Excellence mag Aug 07 issue: BA recommends eccentric bearings

blue72s · 07-23-2007, 12:17 PM

Did you see BA's recommendation about eccentric bearings for high rpm applications?

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If you plan to run your (3.0) engine above 8000 rpm, I recommend hiring someone to grind your crankshaft for you. I would use the trick, smaller diameter NASCAR bearings and connecting rods.
The bearings are slightly eccentric, so that - at high rpm - they go towards being round instead of towards eccentric in the way stock bearings do. Speciality shops can machine the crank to your stroke of choice and then fit the NASCAR bearings, and have custom rods made for the smaller diameter journals. By using the Clevite bearings, you can also have the 3mm radius ground on the crank like those used on the RSR engines to prevent high rpm crank failures.

1. Has anyone here tried NASCAR eccentric bearings?

2. Can NASCAR eccentric bearings be used for the standard 66mm crank without having to grind down its journals?

Mahler9th · 07-25-2007, 06:01 AM

A number of folks have apparently gone to Clevite bearings. You may want to contact Custom Crankshaft Repair for your specific questions. They have moved from Redwood City, CA to San Mateo, CA Armando at CCR knows a lot about rod bearings. A lot.

TimT · 07-25-2007, 06:20 PM

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Has anyone here tried NASCAR eccentric bearings?

Yes, we have used them in a few engines

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2. Can NASCAR eccentric bearings be used for the standard 66mm crank without having to grind down its journals?

No, not only do you have to resize the journal, you have increase the radius of the fillets.

We have used Armondo to do this, and Recently found another machinist that can do this.

blue72s · 07-28-2007, 06:57 PM

Thanks Mahle and Tim. I was hoping more people would chime in.
I'd like hear opinions about how good the bearings are. Are they a lot better than stock bearings? Smoother at 8,000rpm? Rough at low rpm? More powerful? More reliable? Longer engine life span?

kenikh · 07-29-2007, 08:50 PM

I also know of someone who had a custom crank made so they could use NASCAR type bearing thorughout their 2 liter race car's motor. Apparently works fine.

blue72s · 03:17 PM

A quote from the thread 'Carrillo Rods':

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The vibratory signatures are totally different between the 66mm and 70.4mm ones.

66mm cranks are just fine and will not spit the flywheel off, no matter what. If you can spin it to 10K+, you'll not have a problem as I've seen plenty of those RPMs logged during a missed shift.

On the subject of vibratory signatures, will a modified 66mm crank (53mm rod journals with large fillets) still be the same as the stock unmodified 66mm crank?

Steve@Rennsport · 08-02-2007, 07:07 PM

Quote:

Originally Posted by blue72s

A quote from the thread 'Carrillo Rods':

On the subject of vibratory signatures, will a modified 66mm crank (53mm rod journals with large fillets) still be the same as the stock unmodified 66mm crank?

Oh yes,....that will not be any problem,.......

blue72s · 08-04-2007, 07:38 AM

Thanks.

turbobrat930 · 08-04-2007, 10:35 AM

I have not run my engine yet, as I am still wiring the EFI system up. BUT, I had Armundo at CCR stroke my crankshaft. It had two damaged rod bearing journals as it was, so paying the little extra was a no brainer. He offset ground the rod journals, gringing down to a Chevy journal size, I believe two inches? This offered an increase of 4mm worth of stroke. With the increase in bore size, I have now bumped up my displacement from a 3.3L to a 3.6L....
I bought my P&C's from JB Racing in Talaveras, FL, and they also did all of the machine work, P&P the heads, etc.
Mike Bruns at JB Racing is a wiz at this stuff. He already had custom Pauter rods ( they order them in sets of 10), to fit the new rod bearing diameter, and also had the NASCAR Clevite bearings in stock as well. It was not cheap, but the quality of the bearings is much better than what usually goes into these motors. I am about 2 months from firing it up, and will let you guys know how it goes.

BTW, when the crank arrived back from Armundo...it looked like jewelry! Incrediblly clean and what a polish on the rod and main journals!!!! I also had the center Oil mod done to the crank and main bearing as well.....

blue72s · 08-05-2007, 05:06 PM

Quote:

Originally Posted by turbobrat930

He offset ground the rod journals, gringing down to a Chevy journal size, I believe two inches?

2 inches is 50.8mm.
3.0 and GT3 rods are 53mm. I hope Clevite also makes this size.

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had the NASCAR Clevite bearings in stock as well. It was not cheap, but the quality of the bearings is much better than what usually goes into these motors.

How much?

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BTW, when the crank arrived back from Armundo...it looked like jewelry! Incrediblly clean and what a polish on the rod and main journals!!!! I also had the center Oil mod done to the crank and main bearing as well.....

Great

turbobrat930 · 08-05-2007, 07:01 PM

Blue, I was misleading on the statement that the bearings were expensive.... actually I think the were as much or cheaper than the German bearings. What I meant by that statement was that the whole process to include stroking the crank, buying the Pauter rods, bearings, center oil mod to both the crank and one main bearing, etc, etc....was not cheap.... but worth it..... IMO

I bought my bearings, rods, etc, from JB Racing...So, you could check with them for pricing... Sorry if it was misleading