Contour Enthusiasts Group Archives Forums General Troubleshooting what I found in my old SVT motor-

look here for a grand suprise- DOH!

Was that an oil starvation death ??

Sorry to hear about it ....

definatly-
but in a catastrophic way - I mean 4 of the 6 bearings- thats just weak rods- there is no other way to put it- youll notice that everyone that tunes up duratecs ditches the POS powdered rods in favor of steel ones- none of this would happen if it werent for the rods-
the oil starvation is a problem but an even BIGGER problem are the rods- they get out of shape on the bottom end because of their make up and go oval instead of round- this bites the bearings and spins them - oil is a problem - but conrods are THE PROBLEM!

So I guess anyone going for a Turbo is going to have to budget for forged conrods & pistons then !!

BTW .... does the Noble M12 version of the Duratec use forged internals ??

Originally posted by Horse:

---

they get out of shape on the bottom end because of their make up and go oval instead of round

---

First that I have ever heard of this. They use sintered rods in the 4.6/5.4/6.8L modular engines as well. Pre-2003 cobras used sintered rods. Can you elaborate on how you determined that they go out of round in service?

really easy- first of all the Cobra R ditched the powdered rods in favor of forged Manley rods because they knew the rods were junk. the Noble M12 GTO uses steel rods- also the its new M12 GTO 3R uses the 3L with the same turbo setup for 400 hp.

The connecting rods made of sintered metal are made from powdered metal forged together- sintered metal is notoriously weak. they are made in one piece and then the big rod end is broken so that it can be used around the crank without using a modular crank- which is VERY expensive and not as strong as a forging. when you get machined sintered metal around its large crank bearing that has been broken to split it around the crank, it is very weak. (remember we are talking in relative terms here) Forged steel for instance is a large quantity of either molten steel or an ingot of some type- which is then forged (smashed) into shape- the density and strength charictaristics of forgings are amazing! Sintered metal is a step above a casting but a step below a true forging.

when the rods are weak in their large end they will tend to "mutate" from a round bearing surface to an oval one. (again this is relative- mabey a few hundred thou) this change in shape does not allow the metal bearings to function correctly. for those who dont know the bearings are called a Plain Metal Bearing- or depending on the makeup they can be called Tri-Metal bearings. they are about 1/16 inch thick - almost like a metal shim- and when the big rod end ovals it bites the bearings- and spins them- this creates many many problems- if youll refere to my other post- youll see which bearing did what-

When I say the rod bites the bearing you must understand that the con-rod has two grooves and it does indeed hold the two bearing halves in place- they are stationary in the rod and the crank bearing surfaces rotate within the rod end- so when the rod end bites the bearings it presses them into the crank which actually spins the bearings- and the two little teeth that sit in the rod end grooves get wiped off by the rod - then there is nothing to stop the bearings from free spinning within the rod end, where they either get chewed up by the rod end or the crank. (or in my case two welded themselves to the crank journals and one chewed up a rod end, and one set got so chewed up they spun into each other spoon style, and continued to get eaten away.

Originally posted by Horse:

---

thats just weak rods- there is no other way to put it- youll notice that everyone that tunes up duratecs ditches the POS powdered rods in favor of steel ones- none of this would happen if it werent for the rods-

---

That's not proof in the least!

3 years of road racing at 8000rpm & ~260HP.
Numerous S/C SVT's at 270+ FWHP for ~ 2 years and 30k miles.
My car at ~250HP & 7500rpm dayly thrashed on.
Same rods in all the Jag motors, Mustangs, etc.

I strongly beg to differ as do those examples

Your examples are really worthless for comparison. Custom engines MADE for boost or Hi-Po race only.

BTW - crank whip accounts for the bearing damage you describe. The Duratec is known for bad crank whip. DMD anyone. Also once you badly damage even one and lose oil pressure the rest can go in a hurry.

Originally posted by Horse:

---

without using a modular crank- which is VERY expensive and not as strong as a forging.

---

A modular crank..what the heck is that? Maybe you mean nodular iron (i.e. cast iron cranks) Which are CHEAPER and not as strong as forged. You do know that all Duratec cranks are forged?

Originally posted by Horse:

---

"mutate" from a round bearing surface to an oval one. (again this is relative- mabey a few hundred thou)

---

Are you sure you know what you're taking about here? Total cylindricity spec of the big end of the Duratec rod is 10 microns (0.0004"). That's a lot smaller than a few hundred thousandths. Do you have any measurments of rods with out-of-round big ends to back up your claim?

well guys- what do I say here-
I KNOW what im talking about-
I dont hypothesize about things- unless I know what im talking about I dont say anything- (more than I can say for a few poeple I know)

just because a particular type of connecting rod is used in a lot of applications doesnt mean its a good design- for heavens sake seat belts wernt in cars untill Volvo came up with the idea- so should we all take them out of our cars?

and as far as "nodular" I suppose you are referring for nodular cast iron- not at all what I am refering to- I said modular- you know made in pieces- many many race cars and a few street cars used modular cranks- this allowed them to use either needle or ball bearings inplace of common of plain metal bearings in the journals of both rods and mains.

I think a few people here could benefit from reading a little book:

Carrol Smiths "...to win" series. if you have read and understand these let me know then we can talk on an intellegent level- also on the concentricity thing- HA I can change the concentricity of the big end of a rod journal by thousanths with a torch. so what do we think happens to an engine with a spun bearing- well its lower end gets a wee bit toasty- ehem ehem oh and BTW yes I do have the con rods of the engine- but no you cant measure concentricity once they have been stressed and removed from the engine very accuratly- so any measurment I would take would be flawed.


like I said - and have said, and will probobly have to say many more times- unless I know what Im talking about I dont opine- id ask you to do the same.

well off to take pics of the stuff to sell on ebay

You describe 4 spun bearings..it sounds pretty impressive that the rods were not in peices..

Did you have a DMD on that engine..it really SOUNDS like crank whip beat the crap out of things.