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Hello guys

I just start my new engine and achieved a few kilometers with the followings species





1293
Modified head
Med gearbox, and Med flywheels
SW5
KAD RACE oil pump (maybe the cause of my problems)
CSI swiftune dizzy etc..
Oil relief valve fitted with S Spring
S oil cooler

The engine works very well but the oil pressure is not as good as expected

For example I achieve 30 miles yesterday with an oil cooler cover, the pressure was 60 PSI at 4000 rpm and 15/20 at 1000rpm, the weather wasn't too cold, about 10 degrees

I decided to remove the oil cooler cover and 1 mile after the pressure was so much better 25 psi at 1000 Rpm and 75/85 at 4000 rpm

I'm wondering what was the problem,

Oil overheating that could lower the pressure?

Oil pump ? I know that the race oil pump are supposed to give less pressure at low rev

I checked everything but I would like your advise before to pull the engine out as it's brand new there no reason to have failure

One of my friend told me that the S relief valve spring could cause oil pump gasket failure?

Try the standard relief spring. Had the same problem in my "S" and now the pressure is 75 at 4000 30 at idle.
Its just worth trying it for a very small price.
6K853 0.75p (This is the standard one)
AEA536 1.05 (This is the S one)

My thoughts .. can you be sure that your whatever type of Oil Pressure Gauge you are using is reading correctly ?

Rolandino wrote: ↑Sat Jan 23, 2021 10:14 am Try the standard relief spring. Had the same problem in my "S" and now the pressure is 75 at 4000 30 at idle.
Its just worth trying it for a very small price.
6K853 0.75p (This is the standard one)
AEA536 1.05 (This is the S one)

The S is shorter and made to work with the ball bearing instead of the standard relief valve? the ball bearing seems to be thicker so may make the spring harder ?

Polarsilver wrote: ↑Sat Jan 23, 2021 10:15 am My thoughts .. can you be sure that your whatever type of Oil Pressure Gauge you are using is reading correctly ?

My oil pressure gauge is in good condition, I just used it 2000 miles on my ex race car

Are you using a ball or the conical valve in the relief valve? I have found the ball can give variable oil pressure readings. If you are using the conical valve it may well be sticking slightly. When you built the engine did you lap the valve in to be sure it seated correctly?

That you are getting variable pressure points to the valve to me. I would expect higher pressures with cold oil so it will not be owing to that.

D

Ive never built an engine that hasn't had 70/75 psi at idle when new with the valve opening at about 80 psi. I'd look at the relief valve to start with to make sure it's not sticking as others have mentioned.
I see you're using a Swiftune cam, did you check cam end float with the oil pump fitted?
There have been quite a few cases of the ball bearing that blocks the drilling in the oil pump drive end of the cam sitting too proud preventing the oil pump seating properly and leaving no cam end float.

Hello Imack

I just took out the relief valve, and it's in good condition, only a few marks but nothing serious

I didn't check the cam because I didn't built the engine by myself, but the engine builder was really good

I would never, ever, ever use a ball . it wrecks the base where the normal bullet faces up to. What Ive always done is lap the bullet by poking a round piece of timber in it and use toothpaste to grind it in (a very small bit is needed) Then clean it all up with an ear bud. Use a new copper washer, hopefully a genuine one rather than the crappy one MSC sell. Its round and doesnt squish up, so the pressure is a little bit less than it should be.
The thick one, even when tightened down is 0.025 thou thicker, ie half a turn of the nut.

I made some more test this afternoon with a standard spring

When cold the pressure is about 70 PSI

when hot at idle the oil pressure is at 25/30 PSI @ 1000 rm and about 65/70 psi at 4500 RPM when warm I didn't drive it too long about 5km but I let it warm 20 minutes in the garage

I don't know which is the best option, there S spring or the standard one, the S one give a nicer pressure?

Interestingly if you look at a new replacement oil seat insert,( yes the seats are removable) they have 2 sides which are slightly different the conclusion I came to is one side is for the ball the other is for the valve. So I just wonder whether swopping ball for valve is that straight forward?
I have never used the ball all my s motors used the valve.
On oil pressure: in the day Andy Barton always told me a good s engine should have 75psi at 4000rpm or just below and that was the critical figure.

I read somewhere in the wizard that the good oil pressure was about 55/60 psi

My pressure is a little better withe the S spring, the oil pressure is always a disputation

60psi at 4000 revs and 20-30psi at tick over properly hot , is fine. Anything over 60psi is sapping power. As an aside Paddy Hopkirks 6EMO , runs at between 40 and 55psi all the time, and that it is a very fit and ultra reliable engine

I have only recently been converted on the oil pressure, always thought you needed 80psi, old school. My new 997 built engine runs and tickover at 75psi stone cold, when hot, been on a 40 mile run, it is 45/50psi at 3k, 65psi at 4k and tickover 25/30psi. No oil cooler.

Thats perfect!

Thank you for your help guys! now it's time to find the clutch and gearbox problem...

SMOKE GREY wrote: ↑Sat Jan 23, 2021 7:28 pm 60psi at 4000 revs and 20-30psi at tick over properly hot , is fine. Anything over 60psi is sapping power. As an aside Paddy Hopkirks 6EMO , runs at between 40 and 55psi all the time, and that it is a very fit and ultra reliable engine

I have only recently been converted on the oil pressure, always thought you needed 80psi, old school. My new 997 built engine runs and tickover at 75psi stone cold, when hot, been on a 40 mile run, it is 45/50psi at 3k, 65psi at 4k and tickover 25/30psi. No oil cooler.

Forgot to say, I have the S pressure spring and standard valve.

agricola wrote: ↑Sat Jan 23, 2021 6:20 pm Interestingly if you look at a new replacement oil seat insert,( yes the seats are removable) they have 2 sides which are slightly different the conclusion I came to is one side is for the ball the other is for the valve. So I just wonder whether swopping ball for valve is that straight forward?

I was thinking the same.

OP.. What is the oil cooler you have fitted? From what I have seen the KAD pump shouldn't give lower pressure at slow speed. You can always try adding a flat washer under the spring of the oil pressure relief valve, this shouldn't change the idle pressure, if it does there is an issue relating to the valve.

In the day75 psi was used as a gauge for bearing condition. Oil and times change the standard pump is 6gpm and you can now get 9gpm pumps so you rightly you can adjust pressure downwards but the hp gains of dropping 10 psi is minimal psi x gpm /1714 or about 1/20th of a horsepower but 65psi sounds fine.

Rolandino wrote: ↑Sat Jan 23, 2021 10:14 am Try the standard relief spring. Had the same problem in my "S" and now the pressure is 75 at 4000 30 at idle.
Its just worth trying it for a very small price.
6K853 0.75p (This is the standard one)
AEA536 1.05 (This is the S one)

Ditto. Engine I've just built was way too high on the S spring. Put a standard one in and it was much better.
Paul

Nuther "low pressure" guy here, I aim for 45-50 pounds at 5,000 rpm, 10-15 at idle in all my builds.......You just don't need any more than that.....

Also only use 5 or 10W-30 oil, no cooler ever.........

Been doing that for over 50 years, haven't blown a motor up ever because of that (and, I do occasionally try)........