Are 2.2 Rods better than 2.0 rods?

blau911 · 07-23-2003, 07:17 PM

An experirenced Porsche mechanic I was speaking with today told me that when I rebuild my early 2.0S engine ina few weeks, I should use 2.2T E or S rods instead of the 2.0 rods, regardless of whether the 2.0 rods are nitrided or not nitrided.
Any truth to this? If so, what makes the 2.2 rods so much better?

Wayne 962 · Wayne 962's Garage

They are a slightly different design. I used to know this off of the top of my head, but some new information has slipped into my brain, replacing the spot where this particular nugget of info was held.

In general, there aren't any large performance or reliability issues with the earlier 2.0L rods - this isn't a major issue.

-Wayne

Tyson Schmidt · 07-23-2003, 10:02 PM

Funny, everything I've heard is that it's just the opposite. The Factory didn't have good luck with 2.2 rods in their racing engines, I'm told.

I plan on building a short stroke 2.5 or 2.7. When asking around, I was told by many race-engine builders to use the 2.0 rods with the 66mm counterweighted crank.

blau911 · 07-24-2003, 06:13 AM

Since there is no overwhelming consensus on going to 2.2 rods (at least so far), looks like I will stick with my own 2.0 rods and save the money for something else. I do expect to redline it occassionally, when I am fortunate enough to find to nice open road and few people. But no serious racing.
Anyone know where I can send my rods to have them checked after I open up the engine? Also, anyone know where I can send them to be re-nitrided and what that will cost? Thanks all.
By the way, I did buy your new book and am enjoying reading it. I must admit that some of the subject matter is a little over my head, but I expect that over the year or two I wil be able to understand it by having to deal with some of the subjects first hand in my garage and/or picking my mechanic's brain. It's the least they can do for how much they charge!

Scott Clarke · Scott Clarke's Garage

I think that the rods were revised for the 2.2 motors in order to increase the size of the rod bolts. I have also heard that the 2.0 rods are prefered, but I have never heard an explaination as to why.
-Scott

andrew15 · 07-24-2003, 09:01 PM

Odd - I too have heard that 2.0 rods are preffered to the 2.2 ones.

Regards,
Andrew M

Wayne 962 · Wayne 962's Garage

If you read the book a few times, a lot of the stuff becomes a bit clearer...

I'll see what I can dig up on this rod issue...

-Wayne

Scott Clarke · Scott Clarke's Garage

Bruce Anderson's book, second edition, page 65 shows 2.2 and 2.0 rods side by side. The 2.2 rods are much more stout around the big end, and the rod bolts are longer. It looks like the 2.2 rods would be quite a bit heavier than the 2.0s. If the 2.0s don't break, it seems like they would be better than the 2.2s.
-Scott

tops911 · 07-31-2003, 09:37 AM

I've read that the 2.2 rods were not very successful in racing. It was in Bruce's book, Panorama or Exellence. If I recall right, the 2.0 were the choice for racing. I have a 2.2T engine so I can rember the the disapointment after reading about the rods and the non counter weighted crank.

Wayne 962 · Wayne 962's Garage

Right the 2.2T engine is a good solid engine, but not something that you can easily upgrade. It's limiations are:

- Mag Case
- Zenith Carbs
- Non-counterweighted crank
- T Pistons
- T distributor

I think there's one more thing, but I can't remember off the top of my head...

-Wayne

Wayne 962 · Wayne 962's Garage

Okay, I did speak with Tom Woodford (my Technical Editor for the Engine Rebuild Book) today, and he can't recall any significant preference for 2.0L or 2.2 rods. He did remind me that you cannot use the 2.2 rods in the early aluminum cases without some modifications. He does have factory documentation that says that the 2.2 rods are stronger than the 2.0L rods, however, he almost exclusively uses 2.0 rods when he's rebuilding an early 2.0 engine. Go figure?

He also told me about a cool crank he saw the other day at Carl Thompson's place. It's a 9-bolt crank with a 66mm stroke. This would mean that you could make a short stroke 2.8 out of a 911SC or Carrera 3.2 engine. (this would be the alternative to running a Euro Carrera 3.0 case like the one that I have).

-Wayne

jluetjen · jluetjen's Garage

Quote:

I think there's one more thing, but I can't remember off the top of my HEAD...

Er... The heads maybe?

Wayne 962 · Wayne 962's Garage

Well, the heads have different ports, but from a performance perspective, I think that they will work. They are not as limiting as the other elements of the engine...

Oh, I think I remember - the cams need to be expensively updated to the 'S' cams, maybe?

-Wayne