Short stroke options

[Flieger]

I cannot see nitriding adding more than a couple grams, if anything. Or do you mean the 2.2 rods are heavier than the 2.0 rods? They are the same stroke, so I would think they would be equal.

Bruce Anderson's 911 Performance Handbook shows photos of the 2.2S nitrided rod, 2.4S rod, and 2.7RSR soft-nitrided rod. Is there a difference in strength between the 2 nitriding processes? I think one was called Tenifer and I cannot think of the other. What is the chemistry/metallurgy going on? How does it toughen/harden the steel?

Thanks for any info.

[C.Plavan]

"Rods- I would use 2,2 rods, they are stronger than 2,0, and the nitrided S rods are just expensive collectors items. Of course these rods are heavier. ARP rod bolts are a must."

John, why would you not want to use nitrided rods in a performance engine?

thanks!

FYI- In my #1 2.5L race motor I used 2.0L rods with ARP rod bolts. I rev'ed up to 7800RPM (Short Stroke) and sometime up to 7900RPM. No issues at all and they are not nitrated rods. The 2.0L rods are lighter. The other problem (maybe not anymore) with the 2.2L rods is that ARP did not make rod bolts/nut kits for those rods.

Personally, I think nitrided rods are a waste. I put close to 100 race hours on this motor without any failures. (This motor is sitting in my garage just waiting for a normal bearing change- and maybe twin plug )

In my #2 2.5L I used Pauter rods because they are even lighter than the 2.0L rods. This sucker can rev 8000+ if I wanted to.

[saintdave]

I have noticed 911T heads seem to be quite cheap, are they of any use for this application, if not what would you use?

[C.Plavan]

Stock 2.2L-2.7L heads have the same valve sizes- The ports are different. A 2.2L "T" ports are 32/32 compared to and 2.2L "S" 36i/35e. You can open up the ports and intakes to accommodate the motor type you build. Porting is cheap.

[super9064]

I have noticed 911T heads seem to be quite cheap, are they of any use for this application, if not what would you use?

2.2 T Carb heads are best suited because they do not have injector ports, assuming you were going with Webbers or PMOs.

[304065]

The 2,2 rods have more metal added around the big end and are definitely heavier. The lightest 2,2 weight group is 700 grams. The heaviest 2,0 weight group is 650 grams. ARP bolts (which are available) are heavier than stock Kamax bolts.

As far as the Nitrided rods go, I'm with Chad-- I've heard of 2,0 normal rods being used in performance engines with no issues. The Factory Nitrided the 2,0 through 2,4S rods, probably they thought the surface hardening would make the rods more durable in higher RPM operation.

[BURN-BROS]

Hi John, I am looking thru the ARP catalog and cannot fnd an app for the 2.2

Let me know if ARP has stepped up so I no longer have to mod 2.2 rods to fit 2 liter bolts.

[304065]

Hey Aaron, I hope you are doing well.

I looked at the same page of the catalog, page 32-- so even though they list it, you're saying it's only a 2,4 through 3,0 bolt? Seems like they should tell you that up front. I saw a post from Henry that said that they don't make one for the 2,2. I'll shoot their tech people an email and ask-- you're probably right.

What do you have to do to the 2,2 rods to make their bolts fit? Looking at the size, maybe relieve the spots on the big end where the head and the nuts seat with an end mill in order to get the nut on?

Here are the various bolts-- photo credit John Luetjen (that's his granite countertop). Left to right-- 2,0 2,2 2,7.

[Flieger]

Thanks for the info, Herr Cramer.

[kenikh]

When it comes to rods, these are my new choice:




My set came in at 539g/ea with the ARP bolts in place. Compare that to stock rods:

The lightest 2,2 weight group is 700 grams. The heaviest 2,0 weight group is 650 grams. ARP bolts (which are available) are heavier than stock Kamax bolts.

Then again, don't compare the price to a 2 liter rod, as these will set you back $1000 over the price of a rebuilt, complete set of 2 liter 's' rods.