MelloYellow

Is it normal to see a bit lower oil pressure readings from a forged motor vs. stock? Is it true they have a bit looser tolerances than stock, flow more oil but show less pressure?

Am seeing a bit lower oil pressure than my old motor. Did change to a lighter oil temporarily and also have a new Vortech sucking oil out of the pump now too.

Thx!

Scalpel

iTrader: (4)

It depends on how close your clearances were set compared to stock. It's builder dependent.

SAM98WS6

what are your specs?
Mine were .0024rod .0025main and I have 40psi with 10w30M1..no reason at all to use anything thinner on these motors.

MelloYellow

Not sure. It's an MTI motor.

I normally run 10W40 here in hot Florida, but have 5W30 in there temporarily since we used dealer Mobil1 oil. Will be changing it shortly. I'm used to the pressure readings with 10W40 RedLine.

Anyone know MTI bearing specs?
Any thoughts on the Vortech oiling system effect on oil pressure?

MyLS1Hauls

iTrader: (2)

Vortechs just mist the oil into the supercharger, therefore it uses very little volume. I'll be the lower pressures are related to the main bearing tolerances. STD replacement Federal Moguls will give you more clearance than a stock STD bearing. Some places use a +.001" bearing to tighten the clearances back up. The only way to know the actual specs is if MTI recorded it (they should have) or take it apart and measure it.

2001CamaroGuy

iTrader: (6)

...

Fireball

iTrader: (21)

thats what I found personally. Had std FM main bearings and only saw 30ish psi hot oil pressure @ 1000 rpm. Tore motor down and measured clearance at 0.003 inches. Rebuilt with +.001 bearing (.002 clearance) and now have 42-45 psi hot oil pressure @ 1000 rpm

KGSloan

i have no idea what my clearances are, but my forged motor has 45psi hot idle, and over 60 while cruising.

my motor was built by LG motorsports, btw.

Viper

iTrader: (6)

JPR motor here, idle at 27-30psi hot, 60-65 at WOT. Considering pulling it apart at now 11K ( and a busted valve spring ) and rebuilding it with proper bearings. Sadly have to get the heads reworked as well since his flow bench was miscalculated.

MelloYellow

Thx for the feedback.

What are the benefits of looser bearings?
Is lower pressure always bad?
Does looser have higher flow?

gun5l1ng3r

I second the questions of MelloYellow.

Scalpel

iTrader: (4)

What are the benefits of looser bearings?

Looser clearances allow for less friction thus increased HP gained by negating possible frictional losses.

Is lower pressure always bad?

It depends on how low it is at hot idle and at high RPM driving.

Does looser have higher flow?

Holding all things constant let's look at this. If we make the clearances looser we increase the potential space between the bearing and journal(s). This potential space is filled by the oil that is pumped through the journals via the oil pump. The oil pump can only pump as much oil that can be pulled into the pump and pushed out of it. So, unless you alter the oil pump to increase its volume then you really can't increase the volume of the oil being pumped in a closed system such as this (engine).

MelloYellow

Am currently seeing 20psi Hot at idle.
Is making me paranoid.

Need to call MTI to check their bearing clearance specs.

May replace the stock oil pump for peace of mind this week.
How long should an oil pump swap take with the motor in the car? Any major headaches involved?

Camaroholic

iTrader: (1)

With a vette, I think the major PITA is the steering rack. It's gotta come out.

jMX has instructions on oil pump swap on his site at http://www.ls1howto.com - his 'vette heads/cam instructions show the oil pump.

MelloYellow

Thx! If the rack has to come out, that may delay this. Uff.

Scalpel

iTrader: (4)

Yes, the rack definately has to come out.

slyws6

I see 60-65psi at idle when cold and 55-60 once warmed. Terry Wilkes at Racetech ---> built the shortblock

-Sly