Quote:
Originally Posted by Richard L
I am trying to clarify between knock threshold and MBT.
Tuning these days, knock threshold arrives much early before reaching MBT, it appears that no one are too concerned about MBT. I wonder if it matters or not whether if MBT is the main aim anymore?
The general road car tuning strategy seemed to be accepted as follows:
Run as much boost until the flow linit of the turbo is reached, dumping as much fuel as possible until egt is below 900C. Wind on as much ignition retard as possible until knock disappears.
I was wondering if this common method can be improved? with or without water injection.
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I was hoping for an answer to this question. I run J&S safeguard on two heavily modified engines, one a Cosworth YB and one a Porsche 930, 3.5L twin plug both with stand alone ECUs (Performance Electronics PE3's).
I can therefore say I know quite confidently when these motors are running close to or at the knock limit. Now, I have not dynoed these cars to see if I am beyond the MBT and might actually benefit from reducing timing, but in my experience, most heavily boosted cars I have had were knock limited in terms of power delivery. I have ordered water injection kits of both cars, and was going over my 'strategy' for tuning with it. Initial thoughts were just like Richard mentioned above....essentially run timing up higher, and maybe set AFRs at 12 to 12.5, watching EGTs and keep a few degrees away from knock on my water injection timing maps. Would you guys agree? Obviously, I should probably get them on a dyno, but I probably wont get round to it.