The machine shop wants to know what it is to properly hone my cylinders, and I didn't save any from the old pistons Does anyone know?

 

I'm not sure to fully understand your question but the first thing you want to know is your technician need to confirm what is the tolerance between the piston you are putting in the engine & verify the tolerance with the cylinder wall.

The maximum tolerance between the cylinder wall and the piston is .004 or .005 if I remember correctly, I dont have my spec sheet in front if me but from the bottom of my mind, I remember that the tolerance on my block was .007 and out of spec for stock size piston.

I took the decision with my technician to have the engine honed oversize in order to match the custom .020 oversize piston I ordered later. The shop will machine the block to have .003 of clearance between the cylinder wall and the piston.

If your block is out of spec, you have the following choice:

1- Hone the cylinder wall by let say .020 and order custom piston.

2- Sleeve the engine and use stock piston or custom oversize.

3-Replace the engine block, but if you buy a used one you may end-up back to the beginning.


I hope it help.

AA

 

His question relates to the material used in the ring. There are different honing techniques required for different metallurgies.



Sorry I can't help with your question OP.

 

That is exactly it. doublea what did you have the machine shop do? I feel like these guys are trying to do the best job and who am I to stop them

 

I didn't know that different honing technique would be used depending on the ring material, I thought it was related to how the engine would be used, ie: race car that is N/A or race car that is boosted or or a street machine. The custom piston I ordered are not arrive yet so I dont think the shop fm wouldn't know until he see what material was used for the custom piston. I remember the foreman saying that whenever they honed a block for a boosted application the cylinder lower portion is not totally circular and you need to have the wrist pin set @ .040 instead of being in the center but the stocker are also at .030 or .040 apparently this allow for more HP.

 

There are different stones/grit, varying RPM and up and down strokes per minute used during the honing process to maximize the chances of the different ring materials seating properly.



And the last thing you mentioned is wrist pin offset and is usually a function of a motor's rod:stroke ratio, piston material/skirt design and piston-to-wall clearance. It increases rod angularity on the power stroke to reduce piston slap (noise).

 

This is very well explained and I couldn't have explain the way you did, my french brain doesn't allow me to have such ability to formulate nice sentence in the Shakespeare language. Most of the time when I want to explain something complex in English, it require me a lot of attention and I literally struggle to formulate what I want to say. I'm pretty good in french but most of you wouldn't understand what I'm saying.Lol

Thanks again.

AA

 

haha well said, you can definitely post in french and I'll probably understand 5% of that... 10 years of Canadian education gone to waste

I figure it is just like you said nismology. The shop says most import rings are chrome, so I'll go on a leap of faith that Nissan hasn't done anything funny with the VQ.

Something else that has come to my attention and somewhat bothers me. The FSM calls for out-of-round and taper measurements with the block unloaded, but a common practice is to hone with a torque plate to achieve roundness with the clamping force of the head. Has anyone else picked up on this discrepency? what has your machine shop suggested?

 

Somehow I highly doubt that VQ rings are chrome. None of the new OEM rings that I've seen have that bright silver finish. For reference, these are new OEM VQ35HR rings and look similar to what I've seen for other VQ's.



Yea those measurements should definitely be taken with a torque plate and crank caps/girdle installed and torqued down.

 

hmm that definitely doesn't look like moly rings (which would have a bronze color?) but more like a nitrite coating...

 

Alright guys, got talking to DaveB today and he confirmed that the VQ30DE-K (I suppose these are the same for all VQ30s?) are a chrome-tipped top ring and an iron 2nd ring. Now we know!