Andrew, I don't have any data on the rate of increase, as it's simply too hard to capture. All I can do is note the start and end temps on a zero-to-whatever WOT run, either time or distance. If I had a second person who could watch the gauge and write down data during the run that might work, but I don't have the free time at the moment. At ~100mph it's up to approx 1300F with the fuel delivery increased 0.5 turns.
About peak temps, you should read my post here: http://buymbparts.com/forum/showthread.php?t=395 What I'd add to that is I would be comfortable running up to 1300F but I would probably back off at 1350F, and I'd prefer under 1300F for extended periods. Even without WI or IC, I almost never see anything close to these numbers in normal driving. About the boost controller, I think that may be overengineering things a little. There's no advantage to extra boost with a cooler engine, etc. I make the same power with 12psi that I make with 17psi and so far I can't see ANY advantage to running higher boost pressure than is needed to make peak power. It would just increase backpressure pre-turbo and subsequently increase EGT's. Now if we're talking about replacing the stock turbo with something different, that's another story (and much more complicated.) What I *would* be interested in some type of thermocouple safety switch, that would kill the ALDA signal line if EGT's exceeded 1400F or so. That would be nice for a little peace of mind on a 'tweaked' motor. On a side note, it's my current belief/theory that Mercedes installed the overboost circuit NOT because the pump can deliver more fuel than needed for factory power specs (it can't), but because if the wastegate jams closed and boost goes to 18+psi, the EGT's could get beyond safe levels and cause damage. I'm not sure Marshall would agree, and I don't have any proof at the moment, but it's something to kick around in the ol' noggin. Note that later (1990+?) OM60x engines deleted this circuit but I think they simply had other computer controls doing the same thing, just in a different way. :-) Best regards, Dave M. Boise, ID > ---------------------------------------------------------------------- > Date: Fri, 8 Jul 2005 20:38:28 -0400 > From: Andrew Cunningham <[EMAIL PROTECTED]> > Subject: Re: [MBZ] Turned up fuel on OM603, sans IC or WI > > Dave, > > I was looking for the rate of increase during the run not just the end > points. Within a typical (current config no WI) 0-100mph run how many > seconds does it take to get to 900, 1000, 1100, 1200 ack 1300? > > The other thing that I was wondering was how long (seconds/minutes?) > would you be confortable running at 1200F? If you could run WOT for a > minute, what would you consider your max temp? > > The reason why I am asking is I am designing a boost controller with > an EGT Type-K feedback. This would allow more useable boost (maybe > 16psi+) earlier when the engine is cooler and slowly reduce (down to > maybe 10-11 as needed) the boost to prevent EGTs from going too high. > You keep the pedal to the metal, as temps increase the boost drops > which also reduces exhaust back pressure. I have a few complete > designs that I am considering. > > I am at the beginning design stage of an injection pump controller > that adjusts the pressure signal to the ALDA. The basic concept is to > adjust the fuel delivery based on the intake temperature and pressure. > I don't have all the pieces or figured out how it will all connect > yet, but I am learning how to program a microcontroller to handle the > adjustment. > > Charge density should be proportional to the absolute pressure / > absolute temperature. Typical charge density is around 0.05 psia / K > with no turbo and maybe up to 0.10 psia / K with an intercooler. > NOTE: the EGR must be disabled for this to calculation to determine > how much air you have to burn. > > At a given charge density, there should be an ALDA pressure that > corresponds to a near perfect match for the fuel. This way, when you > floor it you will have exactly the fuel you can use based on how much > air you have to burn. The trick will be to use a 10 point calibration > curve from no turbo all the way up to full boost. > > One thing that I haven't confirmed yet is: > On a given 617 injection pump, the pump squirt/rev is independant on > the actual rpm. i.e. if the throttle position and ALDA pressure is > the same at 1000 rpm as 4000 rpm, will each rev of the engine will > inject the same amount of fuel? > > Anyone know if that is the case? > > Thanks, > Andy
