Quote:
Originally Posted by parmas
I tuned my engine like FL_Rubicon mentioned here, the only difference is that I tune via ecu directly into the map not using knobs.
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And I do plan to send the adjustments I made along with the logs of them to my tuner to let him put it in the tune file. I will use that for day to day. When out on the granite rocks, I may still run a more conservative pure water tune.
Quote:
Originally Posted by Flr Power
You just proved me you don't fully understand tuning to MBT. You are basically telling us that you are tuning close to knock. The problem is that with WI and when you spray a lot, you can go past MBT and still have no engine knock.
That would put excessive stress on the engine without any audible or knock sign. The PCM or ECU would not know you have past MBT because it would not knock given enough effective octane increase brought by the WI...
The MBT is NOT determined by the PCM. It remains in open loop only to be modified by a few timing tables. For maximum engine performance and durability it is important not to exceed MBT and having the right timing tables set on the safe side of things. So yeah, sorry but I still consider yourself as a newbie based on your tuning strategy and explanations.
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Sure. Fair point. Then again, I am making no claims as to being an expert on the subject. Just that I am learning a lot about WI/WMI. I also feel that I am getting good results and that I am not in any danger zone.
This thread is completely off topic and I am on WM49 now anyway - not pure water. I found a local source for methanol that is not over priced so will start mixing my own (50/50 by weight).
While there may be excess stress being put on the engine, it is really not clear what actual harm will be caused here without registering detonation. I feel that I am sized correctly and not overspraying. I have gain set to zero (12 o'clock).
How many engines have you actually seen or heard of that failed as a result of not getting MBT correct where there was also no trace of detonation?
How does one determine the correct MBT? Are you able to do this yourself or enlighten those of us who are interested?
Do you have an ability to conduct a spark sweep process and can you possibly explain to the noobs how to do this without a dyno? That would be fantastic.
I have definitely heard of an engine fail a swift death by detonation when the stock tune was left in place after a supercharger install. It was ugly. Catastrophic failure, requiring a complete engine replacement. In that case, the person posted about hearing a can of marbles when he hit the throttle (boost). The engine was toast in something like 50 miles. Fortunately he paid a shop to do the install and the shop goofed by forgetting to load the tune so the new motor was on them.
Still - failure by messing up the MBT... Any actual cases? How does getting it wrong manifest itself short term? Lower HP? What about long term? Any documented cases?