My 383 LT1 is being put together and I need to get some advice on an oil pump.

The build is going to be for a large single turbo. The motor is fully forged. I have a canton 6qt oil pan. Should I be looking at a high volume pump or a high pressure pump? The motor is spec'd to run 20W50 if it makes a difference.

 

I run a Melling 155HV with my canton pan. Seems to work fine.

Be careful with high pressure stuff and turbos, some are more sensitive to pressure and you may end up rigging up nitrous jets etc...

 

I was hoping someone like you might chime in.

Thanks for the info.

 

Check with the turbo manufacturer with this. The oiling system of a turbo is typically VERY small and works more on oil misting than bathing. Easy to overpressurize the shaft seals. The manufacturer should be able to recommend/provide a restrictor oriface if needed.

 

Well this issue can also can be tackled by using an oil restrictor on the turbo. I know turbonectics require it but borg warner does not.........

 

I'll have to speak with the turbo manufacturer and find out what they say.

 

I have zero turbo build experience. That said I understand the oiling system and with 20w50 I would want a high pressure pump so it pushes oil through the motor rather than just the bypass.

 

I had a HV pump before, and running the thicker oil of 20W50 I always had exceptional oil pressure. But now that I am going turbo instead of supercharged, I wasn't aware of the differences and wanted to check.

 

Oil pressure is not that meaningful, it is NOT pressure that keeps the crank off the bearings. Stop and think about the surface area of a bearing with 50psi oil compared to even just cranking compression against the surface of a piston.

We measure oil pressure to watch for deviation from norm and because it is easy to measure but flow is what keeps the crank afloat. If you run a HV pump be aware more than a few guys have had them eat the LT1 oilpump drive gear, so it would be prudent to figure on periodic inspection.

 

Agree that the thicker oil and HV pump is gonna put a serious strain on the oil pump drive gear.

 

Pump pressure is dependent on RPM range. If you're spinning above 6k then a high pressure spring would be a good idea.
Pump volume is dependent on your bearing clearances which will be greater in a high powered turbo motor. You only want more volume if you can move it.
Most HV pumps are +25% which is more than overkill and can chew the drive gear. Melling makes a +10% pump w/HP spring which is what I went with, p/n 10552.

 

Ask your builder if the bearing clearances will be wider than stock. The spec of the 20-50 suggests that. If so a HV pump is often used in those builds.

 

DING DING DING

Yes, the tolerances are wider than stock, thus the builder recommended the use of 20w50.

 

I have some pretty sloppy bearings in my motor, and only run 15w40, even that is prob overkill.

Anything past .0025-003 is wasting oil and creating heat, so 20w50 screams overkill to me. May want to consult your builder on what exactly he gave you tolerance wise.

Worst case, get a block heater, cause dem cold starts... sheesh.

 

Yeah I get that but everything I said still stands.

The pump moves a given amount of oil per rotation, restriction creates pressure. The max pressure is determined by the spring and once reached oil starts bypassing the engine and is fed back to the pickup. 20w-50 is going to make a HV pump go into bypass pretty quickly.

A high pressure pump keeps pushing more volume across the bearings before going into bypass.
People worry about idle pressure but the engine sees no load at idle.

 

Guys, I appreciate the info and the concerns, but you need to understand that my motor was built back in 2006. It was made with tolerances that allowed the preferable oil weight to be 20W50. It was supercharged and ran flawless for 8 years and countless thrashings all with a HV pump.

I found an oil galley plug had popped out last fall and am having new bearings put in the motor and having it taken apart to be sure it's safe (BTW, builder says it's over all fine but thought new bearings and a fresh oil pump would be wise since it's apart anyways).

The only reason I am asking again now is that I am going the turbo route. Nothing else will have been changed. So if there is no difference turbo wise what oil pump I use past needing to find if I need a restrictor for the turbo itself, the 20w50 weight should remain fine.

 

If the pump showed no damage I would MUCH sooner worry about the drive being replaced than the pump. Pump is the best lubed part of the motor, no debris I would reuse it.

 

Its 8 years old, and the oil galley plug was ran through the motor and likely the oil pump as well. Its getting replaced.

 

I assume the turbo will have an oil feed. Will the turbo bearings be ok with that thick oil?

 

FWIW a 19 year old, 120k mi original oil pump drive gear with the last 30k mi a HV pump and 20-50 oil was used on a motor with wider bearing clearances than stock.

Looks brand new and still in the motor today

The "reports" of wiped drive gears and HV pumps....may have happened but whether that particular motor was built with wider bearing clearances vs stock is rarely (read not) noted. I suspect in cases where a gear was wiped (assuming not due to cracked/broken plastic top resulting in gear lifting up and striping) was due to using a HV pump with stock bearing clearances. HV pumps have their applications. Not all motors, especially stock ones, should use one.

and the myth of a HV pump sucking a oil pan dry.....please.....but the internet is full of stories it does.