LSA Oil System Guide

oil pump

Welcome to the LSA Oil System Guide, in this article we go over how to keep your engine safe at peak performance.
On the LSA platform once the HP is increased to around 460rwkw (620rwhp) the actual force created from that pressure can be enough for the crank to flex, it only needs to flex 2 to 2.5 thousands of an inch (0.05mm – 0.06mm) for the crank to touch the main bearings. Then this can happen to your bearings…
(photo from LS1Tech)
engine bearing LS

The Factory LSA Oil Pump:

The factory LSA pump is actually a really good pump, many people assume it can be upgraded to a better flowing pump. This is actually a large misconception. The stock LSA oil pump is actually identical in flow to a Melling 10355 which flows 33% more than your baseline stock LS1 oil pump. The only real benefit to changing out the stock LSA oil pump to the Melling 10355 is the hard anodized plate and the 10% stiffer spring, otherwise the 2 pumps are identical and there really isn’t a higher flowing pump available.

EDIT: 28/Nov/2019:

Update to this tech article. In November of 2019 Melling must have had burning ears or maybe they read our tech article. Anyway the good news is NOW there finally is a pump and only 1 pump that is actually better than the stock LSA oil pump and that’s the Melling 10355 HV, this pump has an additional 20% more flow over the standard 10355 and comes with a higher pressure spring. We’ve not yet used one ourselves but this is now your ONLY upgrade version of pump that should be considered on the LSA, as above the standard 10355 is the same as the stock pump, however the 10355HV it does have more flow and more pressure when the higher pressure spring is installed. This pump is probably not needed for most people, but if your in the middle of an engine build this is now an option for you which finally actually is an upgrade not a downgrade.

LS Oil Pump Flow Rates:

This is exactly what some people even mechanics get confused about what oil pump to use or upgrade to with the LSA engine. We will break it down here for you, all of the below pumps are in reference to how much more they flow over a base LS1 oil pump:

Melling 10295: Same volume as LS1, 10% increase in pressure over LS1 based M295 oil pump.
Melling 10296: 18% increase in volume, stock pressure over M295 and 10295 oil pump.
Moroso 22120: 18% increase in volume, stock pressure over M295 and 10295 oil pump.
Melling 10355: 33% increase in volume over the 10295.
Factory GM LSA: 33% increase in volume over the 10295.
Melling 10355HV: 53% increase in volume over the 10295.

How to get your Oil Pressure higher:

The LSA engine bleeds off oil pressure from 3 main areas.

  1. Pressure relief valve in the sump
  2. Pressure relief valve in the oil pump
  3. 8x Piston oil squirters

Deleting the Sump Pressure Relief Valve

When GM designed the oil sump for the displacement on demand engines (AFM L76,L77, L99) the sump had a built in pressure relief valve designed to protect the AFM valley plate solenoids. This valve pictured below bleeds off oil pressure at 55psi, you cannot achieve any higher than 55psi of oil pressure until you delete this valve. This sump carried over to many LS based engines which looks to be a cost saving measure instead of re-tooling for other engines. The valve is not needed on any LS engine that is not equipped with AFM/DOD. Since the LSA engine doesn’t have DOD we delete the valve and can then start the process of gaining more oil pressure.


In order to block the pressure relief valve off you will need to obtain a 14mm x 1.5mm threaded bolt roughly 12mm long with a crush washer or O-ring, you can even use an oil sump plug and just shorten the bolt if it is too long. If the bolt is too long you will restrict oil flow, so ensure that your bolt isn’t too long.

Shimming the Oil Pump

Next you want to create additional oil flow and pressure, the relief valve in the oil pump also bleeds off at 55psi, this valve is controlled via a spring, so you can simply add washers to shim the spring up for increased pressure. Typically we add 4mm (160 thou) of washers to a factory LSA oil pump, if it is a Melling 10355 with a 10% higher pressure spring we shim them up 3.5mm (140 thou).

After this is completed both the sump and oil pump relief valves you can expect to see 60-65psi of oil pressure at full throttle.

We did this on our stock bottom end LSA that ran 9.700 at 148mph it lasted very well and when the engine was pulled down the bearings were fine.

LSA Piston Oil Squirters

squirterThe piston oil squirters are designed to take some of the heat out of the piston, they have a check valve inside them which opens them up after 42psi of pressure is achieved. This is a main point of oil flow loss especially since there is 8 of them. We did not do this on our LSA engine as we wanted more piston cooling however if you desire even more oil pressure you can replace the squirters with a smaller unit from Katech in the US, their squirters will simply spray less oil on to the base of the piston and will increase the oil pressure even further than the above modifications at “some” sacrifice to piston cooling.


The factory LSA oil pump is great, you simply need to increase the oil pressure, when ever you increase HP to your car you usually need to also do supporting mods, whilst the oil system upgrades listed here will not result in a gain in HP, they will result in a longer living engine. Any engine pushed harder and harder will die sooner, everything has a life expectancy, from your light globe to your engine, the harder you work that component the sooner it will fail. The LSA can certainly make a lot of HP, just be sure to take good care of the engine. You can also never change your oil too often.