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During cruise on the highway you can run as lean as 18.2:1afr on a stock 928 with spark blow out.
So long as you are not going up a hill you are fine.
I have run my car for years with a lean burn at highway speeds, the only downside is higher emissions.
There are many new cars which do this too and have a special catalytic converter to reduce the emissions created when lean burning.
Under moderate throttle I target 13.1:1 and at WOT I target 12.5 for NA, and 12-12.2 for a boosted car.
During cruise on the highway you can run as lean as 18.2:1afr on a stock 928 with spark blow out.
So long as you are not going up a hill you are fine.
I have run my car for years with a lean burn at highway speeds, the only downside is higher emissions.
There are many new cars which do this too and have a special catalytic converter to reduce the emissions created when lean burning.
Under moderate throttle I target 13.1:1 and at WOT I target 12.5 for NA, and 12-12.2 for a boosted car.
It would be nice to do that . Probably get near 30mpg
If only someone would invent a system for the 928 that would allow you to switch to whatever fueling map you wanted, while you were driving. That would be pretty cool!
If only someone would invent a system for the 928 that would allow you to switch to whatever fueling map you wanted, while you were driving. That would be pretty cool!
just a switch and a dial to lean out while on the freeway would be great. lean out to 18:1 just before misfiring, and then get 30mpg! (and make all sorts of pollution! )
If only someone would invent a system for the 928 that would allow you to switch to whatever fueling map you wanted, while you were driving. That would be pretty cool!
Well ****... I just wen to pick up the car to do the fueling this weekend and whatnot, and the friggen Accuump is leaking! About a Qt of oil in the cowl and all over the floor. It's definitely from from the tank. Not sure if it's end caps, pressure relief valve or something else.
Originally Posted by Rob Edwards
If only someone would invent a system for the 928 that would allow you to switch to whatever fueling map you wanted, while you were driving. That would be pretty cool!
Well ****... I just wen to pick up the car to do the fueling this weekend and whatnot, and the friggen Accuump is leaking! About a Qt of oil in the cowl and all over the floor. It's definitely from from the tank. Not sure if it's end caps, pressure relief valve or something else.
I fear this on my own track car. ESPECIALLY after just plunking down close to $200 for three gallons of AMSOIL. Which is why I've decided not to hook up the Accusump until after I've got the engine running. Hope its an easy fix.
Originally Posted by GregBBRD View Post
I've got some experience with this....
16 to 1 is only going to work on trailing throttle and perhaps in very low load for very short distances.
Engine damage will occur attempting to maintain freeway speeds on level ground.
interesting that lycoming would disagree with you entirely. point is moot, in that it would be hard to get a car to tune at 16:1 anyway, but in actuality, it wouldnt ping there. just be low on power.. very low! in fact, calculated egts and chts would be the same if the car was running at 8:1. you see greg, as you go lean, the temp goes down substantially, right up until you start to miss. as does the power too, so the entire discussion is just that..... a discussion.
I think the difference is at cruising altitude load is tremendously diminished ( flaps and wind resistance due to altitude) so they could save fuel for long distance runs....
If only someone would invent a system for the 928 that would allow you to switch to whatever fueling map you wanted, while you were driving. That would be pretty cool!
_______
the lynx g 4 brain in the gts will allow 5 different fuel maps...
I fear this on my own track car. ESPECIALLY after just plunking down close to $200 for three gallons of AMSOIL. Which is why I've decided not to hook up the Accusump until after I've got the engine running. Hope its an easy fix.
It's the o-ring on the oil side. Will send in to have them re-build and test. Thought about doing it myself, but there is a lot of internet chatter about clamping it wring when removing the end-cap and having to replace the whole thing.
$200 for 3 gallons? I jsut bought 4 for $165 directly from them. Still not cheap, but sounds like you got hosed.
If only someone would invent a system for the 928 that would allow you to switch to whatever fueling map you wanted, while you were driving. That would be pretty cool!
You can do that with a higher end Motec or Pectel Ecu.......
OK boys... Things are still not fixed. The car is still too lean for WOT operation. Here's what I've done.
* I replaced the FPR with the 87. FP at the rail at idle is ~48 PSI.
* I (open-air) calibrated the Innovate Wide-band.
* I tested the WOT Switch at the LH, at it clearly is working.
I took this video so you can see what's happening. After I shout this, I tried the stock chips as I was thinking that maybe the stock chips would cause it to run pig-rich with the higher fuel pressure, but it didn't - it ran almost exactly the same... maybe a tad better at WOT.
Hey I was just looking at the engine, and it occurred to me that these don't necessarily look like 19 pound injectors. What do 24 pound injectors look like?
09-11-2015, 03:00 PM
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About a Qt of oil in the cowl and all over the floor. It's definitely from from the tank. Not sure if it's end caps, pressure relief valve or something else.
