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Feckin Oil Pressure


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Been getting some weird decreases in oil pressure on my car and I don't know what the hell it can be. It's a Hayabusa engine with a TTS/Pace dry sump, a Laminova, and pretty standard pipework. Oil is 10W40.


I've extracted some data and posted some graphs here


This was all at Llandow on Saturday:

This is revs vs oil pressure. The revs figure is wrong but the graph is right.


This is longitudinal G vs oil pressure


This is lateral G vs oil pressure


I seem to get this oil pressure drops anywhere - well, I can't see what they seem to be related to. In the data I've posted, it occurs in 2 places - both on straights, i.e. here and much worse here


I'll have it apart and see if anything's looking dodgy this week. I'll also add the oil pressure warning light to the datalogger - it's a different source to the pressure sender and will be able to corroborate the signals I'm getting now. In the mean time, has anyone got any ideas what on Earth might be happening?


I've included a data file which can be manipulated with the RaceTechnology software downloadable here












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What a bugger Adam... hopefully someone with more years than us of experience on engines and oil issues will come along soon.


From a rough analysis I did of the raw data it looks like the oil pressure is pretty much diretly proportional to the revs. So the sharp dips in pressure align to sharp dips in revs to. The low gets near to 1 bar which isn't great.


How well calibrated/accurate is the oil pressure reading?

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Adam, was sorry to see you packing up early at Llandow.

I hope you get it sorted.


Just a thought, but the revs/pressure link looks way too perfect to indicate reality to my untrained eye. I'd guess that it proves its a sender/display wiring issue. Can't

believe oil pressure can react THAT quickly to a change in revs.



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Talking of oil pressure !!

My 97 supersprint crossflow with 16k on the clock runs really low ,as in 1 bar at idle when warm.Ive been told along the way that this isnt a problem,but wouldnt mind some other views on it.Seems to run fine,max revs at 6500 and no smoke.Any thoughts?





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"Can't believe oil pressure can react THAT quickly to a change in revs."


Alan: The oil pump is mechanically driven so I would expect it to react just like it does - i.e. as revs increase, so does pressure and visa-versa. This is actual readings remember, measured 100 times a second . . . different to what you see on a heavily damped gauge that will remove all the dips and peaks.

Maybe it's OK, I don't know *confused* I am pretty sure it's not senders or wiring, but just incase it is; I'm currently checking it all and wiring up the oil pressure warning light to the datalogger . . . we'll see if it triggers at the same time as the dips when I go out next.

Bloody engines ☹️ . .. pain in the 🙆🏻



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Hi Adam.

I suspect the oil pressure relief valve is stuck / sticking. Oil pressure following revs tends to suggest this as the problem rather than it being a false reading.

Is the pressure pump the Hayabusa original or part of the Pace pump? I know some Pace pumps come with integral PRV and this would be easy to dismantle & clean / check. If it's the standard Hyabusa PRV I suspect it will be more difficult to get at.

Hope this helps.


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Adam, if its any consolation I had exactly the same sort of issue's with oil pressure & it drove me to total distraction ☹️ Everyone had an opinion but no one had the answer ☹️

Spent money having the engine stripped after repeated low oil pressure warnings at various points on track, found to be in perfect nick, had a high pressure oil pump fitted no difference, changed the oil supply hose sizes to massive buggers with all the hassle of getting bigger fitting to match welded on all over the place, had the oil pick up points moved in the dry sump pan & generally fettled to the best of everyones knowledge, changed the oil pressure relief valve, had a 7ltr dry sump tank made etc etc.


Ultimately after all the hassle of these changes with the running round not to mention the cost incurred, it made hardly a jot of difference to the incidense of the flashing oil pressure light, costing me a rear wing at MIRA running off the track whilst keeping an eye on it, not to mention the incident at Brands 😳


So I concluded there is something odd about Busa dry sump oil pressure & simply turned the oil pressure warning light threshold down to 15psi & don't worry about it anymore, which I recon is probably what you should do *smile* (But thats your call *wink*)



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Ian: The oil pressure relief valve is the only thing I could think of. I have a standard Busa pressure pump (I was told there was no point in fitting a high pressure one, even though I was happy to buy one). The PRV is on the bottom of the engine and is relatively easy to get at. I'll check it when I take the sump off as I'm probably going to check the gauze filters.


DSL: I've already done everything you did when I first did the install - big tank, -16 oil supply line, now shortened and very direct which needed a new lower engine mount and new sumpguard *mad*. DJ said something at Llandow - basically, that most people either don't know about this sort of thing or don't want to know . . . I reckon he's right and that I should just turn the low level alarm off, after all; these are just split second losses of pressure. I really don't want to stick my head in the sand, but what can you do? BTW, I remember when you went off at MIRA . . . I did the same at Goodwood a couple of weeks ago 😳, at Lavant . . . straight over the gravel. They say a little knowledge is a dangerous thing - this is very true, especially when that knowledge comes flashing up on your dash and you're hurtling towards a bend at XXXmph.



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Not much rhyme or reason to that lot is there.

As it is d!cking around so much gotta suspect the electrics of the sender or as others have said the pressure relief valve.

How is your sender system connected / grounded.


Are we looking at 1.2 bar on that scale marked analogue 2 or?


Do you have a secondary instantaneous low pressure switch / warning light -

Does that come on at any point in the proceedings?

The switch is much more reliable than any sender I have had / heard of.

If you don't have one I'd fit one and see what that says. 36psi one is good for normal pressured engines. If the light comes on you have problems *biggrin*


Don't forget to add lightness :-)

My 2002/2003 racing pics


General pics (mostly of 7's and cars).




Edited by - stevefoster on 12 May 2008 22:11:51

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Steve: Analog2 is voltage . . . I haven't worked out how to use the software well enough to have the axis reading psi 😳


Do you have a secondary instantaneous low pressure switch / warning light

Yes, but these dips only last a fraction of a second and there's too much going on to see a flash on the OP warning light. I've already done a DSL once *tongue*, I'd rather not do it again. It's now wired for logging though so we'll see . . .


How is your sender system connected / grounded.

Standard RaceTechnology sender (c.£100) and wiring, so I'm sure that's not at fault.


The oil pressure warning switch is right by the oil pump where as the electronic sender is in the top of the engine. .. maybe, just maybe, there is a difference between these two places - we'll see now it's all wired up though.


I'm going to be knocking on Think's door when they open tomorrow for some gubbins that will give me more information to mull over, and some bits to change next time I drive it if I still get these readings.



Any other Busa owners have oil pressure data logs I could look at please?




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Can you do X-Y plots of the data? A plot of oil pressure vs. revs and against other x-axis variables would help you find out the correlation to any physical cause.


Are you sure your instrument earth's are wired in OK to the Race Technology kit. I'm clutching at straws because other instruments would show the same pattern related to revs.

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Right . . . after chatting this through with DJ (ta again *thumbup*), he's pointed out that the blips correspond to down changes.

I've taken it all apart and everything looks OK, no sign of anything wrong and the PRV is fine. I'll put it all together again, and with additional logging showing the oil pressure warning switch and the gear changes, I should be able to narrow down what's going on. I'm reckon it must be a characteristic of the engine, well I hope it is.

For this weekend I will change the oil pressure smoothing on the dash so these data blips, whilst being recorded, won't trigger the alarm.


I'd still like to see some more Hayabusa data logs if you have any *thumbup*


Peter: I'll do some more graphing when I've got it all back together . . . bl00dy work PC won't allow me to install Race Technology software and I have a phobia of Excel *wink*



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Simon: That's what I'm going to do . .. have dash/alarm using a smoothed signal (probably 4hz) but keep the underlying data at 100hz so I can see what's going on if I want to.


Rob: I wonder if the downshift opens oil ways or something in the gearbox which causes the loss of pressure *confused* That would explain why the oil pressure goes below idle pressure and why a slow shift had more of an effect than a quick shift *idea*

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when it is hot 80 degrees idle oil pressure is about 10psi, I believe this is correct and as to be expected. So I still get a warning all the time at idle, which at the minute is not too off putting.


Rob 😳

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the up changes are a lot quicker on your logs and these dont produce such a significant drop in oil pressure as the down changes


I would be tempted to go out on the road and once its all nice and hot try some verying speed up and down changes and then review the data again.


It looks to me like the drop in revs or the ignition cut on down change (?) is related to the pressure drop. The traces appaer to be in order on the up changes and under load on the straights, plus the pressure is unaffected by G force - some downchanges have low braking G force on your traces - like where you drop a few gears through the chicane .


Again straight line testing on the road up and down the box would rule out G force.


I would be interested to see these further traces.




Taffia rear gunner


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