DIY Accusump for Engine Durability
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:
Backstory
If you've been rading 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 way to add a bit of safety margin to the setup while I was already in there.
At this point it's worth mentioning that I've had many people tell me everything from this is entirely worthless to it's the only thing keeping the car alive... all on the same post! There's a lot of anecdotal information out there, from folks like me who have gone 55 events without a failure at the time of the install to folks who told me they can't make one lap at 80% pace without triggering their oil pressure light. From bad installs to worn out parts to mercury being in retrograde or some unknown stuff like that... there's no guarantee you need this, and even if you can point to where you need it you're probably too late at that point. You install this so you probably don't ever need it, and it's a modest weight penalty to get that safety margin so... why not?
Back to the oil cooler install with my accusump plan though... I had plans to mount where the windshield washer fluid reservoir was, and hopes that somebody with a 3D printer and scanner would work with me on designing something for this up. I know if I had the skill and know how i'd be intrigued by such a project... but alas most folks aren't like me and didn't want to spend their spare time on other peoples bad ideas, they have plenty of bad ideas of their own they can barely find time for!
So 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, and I 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... and I think it's time to try the DIY Accusump on my own!
Development Process
So I've already got an oil cooler setup. I imagine most folks tracking a C5 Corvette have 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. So it is fairly safe to design this around most folks having 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!
Not only is there a fair bit of space there, but the output of the accusump has a fair bit of space. 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, and I'll get better pictures later, 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!
(TBD: Picture of final brackets in place holding the entire thing together)
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!
(TBD: Picture of switches)
One thing we already had going on was some switches inside of the car. You'll need to navigate this yourself but we took the 12v constant for the radio 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!
Parts List and Installation Steps
- Accusump (2qt)
- Accusump Mounting
- Brackets
- Mounting Hardware
- Braided Line
- AN fittings
- Electric ball valve
- Switches
- Wiring
- Tools
- Rivnut Tool
- Koul Tool for AN fittings
- 3D print your own if you want to.
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?