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Discussion Starter #1 (Edited)
I spent all day trying to dial in the tune to get the most timing I can. No problems until I hit 21*. I'm on 91 octane, but I'm also spraying 250/cc 50/50 meth. Why can't I get past 21*? I've seen other setups where they are running 30* timing with meth. Is that just where it's going to be for 22psi? AFR's are right around 11:1.

Are my expectations just off? I'm under the impression I can run around 25*-30* with the meth. What does a BWS on 91 normally run for timing?

As far as I can tell, the engine is fine. Compression is 145 across the board and I put the PCV on a vented CC. Already replaced knock sensor and everything else I can think of.

I spent quite a bit of time reading up about fuels, detonation, plug gaps, EGTs, exhaust pulses, etc but so far I can't think of what I can do to improve the situation.
 

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Many many variables here and I'm sure tuners with more seat time than I will chime in.

With my set up I would consistently get 27.0/27.5* @ 5500 RPM

In my opinion, start with good fuel. I've had good luck with this product RACE GAS | Racing Fuel Concentrate

Good Luck!!!
 

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Discussion Starter #3
well fuel isn't a solution. I already use chevron 91 exclusively in all my vehicles.

I made this post in frustration, but today I figured out the issue which that I have a cracked exhaust manifold. So that's what the problem is. Already pulled it off, going to get it welded up and then I should be good to go.
 

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Discussion Starter #5
Well, I'm going to guess that it's because of this. It makes perfect sense based on the way the logs look. Installed a new one tonight, will button it up tomorrow and do some testing and report back.

 

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Discussion Starter #6
Well, no dice. Still knocks if I try to go over 21* timing so matter what I do. Doesn't seem to be as bad as it used to be, adding 6* timing results in a 3* STKR where as it used to be 2* would cause LTKR.

Anyone have any ideas at all?
 

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post a data log..

how about the basics,
try new coil and Plugs - NGK 4306, lztr5a-13 -- gap .040
pull the injectors pressurize and fire off each one.. make sure there is a good mist..
 

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Discussion Starter #8
I suppose it would be helpful to provide some info for you, right? :)

Log file: https://dl.dropboxusercontent.com/u/28298990/1B3AS66S15D216970_07.log

Here is what I've already tried

Only run cheveron 91 (or shell if I have to, never anything else)
NGK 1 step colder plugs, gapped 0.034 and 0.040
NGK 4306 gapped 0.034 and 0.040 (less than 500 miles on these plugs)
Boost leak tested
replaced the cracked manifold
exhaust leak checked
brand new valves, guides and seals
put the PCV on a vented catch can (was on a catch can with a check valve)
did several cleanings using mopar ccc
been running 50/50 meth for a few months now
coil was replaced less than 1 year ago
plug wires are less than 1 year old
added heat shielding where I could
injectors are less than a year old, but I'll give that test a try. I've been wondering how to test which cylinder(s) are knocking thinking maybe 1 or two of them are leaning out, but how could that be with meth?
replaced knock sensor

I know I've done more, just cant think of anything else.
 

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Discussion Starter #10

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Discussion Starter #12
Like I said in the other post, dump some race gas in it, turn off the Meth and see what happens then.
I've added octane booster before, it did help. That's why I've been trying to clean the pistons, run meth, etc. I was thinking it was crap on the pistons creating a hot spot.

Just about done with the leak down test, cylinders 1 and 2 look good, need to check 3 and 4.
 

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I've added octane booster before, it did help. That's why I've been trying to clean the pistons, run meth, etc. I was thinking it was crap on the pistons creating a hot spot.

Just about done with the leak down test, cylinders 1 and 2 look good, need to check 3 and 4.
The meth probably has cleaned the pistons already, it doesn't take much for the steam created by the water to do that.
Bro, put the race gas in and try it.:wink: Quit being so stubborn.
Even Stage 3 cars didn't like octane booster in HOM mode and would jump out of it because of knock.:wink:
 

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Discussion Starter #14
Here are the results. The compression test was the same on all cylinders and I let it pump 5 times each. Click the image for a big version, but as you can see, leak down was acceptable.

as far as race gas, I'll have to find a place to get some. I don't like running octane booster. I thought the pistons were clean, too. If you look in the plug hole, they look good, but i stuck my borescope in there and there is still some garbage. I was assuming that was the issue, and I guess I have to assume that's the issue still.

 

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If you look in the plug hole, they look good, but i stuck my borescope in there and there is still some garbage. I was assuming that was the issue, and I guess I have to assume that's the issue still.
No! The true tell is the spark plugs. Detonation shows up as shiny flecks or black/dark brown carbon flex on them. The shiny flecks are the worst ones as those are the aluminum from the pistons.:wink:
One man's garbage is another man's 'No Problem Man'.:smile: A bore scope is only usually used to check more catastrophic issues than you are worrying about. Combustion chambers are not the pretties things to begin with....................even on a perfect running engine.
 

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Discussion Starter #16
No! The true tell is the spark plugs. Detonation shows up as shiny flecks or black/dark brown carbon flex on them. The shiny flecks are the worst ones as those are the aluminum from the pistons.:wink:
One man's garbage is another man's 'No Problem Man'.:smile: A bore scope is only usually used to check more catastrophic issues than you are worrying about. Combustion chambers are not the pretties things to begin with....................even on a perfect running engine.
haha, spark plugs look brand new thanks to the meth. Before they had brown freckles and very tiny spots that "looked" metallic, but I wasn't able to get a magnifying glass good enough to examine it closely enough.

But, if the the crap on the pistons is causing a hot spot, that could cause it. But, you'd think that water alone would help that, it didn't. You'd think water and meth would help that, it didn't.

Let's say low octane is the cause. What exactly is the problem? Since this is detonation (happening after the spark), what is causing the knock? Too much heat causing too fast a burn rate? Not getting a complete burn, then the hot spot igniting the mixture again? But is so, with what air? If low octane is the issue, why doesn't meth help it out? I found some numbers on the interwebs that suggested 91 + meth = 114 octane. I don't know if that was 100% meth or whatever, but let's say that since everyone is suggesting 91 sucks and the best you can get is 93, would meth not bump that 91 to at least a 93 equivalent?

If it's heat, why does the water not help it? IAT's when spraying are always lower than ambient temps outside.

Could it be valve overlap some how that is allowing fresh air through the exhaust valve? I would suggest it's maybe an exhaust valve that isn't closing right and letting boost out, but the leak down test suggests that's not the case.

See where I'm going? I have no idea where to go next. Only theories which may or may not be valid.
 

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haha, spark plugs look brand new thanks to the meth. Before they had brown freckles and very tiny spots that "looked" metallic, but I wasn't able to get a magnifying glass good enough to examine it closely enough.

But, if the the crap on the pistons is causing a hot spot, that could cause it. But, you'd think that water alone would help that, it didn't. You'd think water and meth would help that, it didn't.

Let's say low octane is the cause. What exactly is the problem? Octane Rating is simply put resistance to detonation. Just becuase the pump says 89, 91, 93 whatever doesn't mean that it is always truly that and from what I understand CA and some States like to oxygenate their fuels this time of year.
Since this is detonation (happening after the spark)Actually what you are experiencing is PRE-Ignition - before sparkplug fires, what is causing the knock? Pre-ignition, fuel and air in the chamber burning too early from somewhere opposite to where the spark plug is located, then the sparkplug lights off milliseconds later what is left in the chamber. The 2 flame front collide and this is what you hear as "detonation".
Too much heat causing too fast a burn rate? Yes. Low octane possibly not being able to resist ignition of the mixture before it is supposed to by the sparkplug
Not getting a complete burn, then the hot spot igniting the mixture again? No, the mixture went off early mostly due to heat, hot spots happen because of the heat not create it
But is so, with what air? Well since it is pre-ignition, it has no air so this theory is not valid
If low octane is the issue, why doesn't meth help it out? Maybe your thinking is flawed, like trying to pee on a bonfire to put it out.;)
I found some numbers on the interwebs that suggested 91 + meth = 114 octane. I don't know if that was 100% meth or whatever, but let's say that since everyone is suggesting 91 sucks and the best you can get is 93, would meth not bump that 91 to at least a 93 equivalent? Stop reading too much on what you see on the internet, it cannot and doesn't apply in every situation. The race gas will tell you 100% if bad gas is your problem. Meth is a bandaid being applied in this situation trying to figure out and fix a root issue. RACE GAS WILL TELL YOU FOR SURE!

If it's heat, why does the water not help it? IAT's when spraying are always lower than ambient temps outside. Again- bandaid

Could it be valve overlap some how that is allowing fresh air through the exhaust valve? I would suggest it's maybe an exhaust valve that isn't closing right and letting boost out, but the leak down test suggests that's not the case. OCD and thinking too deep. I understand your frustration but dude Try the race gas!

See where I'm going? Not really because you are not listening to us!
I have no idea where to go next. We made suggestions of the Race Gas but you keep bringing up other things that until you try the Race Gas has no point in this troubleshooting now.
Only theories which may or may not be valid.Finally, I hope you realize you are going off on tangents that are frustrating you even more. And making people trying to help you give up and move on.:frown:
Sounds like you don't want to give up that what you are seeing on the pistons is the cause, so see my comments above. And Try The Race Gas!:wink: Then if that doesn't work you can start looking at other stuff.
 

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Discussion Starter #18
Sounds like you don't want to give up that what you are seeing on the pistons is the cause, so see my comments above. And Try The Race Gas!:wink: Then if that doesn't work you can start looking at other stuff.
ok, so race gas. Then what? If the problem is still there then it's mechanical, if not, it's combustion, correct? I've already been through this with the octane booster, it gets rid of the knock so I imagine the result will be the same with race gas. If it's combustion problem, then what would that problem be?

I'll go back and re-read your suggestion to make sure I'm understanding.

Don't think that I'm not listening, it's about all i can do at this point. and I appreciate any and all input, positive or negative. I do tend to go off on tangents, but I've found quite a few things this way :)

I disabled the meth and removed all my timing adjustments to see where my AFRs are. figured I'd start from the beginning. I got 4.5* STKR and 1.5 LTKR at 15*. That seems pretty bad to me.
 

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Discussion Starter #19


Ok, now that I've spent $100 on fuel. I see 0 knock with 21* timing at the top end. What does that tell us?
 

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To me and others can chime in if they want. The 91 octane you are getting is crap. Quick question at this point. What meth are you using? Mix your own or blue windshield washer fluid that says it is 50/50?
The meth could also not be up to what you think it is.
In this case the internet has many videos that tell you how to mix it and ways to check. Zeitronix comes to mind. ;)
 
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