3.0L stock rods & bolts

atelier14 · 05:05 AM

Hello,

Because we are in the final stages of fine tuning my warmed 3.0L SC engine with 40 Webers, GE 60 cam and JE 95mm Pistons I fear the stock rod bolts on the stock rods might not hold to the estimated max 7,1-7,2k RPMs where we plan to set the rev limiter to.

Would you think that the stock rod bolts will probably cause a problem here and we definitely should change them to ARPs?

Thanks for your input,
Christian

MBruns · 05-09-2010, 05:18 AM

For what you describe the stock rods will work well with ARP/race bolts, providing they are properly resized,magnafluxed,rebushed etc. and most importantly the rod bearing clearance is proper and not too tight. I would also recommend using the GT3RSR bearings instead of the street OEM or glyco bearings as the quality of the street bearings has not been very good for severe duty.

Mike Bruns JBRacing.com

atelier14 · 05-09-2010, 07:18 AM

Thanks, Mike.

So you would recommend no to use stock rod bolts for my application?

The long block is finished and actually in the car right now, so changing the rod bolts to ARP would induce lots of work here...

BURN-BROS · 05-09-2010, 07:21 AM

The stock rod bolts will work for the rpm range you have stated. However I would still upgrade as it is relatively cheap insurance.

Steve@Rennsport · 05-09-2010, 05:07 PM

I think Mike & Aaron offer solid gold advice,.....

Cheaper and more convenient to do this now rather than deal with any consequences from extended high RPM use.

kenikh · 05-09-2010, 07:58 PM

Quote:

Originally Posted by MBruns

GT3RSR bearings instead of the street OEM or glyco bearings as the quality of the street bearings has not been very good for severe duty.

Mike Bruns JBRacing.com

WTF??? I called my Porsche dealer and they told me all GT3 rod bearings are the same part number as the SC. Please explain, because I just DFL coated a set of Glycos I was told were the same as GT3.

Geronimo '74 · 05-09-2010, 09:21 PM

Quote:

Originally Posted by BURN-BROS

The stock rod bolts will work for the rpm range you have stated. However I would still upgrade as it is relatively cheap insurance.

3litre rodbolts are 10mm instead of 9mm for the 3.2, so you should be fine.
9mm bolts are marginal in strength in the higher RPM range, the ones you have are stronger.
It never hurts to upgrade to ARP though.

Steve@Rennsport · 05-09-2010, 11:25 PM

Quote:

Originally Posted by kenikh

WTF??? I called my Porsche dealer and they told me all GT3 rod bearings are the same part number as the SC. Please explain, because I just DFL coated a set of Glycos I was told were the same as GT3.

Hi Kenik,

The person you spoke with at your dealer is quite mistaken,....

GT-3 rod bearings carry a 996 prefix and SC ones have a 930 one; they are totally different parts.

These good bearings are not available through the aftermarket and are dealer items, only. Naturally, they come in Porsche boxes, not the red & black Glyco ones.

atelier14 · 05-10-2010, 01:09 AM

Lots of good advice here, thank you!

So the GT3 rod bearings are available through Porsche dealers? Could anybody state the spare part #?

Geronimo '74 · 05-10-2010, 01:15 AM

according to PET 6

996 103 121 94 (for the GT3 2004 and onwards.)

MBruns · 05-10-2010, 04:21 AM

That is the part # for the RSR bearing, It is treated as a motorsport part in the US and the dealers can't get them. And PMNA sure won't sell them to you unless it is packed in your freshly rebuilt race engine

Mike Bruns JBRacing.com

MBruns · 05-10-2010, 04:24 AM

Kenik, the real problem with coatings on those bearings is the build up per shell can be .0004 in. and that reduces the already too tight oil clearances in most cases unless you coat,measure, and then have the crank ground to size.

Mike Bruns

billybek · billybek's Garage

Quote:

Originally Posted by kenikh

WTF??? I called my Porsche dealer and they told me all GT3 rod bearings are the same part number as the SC. Please explain, because I just DFL coated a set of Glycos I was told were the same as GT3.

From the last few months of reading this forum, it would seem that the dealer supplied bearings go through a more rigorous selection/inspection process than the aftermarket bearings. Sounds like you are ok. (not GT-3 bearings though).

kenikh · 05-10-2010, 10:06 AM

Can this be right?

Pelican Parts - Product Information: 996-103-121-94-M100

Pelican sells them for $25/set. Doesn't sound right.

kenikh · 05-10-2010, 10:08 AM

Looked again. I did order the right part number:

996-103-121-94-M100

But they came in a red and white box. Odd.

MBruns · 05-10-2010, 10:25 AM

Its probably 25.00 per shell (or 50.00 per rod) that is the right part # post a pic when you recieve them
Mike Bruns

kenikh · 05-10-2010, 10:32 AM

Will do.

Steve@Rennsport · 05-10-2010, 11:37 AM

Quote:

Originally Posted by kenikh

Looked again. I did order the right part number:

996-103-121-94-M100

But they came in a red and white box. Odd.

Did you get them from the Dealer?

kenikh · 05-10-2010, 12:06 PM

Quote:

Originally Posted by Steve@Rennsport

Did you get them from the Dealer?

No - a friend who has a local shop got them for me. I am getting the parts back in a few days...I'll look more closely when in hand.

Steve@Rennsport · 05-10-2010, 04:18 PM

FWIW,..Dealer-sourced bearings are far preferable to aftermarket ones and thats all we use in these particular engines.