piston options?

[sonic blue l]

Well have my engine tore apart due to lifter failure, piston contact with valves so I decided to might as well put all new pistons in. Just curious if piston ceramic coating is worth it? Trying to gauge the worthiness on a daily driver if one is using international pistons. Same with the de lipping, if using ih pistons should one even bother?

btw taper is .0005" so im not too concerned about that, but out of round is a bit at .0015". if memory serves the bore is 3.865" measured across the thrust angle, a .00015" max tighter across the non thrust. Its still in spec for out of round (spec is .002"). Debating if I should rebore, but I don't think I really have too. I guess it really depends on the replacement piston size as I think a ridged hone would take some of that out. That is if there is room to hone that much.

when pistons are coated is it just the tops?

Thanks.

 

[sootie]

delipping is not necessary with IH HD pistons. in fact, if you are in a cold climate, keep the little lips they have.



Ceramic coating is very wise to do. usually only costs 300-400 and drastically helps keep the pistons from cracking.

 

[sonic blue l]

so in your opinion coating would be more important then the delipping?

what about valve reliefs?
I'm probably going to wait and get a colt stage 2 cam when available. (on the fence about a regrind stage 1 since my cam has to be welded) Geoff from colt told me that it was not required, (I will still check), but Id hate to have it all together and then pull it back apart.
I was not going to do valve relief's for the same reason as keeping the lip as I do live in cold climates, although I mostly don't drive the truck much in the winter.

Do you know if delipping reduces compression more then a .060" valve relief?

Also what do you think of my bores? Good enough to not worry? (I know I still have to size the pistons, but if they come stock size then it will be only a light hone to remove any glaze, but wont do much to any bore out of round,

Thanks.

 

[sootie]

i would coat before delipping if i had to do one or the other. mine are delipped, fly cut and coated lol...cold starts suck

i did valve reliefs for insurance as i have had piston contact in the past. i only have a stage 1 cam.

im not smart enough to comment on the bore measurement,

 

[sonic blue l]

just smokes a lot or hard starting? both?

 

[NY_Mott]

Yea Sootie ^^^^ what he said.... Have been reading everything I can on the pistons and rebuild, this is the first if seen anything about cold start issues. ( not that I don't believe you; just looking for more info)


08CCSB -Rudy's delete, studs, Afe-cai, 5"MBRP, black max, 4"revtek, PMF
F/F T-bars

 

[sootie]

it never doesnt start, it just lopes pretty hard until the engine temp gets up to 100* and heavy whitish blue smoke kinda like a pulling a tractor when thy first start up. strong diesel smell-basically it is incomplete combustion becasue of the reduced compression. not even noticeable in the summer just we have had a freaking cold winter up in canada and when it is -9 and below it is really noticeable.

 

[SlowSmoke]

I also have flycut and coated pistons in my 6.4 with a stage 2 colt cam in it. It does stink and smoke blue when cold, but always starts fine. Once warm it clears right up. In my opinion, i would get the pistons cut and caoted if you are going to go with a stage 2 cam, but if only going with a stage 1 you will be fine. Coating is worth it in my opinion. As far as bore size goes, i can get my hands on a set of .020" International HD Piston and coat them for you. This way you get the better piston and have a new bore to work with. I will have to check if i can still get those pistons though, there was limited supply made.

 

[sonic blue l]

I also have flycut and coated pistons in my 6.4 with a stage 2 colt cam in it. It does stink and smoke blue when cold, but always starts fine. Once warm it clears right up. In my opinion, i would get the pistons cut and caoted if you are going to go with a stage 2 cam, but if only going with a stage 1 you will be fine. Coating is worth it in my opinion. As far as bore size goes, i can get my hands on a set of .020" International HD Piston and coat them for you. This way you get the better piston and have a new bore to work with. I will have to check if i can still get those pistons though, there was limited supply made.

actually I was going to get the pistons from you, ive already bought a few things from you. Just doing the repairs in my garage on a spare engine so im just piecing it together as funds permit. Original engine is still in truck and running fine. I was actually going to order pistons from you this week, but im trying to determine which options will suite my needs. I don't really want to re-bore unless I have too. The block is still in spec so I don't want to thin things out unless I have too, besides I don't know of a good machine shop so I don't want to end up worse off then what I started with.

I'm also going to grab a 72 atmo from you before the engine actually goes in the truck. Hope to have it all done by june so I figure that gives me time to spread the cost out.

Truck will be to tow my holiday trailer, mostly looking for a tow monster with lower egt's. No drag racing or sled pulling or anything like that. I'm still on the fence with the stage one regrind, just not sure if there are draw backs to it vs the billet stage 2. Honestly if the stage one was a billet i'd probably go that route, just worried about a welded cam.

 

[sonic blue l]

just to add the 3.865" is actually on the small side of spec, so depending upon the pistons I might have to hone to size anyway. Do you recommend the factory piston clearance or slightly more?

 

[SlowSmoke]

just to add the 3.865" is actually on the small side of spec, so depending upon the pistons I might have to hone to size anyway. Do you recommend the factory piston clearance or slightly more?

We build them all to factory clearance and have good luck. You must be the guy from Drayton? We've also had good luck with regrinds from colt, but i understand where you are coming from. We have built a truck with a stage 2 cam without flycutting the pistons also. Colt says if the heads and block haven't been decked, there is about 0.030" clearance there which is all you need. I am running the 71/59mm turbos on my truck on stock injectors, and i've never seen EGT's over 1200 on a 250hp tune. If you want to stay stock bore, i would for sure go with coated HD pistons if you want to spend the few extra bucks over the de-lipped Mahle's.

 

[sonic blue l]

yeah im from Drayton.

Thanks for the help, im pretty sure I will go with the stock bore, coated pistons. Engine/heads have never been machined. might still just go with a stage 1, as when I get my mind on something I just want to get it done. Cant reassemble until I get a cam.
Do you notice much of a difference between a stage 1 and 2 on your builds?

So who makes the stock bore HD pistons? Do you stock them?
(heading to Red Deer in a couple weeks so i'd like to stop by if I get the chance)

 

[sonic blue l]

just a thought. what's the benefits of delipped pistons if it causes smoke during cold start?

I wonder what a manual compression test would be on a delipped piston vs a non. Typical compression for this area should be 380. less then 350 is poor, less then 300 wont properly support combustion.

 

[sootie]

the purpose of delipping is to remove the narrow point of material that is prone to cracking and melting due to the spray pattern always hitting there and causing concentrated high egts. think cutting torch.

 

[Cknox121]

I coated mine...

 

[sonic blue l]

the purpose of delipping is to remove the narrow point of material that is prone to cracking and melting due to the spray pattern always hitting there and causing concentrated high egts. think cutting torch.

yeah, but if the ih pistons are better then why bother?

do you happen to have a pic of a non modified ih piston?

google is not really conclusive in the fact im not sure if they are actual ih pistons. Some are delipped and some are not. The non de lipped appear to have no thin ridge like the factory, but a thick edge. (from what I could tell by a picture). If those are indeed ih pistons, then one would think the " thick " lip would be more resilient then the thin edge factory pistons.

 

[sonic blue l]

I coated mine...

I think im leaning towards that too. I was unsure about flaking off and longevity, but coating has been around for awhile so I'm not sure if that concern is even a concern to have.

 

[sootie]

yeah, but if the ih pistons are better then why bother?

do you happen to have a pic of a non modified ih piston?

google is not really conclusive in the fact im not sure if they are actual ih pistons. Some are delipped and some are not. The non de lipped appear to have no thin ridge like the factory, but a thick edge. (from what I could tell by a picture). If those are indeed ih pistons, then one would think the " thick " lip would be more resilient then the thin edge factory pistons.

you are correct. factory lip is thin and sharp, HD is thick and rounded. yes it is more resilient-in fact i know if no failures from cracking on hd pistons. delipping is just that much better. also note-i had zero cold start smoke with hd pistons.
here is a pic of the HD pistons i used to have in my motor...

http://powerstrokearmy.com/forums/showpost.php?p=843844&postcount=100

 

[sonic blue l]

you are correct. factory lip is thin and sharp, HD is thick and rounded. yes it is more resilient-in fact i know if no failures from cracking on hd pistons. delipping is just that much better. also note-i had zero cold start smoke with hd pistons.
here is a pic of the HD pistons i used to have in my motor...

http://powerstrokearmy.com/forums/showpost.php?p=843844&postcount=100

Thank you, I appreciate the pic.
I think those style coated should work well for my needs.

So I see your block cracked .
I'm going to use stock head bolts, out of fear, besides I think they will hold for what im doing.

 

[sootie]

Thank you, I appreciate the pic.
I think those style coated should work well for my needs.

So I see your block cracked .
I'm going to use stock head bolts, out of fear, besides I think they will hold for what im doing.

dont use tty head bolts. just do studs properly. a calibrated torque wrench and dropping torque on the holes that are prone to cracking works fine.