Oil Accumulators

[raypratojr]

Are oil accumulators really worth it? Most people mount accumulators in the pass compartment. Therefore there must be at least 5-6' of line between the accumulator and the block. If the accumulator has approximately 100 psi of oil in it, and the engine loses oil pressure, that 6' line also loses pressure. Once the valve releases the oil in the line, the pressure immediately drops in the line itself. Then that oil, at a lower pressure has to travel into a block adapter and fill up the filter. Then there's got to be a pressure drop through the filter before it even gets to the oil galleys of the block. Then it's gotta travel through the block to the bearings and still have enough pressure to do adequate lubricating? Is this accurate? Sounds to me that they're more hassle then they're worth. I can't see them being useful unless they're mounted within a foot of the block. I lost a 4v motor last year due to a spun main bearing and want to take preventative measures for the new motor. I have leads on a 1.5 qt accumulator but can't wrap my head around how they could possibly be effective. Thanks

[edhunter]

Ray, I'm guessing you're using the electric valve that only opens when it senses low oil pressure at the switch location...

 

I just put an accusump in my 05 build... I had it in the fox car, but never really knew if I needed it or not... but I never had low oil pressure. When I put the pushrod engine in the 05 car, I used an external pump and a really nice custom pan with numerous trap doors. I didn't figured I'd need the accusump since the pan appeared to be much better than the canton pan I used on the fox. I ran the car for just a few laps at VIR in early November, and saw my low oil pressure light flickering under heavy braking. I dont' think it lights unless the pressure drops below 15psi. So even with an external pump and nice pan the pickup is sucking air. I know the pickup is set right in the pan, so it's got to be poor oil control. So one of my winter projects was installing the accusump. I put it in the passenger seat area, and have an electric switch. Only it's open all the time 12v power is to it, so the sump "sees" the same pressure as the rest of the system. A manual valve will do the same. That's usually around 65-70psi. It'll feed oil under pressure into the system the second the main oil lines drop pressure (pickup uncovers). Granted the pressure will continue to drop the longer the sump is pushing oil into the main lines, but it'll feed the engine for several seconds until the pump picks up oil again. When I shut off my engine the accusump shows around 65psi on it's pressure gauge - turn the ignition on, the valve opens, and my dash OP gauge reads over 20psi for 10 seconds or so without starting the engine... (I have the 3qt accusump and would rec. the same for a V8 engine).

I'm a believer in it's ability to help save an engine. Cheap insurance. I'd rather not have to use it due to the weight gain but it's better than losing an engine.

[UBR]

Ray,

 

You have part of the logic correct. Resistance increases over distance, so the longer the hoses, the less pressure at the engine end when the valve opens. But the key is to keep a minimal pressure in the engine at all times. The oil passages are a closed system. Braided lines don't expand much so the most pressure loss will be due to resistance and not system expansion. As long as there is enough pressure at the Accusump end to overcome the resistance of the lines, there should be enough extra oil dumped into the closed system to maintain the minimum pressure you need for a few seconds. And that's really what they are good for. A few extra seconds while the system stops sucking air and can recover. They aren't going to save an engine from a pump failure or hole somewhere unless you are really fast on the kill switch.

 

We have one in our Fox. It's mounted on top of the trans tunnel. Right under my elbow. Our S197, with the same pushrod motor, doesn't have one.

 

It's slight insurance. Don't know how much. The only oil related engine failure we have had in either car was due to an oil pump coming loose because the former shop that put it together didn't Loctite or wire the bolts in. An Accusump wouldn't have helped that.

 

j

[Al Watson]

I definitely suggest getting one Ray, and forget the small 1.5qt jobber, I recommend the 3qt big one. I lost a motor due to loosing oil pressure in high G turns, no matter how crazy of an oil pan you have a wet system is always vulnerable to momentary losses of pressure as the oil uncovers the pickup. I also suggest you get at least a #10 line (#12 better), oil filter adapter, 3 qt accusump and manual valve and a 30psi low oil press warning light so you know when it happens.

 

my setup:

3 qt accusump, manual valve, #8 line about 6-8ft long (soon to make #10), filter adapter, 30 psi warn light.

 

Operation: open the valve start the car and go race. typically I have about 50psi of oil pressure when its hot, when I uncover the pickup (which happens regularly) I can see the gauge start to drop, it basically goes from 50 to 30psi when it first happens and the light gets me to look at the gauge, it only drops to 30 for maybe a sec or two and comes back. cheap insurance.

 

At the very least get a 30psi warn light, cheap enough.

[99cobra2881]

I read this method on corner-carvers.com

 

Key on. (Yeah my race car still has a key.)

 

Open manual ball valve.

 

Close manual ball valve.

 

Start car. Let car warm up.

 

Slowly crack valve. While watching pressure gauge.

[marshallmosty]

I have a Accusump 3qt on my AI FOX. I had issues with the stock pan and high speed sweepers, so went to a 7qt Canton pan and the accusump at the same time. Also installed a 20psi idiot light. Before the pan and accusump, I saw the light more than I would like. Now, the gauge never drops below 50psi (hot pressure). Cheap insurance and they are rebuildable (by Canton) for approx $80. I had my seals start to leak last year and shipped it back to them. The service is $60 and return shipping is $20 IIRC.

 

Good luck. Just do it and never think of it again.

 

Also, as several have posted, it acts as a nice pre-luber during startup.

[CantonRacingProducts]

Are oil accumulators really worth it? Most people mount accumulators in the pass compartment. Therefore there must be at least 5-6' of line between the accumulator and the block. If the accumulator has approximately 100 psi of oil in it, and the engine loses oil pressure, that 6' line also loses pressure. Once the valve releases the oil in the line, the pressure immediately drops in the line itself. Then that oil, at a lower pressure has to travel into a block adapter and fill up the filter. Then there's got to be a pressure drop through the filter before it even gets to the oil galleys of the block. Then it's gotta travel through the block to the bearings and still have enough pressure to do adequate lubricating? Is this accurate? Sounds to me that they're more hassle then they're worth. I can't see them being useful unless they're mounted within a foot of the block. I lost a 4v motor last year due to a spun main bearing and want to take preventative measures for the new motor. I have leads on a 1.5 qt accumulator but can't wrap my head around how they could possibly be effective. Thanks

 

Depending on your set up you will see some pressure loss along the lines. However, we do have several people that run our Accusumps in their trunks successfully. Of course as has been stated it's effectiveness is conjecture as there are really no measure for how well it's working. There are several ways to set them up that can help maximize how well they work. With a manual or electric on/off valve setup the oil is going to discharge as the pressure in the system drops, so as you lose pressure in the accusump lines the oil will push into the system. The accusump should be charged with 7-10 psi which is enough to overcome the psi loss in the lines but not enough to force oil into a properly functioning oiling system. With an EPC switch there is a set pressure at which the valve will open and discharge the oil. Again, the pressure in the air side of the accusump is just enough to push the oil into the pressure gaps in the system. The advantage to the EPC switch is that you have the full capacity of the Accumulator at the point where the pressure drops below the threshold. If you go with the EPC swtich you can also wire in a light to the switch that will allow you to see when the Accusump is discharging. This information can be helpful in showing you where your oil pressure is hurting on a course or can give you piece of mind that the Accumulator is doing what it's supposed to. Hope this information was helpful.