Crank Advice Needed

[im4duke]

Sent my 3.3 turbo crank out to be polished to see if it would clean up. Unfortunately, one rod journal did not. Could use some opinions on what to do. Here are the options I know of:

1) repair it - grind the journal in question, reharden (nitride), accept that the rehardening process is not as durable as the original and watch religiously for signs of failure for the next ??? miles. I think this may cost around $500.

2) buy a used std-std 3.2/3.3 crank. Cost $1000-1500? Aside from cost, what's the downside if the crank measure std?

Are there other options? I have heard of some using other cranks, but I imagine that requires custom rod lengths etc.

By the way, my application is mainly street. New stock C2 turbo Ps&Cs, less than 1.0 bar boost, CIS, twin-plug. Not trying to achieve massive HP, just good reliable fun over stock.

Suggestions welcome and appreciated.

Thanks,
Maxx

[ajwans]

When I asked this question I was told that all the journals must be ground
undersize if one was off.

andy

[911st]

Buy a good used 964 crank and rods. Makes for a very nice 930 Turbo as it gives a bit more compression and much better lower end.

Then sell off your crank w full disclosure.

Just a thought.

[304065]

Send it to Armando at CCR and have it ground for 2" NASCAR bearings

[im4duke]

Thanks for the responses guys.

ajwans - You may be right. Is that because bearings are sold in sets or is there a mechanical reason?

911st - Is the 964 setup a longer stroke? Would I have a piston-to-head contact issue?

John_cramer - I have read the 2" nascar bearing thread. Early in the thread you state that it only makes sense for race applications and not for street. Have I misinterpreted your postings there or misunderstood some sarcasm here?

To be clear, my goal is a reliable street car with a modest increase in HP.

Thanks again for the responses.

[911st]

More than a fue 930 builders have done the 964 crank thing.

With the 964 crank you neet the rods also so you end up with the same deck height. The loner compression stroke works to increase compression some. I am not sure but there may be small need to clearance something w the longer stroke. I think it is just grinding a little off the oil pump.

I am not an expert but it seems that Porsche used technology that made for motors that can go 200k plus miles. There cranks seem to be over engineered for the application.

If you are building a 200k mile motor getting a factory crank is a best bet. If you are ok w a motor that will probabbly also go that far, do not worry about having your crank turned and use oversize bearings.

If you conceder the 2" bearing you will have to also buy rods. However, this gives you a chance to increase or decrease your stroke and compression by playing w your deck height at the same time.

I would not have issue w doing the 2" for a street car.

I think the 964 crank is a bit more proven and may be more acceptable should you want to resell the car latter.

[ajwans]

ajwans - You may be right. Is that because bearings are sold in sets or is there a mechanical reason?

I wondered that myself actually. Would the 1 undersize bearing be the first to wear?

andy

[911st]

My guess is doing one would through off the balance or harmonics off on the crank.

[Henry Schmidt]

What we have been doing for years is regrind the crank rod journals for 3.0 rods. 53 mm with a large fillet.
While your at it you should cross drill the crank. Remove galley plugs. Then heat treat the finished product and replace the plugs.
The large fillet adds strength and the cross drilling improves oiling to the #2 and # 5 rods.
The 53 mm journal allows you to choose a number of connecting rods that are readily available. 3.0 911 SC rods. (10 mm bolt 127.8 center to center length improves strength and rod angularity).
The new journal (as raced on all 911 based factory race engines except 906/910) will allow the use of any after market 3.0 rod (Pauter, Carrillo or ?).
This journal size also puts all the GT3 Pankl rods in play.
The two issues that need attention when using the 3.0 factory rod are deck height and pump clearance.
The deck can be addressed by simple base gaskets or by trimming the perimeter of the piston top. We do this and add valve pockets so that more aggressive cams can be use. Raising the piston into the head also adds compression [be it very small].
We have been using this modification for about 12 years and have never had a failure caused by this modification.
The best place for this modification that we have found is MCI. call Dave @ 714-549-2388 http://marinecrankshaftinc.com/

[kenikh]

Originally Posted by john_cramer

Send it to Armando at CCR and have it ground for 2" NASCAR bearings

Beat me to it.

+1

[Henry Schmidt]

Originally Posted by john_cramer

Send it to Armando at CCR and have it ground for 2" NASCAR bearings

When you use the "Nascar 2.0 inch" = Chevy bearings you must use a custom rod.
How much is that? $1,600-$1,900? 3.0 rods are $200+ bolts and rebuild. All other cost are the same. $1000+ seems like real money to me. What say you?

[kenikh]

Originally Posted by Henry Schmidt

When you use the "Nascar 2.0 inch" = Chevy bearings you must use a custom rod.
How much is that? $1,600-$1,900? 3.0 rods are $200+ bolts and rebuild. All other cost are the same. $1000+ seems like real money to my. What say you?

Custom rods are the rub apparently.

[304065]

Originally Posted by Henry Schmidt

When you use the "Nascar 2.0 inch" = Chevy bearings you must use a custom rod.
How much is that? $1,600-$1,900? 3.0 rods are $200+ bolts and rebuild. All other cost are the same. $1000+ seems like real money to me. What say you?

Hmm. . . the 3,2 crank journal is larger diameter than the 3,0 so it can be turned down. What is the journal width of the 3,2 rods, is it the same as the 3,0?

[im4duke]

2 shops I spoke to today said Armando can likely repair my crank to standard with minimal compromise to durability. I don't know the details of the repair process, but figure it must involve welding. If this is the case and it can be done for around $800 or less, it seems to be a good option. I am trying to reach Armando to learn what is invovled and what to expect from a repaired crank.

Henry, thanks for chiming in with your suggestion. That also seems like a good option. In that situation, I think it would be wise to have someone like yourself coordinating the total package to ensure that everything works together correctly (i.e. crank, rods, Ps&Cs, heads, etc) even though I plan to assemble myself. I will call you to discuss further.

Anyone with firsthand info on the 964 crank suggestion?

Thanks,
Maxx

[911st]

Might try Andial or IA on the 964 crank.

A bunch of guys were doing it several years ago. I think you end up w a long stroke 3.4 or 3.5. I forget if it rases compression 1/2 point of a full point.

The combination of more leverage at the crank, more total volume and a bit more compression adds up to a much better bottom end than the change in size indicates and more everywhere. Works great w the ports opened up and 964 cams.

Start a post on 964/C2 crank in a 930 and you should get some hits by people that know more than I .

I think that all the choices are going to come in about the same. I guess about $1500 for a C2 crank w rods.

Please verify the details, I know this is an accepted mod and should add value on a resale as it is Porsche parts.

If you were going for a motor that was going to spend much time over 7k the cross drill mod is great. I had him do this on a 2.4S motor I did once.

[im4duke]

Thanks, 911st. I will give Stephen a call as well. I do want a slightly higher CR than my stock Ps&Cs offer and I already have 964 cams and larger ports.

[Henry Schmidt]

Remember that 3.0 rods on a 3.3 crank will produce a slightly higher compresion ratio, not to mention better rod length to stroke ration.
The 964 crank goes in exactly the wrong direction. Longer stroke / shorter rods. Just plain gooooooofy.

We have used the 964 crank in the past and my opinion of the 964 crank is that IT IS A BOAT ANCHOR. It really what's a harmonic balancer to function with serious vibration.
Size is great if tuning isn't an option.
For some one interested in the 964 crank for a 3.3 turbo, we have the last 964 crank we took out of a 930.
I have always been in favor of building an engine that fit engineering principles.
That generally means short stroke.
We are in the process of manufacturing some 9 bolt, 66 mm cranks. The will allow us to build short stroke 2.8 from 911SC (66x95), SS 3.0 from 3.2 66x98 and SS 3.2 from
3.6 engines 66x100. Can you say 9500 rpm?

These cranks are being made to fit the GEN II GT3 Pankl titanium rods. 3.0 big end and 130 mm center to center.

JOHN: the journal width on the 3.0, 3.2 Carrera, 3.3 turbo and 964 are all the same.

[911 tweaks]

I can hear the high rpm scream already here on the east coast just thinking about how sweat a set up Henry is cookin up with the new cranks... Saaaaaaaaaaaaa-Weat !!!
Bob

[kenikh]

Originally Posted by Henry Schmidt

We are in the process of manufacturing some 9 bolt, 66 mm cranks. The will allow us to build short stroke 2.8 from 911SC (66x95), SS 3.0 from 3.2 66x98 and SS 3.2 from
3.6 engines 66x100. Can you say 9500 rpm?.

Cat's out of the bag, huh?

The only question I have on a 66x100 motor is how do you get valves that big to return without floating unless you go with titanium valves? And how do you get ports big enough to breathe at 9 grand for a motor that big?

[im4duke]

Thanks for the input everyone.

I contacted Armando and Marine Crankshaft. Both have great referrals and reputations based on my short research. In the end, Marine Crankshaft was 60% less expensive, answered the phone and was friendly to boot. They do not replace the galley plugs, but Dave offered to work it out with Ollies for me.