Tig welding 4047 on block
- Thread starter shushikiary
- Start date
E85 is much harder to ignite than gasoline (and thus it's detonation resistance), so I'd agree that these are likely non ignition events and not knock that the ECU is detecting. Maybe it's detecting the fuel igniting in the exhaust/turbo instead? Though you'd think that would make a nice crackle pop you'd hear.
I bet it likely has something to do with the method they are using to detect the frequencies used for knock from voltages made by the piezo electric knock sensors.
I bet it likely has something to do with the method they are using to detect the frequencies used for knock from voltages made by the piezo electric knock sensors.
I wish I knew. I even get confused by timing pulls vs actual knock pulls. Why would it (DME) pull timing even on a stock tune ? Because its trying to avoid knock is what I have read, BUT why or how does it detect pre knock if it doesn't actually knock
Its mostly due to the fact that there's a large piece of aluminum in the block now. Doc vu and some others had a big thread about it on how closed deck motors false knock a ton more on the stock dme just due to the fact that this is an open deck motor from the factory. Some other people's preference is so re sleeve the motor instead of closing the deck to help with the tuning of the motor on the stock dme. Both options make big power one is just harder to tune on stock dme
I think you quoted the wrong post, we were talking about why on a stock motor there seem to be so many false knock events even with E85.
People have been having issues with the false knock on closed deck motors since all the way back in 2012 and even earlier when Terry (at BMS) had one and put some resistors to quiet down the knock sensors.
It makes sense given that the knock sensors are looking at frequency response and you completely changed the resonance frequency of the block by adding the closed deck piece as well as changing the "impedance" of the block, which then makes the transmission and reflection coefficients change. The transmission coefficient gets larger and thus you transmit more energy at each frequency from the cylinder bore to the edge of the block and so you see a larger voltage for the same event at the knock sensor, so it totally makes sense that you get false knock given the stock tables.
People have been having issues with the false knock on closed deck motors since all the way back in 2012 and even earlier when Terry (at BMS) had one and put some resistors to quiet down the knock sensors.
It makes sense given that the knock sensors are looking at frequency response and you completely changed the resonance frequency of the block by adding the closed deck piece as well as changing the "impedance" of the block, which then makes the transmission and reflection coefficients change. The transmission coefficient gets larger and thus you transmit more energy at each frequency from the cylinder bore to the edge of the block and so you see a larger voltage for the same event at the knock sensor, so it totally makes sense that you get false knock given the stock tables.
Put 2x 100k pots in series, one each knock senseor, set to 50khm (half their range). Super knocking gone, no more timing reductions and she sounds/feels good, so very likely false knock.
Link to the latest log: https://datazap.me/u/shushikiary/po...7-28-29-30&solo=14-16-24-29&mark=80-104-56-47
Just needs a little work at high RPM to keep boost up, but holding 23 psi to redline on a built head at altitude isn't bad.
I'm going to shoot an email to Garret to get their suggested max RPM for the turbo just out of curiosity.
Link to the latest log: https://datazap.me/u/shushikiary/po...7-28-29-30&solo=14-16-24-29&mark=80-104-56-47
Just needs a little work at high RPM to keep boost up, but holding 23 psi to redline on a built head at altitude isn't bad.
I'm going to shoot an email to Garret to get their suggested max RPM for the turbo just out of curiosity.
Frequency should be a function of bore diameter. Closing the deck might increase amplitude.
I haven't followed the topic closely but why are the physical signals being altered when the tables can be adjusted in the dme, while listening for knock on the dyno?
Just like how one would love to think that changing the material in an antenna would not change the frequency and it should totally depend solely of the shape of the antenna our wonderful assumptions that those things are all friendly and linear is a dream. Because the speed of propagation of the waves changes with the material, the frequency does as well, so even adding the closed deck will indeed change the frequency, though by a much smaller amount than bore diameter would change it.
The table (singular) we have is not enough. There are several other tables we'd need to find as Jake (other Jake) has talked about that we don't have, which is why the single table alone that we have is not enough. This is why both Terry and Jake have said that they have not been able to fix the false knock issue without modifying the sensors.
The table (singular) we have is not enough. There are several other tables we'd need to find as Jake (other Jake) has talked about that we don't have, which is why the single table alone that we have is not enough. This is why both Terry and Jake have said that they have not been able to fix the false knock issue without modifying the sensors.
5000 mile update.
Engine seems to be doing fine. She's quite noisy at cold start up and at idle. You can really hear the valve train, but it seems to be holding up. Not sure if that's because of the upgraded springs, closed deck transmitting more sound, or what, but it does sound nice.
The head gasket coolant leak comes and goes, it goes through maybe 20ml of coolant a week because of it.
Other than that, zero issues so far. Super knock is gone with desensitized tables and pots. Been driving it a lot recently because even at 12mpg in city it's way cheaper to drive on E85 than any of my other vehicles.
Engine seems to be doing fine. She's quite noisy at cold start up and at idle. You can really hear the valve train, but it seems to be holding up. Not sure if that's because of the upgraded springs, closed deck transmitting more sound, or what, but it does sound nice.
The head gasket coolant leak comes and goes, it goes through maybe 20ml of coolant a week because of it.
Other than that, zero issues so far. Super knock is gone with desensitized tables and pots. Been driving it a lot recently because even at 12mpg in city it's way cheaper to drive on E85 than any of my other vehicles.
Well remember I'm at altitude, ambient here is about 12.2 psi.
Boost pressure is usually 25.5 in the mid range and tapers down to 24 or so at redline.
Boost pressure is usually 25.5 in the mid range and tapers down to 24 or so at redline.
Yea you just wire them in series with the knock sensors, so I found the wires on the ECU harness that the knock sensors are on an just cut them and then soldered them in.
Well my X clutch is on its way out... won't hold under peak boost anymore it just chatters.... violently, and the engage point is much higher than it was before (in pedal travel). Clutch made it about 20k miles, but it's the 6 puck ceramic so I didn't expect it to have a super long life. All of its life has been under at least upgraded hybrids (VTT GC lites, then 2 sets of VTT GC+, then this setup), so it's had a rough life.
Given the X clutches are on back order for several months I'll throw a Motiv ST in there and see how it does.
Given the X clutches are on back order for several months I'll throw a Motiv ST in there and see how it does.
I sold my Motiv to go with XClutch. YMMV ... I've heard great stories and not so great ones ... and so a tough read.
Yeah I'm currently having some issues with my spec I don't think any clutches are without flaws
Well the motiv ST is doing well, its engagement is a little more chattery but at the same time more forgiving than the x clutch, much lower engagement point.
JB weld is doing well, thankfully where that hole is doesn't seem to have a lot of stress on it, got lucky in that I think.
I threw a cast VTT valve cover on it when I assembled everything. It's seeping through the porous casting even with the black crinkle on it and the coating they put on the inside to help. I got a can of glyptal and will eventually paint the entire inside of the valve cover with it to make it stop as that's what all the old hot rod guys used to do for their cast aluminum valve covers.
JB weld is doing well, thankfully where that hole is doesn't seem to have a lot of stress on it, got lucky in that I think.
I threw a cast VTT valve cover on it when I assembled everything. It's seeping through the porous casting even with the black crinkle on it and the coating they put on the inside to help. I got a can of glyptal and will eventually paint the entire inside of the valve cover with it to make it stop as that's what all the old hot rod guys used to do for their cast aluminum valve covers.
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