Turbo LQ4 - Which Cylinder Knocks First?
 

Hey All,

I'm new to the site, but I've been lurking for a little while. After reading and gathering some information for a couple months, I'm part way through an eBay build on a 2000 Silverado 2500.

BUT.

I'm taking a slightly different approach than others with their eBay builds.

Instead of throwing the typical list of parts at a bone stock LQ4 and 4L80E, I'm focusing more on the data acquisition side of things instead of spending a bunch on the hardware. I've set myself up with a wideband lambda sensor, egt probe, exhaust pressure sensor, and intake runner TMAP on each cylinder in order to understand how each cylinder is performing. I also was able to purchase some sweet new Kistler equipment off of eBay, so I will be installing a cylinder pressure transducer into one of the cylinders (along with a shaft encoder) to measure the indicated work for that individual cylinder. I can go into the reasoning or science/thermodynamics if anyone would like me to, but I really need to figure out which cylinder to put the pressure transducer in.

I'd like to put the sensor in the cylinder that most people have had detonate in the past. If you all could weigh in on the cylinders that you have seen knock or had piston ring land failures, I'd appreciate it!

Thanks,

Cal

Cylinders 7 and 5 are the most prone to failure if that tells you anything.

The rear cylinders normally run the hottest, so 7/8 but it's truly hard to say which one it could happen the most on.

Stock pistons could break on any of them if there was enough knock and anytime I've logged for knock on all cylinders it's still partly of guess for the computer because there is only 2 knock sensors and they are in the valley of the engine.

Should be neat to see what data you can get with what you are doing though.

I always heard 7 on ls

Thanks for the replies everyone. I'll be putting the transducer in #7 based on this input.

I'm planning to make much of the information I collect available on this site. Hopefully it will shed some light on what's actually happening inside the LS cylinder and how specific modifications change combustion characteristics. I'll start up a different thread about the combustion side of things once I get some spare 317 heads in house and start machine work.

-Cal

If you're local to the twin cities maybe I'll even see it driving around once this frigid winter air goes away.

I'm in Roseau for the next 6 months, but after that I'll be local to the Forest Lake area. Shoot me a message if you ever want to meet up

Since you made your decision, I am changing this from a cylinder poll to a "guess what you are planning" contest. I will be the first contestant. Based on the sensors that you have accumulated, I am guessing that you are planning a revolutionary new intake manifold. Otherwise you would have eight oxygen sensors and eight pressure transducers. If the reason that you are using only one pressure transducer is the machine work involved, and not the need for an eight channel amplifier, have you considered these sparking plug cylinder pressure transducers?