Engine build Questions.

SmokinCAT

SmokinCAT

Cheap and Easy.
Joined
Sep 13, 2008
Messages
3,162
I have a few questions about some bottom end work I plan on doing.

I have heard alot of people talkign about polishing rods here lately, why is this done? Is it to reduce windage?

I plan on having my pistons and rods balanced and shot peened, but I was also considering having the cryo treated as well. Does the balancing need to be done before the cryo work?

Also has anyone had any luck of experience with coated pistons, of the few sets I have seen it looks to be worth the money to have it done.

Im looking to make the stock part a little stronger, aftermarket stuff is very hard to come by for a big engine.

Thanks.
 
SmokinCAT said:
I have a few questions about some bottom end work I plan on doing.

I have heard alot of people talkign about polishing rods here lately, why is this done? Is it to reduce windage?

I plan on having my pistons and rods balanced and shot peened, but I was also considering having the cryo treated as well. Does the balancing need to be done before the cryo work?

Also has anyone had any luck of experience with coated pistons, of the few sets I have seen it looks to be worth the money to have it done.

Im looking to make the stock part a little stronger, aftermarket stuff is very hard to come by for a big engine.

Thanks.
Click to expand...

Lightning and polishing rods serves a few purposes.

the lighter the rod the less HP you will lose do to reciprical and rotational drag.

Polishing is done to reduce stress risers on the beam and the big and small end. this eliminates a crack from forming from an exsisting edge or ridge

Re heat treating can be worse than leaving it alone, depends on the material and history of prior heat treatment.

Swole has some pics of the way a rod should look when done correctly.
 
polishing rods reduces the stress risers left by the forging. Coating pistons would be my suggestion, i have mine done but i havnt started the truck yet nore seen any after tear down, it only makes sense and its fairly cheap. I would have your rotating assembly fully balanced for sure. As far as cryo freeze... i look at it as i would rather have a rod bend than break. If you cryo a stock rod and if it sees the stress of damage my guess it would rather break than bend. My vote...no cryogetic freezeing. Take all your parts to a engine builder and have them balance and polish everything, then send out to have pistons coated.
 
The others are right on the rods, IF YOU are doing the polish work - only grind or polish parallel to beam, NOT across the beam. Besides you are not going to change the wt. enough to matter anyway. Coating is excellent - We have coated pistons & brgs in our diesel that ran 3 seasons of pulling and still look like new. We also cryo-d our engine parts [ do all machine work first] , I checked valve spring pressures after 3 seasons still within 5 # of when installed. [ stock springs! ] I have a cryo facility about a half-hour away from me. YES to coating, Yes to cryo, You must balance when you change anything on rot. assm. . We checked a stock cummins crank last week and it was out
5 grams in rear and 2 grams in front -pretty good for for stock american stuff. Also think about your damper as well. If you're near me I can do this stuff!.
 
finishline mach said:
The others are right on the rods, IF YOU are doing the polish work - only grind or polish parallel to beam, NOT across the beam. Besides you are not going to change the wt. enough to matter anyway. Coating is excellent - We have coated pistons & brgs in our diesel that ran 3 seasons of pulling and still look like new. We also cryo-d our engine parts [ do all machine work first] , I checked valve spring pressures after 3 seasons still within 5 # of when installed. [ stock springs! ] I have a cryo facility about a half-hour away from me. YES to coating, Yes to cryo, You must balance when you change anything on rot. assm. . We checked a stock cummins crank last week and it was out
5 grams in rear and 2 grams in front -pretty good for for stock american stuff. Also think about your damper as well. If you're near me I can do this stuff!.
Click to expand...

i've seen them off as much as 30 grams front to rear, and some that are like you said very close. Still very good for what it is.
 
Mine were off around 30 grams.

8a425238.jpg

4e2f2fb7.jpg

(this was not the finished product, but it gives you an idea.)
 
You must log in or register to reply here.
Back
Top