and scanner would collaborate with me on designing something for this up. I know when I have the skill and know how I enjoy working with others... but alas most folks aren't like me and don't want to spend their spare time on other peoples bad ideas... which to be fair most folks they have plenty of bad ideas of their own they can barely find time for so it is what it is.

Fast forward a few years and a ton of events later... I've got a car that is winning races and setting SCCA class records, I've leveld up my CAD skills and designed my own chassis mounts using said skills. I also finally ditched my ridiculous SLA (resin) 3D printer in favor of a Bambu 3d printer and then got an even bigger badder Bambu 3d printer. I'm now looking at more and more grippy tires and... it seems like now is the time to take my increasing skills and needs and figure out how to add an accusump!

Why Get An Accusump?

So what even is an accusump and why would a person get one? Here's my short version:

An Accusump is a cylinder with a piston in the middle. On one side of the cylinder you connect your oil system, on the other side is air. Your oil system will fill the cylinder with oil, compressing the air on the other side of the piston. In the event oil pressure drops, the air pressure on the backside of the piston will shove that excess oil back into the system, giving you a buffer against oil starvation in situations like hard cornering or heavy launches where oil may slosh away from the oil pickup, or should oil pool in the upper regions of the motor and not be returning in time to the oil pickup.

You can also get the full story from the company itself as interviewed by High Performance academy:

Now I'll openly admit, there's a lot of opinions floating around on these from different folks. Ive literally had conversations with groups of folks and had multiple people tell me these are worthless while others swear up and down they're amazing. Some folks even call these "a bandaid on a bullet wound", or "addressing the symptom, not the problem"... and that last bit might be true.

Where the accusump is a bit of addressing a symptom is that in order for the accusump to be of much value, there needs to be a drop in oil pressure at some point. That means something is going amiss. There are many solutions folk use for this like baffled oil pans, dry sump configurations, etc etc. Heck the C5 Corvette specifically has it's "batwing" shape to help keep as much oil as possible by the pickup under notable lateral or longitudinal loads.

On my Corvette, I don't actually have an oil starvation problem at the moment, knock on wood. However, I may start to find it as my pace continues to increase and I start to setp up into more aggressive tires like the new Vitour 100TW offering. When the situation comes up where I need an accusump... I'd rather have it.

PLUS there is one added bonus to mention... engine pre-oiling. Ever notice how you turn on your car and it takes a second for oil pressure to build up? Cold starts are some of the largest sources of wear on an engine. With an accusump, you simply open the valve and you've got two quarts of pressurized oil that are shoved through the oil galleys as the engine is turned on, reducing engine wear from cold start ups.

So is an accusump as good as a 5 stage daley dry sump system or newfangled baffled oil pan offerings some companies are coming out with? No probably not... but they are a reasonable part of the system that may just help increase your long term reliability should you ever find there's a limit you didn't know you possessed.

Development Process

So I've already got an oil cooler setup. Most folks tracking a C5 Corvette seriously will want some sort of oil cooling, whether it's integrated with the radiator like Spec Corvette stuff does or they're using my front mounted design or any of the other various offerings out there. Assuming that's the case,  it is fairly safe to design this mount around the assumption that a person interested in this will have some sort of forward oil cooling setup with a "send" going into it, and a "return" coming off of the oil cooler.

(Add Picture here of all the plumbed in lines)

The plan then is to put a one way valve on the return side of the oil cooler first and foremost to prevent back feed, I can then add a T fitting somewhere down the line which will branch off to the accusump. Thus if oil pressure drops, the accusump won't backfeed through the oil cooler, it'll just focus on getting oil to the motor. From the T-fitting I can also put an electric ball valve mechanism which will allow me to turn the accusump on and off from inside the cabin.

Now as mentioned way above, my original planned location of the windshield wiper reservoir wasn't going to fly... but a fellow had told me they had success putting it in the rear fender cavity, and sure enough, there's a fair bot of space here! I've seen several installs now that work in that space, many with interesting orientations. I went with the above orientation as it fits well enough and there are structures to easily attach to.

Not only is there a fair bit of space there, but the output side of the accusump has a fair bit of space as well. The space afforded to this install from this location will allow you to route an oil line out and along the frame, safely away from the headers and in general giving it a well protected location.

Another benefit to this area is that there are two exceptional locations to tie into for mounting your accusump. The first is pictue here, where the firewall  and windshield structure is ties into the frame via this square tubing. A little bit of design in OnShape later, and I've got a sheet metal piece designed up that I can have made out of 1/8" aluminum, and I was also able to test print and confirm the location.

The rear bracket is a bit hard to see, but it connects to the chassis via a bracket that mounts under two bolts that help attach the firewall and windshield upright structure all together. This gives us a very strong location to tie into, and we were even able to make all of the bolts involved in this process accessible!

Here is a picture of the final aluminum brackets from SendCutSend in place all designed up and attached along with the band clamps that attach to the actual accusump in place. The left bracket is held in place by 2x M6 rivnuts through that square tubing piece for ease of removal and reinstallation.

In the end this gives us an exceptional place to mount everything up and we've got brackets that can be reproduced endlessly by SendCutSend to allow YOU or anybody else who wants to copy what we've done to do so! Mounted it looks just like above, with great

One thing we already had going on was some switches inside of the car. We took the 12v constant for the radio (which we don't have anymore) and brought it into this area and then connected that up to our switches. Now what switches you use, where you mount them, and how you get them power you will need to navigate, but here's how we went about it, and not only does it allow us to have accusump, but our cool shirt is on here and we have two spots remaining for transmission and differential cooling!

With the accusump in place and an oil cooler already plumbed in, you'll need a way to integrate the Accusump into the system. Enter, the Accusump Charge Manifold (A $1000 name for $60 of parts). The system picture above is actually oriented "backwards" from how I will mount it, but the jist goes that from right to left: Oil enters into a one way valve, connects via a female to female adapter to a T fitting, which has a female connection on time. The top goes up to a 90 degree fitting which is attached to an electric ball valve setup. The electric ball valve goes ontwards to the accusump, and the other end of the T fitting goes onwards to the engine return.

This design means that in the event oil pressure from the motor drops, the accusump will push it's pressurized oil into the system, but not possibly backfeed to the struggling oil pump through the oil cooler. The electric ball valve also allows the driver to easily turn on or off the accusump from the comfort of their car, making it easy to pre-oil the car on startup or to build up pressure and then shut off prior to turning the car off.

Parts List and Installation Steps

Track Testing & Data Driven Results

(TBD: Picture of the car in the rain to show you what our season is like)

It is unfortunately winter time here in the PNW, which not only means rain, but my local track just straight up gives up on being a race track and converts to a Christmas Light drive through experience.

My only respite being the occasional drive down to Souther California when the passess between me and California even allow safe passage while towing. As soon as I can get this out on track though and I can devise a way to log oil pressures, I'll try and do so with the accusump off and then the accusump back on again and see if we can spot a difference.

Some problems we may experience is that the sampling rate on this 25+ year old ECU from Chevy is a pretty low resolution, likely only giving us 1-2 samples a second. This may not catch any moderate dips in oil pressure.

I think it's also worth mentioning I've now gone 55 events on this car without an accusump and it seems to be alive and well as a motor. I don't think this is nescessarily a modification these cars need, but it's one of those things that should you find yourself needing it, it may already be too late... so why not throw some cheap insurance at your engine?