Oil Pressure - too high?

[Eldavo]

Turbo-ed MX-5?

 

[scam75]

I'm using a fully synth 10w-60 oil and my gauge reads just past 5 when revved with the engine is cold. I reckon it goes to about 6. The lowest I see is 4 bar at very hot idle. I have a rebuilt engine with new rings etc.

Once my oil is up to temp I get 5 bar exactly when driving and 4 to 4.5 bar at idle depending on how hot the oil is.

I have covered about 4k miles on this oil and not blown any seals anywhere. I am thinking going to 10w-50 though at next oil change.

Stuart

 

[edh]

ORIGINAL: Eldavo

Turbo-ed MX-5?

Can't see the point really - adding a turbo just makes the car less reliable - and the main benefit of an MX-5 is that you can thrash it all day. Turbos give you all sort of issues on heat management and mapping.

Makes much more sense just to buy a faster car

Having run a couple, I'm not a fan of turbo track cars and will stick to n/a

 

[edh]

ORIGINAL: scam75

I'm using a fully synth 10w-60 oil and my gauge reads just past 5 when revved with the engine is cold. I reckon it goes to about 6.

Stuart

Are you psychic? []

I can't see how you can be sure of anything apart from that your oil pressure is 5+ bar - and that's assuming the gauge is working OK...

I still suspect that my old OPRV just had a couple of moments where it stuck & that was enough to blow the seal - this was at WOT, changing gear at 6k rpm, so at a point where the pump would be generating the maximum pressure.

 

[944 man]

ORIGINAL: edh


The later MX-5's were out as well - Roddison motorsport were there with their Mk3? race car (no idea really on the different Mk's) which was definitely quicker than me. Of course that may have more to do with driver skill and commitment - still haven't really got Charlies 1 / 2 nailed in the 944, and a narrow track and wet grass make it quite intimidating.

Paul Roddison can set up a 944 nicely too. Based in Sheffield near to Meadowhall, people might remember me mentioning him when I said that a proper geo can be done for £80.

 

[scam75]

ORIGINAL: edh

ORIGINAL: scam75

I'm using a fully synth 10w-60 oil and my gauge reads just past 5 when revved with the engine is cold. I reckon it goes to about 6.

Stuart

Are you psychic? []

I can't see how you can be sure of anything apart from that your oil pressure is 5+ bar - and that's assuming the gauge is working OK...

I still suspect that my old OPRV just had a couple of moments where it stuck & that was enough to blow the seal - this was at WOT, changing gear at 6k rpm, so at a point where the pump would be generating the maximum pressure.

Not very pyschic no but my gauge goes past 5, up to what would be about 5.5 and guessing by the speed it rises and falls up to that point I don't think I'm too far off! I get bang on 5 at idle on cold start up but it climbs past 5 when revved. I have a brand new sender btw. However my readings are all spot on once the oil is up to temp so don't think they can be too far off spec during the heat up process. However, I may be wrong!! I'm thinking dropping to a 10w/50 will see the pressures down a little when the oil is cold and hopefully not climb past 5 bar when revved.

Stuart

 

[944 man]

A failed sender elevates the needle up the gauge far higher than the scale limit, suggesting that 5 - 6 - 7 BAR can be loosely indicated, depending on the range of the sender itself.

 

[edh]

You're all guessing though

When my new gauge shows 6-7 bar etc.. the dash gauge shows approx 5

My hypothesis is that 7 bar is not unusual at startup and nothing to worry about. I suspect that the pressure needed to blow an oil filter seal is a fair bit more

 

[944 man]

Im hypothesising, yes. Is the original gauge ever accurate, though? If it is, is the sender able to measure over five BAR? Should seven BAR blow a seal? I owned a 924 many years ago and they have a ten BAR oil pressure gauge and mine regularly measured over seven BAR, hot, without issue and ten cold.

 

[edh]

That's what i'm saying...the OE gauge isn't that useful - it tells you that you have some oil pressure...or not (And if you don't have a gauge at all, you just stop worrying about it)

I think the OE sender is a 5 bar one (I'm running a separate 10 bar sender in a sandwich plate under the oil filter)

7 bar doesn't blow a seal - at least I've proved that much.

 

[scam75]

Yes definately guessing but I think it's safe to say 7 bar when cold should not be an issue. The OEM senders are only rated up to 5 bar and are probably not the most accurate in the world. They are useful though for seeing you have some oil pressure and watching how it behaves when hot/cold, driving/idle etc. and yes probably more of a distraction than anything else. Definately rather have the OEM one than nothing.

I started all my oil pressure watching after my engine rebuild and new sender at same time. My oil pressures were odd to say the least and after fiddling with seals and alignment on the OPR valve and switching to a thicker oil it turned out my new sender was duff! The next new one reads out what I described but is 100% consistent at least and the gauge needle doesn't twitch. The faulty sender was causing much needle twitching and sudden unexplained pressure drops. Of course instantly condemning a brand new part didn't cross my mind!

Pressures all seem ok now if maybe a tad high on start up but as discussed probably no need for concern. The time I spend looking at oil pressure, boost pressure and AFR readings it's a wonder I ever look at the road!!

Stuart

 

[Hilux]

Cheapest track cars are always going to be small FWD hatches, closely followed by the MX-5. At Cadwell yesterday, one of my friends was there in his Mk 1 MX-5. He's previously had a number of turbo jap nutter cars, and bought this last year. He may only have 100hp or so, but he wasn't much slower than me round most of the circuit as power doesn't help you through the twisty bits...

Reminds me of...........................me!

Golf Mk1 (with 2.0L 16v ABF engine - big brakes and other shiney stuff) always on the limit - currently about 180bhp per tonne - mad massive fun.

I was so impressed with two chaps in reasonably standard MX5 Mk1 Eunos's I bought one! Took me ages to get past them!! They are very very light and phenomenal if set up correctly with razor sharp handling and turn in - fully adjustable front and rear suspension as standard!! There is a lower spec 90bhp engine but buy the right one with the more powerful engine and in decent condition will put out about 115bhp - problem is the wife likes it too much but I`ve slipped in some half decent coilovers and roll bar and she hasnt really complained (yet). Looking to supercharge mine and sort it properly for the track this winter - dont tell her what the whine is!

Not withstanding all of the above - the 944 is still a fantastic (yet refined) car.

 

[944 man]

The recuced power NA is the 1.6l that was sold here after the 1.8l was launched. JDM cars, earlier UK 1.6ls and any 1.6l NB are all full power.