6 replies to this topic

[bremboy71]

Good one fello Mitsu people, 

 

I have looked all over for the standard value of a 4G93 DOHC oil pump, since i have just instaled a Defi Oil Pressuer gauge i need to know what is the standards for this model or is this a standard for Mitsu?

 

Thank you for the help

[White Knight]

Mate, for the 63 stock oil pressure is 15psi at hot idle and above 75psi at high rpm. I can't imagine much difference, I do hope this helps mate. Best of luck, cheers.

[Evo-00x]

There's an oil pressure thread in this forum somewhere for the 4G63.

Someone might have put their 4G93 figures in it? 

[VIN18M]

My 93t reads about 40psi at cold start (2,100rpm), then drops to 20psi at hot idle.

[White Knight]

Honestly doesn't sound bad at all to me mate. Don't stress too much just because you have a gauge now. No offence dude.

[Evo-00x]

I know its not 4G93, but what we mainly see in the 4G63, or at least what we aim to get is about 60-70psi maximum at cold startup idle and the oil pressure then starts to drop slowly as the oil heats up. 

When the engine has reached normal operating temperature we're normally looking for about 20psi at idle between 1000-2000rpm, then about as close as possible to 10-15psi for every 1000rpm+ there on. 

e.g. 3000rpm = 30-35psi; 4000rpm = 40-45psi..... 8000rpm = 80-85psi. In fact most may be slightly a little higher than ideal.

There is no exact number as everybody's got different engine setups, using different oils, running with/without balance shafts, has different mods with ported oil pressure relief valves or modified oil pumps and pulleys that effect the oil pressure. 

So if your normal operating temp idle is close to 30psi then thats still OK. But take into consideration the oil pressure at high rpm where it counts the most! 

Are you revving it past 8000rpm? Are you seeing 90psi+ oil pressure? If so then you need to do some modifications as mentioned previously to lower your oil pressure.

Its been known for some time that our OEM oil pumps dont function very well above 8,000rpm.

 

Here's an extract from Magnus Motorsport about the cons of using the OEM oil pump in a 4G63 engine that sees over 8,000rpm:

 

Simply put It comes down to a few things as to why the Stock oil pump will not work within what we are trying to do.

-The stock oil pump was designed to turn at a maximum of 8000 RPM.

-The pressure relief valve is designed to handle enough f low f or the stock pump at 8000 RPM

(7000 in the DSM's case) Unless it is enlarged it cannot bypass enough oil, unless it is shimmed

sometimes it won’t make enough pressure.

-Any overdriving of the OEM Oil pump (8000 plus RPM); because it is a positive displacement

pump, will pump a large amount of oil into the cylinder head. From which it has a hard time

returning.

-The EVO only has a f ew small drains in the cylinder head to return oil, The DSM has half of

what the evo has. This makes f or a dif f icult path to replenish the oil reserve in the pan

- This drain problem can be compounded by the f act that many motors have too much blow by

because they are running the wrong piston and pin at high RPM’s the pistons are def orming and

causing the rings to no longer seal. Most companies use "of f the shelf pistons", these are

knock of f s of the pistons we used 10 years ago, those aren’t going to cut it today, and they

cause these issues, consider new pistons as well.

- High RPM launch control, Cornering, Launching, Braking, any one of these will upset the oil

level in your car. In drag racing what we experience is 2 step launch control f or 2- 4 seconds

(depleting the pan of oil) a multiple G-f orce launch, moving the oil to the back of the pan. High

rpm runs in the 8500 – 11,000 RPM range, f urther deplete the pan of oil. Compound thiswith

trying to drain back through only 3 holes in the DSM engine’s case while excess pressure f rom

the rings is trying to push its way up to the valve cover.

Edited by EVO-00X, 07 August 2014 - 04:33 PM.

[bremboy71]

Gentilmen , Thank you ever so much for your help and time to input your knowledge.