6.0 E85 4psi boost, trouble with Knock Retard

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06-30-2020
peteruehle

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6.0 E85 4psi boost, trouble with Knock Retard

Hello, this is a new setup and the first time I have tuned a turbo or with E85. Setup is 1994 Mustang with 04 LQ9, stock block with 228/230 cam and springs, ls1 intake, decaped flex fuel injectors (flow tested) 78/75 cast turbo, E85, non intercooled, SD tune. I am fighting knock at idle, on decel and accel. I am only running 9 to 13 deg advance under boost and I am still getting KR with only 4psi of boost. I started with 13 of timing and backed if off where I was getting KR. I made a change to the burst knock setting but it didn't seem to help. I don't believe the exhaust is hitting anything to cause the KR. It will knock in park in the driveway.
In the scan attached I was using the spark control to test 11, 13, 15, 16 degrees of advance and the car really picked up power with timing but the knock has me concerned.
I am targeting .78 Lambda under boost and I am pretty close to that target. I am also having trouble getting PE to kick in before boost for some reason but I don't think that should affect knock under boost.
I would love to get your opinions to get this resolved.
Thanks in advance for any suggestions.
06-30-2020
RDF1

Wouldnt hurt to put some new knock sensors and a harness on it and see if it goes away?
You should be able to run 18* timing on 4psi with E85 easy.
06-30-2020
peteruehle

Quote:

Originally Posted by RDF1

Wouldnt hurt to put some new knock sensors and a harness on it and see if it goes away?
You should be able to run 18* timing on 4psi with E85 easy.

That could be worth a try, they are less expensive than I thought they would be. I did check and confirm it is not setting a code for the knock sensor.
06-30-2020
Frost

Quote:

Originally Posted by peteruehle

.... decaped flex fuel injectors ....

I'd throw those in the woods!
07-04-2020
pknowles

I'm also in the middle of tuning an LQ4 with a cast 78/75 turbo except I have a 212/218 cam and an intercooler. I'm finding that if I use too little timing, I see knock, but add two degrees and it goes away. I know it doesn't make sense, but it's what I'm seeing. I was initially running 12 degrees everywhere in boost to be super safe (first turbo), saw knock at low boost like you with ~50% Ethanol. Then made a more realistic timing table and knock went away. I'm using around 22 degrees at 100KPA, 20 degrees at 135 KPA, and 18 degrees at 150 KPA if that helps. I've had two days tuning this, so I'm using those as starting points. Not ideal, but a place to start.

Ditto on replacing knock sensors and don't forget the wiring harness as well. They are cheap and not hard to change. I changed mine a while back because the outside was all corroded and I was in there.
07-07-2020
peteruehle

Quote:

Originally Posted by Frost

I'd throw those in the woods!

I understand the reluctance to use decapped injectors but I flow tested them and verified the spray pattern myself. It took 16 of them to get a set of 8 that flowed well so if they were not flowed tested I would suspect them as well.
07-07-2020
peteruehle

Quote:

Originally Posted by pknowles

I'm also in the middle of tuning an LQ4 with a cast 78/75 turbo except I have a 212/218 cam and an intercooler. I'm finding that if I use too little timing, I see knock, but add two degrees and it goes away. I know it doesn't make sense, but it's what I'm seeing. I was initially running 12 degrees everywhere in boost to be super safe (first turbo), saw knock at low boost like you with ~50% Ethanol. Then made a more realistic timing table and knock went away. I'm using around 22 degrees at 100KPA, 20 degrees at 135 KPA, and 18 degrees at 150 KPA if that helps. I've had two days tuning this, so I'm using those as starting points. Not ideal, but a place to start.

Ditto on replacing knock sensors and don't forget the wiring harness as well. They are cheap and not hard to change. I changed mine a while back because the outside was all corroded and I was in there.

Thanks for the feedback, I will try adding timing to see if it helps. For now, I turned the knock sensor sensitivity down and set timing under boost to 14 deg. It ran so much better but my IAT was getting very high in this hot weather so I am going to add an intercooler before I do any more tuning.
07-07-2020
pknowles

Quote:

Originally Posted by peteruehle

Thanks for the feedback, I will try adding timing to see if it helps. For now, I turned the knock sensor sensitivity down and set timing under boost to 14 deg. It ran so much better but my IAT was getting very high in this hot weather so I am going to add an intercooler before I do any more tuning.

Curious, what temps were you seeing? It's hot and humid here in Maryland, but I was out tuning this past weekend. With my intercooler, I'm only seeing about 10 deg over ambient temps with 10 psi boost pressure. IAT's taken a foot before the throttle body and of course that doesn't count the E85 evaporative cooling in the intake track.
07-08-2020
peteruehle

Quote:

Originally Posted by pknowles

Curious, what temps were you seeing? It's hot and humid here in Maryland, but I was out tuning this past weekend. With my intercooler, I'm only seeing about 10 deg over ambient temps with 10 psi boost pressure. IAT's taken a foot before the throttle body and of course that doesn't count the E85 evaporative cooling in the intake track.

What intercooler are you running? I would love to only see a 10 deg increase.
Last scan it was ~ 90 deg out, boost was 7 PSI and IAT was 196 F, about 100 deg over ambient. I have the IAT in the ls1 intake where the EGR would normally go. My IATs keep going up after I am out of boost before they start coming back down. I never expected that much temp gain with that low of boost pressure. Ordered the air to air cooler the next day. I am planning to move the IAT to the intercooler outlet because of heat soak in the intake when the car is off. I'm hoping this will help with heat soak.
07-08-2020
pknowles

I have the trick turbo 3" inter cooler. I like that design because I didn't have to hack anything up or try to stuff pipes around the headlights, which are harder to fit with the big radiator. Some of the inter cooler is blocked by the front bumper, but it works. It's a thick heavy inter cooler, so some of the cooling simply comes from it's thermal mass. It was 92 degrees and humid on the way home tonight and I saw a max of 105 in low speed cruising, with the AC on. Once it crept up to 116 just after sitting at two long stop lights due to heat soak. My cold side piping goes all the way down to the core support and back up, so I get a lot of cooling through it as well.
07-08-2020
Frost

Quote:

Originally Posted by peteruehle

I understand the reluctance to use decapped injectors but I flow tested them and verified the spray pattern myself. It took 16 of them to get a set of 8 that flowed well so if they were not flowed tested I would suspect them as well.

There is no legit short-pulse or GM offset data for them. There's no argument you can make here. This is the boat that you are in: http://injectordynamics.com/articles...-and-dipshits/ I'm not saying they are the issue that you are chasing either to be clear..
07-09-2020
kingtal0n

Quote:

Originally Posted by peteruehle

What intercooler are you running? I would love to only see a 10 deg increase.
Last scan it was ~ 90 deg out, boost was 7 PSI and IAT was 196 F,

Sounds like you have a massive boost leak or need to relocate the IAT sensor

With the correct size intercooler the IAT should not rise much more than 10*F above ambient. Even on the hottest day in Florida, and Dyno Day (no airflow from driving the car on the highway to 130mph) I only saw 10*F above ambient with 16psi of boost. With straight 93 only

My iat is in the intake pipe just before the throttle body.

Also I've tuned around 100 other cars and see the same general trend. Whenever the IAT starts to spike its almost always a boost leak
07-16-2020
peteruehle

Quote:

Originally Posted by kingtal0n

Sounds like you have a massive boost leak or need to relocate the IAT sensor

With the correct size intercooler the IAT should not rise much more than 10*F above ambient. Even on the hottest day in Florida, and Dyno Day (no airflow from driving the car on the highway to 130mph) I only saw 10*F above ambient with 16psi of boost. With straight 93 only

My iat is in the intake pipe just before the throttle body.

Also I've tuned around 100 other cars and see the same general trend. Whenever the IAT starts to spike its almost always a boost leak

I didn't have ANY intercooler when I saw those temps, but I have one now that I need to install.
I don't have any leaks from the turbo to the throttle body, it only has about 1.5' to go. :D
07-16-2020
peteruehle

Quote:

Originally Posted by Frost

There is no legit short-pulse or GM offset data for them. There's no argument you can make here. This is the boat that you are in: http://injectordynamics.com/articles...-and-dipshits/ I'm not saying they are the issue that you are chasing either to be clear..

The decapped injectors were not my first choice, it sucks being on a budget.
07-16-2020
kingtal0n

Quote:

Originally Posted by peteruehle

I didn't have ANY intercooler when I saw those temps, but I have one now that I need to install.
I don't have any leaks from the turbo to the throttle body, it only has about 1.5' to go. :D

Ah. Well, intercoolers subtract some power. Any extra pipe length is going to put additional strain the compressor, more pressure drop over the length, demand more flow rate which adds exhaust gas pressure to the pre-turbine. The only reason we use intercoolers is because:
1. the fuel quality is insufficient for high IAT
2. The high pressure might damage a part (explode an intake manifold or something)

In other words, if you have a plastic intake for example, you want the pressure very low. So intercooling helps with that, you get some extra density and a lower temp.
Similarly if you are using gasoline, it will disagree with high IAT. So the temp drop is required.

but if you are using a metal intake/gaskets, Oring etc... along with superior fuel as E85 (alcohol style fuels) There is no need to intercool.

So basically if your fuel quality and engine parts are up to the challenge then there is no real harm in having high IAT and losing the intercooler. Some of the fastest 2000hp cars I can think of are non intercooled using 200*F inlet temps no issues. Alot of people think intercoolers add power because of the density increase but this is simply not true; they do increase air density but it comes at an energetic cost which is supplied through the compressor flow rate, since temp at the compressor discharge is the same, to get more mass you need more flow/time in terms of volume at the same temp which means higher impeller RPM.