I agree with BradH and AndyF (good company to keep) and have one thing to add: Most of the discussion of "will it knock" or "does it knock" are based on hearing the knocking.

At higher engine speeds at wide open throttle the engine is making so much noise that one cannot discern the knock. If we were to use knock sensors as the only method to tell whether or not the engine was knocking, people might have a completely different understanding of how and why and when knock occurs.

Over the years there have been several posts with pictures of destroyed parts with the evidence from bearing markings clearly pointing to detonation as the cause. Yet, the empirical data is reported as "the engine wasn't knocking". That's because with a big cam below the torque peak enough cylinder pressure bled off to avoid knock. After the torque peak when ram tuning starts to have an effect, knock occurs but isn't noticed.

R.

Lookie here at whats screwed into the side of the block behind the motor mount.
Look at the factory cap milled down with a strap across it. Notice the factory forged crank, and stock block.
How much power do you believe it could have made, for how many passes and heavy road use over years and years? Could this run on pump gas with the right cam? I wonder why most people on here can break a block at 600 hp when I reliably made over 1000?

Thanks, haven't seen that done in centuries.
Is the strap pre-loaded to anticipate ovalling under severe stress? I've seen references to .002" pre-load applied to the center span using shims, or a large fine thread jacking screw in the center of the strap. Fuel bikes used to hold the entire engine down by jacking against the frame above it.

The knock frequency (cycles per second) of actual combustion-related pressure spikes is definitely different from valve lash clatter, valve head ringing, chain roller, skirt slap, etc. and there are commercially available sensors in different frequencies to make sure retard is not triggered by something else. IDK how to determine the best for any specific engine, but probably many large V8s will be similar.

No preload just flat. My intention was to keep the crank in the block if I had a cap failure. Never an issue with the caps. Bearings were inspected and replaced every 2 years.

The Ecu was electromotive. Now a very archaic system, they were ahead of their time when I was using it. ( not without problems)
I could get reliable knock signatures up to around 4500 rpm. Ecu could not log fast enough for any reliable data beyond that.
That engine had 5 different cams in it. Different combos of cams/ lash / pressure ratios, made huge differences with what I could get away with. This is with real data, from spending my own money on my own car. I always believed that it was mainly due to exhaust contamination... willing to reconsider that theory, but not abandon it completely.

I have a friend with a dyno set up for aircraft engines. Can’t get into what he does, but he has in-cylinder high speed transducers for setting timing curves at “lean of peak” on lyco engs. Very neat to be able to visualize knock coming in. These are very expensive spark plugs!
The sensors are some of the fastest reacting, yet still are only accurate at lowere engine speeds(fine for prop aircraft engines)

Trendz where did you drill/tap for the knock sensor?

Depending upon who you ask, that opinion might get you on somebody's hate list.

Just used the water drain hole. The theaded portion of the sensor is only a mount, there is no pass through. As long as the sensor is touching the material you are trying to listen to, it will work. Sort of like putting your ear to a screwdiver that is in contact with something noisy.

Brad, if you are referring to me, I assure you you are not on my hate list! Much respect for anyones opinion here. Nobody is ever 100% right or wrong.

Timing is everything...

Kevin

YOU MILLED DOWN THE FACTORY CAP AND PUT A METAL STRAP ACROSS IT

Shame on you for thinking out of the box and posting that modification on Moparts


Nice mods

It’s refreshing to see different modifications other than what’s typically seen here

dynamic cr will make, or break a combo. it's true. [/i]calculating[/i] it accurately is just about impossible, and i suspect, therein lies the crux of your grievance. 10 engine builders will give you 10 different sets of parameters for accurately measuring it. sorry, but it's actually super important.

Totally agree !! These are the first steps I take to figure out hhow the engine will react..a hell of a good picture at least !

Alot of good info posted but also as posted I think its just another factor in a whole mixed bag of factors in the total build.

Ive always tried to pick the minds of the racers who are currently/actively racing and winning at it. B cause they be doing somting right.

We started doing that in the early 80-s with our SS pulling tractor 466/6 blocks they have the bottom end design just like a BB mopar.

We machined all flush with a hint off the pan rail and ran an 1 inch thick al plate with long long bolts to absorb some of the shock.

The spark plug transducers definitely have accuracy issues at higher engine speeds. There are also transducers available that are designed to be installed in specially machined cylinder heads, those are accurate at higher rpm than the spark plug versions. It's really awesome technology, but it's usually into the hundreds of thousands of dollars range to get an engine set up with it.

https://www.kistler.com/en/applications/...essure-testing/

https://www.avl.com/-/all-in-one-indicating-systems

The aluminum straps were left .002" proud for some squish. J.Rob

Very nice JRob but I wouldn’t use those springs with that rocker

We use AVL's systems when we do long tern duration and endurance engine testing. for both aerospace and auto manufactures.
Amazing tech,

anybody recall seeing the pictures of flat head fords with the straps across the main caps?

I don't buy in to it, if you asked a Nascar or Pro Stock engine builder if they looked in to it, the answer would be no.

There was a discussion regarding it on one of the Racing Engine discussion groups on Facebook about the very subject recently, it was an interesting read.

Something interesting to me is static compression ratio and efficiency.

Prostock engines aren't much more than 14:1 static, since they fill the cylinder so well. VS normal stuff that will make more power at 16.5 static because they can't get enough in the chamber.

Here's another company that sells cylinder pressure testing equipment that is used with race engines. http://www.tfxengine.com/index.html

Click on the graph of the pressure chart to see more details of what is measured.