Getting 4-6deg KR, DBB 6466 on a forged stroker, Husek duel feed LU trans, DW 400 pump w/billet sender, E85 W/120lb inj, everything is hotwired including Inj harness and VB, with EBrown's BC it will go from 0psi to 25psi in 2 sec, thats where i'm getting KR but looking at PL the KR goes away a few frames later as FP rise's... so the question is can it be spooling faster than the pump can react?
Possible to spool too fast?
- Thread starter TTA308
- Start date
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- Nov 30, 2009
Mine spools twice as fast as that to 30psi with no knock , is the FP going 1 for 1 with the boost ?? Could be false knock . Did you try a 3rd gear pull and check for knock ? Tire spin can cause false knock also . Post up the PL file so we can check it out .
New stock mounts w/ rjc eng. brace, new RJC D/P that fits like a glove, the FP rise's 1-1 but looking at logs it's not fast enough, 18 frames per sec the KR happens in between , then corrects. Also have RJC FM, Axis extreme G chip and translator ...I am thinking its real KR since i raised the base FP to 45 the KR was reduced...
- Joined
- May 28, 2001
Any blips in the fp trace?
SCOOBY DOO
BASED CANADIAN PATRIOT!!
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- Feb 18, 2007
Post a PL log.
- Joined
- Nov 30, 2009
My base FP is at 49-50 psi , it seemed to run better with it higher . Nick Micale (Arizona GN) would set his E85 cars to 50psi base FP .
What is your injector duty cycle @ 25 psi ?
hensleyt
Well-Known Member
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- Feb 20, 2008
Is this at the1-2 shift? I like my RJC brace but I had to have it screwed tight against the frame to make my KR at 1-2 shift to go away. You can't drive it to the tack like that its got some weird hum or vibration. I have replaced the drivers side with a HR and loosened the brace to have about a 1/4 clearance. KR is gone.
What is you AFR at KR ? My AFR was plenty rich and my KR turned out to be false. Take a good look at the plugs when you get back to the pits. Its not the ideal way to read plugs but it will be a start.
What is you AFR at KR ? My AFR was plenty rich and my KR turned out to be false. Take a good look at the plugs when you get back to the pits. Its not the ideal way to read plugs but it will be a start.
Have not messed w/timing yet, I usually nail it from a roll but w/new DR'S set at 18psi it will blow them off at any speed..
Inj duty cycle around 73 at 25psi
Not that i can tell.
WB around 11.8, NB 784
Real busy w/work but will try to figure out how to post a log this wk.
The factory knock system is not very good, based on what I have gathered it essentially senses a sudden change in noise from a steady state condition. It is tuned to be most sensitive around 6k Hz (natural frequency due to bore diameter), but can be set off by a large enough change anywhere else in the frequency spectrum. You will likely have to go through a number of trouble shooting steps. The fact that you are only getting it when you roll into it may indicate false knock.
When you look at the PL logs, at the point the knock starts check your timing and AFR. If the AXIS has the ability to remove timing in that range pull it back, also make sure the AFR is good in that range, but I don't know the electronics and the sample rate is good/fast enough to narrow down such a specific point. You could really up the fueling, either through the axis, or with fuel pressure to see if it goes away.
One test will not be enough, you will have to hammer it in the trouble spot a few times to verify after changes.
If after altering the timing and fueling in the trouble spot, you can't make it go away, it is likely false knock.
Any source of noise that exceeds the threshold of detection will set off the sensor.
Piston slap, a noisy valve train, loose mounts, accessories/belt tensioner, exhaust or any engine part contacting the frame, a loud transmission, loose balancer, loose flex plate ....
When you look at the PL logs, at the point the knock starts check your timing and AFR. If the AXIS has the ability to remove timing in that range pull it back, also make sure the AFR is good in that range, but I don't know the electronics and the sample rate is good/fast enough to narrow down such a specific point. You could really up the fueling, either through the axis, or with fuel pressure to see if it goes away.
One test will not be enough, you will have to hammer it in the trouble spot a few times to verify after changes.
If after altering the timing and fueling in the trouble spot, you can't make it go away, it is likely false knock.
Any source of noise that exceeds the threshold of detection will set off the sensor.
Piston slap, a noisy valve train, loose mounts, accessories/belt tensioner, exhaust or any engine part contacting the frame, a loud transmission, loose balancer, loose flex plate ....
Dan SS2471
Active Member
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- Dec 12, 2008
Is that duty cycle in line with the HP you're making?
- Joined
- May 28, 2001
Knock sensor properly torqued?
No.
With a good fuel system and no drivetrain issues setting off the knock sensor it's possible to spool alot faster and have 0 kr.
Either it rises 1to1 or it doesn't
If you have a lazy fuel system look at the easier things.
Perhaps try a different regulator or test the one you have.
With a dw400 that is pushing all it has around 50psi then tapers down.
Could be a weak or bad pump.
Test the fuel system and measure flow.
If you were 1to1 with a healthy fuel system I would say something is hitting triggering the knock sensor I would look in the downpipe area 1st.
Since the fuel system is not reacting properly need to find out why.
The motor doesnt make alot of power where you are boost wise and that pump if its working right is flowing all it has right in your kr area.
What size return line is on the fuel system?
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- Nov 30, 2009
I was thinking that it is a little lean compared to mine which was at 10.8 : 1 .... zero knock with similar motor setup .
His kr is on the transition and I dont like high11s on e85 either.
Dan SS2471
Active Member
- Joined
- Dec 12, 2008
What do BLMs look like during the Kr and overall? What's the target A/F?