Contour Enthusiasts Group Archives Forums Modifications Duratec Performance Crank Whip

In reply to:

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Do you know if anybody has any pictures of the spun bearings after they removed them? This is interesting, I sure would like to see those bearings.

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Let me see if I can post a pic of my bad bearing. I have it somewhere..gimme a day or so.

The flip side of straight engines is that a I6 has no really bad harmoinc problems... in other words it is a near perfect setup....

BMW doesn't need all the dampers and counter rotating shafts on its I6 engines as many I4s or V6s do because it is such a good package.

IIRC it has no first or second order vibrations that a V6 has.

It also gets away with only 2 camshafts for a DOHC setup (less rotating mass in the valve train as you have half the cam sprockets)

Originally posted by TedS:

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The flip side of straight engines is that a I6 has no really bad harmoinc problems... in other words it is a near perfect setup....

BMW doesn't need all the dampers and counter rotating shafts on its I6 engines as many I4s or V6s do because it is such a good package.

IIRC it has no first or second order vibrations that a V6 has.

It also gets away with only 2 camshafts for a DOHC setup (less rotating mass in the valve train as you have half the cam sprockets)

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Actually I think BMWs have a DM damper and I know at least one tuner who has strongly argued against UDPs d/t risk of bad harmonics.

and they do have only 2 cams BUT they are twice as big/heavy..

I guess terry has left the building. still waiting terry, do you have any answer?


Micah

Originally posted by TedS:

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The flip side of straight engines is that a I6 has no really bad harmoinc problems... in other words it is a near perfect setup....

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I'll add to Dan's statement by saying Toyota developed a DMD for the Supra I6 to quell destructive vibrations. Seems the engines were failing on the test stations with only a normal damper.

I'll see if I can find the link to a website with info about it. They even showed graphs (from 3k - 6k IIRC) of how much destructive vibrations (I.E. crank whip) a DMD reduced vs just a normal damper.

This?

http://www.supras.com/~riemer/sonictech/tet/dualratedamper.html

Originally posted by DemonSVT:

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Originally posted by TedS:

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The flip side of straight engines is that a I6 has no really bad harmoinc problems... in other words it is a near perfect setup....

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I'll add to Dan's statement by saying Toyota developed a DMD for the Supra I6 to quell destructive vibrations. Seems the engines were failing on the test stations with only a normal damper.

I'll see if I can find the link to a website with info about it. They even showed graphs (from 3k - 6k IIRC) of how much destructive vibrations (I.E. crank whip) a DMD reduced vs just a normal damper.

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Make sure to look closely at that Y-axis. Not units of life, bearing wear or stress - just db noise. I personally wouldn't present reliabilty data that way, but hey what do I know

"The factory stock pulley is designed to absorb both torsion and bending
lateral vibration from the crankshaft. This helps the crankshaft deal with
high vibration in the 400 Hz range after the #1 piston fires. Overall this
has many benefits on the bottom end. It helps the crank deal with high
continuous loads as well as overall bearing life, not to mention overall
engine life. Also the drive-line will have a more pleasing sound with very
little 400Hz vibe's setting up."

Scott, true the figure was refering to noise but this was the thrust of the discussion...

Okay, true - there will be "increased engine and bearing life", but we have NO data to indicate what the magnitude of the increase is. Did it increase from 200,000 miles to 400,000 miles? If so, I personally don't care. The only real data they show is how much quieter it got. I will admit that on the straight six supra motor the DMD may very well be required to make reasonable life - it's just not supported in any of the data they present in that paper, and even if it is that doesn't in any way carry over to it's use on our short crank V6 duratec.

Look at the initial press lit. on the PT Cruiser. It mentions that they use a new gates EPDM damper for increased crank life. Has anyone ever seen a problem with torsional excitiation failure on a low revving 4 cylinder engine? No, but theoretically they are right - the crank should last a whole lot longer with that damper. You could probably pull it out of the rusted out shell of the car in 20 years and use it again if you really wanted to

I'll readily admit that I'm just guessing, but I'm intrested to see more on procyon's opinion of the whole mess - he seems to really know his stuff and indicated he thinks the DMD is "probably" more for NVH than reliability.

Wow. I got quite a few responses here. I don't really buy this whole crank whip thing. That's why I posted this. I wanted to see the reasoning behind it. I am not saying that internal vibrations can't destroy a motor. I think that they're not a factor in the Duratech motors. I think there are some serious problems in the oiling system that cause the majority of the engine failures out there. I have blown up 3 mortors in my 98 SVT. The car only has 52,000 miles. All 3 of the motors have broken in similar ways, high speed, 2nd or 3rd gear right hand turns, taken anywhere between 3500 to 6000 maybe 6500 rpm. I don't mean I hold the car at 6000 rpm through the entire corner either. 6500 would be the max rpm on exit of a 2nd gear turn. The first motor that let go at 35,000 I belive. After a tight 2nd gear on ramp to a freeway. Engine RPM was roughly 4500. It spun several bearings and then would not rev any higher then 3500. I had the oil changed the day before so I know it was full. I watched the guy at the oil change place put the Mobil 1 in by the quart. I checked it myself to. The 2nd motor spun 1 bearing around a really fast banked off ramp I take on my drive home. If I slow down to 3500 or 4000 in 2nd and stomp on it, the car is at 7K by the bottom, 1/2 sideways (I love my Quaife). After I broke the first motor I didn't do this very often, but every once in a while I couldn't help it and at about 48K that was it. Then I did a 3.0L. I figured trap doors in the oil pan would do it. Nope. At button willow raceway my 3.0L with 5000 miles on it which I didn't run all that hard because of the 110 deg. heat, had a shattered piston, 2 broken rods, a hole in the cradle, and 6 spun rod bearings, with EVERY main bearing spun. I was sick of this crap. No one I spoke to seemed to know why this stuff was happening. I have worked at Quaife America for almost 5 years now. I have met alot of neat people (Engine builders, chassis builders, etc.). After David Z, Bito and I removed my engine about 2 months ago I disassembled it and brought it to a few motor builders that I have known. These are guys that have been building motors for record setting, and championship winning bonneville and sprint cars, rally cars etc. They were nice enough to go over these parts with me and diagnose everything. What I learned here backed up alot of the theroys I had about the flaws in the oiling system. I am not putting another 3.0L together untill I can make it bullet proof. As long as the pickup stays submurged the feed side of the oiling system works great. Here is one of the first problems. Ford is really fond of the 'G' Type oil pump I beilive it's called. THe mod motors and the duratech use this style pump. It is different from a beveled gear oil pump. It's alot more efficent, but it can not take the normal 'trash' that goes through a street motor. Ford sets the gears up very 'loose' so they can run in a street motor without jamming on the dirty oil that goes through a street car. The loose tolerences mean that the pump does not scavange well. If the pickup goes dry, it takes alot longer for the pump to pick the oil up. Obviously a very bad thing. It's not an issue in a car where the pickup never goes dry. But the Contour is a different story. If the pickup location wasn't so poor this would not be an issue. It wouldn't be an issue if my next rant wasn't a problem. OIL DRAINAGE. The cylinder heads lack the ability to drain enough oil at high rpm to keep the pickup submerged during high g cornering. Now I didn't test this, but why does the 3.0L, and the 2001 2.5L have 3 drains in the cylinder head? There is a front, middle and rear. the pre 2001 2.5L has a front and middle. what happens to oil in a turn when it is pushed to the side where there is no drain?? the sump drains. Why would ford add a 3rd drain to the 2001 2.5L? Or to take a quote from Terry "Ford don't just do things" or somthing like that. David Z and I found that on a 2.5L 2001 cougar motor he has. I belive bondurant and rousch have found high rpm drainage problems to. I have talked to 2 customers who race cougars who bought gear kits and they have not have not had engine failures since they had custom oil pans made. So I belive it is a little triangle of problems. Poor pick up location, Oil pump scavangeing problems, and oil drainage from the heads. It doesn't happen all at once, but they can happen together and wreck a motor in no time, or slowly. A dry sump or a custom pan and an accu sump are the best solutions according to the guys I spoke to. I am going to have a custom pan made. I'm going to put in a oil cooler, with a t for the Accusump. And I'M LEAVING MY UNDERDRIVE PULLEY. My crank can whip it's heart out. Oh, and I'm going to put the 2001 2.5L heads on my new 3.0L block. 3 drains. I belive a 2 quart accusump should be enough to protect a motor as long as it is checked regularly in a car that is driven hard. Sorry about the long post. I had to get it off my chest. It's getting late, and I should get to bed, I have a long ride to work. BTW, I suppose 'crank whip' could cause a problem in a corner when there is no oil pressure........

Roger