The '2 ton bugswatter' - back for a gentle stroke

[JP]

Another bay picy just cropped up on fbook

[JP]

@quattro84 Weĺl rod ratio was/still is 1.667 could shift wot anywhere I wanted to without issues at wot other than 3rd to 4th 5800-6200rpm which would cause the rpm drop to sit it around 4k on 4th. Without logs unfortunately there is no other info and we can only draw conclusions.
As said been playing with engines for many a year professionally never had it happen before diesel or petrol. So taken this as a knock on the chin and a learning curve.
Like mentioned before also getting into the mapping side of it purely for personal education purposes to have a greater understanding of what goes on real time using the 125channel logging facilities of the maxxecu.

[quattro84]

I cannot believe this is the result of BMEP only. BMEP = torque so a diesel engine would have to be redesigned drastically in order to whitstand this phenomenon described by you. Diesels run 25% higher IMEP without any issues!

For comparison An EVO X on E85 with stock block (about same rod angles, 16mm bearings, High silicon Al cracking pistons, simple head studs, tiny wrist pins) can take up to 750Nm at 2500rpm with no problem for many hours without issues, calculate what that relates to in terms of cylinder pressure. I give it a guess at around 15MPa (150bars) while a diesel in same league needs steel pistons and chrome pins to uphold 22.5MPa.

[newsh]

This is interesting (and must have been very frustrating)

I wonder, hypothetically, would it be possible for an engine to be running more advance than you think? Say if the hall sensor was mounted wrongly? Although then the flywheel pin would have to be wrong by a similar amount, right?

[JP]

Whoops repost

[prj]

What is so special about this engine? What makes it behave differently than any other internal combustion engines? Hammering out big ends with over advancing is common thing, it happens.

It is not "overadvanced". It is knock limited at that RPM and it keeps making more torque with adding timing. So how is it "overadvanced"? Also, we are not running E85 here, remember? FYI, it was just 12 deg of timing at that point.
You are constantly assuming that the timing was advanced past MBT, but you could not be more wrong.

Nothing is achieved by pulling timing at that RPM except making high exhaust temps - the boost needs to go down and be ramped towards redline, as the engine is physically can not take this amount of torque at said rpm.

I think dry sump would solve the issue, but this is just my opinion.

[AndyP]

or you never measured it?

[JariP]

No preignition there, it's not E85.

Hindsight is a beautiful thing though. Of course now the timing or the boost can be dropped. But it takes some effort in finding out what the problem is.

How many exact engines like these exist in the world?

What is so special about this engine? What makes it behave differently than any other internal combustion engines? Hammering out big ends with over advancing is common thing, it happens.

[kamuto]

He is not saying as his experience is part of how he makes a living.

simple question requires simple answer, not 50 words of nothing

[andy10v]

you just don't want to say it or you never measured it?

He is not saying as his experience is part of how he makes a living.

[kamuto]

Same as we always do for high revving strokers (towards the loose side without disclosing trade specs), oil pressure of 1.5bar at idle 3bar at 2000rpm 5.7bar at 4000rpm etc.

you just don't want to say it or you never measured it?

[JP]

Anyway having learned something new last year on a much happier note the car is back out and did it's first car meet outing at the ace cafe last night in over 2 yrs.

And found this rather juicy pic of the bay on fbook :-)

[JP]

what bearing oil clearance you were running?

Same as we always do for high revving strokers (towards the loose side without disclosing trade specs), oil pressure of 1.5bar at idle 3bar at 2000rpm 5.7bar at 4000rpm etc.

[kamuto]

what bearing oil clearance you were running?

[Rocco]

Conclusion is, shift up always to redline

Interesting thread JP, we learn always from the mistakes