[Tom Vaught]

Fatigue failures will happen on any part if it runs enough cycles. No matter how good the part is.

So how many cycles would an expert (like you on this subject) assume before a GOOD connecting rod failure for example? Post up a number

Tom V.

[Formulas]

Tom in the engineering world what exactly constitutes a cycle?

Is it when any give part sees 90-100% of rated load? Something like that is what iam after

.

[TAQuest]

Originally Posted by Formulas

Tom in the engineering world what exactly constitutes a cycle?

Is it when any give part sees 90-100% of rated load? Something like that is what iam after

.

Even if it's less than a cycle there still would be cumulative metal fatigue.

Cycles are just a way to try and quantify it.

[TCSGTO]

Just caught the newest episode where they rescue a 71 T-37 with a 1970 400/4barrel that hadn’t run since the 80’s from a scrap yard in Idaho and road trip it to The Snake River canyon.
Frieburger even said it was the best rescue car they ever had. Very Pontiac friendly show. They even have a HEMI cut down at the end.

[Formulas]

I would like to make a prediction

The flawed Pontiac engine will be here longer than Friedbugger and his show

.

[unruhjonny]

Originally Posted by TCSGTO

Just caught the newest episode where they rescue a 71 T-37 with a 1970 400/4barrel that hadn’t run since the 80’s from a scrap yard in Idaho and road trip it to The Snake River canyon.
Frieburger even said it was the best rescue car they ever had. Very Pontiac friendly show. They even have a HEMI cut down at the end.

ok... I'll look up this episode - thanks for the "heads up"!

[PunchT37]

Is Pontiac the only one with a "design flaw"? There are a lot of engines with design flaws. What defines a design flaw? Not being able to handle over a certain hp?

I can name a few blocks that are risky above about 500 hp. Ford small block. They have a closed lifter valley for the most part. Iv`e seen many cracked from the front to the rear lifter valley after being beat on. Ford Cleveland? Weak cyl. walls. At one time, I believe no one made a 060 over forged piston for them. Same for the Chrysler 340.

I`m sure other blocks have "design flaws" too. Like oiling systems. Buick comes to mind. They did last and performed like the engineers` stated purpose. So, what is a design flaw and is Pontiac the only trash engine?

[Formulas]

The chevy 348 / 409 wasn't a grand slam

[Skip Fix]

Originally Posted by Formulas

The chevy 348 / 409 wasn't a grand slam

Hey now!

[SRR]

Given a choice between a set of conn. rods out of Grandma's 350 or a 455 you know had the crap kicked out of it which ones would you rather use if you insist on using factory cast rods?

[Tom Vaught]

For the engineering durability testing we were doing, (test to the point of failure), we would run the following cycle, (I have posted this in the past).

Some slight variations depending on what we were looking at.

1) Fire the engine up after checking the oil level and the dyno water tower for proper coolant at the correct level.

2) Warm up the engine for 15 minutes at a idle condition. Check for any audible issues as well as monitor the Dyno Operator computer read-outs on the multiple screen displays. If all is good go to step #3.

3) Bring the engine up to the Maximum Torque Point (after determining that point on the specific engine). Run the engine there for 6 hours of steady state running.
Say the number is 4200 rpm. These are smaller engines for the most part.

4) Bring the engine back down to idle rpm for 15 minutes. Listen for issues.
Shut off the engine. Walk into the Dyno Cell and inspect all of the components on the engine visually. Look for water, oil, and fuel leaks.

Typically shift change by then. Afternoon Dyno Guy comes on and gets a briefing on where we are in the testing sequence.

Afternoon Dyno Guy moves to the next step in the sequence. Say it is the Max Torque PLUS 10% higher rpm point.

He repeats the steps above except he does it at the 10% higher rpm point.
Still the engine runs at that point for 6 hours, unless there is an issue.

Morning Dyno guy talks to the Engineer and reads the info from the Afternoon Guys testing. He does not talk to a Midnight Dyno Operator unless it is a Hot Program and we run 24 hours in the day. So Days and Afternoon testing.

The Afternoon Guy comes in, does the same steps again, except he runs 6 hours of Max HP for the engine once he identifies that point for the specific engine.

Day Shift guy comes in and repeats the steps above except now he runs 6 hours of Max HP at a now identified rpm point PLUS 10 PERCENT MORE RPM ADDED.
Obviously the HP point may remain close to the Max HP rpm point or drop with the additional engine rpm. Each engine is different based on the components.
Boosted engines seem to carry the rpm more evenly across the rpm points.

So now you have had 5 Engine Modes on the Dyno:
Idle Rpm, Max Torque Point, Max Torque Point plus 10% additional rpm, Max HP Point, and Max HP Point plus 10% rpm. That is one cycle. Hope that helps.

We have a similar test which is called a 300 HR FIE test. Both of these are ENGINE DYNO TESTS

Some years ago Ford di a little Advertising to prove out the durability of the 3.5L ECOBOOST engine. Videos were made.

Several Marketing Videos were made.
Pull logs up a Logging Camp Trail.
Run the Baja 1000 race.
Pull two vehicles on a single trailer for 24 hours on a NASCAR Track, and then do a tear-down on the same engine which was used in each of the videos.

Not what we did at all. Marketing is different from Test to Failure Dyno Testing.

Marketing Video links are on the web if you look for them.
An example https://news.pickuptrucks.com/2011/0...ooks-like.html

Your question was what is a cycle of testing. We have run engines 2800 hours on the dyno before failure.

Hope I answered that question for you. (usually the poor connecting rods would finally take out the engine.)

Tom V.

[Formulas]

Tom. .. Was looking for a simpler answer really and maybe there is none


No car parts no running assemblies take a length of rod simple steel say 4 inch long let's say you put tension on it and it elongates and breaks at 10,000 lbs after you establish that,

Let's say at 8,000 lbs there is no permanent elongation call that a max working load ?
Iam sure if you take it repeatedly to 7,999 lbs each time that would be a fatigue cycle

Now in the extreme other direction you put 10 grams of pull on it is that a cycle? I wouldn't think so.

At which point in applying force could you chalk it up as a cycle?


.

[ta man]

The thing I like about Frieburger is much of his chatter is what most car guys would say ..Anybody that has watched the Drag Week feed will get to see his true love for everything that has wheels and the people involved. At times I'd like to slap him in the head or say cheers bud!

[Tom Vaught]

A cycle is a period of load testing at a given test condition (in my example).

A combustion cycle would be TWO rod cycles: Intake and compression on one rod cycle and combustion and exhaust on the second rod cycle. Depending on the rpm these cycles change in duration vs the time (a minute) involved. (If I have my wording correct now).

The people from the University of Toledo (Toledo, Ohio) do a nice job of explaining it here. What things we are looking for.

https://pdfs.semanticscholar.org/1ab...93b59eb742.pdf

Tom V.

You can have all kinds of computer analysis performed but at some point you need to verify that the models are correct vs actual dyno testing.

[Douglas Willinger]

How many people encountered a Pontiac V-8 with broken lifter bosses, prior to encountering Pontiac's style, etc.?

[Tom Vaught]

Originally Posted by Douglas Willinger

How many people encountered a Pontiac V-8 with broken lifter bosses, prior to encountering Pontiac's style, etc.?

If I understand your question correctly, I started playing with Pontiacs in 1965.

I first encountered a Broken Lifter Boss with Jim Brady, (a former Pontiac 64 GTO Racer) when he decided to get aggressive on the camshaft .200 lift vs duration specs on his Roller Camshaft.

Prior to that he had a Roy McKenny selected Comp Cams profile and the engine made great power with durability.
He put this other camshaft in at the recommendation of one of the Tech Guys and broke the lifter boss off the block shortly after the installation.

He got another block and had the Butler Lifter Bore "Plates" brazed into the block. No more issues after that work was done. Different Camshaft and lifter profile though. LOL!

Tom V.

[Sirrotica]

When I worked at the local Pontiac dealer in 1970 there was a RA IV block in the warranty pile that had a broken lifter bore in it. What I don't know is if the bore broke out with the hydraulic camshaft in it, or if it had the cam changed before the bore broke out of the block, and then they put the OEM cam and lifters back in to get it warrantied.

The guy that changed the fitted block out said it had the factory cam in it when it came in on the hook.

They had already put a sledge hammer through the water jacket, so it was completely scrap when I saw it. For anyone that isn't familiar with GM warranty, all warranty engines at that time were smacked with a sledge hammer while the factory rep was present to make certain the engine couldn't be used or sold after GM paid the warranty claim on it. In that case it was redundant with the lifter bore broken already.

Since seeing that lifter bore broken I have never seen another one broken, even though I used a solid roller cam in a few of my own engines without any bracing. Two 400s and a 455. The advertised spec on the cam was 320 degrees, by .525 lift, surely a mild cam by todays standards, but when I bought it used I was told the engine it came out of was a 60s era FED. I have no idea if there was any truth to that, or not. The 320 degrees advertised duration put the power band way up there, and it came with a rev kit.

Later I had it re-ground by Crower, somewhere in the 280 degree range, where it was much more streetable, especially behind a T400 with 4.33 gears. The first car it was in with 320 degrees of duration was a 65 GTO, 4 speed with a 3.90 axle. It would run 6500 no problem, until a keeper split and dropped a valve.

[64speed]

Originally Posted by Sirrotica

When I worked at the local Pontiac dealer in 1970 there was a RA IV block in the warranty pile that had a broken lifter bore in it. What I don't know is if the bore broke out with the hydraulic camshaft in it, or if it had the cam changed before the bore broke out of the block, and then they put the OEM cam and lifters back in to get it warrantied.

The guy that changed the fitted block out said it had the factory cam in it when it came in on the hook.

They had already put a sledge hammer through the water jacket, so it was completely scrap when I saw it. For anyone that isn't familiar with GM warranty, all warranty engines at that time were smacked with a sledge hammer while the factory rep was present to make certain the engine couldn't be used or sold after GM paid the warranty claim on it. In that case it was redundant with the lifter bore broken already.

Since seeing that lifter bore broken I have never seen another one broken, even though I used a solid roller cam in a few of my own engines without any bracing. Two 400s and a 455. The advertised spec on the cam was 320 degrees, by .525 lift, surely a mild cam by todays standards, but when I bought it used I was told the engine it came out of was a 60s era FED. I have no idea if there was any truth to that, or not. The 320 degrees advertised duration put the power band way up there, and it came with a rev kit.

Later I had it re-ground by Crower, somewhere in the 280 degree range, where it was much more streetable, especially behind a T400 with 4.33 gears. The first car it was in with 320 degrees of duration was a 65 GTO, 4 speed with a 3.90 axle. It would run 6500 no problem, until a keeper split and dropped a valve.

Yeah I know that block wasn’t salvageable but I know all about “destroy in store” from my days working at auto zone and advance Auto Parts in my teenage years. Took home a lot of “destroyed” items LOL

[djustice]

Just saw the T-37 episode myself, they actually put more effort into this one, put a timingligth to it and after a failed Quadrajet rebuild they put a new edelbrock carb on.
More than can be said for the roadkill garage boneville that just got hauled straigth on the road without fixing the motor mount (it did eventually get over complicated zip-tied to the crossmember motormount bolt holes lol)

[tom s]

Since 1962 I have ever broken a lifter bore BUT never ran a cam with 200 duration at 200 lift or more.Tom