i just blew my rear rotor while not even totally hammering on it. i was under 5500rpms, about 6-7psi, in 3rd gear just kinda punched it. then i let off and discovered i cracked a seal on the rear rotor. i was watching the AEM wideband during this, and it was pegged on "rich" (sub 11.0:1) and right before i let off it was around 11.2-11.4:1

as far as timing, i'm running 18* at 10psi with a 9-10 degree split cause i figured i'd run a little safe until i could pay for the services of a REAL tuner (since obviously i'm lacking in that department)

now what i'm thinking is, obviously i'm not going to see any crazy preignition or detonation with low intake temps, safe timing, and sub-11.0:1 AFRs... could i have had a mismatched pulley this whole time and not known it?

 

what were the intake temps when this happened? Do you have your air temp ignition correction dialed in to back off the timing a bunch when its hot?

 

intake temps were between 90-100*F so nothing crazy.

and yes i believe i have it docking a degree of timing for every 5 *F after 100*. is that adequate?

 

EGT?


-Ted

 

ditto, per-rotor EGT's would help alot in determining the cause.

e.g. maybe your rear rotor injector isn't doing as well as the front?

 

i'm going to swap out my injectors... also last night i discovered that my air nipple on my aeromotive FPR wasnt even finger tight so my fuel pressure might not have been rising as much as it should....

and yeah, i wish i had had an EGT gauge to verify any kind of ignition problem... but i ran the stock turbo for a couple weeks and it ran awesome, so i figured the timing was safe and nothing to worry about. know what i mean? or maybe the stock turbo wasnt making enough power to make it a problem if it was just slightly off..

 

may have been reading rich as the motor was detonating. ignition sounds high for pump gas. I am assuming this is what you are using. The rolling on of the power in a tall gear puts a large load on the engine and the spike in power may have caused the detonation. Or the apez seal could have broken from the excessive load. EGT may have shown the detonation but likely when you loaded the engine it just broke. How old is the engine? new rebuild with Haltech or was it a tired old street engine? I have seen people do this same thing by hammering the throttle in to high a gear and not downshifting. the load on the engine just breaks something. good luck and be careful.

 

well, the engine had recently been rebuilt and broken in by me and had about 1200 miles on it. right after break-in i was running the stock turbo and it ran awesome.

you say 18* and a 9 degree split is agressive on pumpgas (93) and 10psi?

 

My Steve Kan tuned ignition map has 19* advance and 11* split at around 10 psi. 94 Octane.

 

what kind of intake temps do you see at 10psi, and how much timing is getting pulled out at those temps?

 

If your engine runs the atkins apex seals, I think that's the cause since I have seen 3 atkins apex seals engine let go pre-maturely with low mileage recently.

 

Ask, and ye shall receive. Attached is a datalog.

My map does not pull any timing until AIT's go above 50C (122F)