30i Track Day Power Loss

[sjsstl]

I have been at 3 track days with 2 similar G29 30i's and both exhibit SIGNIFICANT power loss regularly during the session. Happens intermittently several times during most sessions including at the beginning so unlikely to be a heat issue and on straights as well as curves. The Sport Display shows the immediate loss of 50% or more power and torque but full power will always return seemingly instantly after 5-20 seconds or so. Shifting down or up does not help. I do not think it is fuel starvation since it happens all around a track and comes and goes nearly immediately.

Thanks in advance for any ideas, I am baffled and doubt a dealer would be of any help with this.

[B21]

Could be oil starvation ..many BMW engines cannot cope with race track G loadings as oil surges in sump losing oil pressure..

The DME if it senses that may try and protect the engine..

It’s definitely an issue with the N20 and N54…

[enuff_zed]

Could be oil starvation ..many BMW engines cannot cope with race track G loadings as oil surges in sump losing oil pressure..

The DME if it senses that may try and protect the engine..

It’s definitely an issue with the N20 and N54…

In which case, despite the OPs last sentence, he is NOT baffled.

[warmasice]

[john-e89]

Could be oil starvation ..many BMW engines cannot cope with race track G loadings as oil surges in sump losing oil pressure..

The DME if it senses that may try and protect the engine..

It’s definitely an issue with the N20 and N54…

OP says it happens on straights too so unlikely I'd say

[B21]

Could be oil starvation ..many BMW engines cannot cope with race track G loadings as oil surges in sump losing oil pressure..

The DME if it senses that may try and protect the engine..

It’s definitely an issue with the N20 and N54…

OP says it happens on straights too so unlikely I'd say

The issue is lag..on the N20 and N54 in the US where they are tracked often, the low pressure would come after the end of the curve and onto the straight..

As I said ‘it could be’ ..open to other ideas !

[john-e89]

Could be oil starvation ..many BMW engines cannot cope with race track G loadings as oil surges in sump losing oil pressure..

The DME if it senses that may try and protect the engine..

It’s definitely an issue with the N20 and N54…

OP says it happens on straights too so unlikely I'd say

The issue is lag..on the N20 and N54 in the US where they are tracked often, the low pressure would come after the end of the curve and onto the straight..

As I said ‘it could be’ ..open to other ideas !

Do you mean turbo lag..? wouldnt have any bearing on oil pressure. Oil starvation would be more commonly known with stock cars on track if it was a major issue Id think.

As I said, unlikely....open to other ideas.

[B21]

On the N54s and N20s oil pickup starvation is a common issue when exceeding 1G cornering..one of the reasons that you see very few raced as it’s very difficult for a successful baffle arrangement and not easy to dry sump them..

https://navardituned.com/products/bafflekit


The 30i engine is a derivative of the N20 FWIW..

[enuff_zed]

OP says it happens on straights too so unlikely I'd say

The issue is lag..on the N20 and N54 in the US where they are tracked often, the low pressure would come after the end of the curve and onto the straight..

As I said ‘it could be’ ..open to other ideas !

Do you mean turbo lag..? wouldnt have any bearing on oil pressure. Oil starvation would be more commonly known with stock cars on track if it was a major issue Id think.

As I said, unlikely....open to other ideas.

If you come out of a curve fast, then accelerate down a straight, all the oil that was over to one side in the curve will now slosh to the back.
After a second or two the oil that the pump has already picked up will have departed to the top end of the engine and the pump will suck air. Therefore, to me it makes sense that it could take a couple of seconds (a fair distance at track speeds) for the oil pressure drop to be sensed. Even then I suspect there is a very short inbuilt delay to allow for glitches in the system.
Then of course, on braking, the oil all sloshes to the front, or side maybe if it's a real novice still braking into the bend.
Depending where the oil pick-up is located, various different scenarios could starve the pump.
So to me, as a track day virgin, but with a fair degree of real world engineering understanding, it is acceptable that oil pressure drop could be the issue.
However, there are of course other issues that could cause this. I would rule out component failure though as this is reported to be exactly the same in more than one car.

[john-e89]

The issue is lag..on the N20 and N54 in the US where they are tracked often, the low pressure would come after the end of the curve and onto the straight..

As I said ‘it could be’ ..open to other ideas !

Do you mean turbo lag..? wouldnt have any bearing on oil pressure. Oil starvation would be more commonly known with stock cars on track if it was a major issue Id think.

As I said, unlikely....open to other ideas.

If you come out of a curve fast, then accelerate down a straight, all the oil that was over to one side in the curve will now slosh to the back.
After a second or two the oil that the pump has already picked up will have departed to the top end of the engine and the pump will suck air. Therefore, to me it makes sense that it could take a couple of seconds (a fair distance at track speeds) for the oil pressure drop to be sensed. Even then I suspect there is a very short inbuilt delay to allow for glitches in the system.
Then of course, on braking, the oil all sloshes to the front, or side maybe if it's a real novice still braking into the bend.
Depending where the oil pick-up is located, various different scenarios could starve the pump.
So to me, as a track day virgin, but with a fair degree of real world engineering understanding, it is acceptable that oil pressure drop could be the issue.
However, there are of course other issues that could cause this. I would rule out component failure though as this is reported to be exactly the same in more than one car.

What makes me disagree with that Enuff is manufacturers have to take into account scenarios of extremes, eg, Porlock hill in Devon is 1 in 4 in places, a modern engine has to be able to keep running with a car stationary on that hill either facing up or down with no oil starvation, usually to wait chuff knows how long for the dipstick towing a caravan that simply HAS prove it can be done to get up there instead of going round the long way-ask me how I know.... Of course on focussed and very quick track cars that's why they baffle or dry sump, but you can still take a standard car on a track day with no issues, as we know thousands do, so that's why i don't think it's oil related as we'd be seeing thousands of engines needing rebuilds yearly, I think modern engines are pretty well engineered in that area.

Could be completely wrong of course, just my thinking from my old mechanics days.

[enuff_zed]

John what you say also makes sense but given anecdotal evidence that other engines do suffer from this I was considering it to be a possibility.
Your hill theory is a sound one too.
Need to put oil in a glass jar, tilt it to 25 degrees and see where it goes up to. Then lay the jar flat and accelerate it and see if the oil moves further

I am trying to think what else could cause this power loss. Seems a given that the DME is doing it on purpose but why?

I just keep coming back to that oil theory.

Perhaps it factors in engine speed as well?

An engine drive pump at higher speeds is going to be much more prone to cavitation and therefore it could be that whilst some oil is still being picked up, it is a lesser volume and the pump is cavitating, hence a lower delivery pressure?

[Smartbear]

John what you say also makes sense but given anecdotal evidence that other engines do suffer from this I was considering it to be a possibility.
Your hill theory is a sound one too.
Need to put oil in a glass jar, tilt it to 25 degrees and see where it goes up to. Then lay the jar flat and accelerate it and see if the oil moves further

I am trying to think what else could cause this power loss. Seems a given that the DME is doing it on purpose but why?

I just keep coming back to that oil theory.

Perhaps it factors in engine speed as well?

An engine drive pump at higher speeds is going to be much more prone to cavitation and therefore it could be that whilst some oil is still being picked up, it is a lesser volume and the pump is cavitating, hence a lower delivery pressure?

Maybe the traction control is cutting the power if it’s being thrown around on a track?
Rob

[Smartbear]

The power on my z4 has also been considerably reduced recently (to zero) that’s for a different reason though

E2DCBD68-FD4A-4C91-84F5-09260CB1AE65.jpeg (139.35 KiB) Viewed 848 times

Rob

[enuff_zed]

The power on my z4 has also been considerably reduced recently (to zero) that’s for a different reason though
E2DCBD68-FD4A-4C91-84F5-09260CB1AE65.jpeg
Rob

Oh FFS!
That is awful Rob. Is it salvageable?
That's an electrical nightmare.
I feel for you.

[enuff_zed]

John what you say also makes sense but given anecdotal evidence that other engines do suffer from this I was considering it to be a possibility.
Your hill theory is a sound one too.
Need to put oil in a glass jar, tilt it to 25 degrees and see where it goes up to. Then lay the jar flat and accelerate it and see if the oil moves further

I am trying to think what else could cause this power loss. Seems a given that the DME is doing it on purpose but why?

I just keep coming back to that oil theory.

Perhaps it factors in engine speed as well?

An engine drive pump at higher speeds is going to be much more prone to cavitation and therefore it could be that whilst some oil is still being picked up, it is a lesser volume and the pump is cavitating, hence a lower delivery pressure?

Maybe the traction control is cutting the power if it’s being thrown around on a track?
Rob

Another possibility, but it's doing it even when you change up a gear, and in a straight line.