The part I quoted.

Never mind then.

Stewart

 

Well then ok, that's been mine.

 

Got WOT results back from tuner.

Fueling was good....so I guess my second compression #S are ok. Tune is done, with good power increases.

So all I have now is a knock I have to figure out. May retune after I figure out knock, as it may be affecting spark.

Side note: it was 75 degrees out when I did my WOT pull. Intake temps during pull were thru the roof...260 ish degrees F. Kenne Bell should have never done this.
I cannot imagine towing in 90 degree weather like this....intake temps approaching exhaust temps.

I am looking into a water meth system...should not need it with a 6 psi system but it is what it is.

 

Wonder if it's my ram horn y pipe?

https://www.ford-trucks.com/forums/1...g-problem.html

Not sure how I would test this senerio.

 

Whereabouts is the IAT sensor located for the 6.8? I have no idea as I don't have one

A restrictive exhaust can contribute to higher IAT numbers, but only if the sensor is close enough to the actual runners of the intake manifold. You can sledgehammer air in all day long under boost, but with a stock cam grind you're only going to be able to get so much exhaust gas out per RPM. Eventually you can theoretically build up enough un-exhausted combustion gasses that they'll revert through the intake manifold and sully the incoming charge, but again - stock cam grind and boost. I could really only see this being an issue if the IAT sensor is RIGHT there on the manifold runners.

Other issues just come with the nature of forced induction. Yes, you're slamming way more air in, but you're doing it through a stock system. The act of compressing the air charge creates a buttload of heat in the charge itself, which is why intercoolers are so beneficial. I don't remember the manifold design on modular's being phenomenal, but it's not horrible either.

For sure the knock is due to the ridiculous IAT it's operating at under WOT conditions, but whether it's preignition or detonation is uncertain... Detonation is from spontaneous combustion due to excessive cylinder pressures and temperatures, whereas preignition is the fuel/air mix igniting before the spark plug due to carbon deposits retaining a ton of heat and basically glow-plugging the mixture, incorrect spark plug heat range, etc... I'd personally lean more towards detonation due to those IAT's you're experiencing.

Regarding posting videos, you can upload to YouTube for free. Once it's uploaded, look underneath the 'screen' the video plays on. You'll see a little arrow with 'Share' next to it (arrow looks like the forward option on most mobile email). Just copy and paste that link, the forum coding should insert the video thumbnail automatically if you copy the right code.

 

Thanks for info.

The oem IAT sensor is integrated with the MAF.
I used a Ford Lightning MAF that has a seperate IAT sensor. I put that sensor in the manifold after supercharger.

Knock is during free rev....no boost. I don't know if it's really knocking during boost...I don't hear anything. Logs show knock though. Going to put in a water meth system to help with IATs.

The Kenne Bell manifold adapter is horrible. There is a 1" tall by 6" wide passageway the boost has to flow thru to get to the oem intake.

PCM was retarding spark ALOT during high IAT. -4.7 something!!!!!

I will try to post u tube video. Thanks.

 

I'm assuming you're going to plumb the spray system into the plenum adapter between the supercharger's compressor body and the OEM manifold?

There has to be an actual solution for combating EGT's without a system that needs constant replenishing.... How are the IAT's during normal driving? I can see it being a longer-term fix on a temp or WOT switch, assuming your normal IAT's are in the safe range...

 

Normal driving IAT is about 130 to 150 in 75 degree weather.

Maybe my cat is not working causing high IAT and some knock.

Have no clue how to test that, other than a test pipe.

 

Sorry I have no advice or anything helpful to add, just a question. How is there no boost during a free rev, with the roots type blower isn't it pumping the same amount of air at a given RPM whether under load or not?
Those are some crazy high IATs!

 

The/most twin screw roots have spring loaded bypass valves as mine does. Valve is held open with vacuum and at about 0 in hg it shuts forcing all air thru twin screw.

Mine even has a valet mode where I can lock valve open so it will not boost at all. So others can't hot rod it.

Just removed all belts to make sure it was not a pulley.

No help still knocks....vacuum in v10 actually turned SC a little when I reved motor with no belts on.

 

Interesting, thanks for explaining that for me.

 

Here is video

 

To me over that video it doesn't really sound like a bottom-end knock. Have you tried using a stethoscope or even a broom handle against the oil pan to see if it's originating from there?

How's the valve train? Lifters and rocker arms are all in good condition? That sounds quite similar to when I had a weak valve spring and the valve was bouncing like hell against the seat. Too much boost can overpower a spring and keep it from closing when it's supposed to. It'll hammer down and bounce whenever it gets the chance.

Bad lifter can cause the push rod to jitter around in the rocker cup as well. It seems to rapid and not pronounced enough to be rod knock...

I haven't followed this entire thread closely so if I'm covering stuff you've already replaced, I apologize.

 

No lifters per say...lash adjusters and no push rods.

When I took valve cover off the #1 intake lash adjuster was not fully up. I lifted the follower up and the plunger in the lash adjuster came up about 1/8". It stayed up after that and I could not push it down.

Ran it with valve cover off and did not seem like noise was in valve train. Valve springs "looked" ok but that's not saying much.

Stethoscope kinda locates knock above water pump on valley ridge. Ran with no belts and knock seems louder...probably cause no fan, alternator or blower running.

I'm hoping exhaust related, but I will be pulling pan to check rods.

 

Lash adjusters, close enough

Was this happening before the swap or is it only post swap? Have you ruled out the injector entirely? I know you mentioned swapping two different ones and it was the same, but disappeared when unplugged. Could there in any way be a bad code in the tune or a harness/plug issue?

Watch this be something ridiculous like excess piston rock due to a bad wrist pin.