roller lifters with 2.8

[Purple pit]

Been waiting a long time for an update. If you are still out there here is one more thing to read.

http://www.epi-eng.com/piston_engine_technology/crankshaft_torsional_absorbers.htm

http://www.epi-eng.com/piston_engine_technology/piston_motion_basics.htm

[88corsica5spd28]

Increases dwell time at TDC so the piston doesn't outrun the flame front.

[caffeine]

Yes I meant 3.1 sized pistons not go back to stock. The shorter compression height would allow a longer rod to be used. I've also read that a longer rod reduces piston speed around TDC allowing for more complete combustion.

[ForcedFirebird]

The longer the rod, the better suited it is for high RPM due to side loading.

[1988GTU]

I would guess that the op would rather have shorter rods for the rpm's it is spinning at?

I don't even want to know how much he has invested in H beam rods and forged pistons but I think right now going back to a stock rod and piston is not a wise choice. And from what I can gather on Ben's website, the 2.8 to the 3400 rod is all the same length at 5.7" They just changed the piston to account for the extra stroke on the 3.1 cranks.

Exactly, 2.8, 3.1, 3100, 3.4 and 3400 all use the same 5.7" long rod.

[3400-95-Modified]

I don't even want to know how much he has invested in H beam rods and forged pistons but I think right now going back to a stock rod and piston is not a wise choice. And from what I can gather on Ben's website, the 2.8 to the 3400 rod is all the same length at 5.7" They just changed the piston to account for the extra stroke on the 3.1 cranks.

[caffeine]

My friend just had an interesting suggestion. Use 3.1 pistons with longer rods to get the longest rod possible in there. Similar to what GM did when they put longer rods in the 3500 vs 3400 which have the same stroke.

[Purple pit]

Damn.....need to get my head on straight. Must be a loose screw somewhere.

[caffeine]

All 2.8s even the older externally balanced ones have neutral balance harmonic dampeners from the factory.

[Purple pit]

Not sure, but I think what David did here could be helpful. The main info is on post #69. There may be other things in the topic too.

http://60degreev6.com/forum/showthread.php/51281-Iron-head-2-8MPFI-Turbo-Install-85-Celebrity/page7

From what little I know you must use a netural(or zero) balance damper for the new crank. I'd say one like that from ATI would be just fine. At this point I'd sure like to know what they use in NASCAR and Le Mans.
Looking at the GTE-AM classes may be the thing to do for Le Mans.

A new thread for a new build sounds like a good idea, just post a link to the new thread in this one when you do, and vise versa.

Sometimes oiling problems can show up on only one a or a couple journals. I'd have to map out the oil system but it's possible that the #2 main gets less oil or is delayed getting oil and that may starve that particular journal for oil. There's no question it got hot from friction, why there was a lack of oil to that journal is what needs to be determined.

[veekuusi]

Might I recommend creating a new thread for the new build? Feel free to link this one at the beginning of the new, but with as long as this one is getting, I feel it would be better to split the 2 builds up.

Hey thats a good idea.
If everybody agrees, I creat a new thread for the new build.
There are 45 00 views in this thread, pretty much I say.

And if anybody has comments or something to this "old" thread, keep them coming.

This foto is from the main bearings.
It can be seen that the #1 and #4 bearings are OK, the #1 got only hurt when the crank snapped,
the silver colour can still be seen.
The crank twisted , the front section of the crank broke, so that there is some damage seen in the bearing surface.
#2 and #3 bearings do not look good.
#2 is the key factor to this issue.

If the issue was the oiling of the main bearings, why do #1 and #4 bearings look OK.
Some of you may remember , there was oiling issue with the dry sump a year ago,
but I am sure the oil pressure stayed this time OK (5 kg/cm2 = 71 psi) .

[34blazer]

The harmonic dampner is mainly used to absorb the torsional(twisting) loading and unloading of the crankshaft. Cant remember the numbers but the 660 has a more prominent secondary imbalance, but not very noticable.

Primary imbalance is the forces that act on the axis parallel with the crank(front to back) and secondary is perpendicular(side to side). IMO the failure was not the dampner but a problem with the oiling of the 2 and 3 main bearings. If it was excessive torsional harmonics, the front and rear mains would be the failure points. Im going to take a wild guess but it sure seems as it the oil pump could not feed the oiling system adequetly, my guess is too little clearance between the pick up and bottom of the oil pan. Could also be oil starvation in hard cornering due to sloshing. Just my 2 pennies...

[ericjon262]

I also remember Will on the fiero forum "porting" the block of his Northstar V8, by opening up holes in the webbing of the block to increase bay to bay breathing, not sure if that would be worth anything on one of our V6's though.