Cracked rear iron... I think

[Sephitrask]

The cause was prolly Big turbo on stock jdm import swap. Chances are it could use a rebuild even without the crack..

[Rotary Evolution]

probably would have been a good idea, the 3 piece 2mm cast iron seals just look for a reason to take out a rotor and housing so this may actually be cheaper than the alternative.

BUT

without reinforcing the block i find that they break irons with less trouble after having been rebuilt recently. the mating surfaces are usually etched together and more difficult to twist on older engines.

[ElTeeFauci]

Haven't found anything yet... won't tear the engine down until I get to monterey.

My afrs we're at 11.x all the way to the whopping 13 lbs of boost I'm running... I can attach a log I took after it happened... before I realized anything was wrong.

[ElTeeFauci]

Not really a big turbo... just a bnr stage 2.

[ElTeeFauci]

here is a sample datalog, and the ignition and fuel maps I've been using.

Using 550/720 injectors, all freshly rebuilt. walbro 255 fuel pump... haven't had any fuel issues to date.

[ElTeeFauci]

I just noticed that I had tooth #1 set to 5 deg BTDC, would that essentially advance my entire table by 5 degrees? Would that be enough to cause detonation given the ignition map I posted above?

[Rotary Evolution]

you mean to the right mark on the pulley? that would be 5*ATDC so your figures would be 5* higher than actual

[ElTeeFauci]

These were the settings at the time of the uh, mishap.

[Rotary Evolution]

i have never messed with a megasquirt, so i would ask someone who has setup the trigger the proper setting. but i would also verify it by setting it to 0 and 5*ATDC if allowable and see where the timing mark goes on the hub(advances or retards).

[ElTeeFauci]

Originally Posted by Rotary Evolution

i have never messed with a megasquirt, so i would ask someone who has setup the trigger the proper setting. but i would also verify it by setting it to 0 and 5*ATDC if allowable and see where the timing mark goes on the hub(advances or retards).

DIYAutoTune's writeup says its supposed to be at 0 degrees.

[Rotary Evolution]

well i say that because if the CAS is timed to the leading mark on the pulley and if the CAS trigger is advanced 10*(standard is 5ATDC/20ATDC for the markings on the engine) then your timing tables will be into the 22BTDC range under full load, which is rather aggressive for pump gas, a bit too aggressive if you ask me without a knock detection device.

but that assumes it is advanced 10 degrees with the correction factor you're using, if the CAS wasn't retimed to adjust for this correction. all this should be verified with a timing light.

[ElTeeFauci]

well, I sourced another JDM S5 TII, and will be picking it up on Sunday. I'll make sure that the base timing is done properly this time. If that timing map is pretty solid, this should be really easy to pick up where I left off.

[Rotary Evolution]

looks fine but that seam where the timing is halved is pretty rough, like someone overly concerned wrote it. all changes should merge into one another versus stepped like that.

same goes for fuel, don't just start dumping fuel once you see positive pressure.

[ElTeeFauci]

That would be Aaroncake that made the timing map. The fuel one was tuned by VEAnalyzeLive (auto-tune based on desired AFRs).

Something that crossed my mind last night was the fuel cut... it was set to come on at 7400 RPM. I dont know why its set up like that... but shouldn't I be cutting spark? It SEEMS a little more safe...

[RETed]

Originally Posted by ElTeeFauci

here is a sample datalog, and the ignition and fuel maps I've been using.

Using 550/720 injectors, all freshly rebuilt. walbro 255 fuel pump... haven't had any fuel issues to date.

Your fuel injectors are too small.
You only have enough fuel injector capacity to handle about 270 - 280hp, if everything was tuned nicely.
By your datalog, your tune is still all over the place.

Look at the max pulsewidth - 89.4%.
As a rule of thumb, you're not supposed to go past 85%.
Anything over 85% will possibly lock up the fuel injector - basically > 85% is the same as 90%...95%...100%.
You ran out of fuel capacity.
This could be one reason why the engine let go.

Don't bother with the older S4 (rear) irons.
I've broken them on a customer's FC @ 320hp on a Dynapack dyno.
Replaced with an S5 (rear) iron, and it's doing 400+ reliably daily driver.


-Ted