3.6 Pauter Rods vs OEM with ARP Fasteners

pantera · 10-09-2010, 01:48 AM

Hi all, I'm going to be rebuilding the top end of my stock 964 3.6 DE car in the next month or so. Today while discussing it my tech he threw out there possibly a set of Pauter rods for part of the rebuild. He's not selling me on it and thought the stock rods with ARP rod bolts would suffice.

This has me thinking thinking though. They are lighter than the stock rods which would lighten the reciprocating mass of the crank assembly. Which would make things easier on the bearings etc. Seems to have many benefits.

Does anyone feel this is a worthwhile investment for a engine that sees DE duty?

Many thanks,

Dan

MBruns · 10-09-2010, 04:48 AM

Dan, the 9 mm rods like the 3.2 thru 3.6 were a problem for anything but commuting it seems, with the cost of buying the ARP bolts, having a shop resize the big ends (needed when changing bolts) at 30. to 40. per rod and replacing pin bushings at about the same cost plus bushings you are not far from a set of Pauters, That is the way I look at it and the bolts in the race rods are good for many torque cycles, ( not something you want to look forward to but) hope this helps.
Mike Bruns JBRacing.com

pantera · 10-09-2010, 09:48 AM

Mike, that was extremely helpful. Coincidentally I was looking on my build price sheet last night and didn't see a breakdown of machine costs for items just a summary. I guess when you factor in as you mention the ARP fasteners and machine costs the purchase of a set of Pauters does make sense while your in their.

For some reason I was under the misconception the 3.0 ,3.2 and 3.6 had pretty robust rods and the bolts were the weak leaks.

Many thanks,

Dan

Steve@Rennsport · 10-09-2010, 10:03 AM

Dan,

While the factory rods are strong enough for your application, they are rather heavy and this places high loads on the rod bearings when used for the track.

Aftermarket rods such as Pauter, Arrow, and Carrillo are lighter (as well as having stronger fasteners), this pays real dividends in reduced rod bearing wear. Given that this is one of the "Achilles Heels" of these engines, I think these are very worthwhile for cars that will be used extensively for the track.

I would also not use Glyco rod bearings in a track car, but thats another story.

pantera · 10-09-2010, 10:49 AM

Hi Steve and thanks for the feed back. Well, given the logical explanations it looks as though I'll go for a set of rods. I have to say this is indeed one of these slippery slopes. I want to do this build with DE durability in mind. The "good stuff" adds up quickly for this topend rebuild.

I am concerned about what kind of rod bearings to use. The car is not trailered to the events but driven their, tracked and driven home. So this thread does not go OT perhaps I'll start another regarding bearings.

Thanks again for your insight,

Dan

Bill Verburg · Bill Verburg's Garage

Quote:

Originally Posted by pantera

Hi Steve and thanks for the feed back. Well, given the logical explanations it looks as though I'll go for a set of rods. I have to say this is indeed one of these slippery slopes. I want to do this build with DE durability in mind. The "good stuff" adds up quickly for this topend rebuild.

I am concerned about what kind of rod bearings to use. The car is not trailered to the events but driven their, tracked and driven home. So this thread does not go OT perhaps I'll start another regarding bearings.

Thanks again for your insight,

Dan

A glance through the Smart Racing catalog is always enlightening

MBruns · 10-09-2010, 04:38 PM

Just be sure to check the bearing clearence with a bore guage to be sure of the rod bearings to crank, most new rods are set up on the tight side of the spec, that combined with a strong STD. crank its too tight to do anything track duty. I agree with Steve on the glyco brgs. the quality has slipped
Mike Bruns

pantera · 10-10-2010, 12:40 AM

Quote:

Originally Posted by Bill Verburg

A glance through the Smart Racing catalog is always enlightening

Thanks Bill, Smart Racing always has some nice helpful things.

Dan

pantera · 10-10-2010, 12:51 AM

Quote:

Originally Posted by MBruns

Just be sure to check the bearing clearence with a bore guage to be sure of the rod bearings to crank, most new rods are set up on the tight side of the spec, that combined with a strong STD. crank its too tight to do anything track duty. I agree with Steve on the glyco brgs. the quality has slipped
Mike Bruns

Mike, I'll check with the tech regarding these clearances. I'll have to make some decisions regarding bearings. Good stuff......

I really appreciate everyones input who replied.

Thanks again,

Dan

Walt Fricke · 10-10-2010, 06:59 AM

Mike

I had assumed that you could just replace the stock 3.2 rod bolts with ARP (or other aftermarket higher strength steel) bolts. The Raceware's I have in my 2.7 with stock rods just bolt in, and I have been able to reuse those when they still met the stretch spec.

So for the available aftermarket stronger bolts for the 3.2 (and the succeeding longer throw cranks) you need to machine the rods?

Why could not a bolt of stock dimensions but stronger steel be made?

Walt (whose education stopped with the 3.0)

MBruns · 10-10-2010, 09:11 AM

When you replace the stock bolts with the same torque the housing bore if its good will be the same, however when you change to ARP's or the like the torque is of different value the rod big end housing bore will change and not be round. So you need to resize the big end and hone to the proper dimension so the bearing crush will be correct and all the above has an effect on the rod bearing to crank journal clearance. If you change the torque even 5 # it will show up on a dial bore guage.
Mike Bruns JBRacing.com

Samujr · 10-10-2010, 10:02 AM

Good information again on this thread. I will be also using std crank and Pauter rods (3.5l twin plug/ITB/etc). May I know if there are other options for rod bearings than Smart Racing, Porsche OEM and Glyco? I have asked from three different part sellers from Germany and one from UK and they always offer Glyco - they always tell that those are same sets as Porsche shops are selling. So I'm ready to order from USA if that is best for my build. Are all of you pros using Smart Racing Calico coated bearings? If you wish you can PM me what you have to offer, in case you are not willing to share your secrets in public.

sda · 10-10-2010, 05:23 PM

I have had great success with sending both my crank and rods to Brian Pauter and he resizes them and uses bearings oddly enough from buick or olds one of those american brands .
I had lots of problems with rod bearings before then .
It was at this same time years ago that I was speaking with one of the people from smart racing and they were just in the process of designing new bearings as they were not happy with porsche bearings either .
If you send your crank I would definitely have pauter knife edge and cross drill the crank

Walt Fricke · 10-10-2010, 08:12 PM

Mike

Thank you. I am glad I asked. I wouldn't have thought it, but then, though I have bore gauges, I'd not have thought to use them.

Difference between a professional engine builder and what I think of myself as - an engine assembler: follow the instructions and bolt the parts together. Hope the folks who wrote the instructions knew what they were doing.

Walt

AlfonsoR · 10-13-2010, 03:21 PM

Quote:

Originally Posted by MBruns

When you replace the stock bolts with the same torque the housing bore if its good will be the same, however when you change to ARP's or the like the torque is of different value the rod big end housing bore will change and not be round. So you need to resize the big end and hone to the proper dimension so the bearing crush will be correct and all the above has an effect on the rod bearing to crank journal clearance. If you change the torque even 5 # it will show up on a dial bore guage.
Mike Bruns JBRacing.com

Mike,

When you check with the bore gage, what range would be acceptable.. i.e. +/-0.25 mils out of round?

MBruns · 10-14-2010, 11:19 AM

Most dial bore guages can't measure .25 mil (.00025in) unless it is on a rod rebuilding machine that toe total range of the dial is only .010 in., we shoot for completely round and no bell mouth and on the nominal size for that given rod, if its out of round .0005 we resize it
Mike

AlfonsoR · 10-15-2010, 08:30 PM

Quote:

Originally Posted by MBruns

Most dial bore guages can't measure .25 mil (.00025in) unless it is on a rod rebuilding machine that toe total range of the dial is only .010 in., we shoot for completely round and no bell mouth and on the nominal size for that given rod, if its out of round .0005 we resize it
Mike

Thanks