Piston / Build question

[James Neidig]

Thanks everyone. I spoke to Mike at Forward Motion today. I am going to pull it down and measure the bore with a good bore gauge. He can get me JE's and rings to work with the bore I have. I will be taking the rods to the machine shop to open up the end for the larger wrist pins as well. Once complete, I will have the option of going with larger injectors, a retune of the stage 3 SMEC, and more boost....but...for now I will keep the top boost at 15psi. Had planned on making Carlisle this year, but it won't be ready with paint & all... Always next year. Thanks again for all the help, I appreciate it!
Jim

[turbovanman²]

Simo: all the oldschoolers running the Venolias in the late 90's were running them at .006-.007 One guy just posted that is in their range, so I'm not totally wrongo.

You realize this is 2010? Things change,

Weisco and Venolias are made of the SAME material, and they require .0035, nothing more. FYI synthetic oils do a much better job than dinosaur guts, better lubrication means closer tolerances. If you made pistons and understood the general populace isnt going to wait for the vehicle to warm up you wouldn't tell them .0035.
Fact-
Fwd told me .0035 is fine for Venolias with synthetic
Weisco has.0035 printed and included with piston kit again with synthetic
Forged pistons are twice as strong..period

Agreed, the JE specs on the sheet list .0035-.007 or close to that spec. They errr on the side of caution as some drivers don't understand with a forged engine, YOU MUST let it warm up before beating on it.

[Directconnection]

Weisco and Venolias are made of the SAME material, and they require .0035, nothing more. FYI synthetic oils do a much better job than dinosaur guts, better lubrication means closer tolerances. If you made pistons and understood the general populace isnt going to wait for the vehicle to warm up you wouldn't tell them .0035.
Fact-
Fwd told me .0035 is fine for Venolias with synthetic
Weisco has.0035 printed and included with piston kit again with synthetic
Forged pistons are twice as strong..period

Once the pistons and engine are hot both pistons are at the same outer dia, its during startup that is the issue because cast pistons have a steel strut cast into them to control expansion. Yes you can run 20+ psi with good gas but good luck with that, how well is octane monitored at gas pumps? You can run cheaper fuel with forged pistons and keep boost low when you want to save a few bucks commuting to work!
Go forged and you cant go wrong.

Is this an arguement, or someone giving out factual data???

2618 isn't quite the same for everyone now, is it? Meaning, low to nearly no silicon content..... vs. the high silicon content of the other forging (4032?) ie: low to no silicon means different rate of expansion even though it's 2618, right?

Piston fitting has a lot more to do than startup... it is soley on INTENDED purposes.

We bore/hone for just about every piston manufacturer out there. (Ross, JE, CP, Wiseco, Diamond, SRP, etc) and we do use the factory spec sheet as our guideline, but also custom tailor the fitment per intended usage. Nitrous... or Blower... or Marine... all require different things, same for the pin fitment, as well. That alone, has nothing to do with startup. (or synthetic vs. dino...) You are right that people can "cold seize" a piston being a tool on startup.

[trannybuster]

The only facts that I know of are what I listed under facts. This argument about Weisco or Venolia material was cleared up some time ago wasnt it..? Only a tool would disagree that differnt grades have no effect, thats not me.
You set piston clearence depending on application BUT in the end when absolute growth occurs they are all running pretty much a close tolerance, if not the piston would rattle around and crack the skirt. Oils make a huge difference, I cant agree otherwise.
Whether you or I agree doesnt matter, hes making the right choice going with forged, his decision is on intended application strictly race or street rod.
My Venolias I went with .005 and have had 0 issues street rodding it. I just installed Weisco and went .0035, time will tell, hopefully A LONG time...
Maybe we should start a thread stating clearly
1-clearance
2-oil
3-issues

[James Neidig]

Thanks again to all. I believe my decision to go forged is the right one.
This is pretty much a mid-life crisis car (I'm 38) so it's main use will be fair weather driving with the occassional whooping of some punk in a Honda with a fart can.... I am going to measure everything out and buy new...if I need to, I will have the block machined again. Oh, and I will be running dino-oil for the first two changes, each at 150 mile intervals before switching it to synthetic.

[trannybuster]

BTW Directconnection Im not debating your 'engine building prowess' nor arguing, nor did I take your thread as such...
Good luck on your engine build..er rebuild lol!

[Directconnection]

BTW Directconnection Im not debating your 'engine building prowess' nor arguing, nor did I take your thread as such...
Good luck on your engine build..er rebuild lol!

No problemo

[turbovanman²]

Thanks again to all. I believe my decision to go forged is the right one.
This is pretty much a mid-life crisis car (I'm 38) so it's main use will be fair weather driving with the occassional whooping of some punk in a Honda with a fart can.... I am going to measure everything out and buy new...if I need to, I will have the block machined again. Oh, and I will be running dino-oil for the first two changes, each at 150 mile intervals before switching it to synthetic.

I would put at least 2000 miles on it before switch to synthetic.