Accusump Install

Oil pressure and the subsequent oil flow it produces is by definition the very lifeblood of your engine and so the question is can an Accusump Install help protect both around a track?

At our very first sprint event in the TVR 3000M at Castle Combe Circuit in Wiltshire (UK) there was an awful lot to absorb. The first time piloting this car out on track having rushed to get insurance and tax, fit silencers, free up extinguisher pulls; tidy the most obvious points and enjoy only limited road miles in between.  With the absence of ABS, traction control and power steering and with all that intoxicating lusty V6 sound filling the cabin the only thing that interrupted the enjoyment mid-lap was the oil light illuminating at times.

an Accusump Install
The clue is on the left. Oil light coming on into The Esses

Set to come on at 25psi as opposed to 15psi the light did not equate to the engine instantly turning into a grenade, it more provided a warning sign. This happened every time we entered The Esses chicane, a combination of braking and turning left, before clearing as soon as power was re-applied between the apex and exit to register a far healthier 75psi once more. It forced a driving approach of one eye on the road with the other on the pressure gauge. The good news was it never dropped below 25psi although left slight confusion on what to do about it.

Back at home I googled ‘V6 Essex Low Oil Pressure’ to learn that a dry sump, baffled sump or an Accusump Install were all potential options. I hadn’t removed it yet but externally could see the sump was already heavily modified being completely flat on the bottom to sit above the low chassis with massive wings on either side. I also knew it contained a full gallon of oil. I narrowed the search to discover that flat bottomed sumps are particularly prone to oil surge under braking on the Essex V6 which has its pick-up pipe at the rear. On one forum someone had spent £800 on a fully baffled alternative with no improvement. For me that left the £2,500+ dry sump option or at £350.00 including necessary pipework an Accusump Install.

an Accusump Install
Accusump proved to be a cost effective way to preserve oil pressure

The next event, Llandow in South Wales, offered a tight technical layout with a huge braking zone at the end of the main straight before going into the Bus-Stop chicane the result of which was devastating. Oil pressure dropped to zero. Something had to be done. Fortunately an oil change immediately afterwards confirmed only a small amount of debris in the sump, phew, and so not a complete disaster but this was the decider, an Accusump Install was no longer an option it was now a must-do mod.

A trip to local retailer Merlin Motorsport sourced the Accusump Install kit and ridiculous number of adaptors. Basically on cars like the TVR 3000M with an oil filter sandwich plate to the oil cooler the easiest option is to break into the latter’s return pipe adding a non-return valve and three-way adaptor. The issue is that the Accusump Install uses American taper threads whilst everything else is BSP. Trying to connect the two involves endless adaptor combinations; still the good news is it does make sense once you get your head around it.

an Accusump Install
Breaking into the return pipe from the oil cooler (brass non-return top left)

Flexible hose wise we went for the Aeroquip FBN option with Fir-Tree adaptors. Heated in hot water before being joined together, with great force, they are guaranteed to withstand 250psi without the need for Jubilee clips. Motor Sport Association (MSA) regulations do require metal braiding for flexible pipes that run into the cabin and so worth remembering that before fitting adaptors to both ends of any Aeroquip FBN hose. Fortunately Merlin Motorsport was able to supply braiding separately and even though not a particularly tight fit is MSA Scrutineer friendly i.e. should ensure a pass.

Initial thoughts were to fit the Accusump itself in the engine bay or on the chassis under the body but because you need to read the air pressure gauge mounted on the bottom of it reasonably frequently, and because Accusump don’t recommend removing it and fitting a remote gauge the easiest option was to locate the Accusump in the cabin. Now storing hot oil at full engine pressure, 75psi in our case, doesn’t sound particularly appealing I agree; rest assured the system is completely safe and as a bonus looks cool in blue whilst on full view in your race car.

an Accusump Install
Accusump looks cool in blue (Note: Manual valve and gauge end angled down to allow air to escape)

An Accusump Install is not though without its technical challenges. For one you have to know which way the oil flows off the sandwich plate out to and back from the oil cooler. Sounds obvious but we got it wrong. The Accusump works against a non-return valve in the main oil feed so that when oil flows towards the engine as pressure drops it doesn’t just fill the sump instead. On the Essex V6 the oil comes out the side of the plate and is returned back down the middle, who knew. Informed, we simply swapped the pipes on the sandwich plate to correct our mistake.

Physics mean an Accusump Install cannot fail with similar setups common place in industrial hydraulic and pneumatic systems. Once correctly fitted it provides a pressurised accumulator of guaranteed oil pressure and more importantly flow for up to one minute. On our 3.0litre Essex V6 we went for the four pint option and when you initially open the valve after start-up, we chose the cheaper manual system, all four pints is drawn from the engine. Close the valve afterward and stop the engine before refilling the sump and your Accusump is primed. Remember though that from this point on there is an additional four pints of oil in the system.

an Accusump Install
Gauge shows pressure and is initially set to around 50psi to check for air leaks

As a manual system you have the advantage of deciding when to open and close the valve and can even prime the engine before a cold start, but as a manual system you MUST remember to close it before shutting down otherwise you risk overfilling the engine with oil. I did it once, realised my mistake and whilst picturing all that extra oil draining back down into the sump immediately re-started the engine to refill the Accusump before closing the valve and shutting off again. No harm done, but an easy mistake to make.

an Accusump Install
As we discovered afterwards you’ll need to box it in to make it legal to race in the UK

The acid test was to come at the next sprint back at Combe. I’d learnt to drive the car a bit more at Llandow and so a return to Wiltshire’s premier circuit was going to be a more stringent test. Lap times were quicker and at The Esses oil pressure never dropped below 50psi at any point under what I suspect were much greater braking and cornering loads compared to the first time out.Our Accusump Install had worked, the light didn’t come on and oil pressure woes were resolved, result.

an Accusump Install
Proof of the pudding. Same corner taken faster but this time no oil light.

From £350.00 fitted, assuming you do it yourself, an Accusump Install comes highly recommended.

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