what would be a dream piston for the 'average' build?

[getchasum]

I''d be interested in hearing some detail as well in an off the shelf 4.1 Stroker.......

 

[earlbrown]

The 4.1 strokers will pretty much be the same as the 3.801 units. The way I have them set up, the bore can be whatever you want (between 2.500" and 5.500" ) and the piston pin can be put wherever you want it. That pretty much covers everything from a stock 3.8 build up to a big bore stroker.

Now If I can just get the damn mail woman to show up with my prototype so I can post pictures of it!

 

[robzombie]

With a set of what I'm building, a rebuild will go like this... First you measure the worst hole and figure out where it will clean up at. Rough hone it to size (no more boring!) and tell me the final bore size. Then, decide what static compression you want using cost effective non custom gaskets. That sets the compression height (no more decking!). As long as the piston isn't too close to the head, that's it!

I've read most of this thread and the one thing that bothers me is when you say no boring is required.

What if it is out of round?? It will require boring otherwise you will have blowby amongst other issues.

You might be able to get away with a hone job and minor cleanup on a low mile engine, but I would have it checked regardless to see what you have.

The block after all is the foundation from which all other parts are decided as well as as longevity of said block.

 

[earlbrown]

If there's no deep scratches you can hone the cylinders round and go from there. Before I started doing this the conventional wisdom was to bore until the worst hole comes clean then go to the next oversize piston. With these, you hone the worst hole clean and then stop. Since we have to run wider than normal ring gaps, taking 1 or 2 thou more than 'normal' is no problem.


Needless to say this has to be down with an actual honing machine. A drill powered 3 stone hone (or those stupid dingleberries) can't do it correctly.

 

[robzombie]

I not sure I understand you.

Are you saying that if the worst hole is 6thousandsth out you would just hone all cylinders to that spec.??

Why do we need wider than normal ring gaps ? That would cause more blowby.

 

[earlbrown]

You always do the worst hole first because.... well... that's the worst one.


Engines with power adders need more ring gap to the hotter temps the rings experience. Under operating conditions the gap closes up more than a low HP N/A engine.

 

[robzombie]

You still didn't answer the question Earl, you sure you're not a politician??

Are you saying that if the worst hole is 6thousandsth out you would just hone all cylinders to that spec.??

 

[earlbrown]

There's no 'spec' to hone it to. The block tells you when you can stop.

Without having the block in front of me and running the machine itself I can't answer it. Plus, that question is a little too simplistic. "6thou out" is only one way to describe a cylinder. You've got taper, ovality, the area where the top ring stops that's hardly ever concentric, etc...

Odds are if I was honing a cylinder that was '6 out', I would go to an even .010". The boat pistons I picutred above are 10 overs. My cylinder measured .006" out on the worst cylinder. It actually came clean at .009" and I final honed it to .010".


With our engines, ring selection is going to define the final bores moreso than the instant a block comes clean.

 

[robzombie]

With our engines, ring selection is going to define the final bores moreso than the instant a block comes clean.

Exactly!

That's why I'll just stick to the way I've always done it.

Hone after bore and know it's perfect and be done with it.

Thanks for your theory on how to bore out our blocks, I just didn't grasp where you were going with it until that last post.

 

[earlbrown]

I think you're the only Buick guy on the planet that prefers to remove more metal than you have to. I can't tel you how many posts over the years I've seen when people rebuild STD bores that need boring just to 'save the block'.


Give me a call on your next build and I'll fix you up with some +.125"s!

 

[Fast4Ward]

Is Rob Zombie really on this board and owns a GN

 

[novaderrik]

Is Rob Zombie really on this board and owns a GN

why not? David Spade is around here somewhere...

 

[juan89]

Any updates on the pistons ? I need two sets.

Juan

 

[Jay J]

Yes--What Juan said. If I remember right, you were going to launch the piston deal last weekend? Or maybe I missed it.

 

[earlbrown]

I did. I've been trying to figure out how to do some sort of 'group purchase' discount.... only with it actually working instead of like most GPs go down. That and working on my whole stupid 'real life' thing!

Right now it looks like the price is right at $450 a set with pins and locks. Factoring in rings has been a pain. A small change in ring size has BIG swings in price both up and down, so I put that idea on the back burner.

Right now it looks like I'm going to put the rings off the the side and working about getting the discounts on those later....


Now, as far as the pistons I have them right at $450/set with pins and locks. In all reality I should be happy and stop there.... but those that know me in real life know that's not how I do things

If I can't get the price much lower than that, I'll still be happy. Right now the retail price of a -custom piston (with a more expensive Buick pin), in low volume- is right at the same price as a non-custom Chevy piston (with a cheaper pin) at jobber price.

Now that I've typed that out and seen it with my own two eyes, I should probably just be happy with it. LOL


Since a normal GP makes a bunch of people pay money and then wait who-knows-how-long just to hammer the manufacture and slow things down even more.... I don't like that idea.
What I'm thinking is a discount for something like 6 weeks. That way when you plunk down the money, they start getting built. Then after 6 weeks if there's still a need, try and get them to either extend it or offer a slightly smaller discount. Then to combat people missing out waiting on the machine shop, a deposit can lock in the discount. Once the bore and CH are known they've got the good price.

 

[broke]

You always do the worst hole first because.... well... that's the worst one.


Engines with power adders need more ring gap to the hotter temps the rings experience. Under operating conditions the gap closes up more than a low HP N/A engine.

Does this include E85 engines?

 

[earlbrown]

Yes and no. If it's a gas build that's running E85, not really. If it's a purpose built E85 hotrod that you're going to beat on, then 'maybe'.


The science is from the fact that a ring runs hotter than a cylinder wall. Since we have to set the gap at room temp it has to be guesstimated what gap words at full temp WOT. As the ring heats up it grows and the gap closes. At the same time the cylinder wall heats up and grows much less.

When gapping rings it's always best to err on the loose side. Best case you lose so little HP it really can't be measured... If the gaps are too tight and the ends butt together, you pop the top off the piston and then all hell breaks loose.

 

[broke]

Mines is a purpose built gas motor on E85.

 

[earlbrown]

Then you gots plenty of room

 

[earlbrown]

Bump. Looks like I've got them at $450 for a set of 6 (pistons, pins and locks). That's 3.8 or 4.1 sizes. Price with rings will be a little different a 3.8L ring sizes are more expensive than 4.1L size.

I'll be ordering 3 sets in common (I hope) sizes, 3.805", 3.832", and 4.000" on Monday to test the waters here and outside of this site.