Diamond Pistons Group Buy

XR7 Dave

Registered User
Looking to put together a group purchase for Diamond Pistons. These pistons will be available in any configuration desired, the first 5 people to get in on this buy will establish part numbers for future SC people to be able to call us up and order pistons thereby avoiding the cost and complications for a custom piston each time a forged piston is desired.

These same people will be able to take full advantage of any and all price breaks offered by Diamond for a volume buy. Final details will be posted Monday.

So far we have 5 people interested:

Mike (Mike8675309)
Scott (Kiwikiwikiwi)
Scott (lilredstang)
Jason (Jason Wild)
Randy (Randy Baker)

I think I may have 1-2 more so it looks pretty definite.

Anyone else speak up now!

:)
 
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I am interrested. And more details.
price.
shipping date.
piston Wt.Vs stock
Rod infor to fit piston wrist pin heigth.
wrist pin style and Wt.

Thanks Randy
 
The diamond pistons I bought used 351 rods. I probably have the spec sheet somewhere. As far as weight I know teh JE pistons were by far the lightest of all options I exlored
 
Thanks Damon.I will most likely mill the backs to lighten &
balance,no matter the brand.Wrist pin Wt. is my main
consern.and if they would have a choise of different
pin styles.I can't do much in lightining hardened parts
like this.

Thanks Randy
 
The pistons should be available in any configuration that Diamond offers. They also offer skirt and crown coatings if anyone is interested.

Pins are also available in different diameters if you want to run different rods.

I will ask about cost for different options. For example:

Skirt coatings
Crown coatings
Pin diameters (stock is .912)
Pin weights (I will weigh the stock parts)
Pin material options
pin lock materials (wire locks vrs spiral locks)
minimum compression heights
turn around time
fitment for stock connecting rods/ and others

And prices for everything.

Any other questions I need to address? I don't think I can get exact weights until the design is finalized, but I will ask. Obviously weight will vary based on some options chosen.

I am calling on Monday so I want to have all the right questions to ask them at one time.

Thanks everyone!
 
So Are We Going To Be Paying Diamond Or One Of The Group Members For These?
The Name Is Scott By The Way, But If You Want To Call Me ?, Thats Cool. I'm Easy Goin. :d
 
Payment will be made to me (SuperCoupes Unlimited), I will be buying all the pistons and in turn shipping them to you.

Jason, stroker pistons will be made based on desired stroke and rod length. This will be a custom piston in any configuration you want.
 
Ok guys, here is the low down.

Options available:

Any compression height you'd want. 6.2" rods would require a 1.3" compression height on the 3.8. Minimum compression height is 1.0".

Compression ratio is a function of chamber size / gasket / and deck height. Most any configuration is available, chamber will be a D shape to match the heads. Valve reliefs will be cut for 1.94" intake valves.

Cost for pistons is $77/ea

Pins (.912") are available seperately in 4130, tool steel, and thinwall tool steel. Cost is 9.75/ea standard and $15.80/ea for tool steel

Ceramic top coatings and moly skirt coatings are available. $21.50 and $15 respectively.

All overbore sizes are available.

Production should take 3 weeks and I'd like to place the order within the next couple days.

Ring package is 1/16, 1/16, 3/16 or 1mm, 1mm, 3mm moly only. No other options are available from Diamond. Cost is $96.40/set and $150/set respectively.

All prices are + shipping. This price is the exact cost of the pistons and options. I am taking no markup whatsoever on this group buy. This will not be repeated so if you want them now is the time to step up.

Please email me with your exact requirements right away. Friday am is the deadline to have your money in.
 
Do you maybe want to start a thread on "decisions, decisions... optimum forged pistons".

How to get you the money? Do you really want to paypal that? I wonder what the cost of a bank transfer would be?

i.e. what are the best most reasonably priced rods that could work with these pistons? How do I know what compression height I want?


Stuff like that. i'm going to see if I can get my block down to the machine shop this week to at least get dimensions off it to determine the overside on the pistons required.
 
Compression height is a function of rod length. Gotta decide on the rods first.

Overbore I'd go with .030. That will be a safe number regardless of what condition the block is in.

For paypal you'd have to ad 3% ($15 roughly). I will accept cashier's check if you have it sent via Fed Ex or other trackable service. Bank transfers suck.
 
I have a set of (8) 351W I-Beam rods with ARP Waveloc bolts by CAT that are brand new I'll sell you for $150 shipped. They will be plenty strong for up to 500rwhp.
 
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XR7 Dave said:
I have a set of (8) 351W I-Beam rods with ARP Waveloc bolts by CAT that are brand new I'll sell you for $150 shipped. They will be plenty strong for up to 500rwhp.

I may be interested in the 351W rods, but I gotta scrape up the $ for the pistons first :rolleyes:
 
XR7 Dave said:
Gotta decide on the rods first.
What would be the motiviation to go with the 6.2 rods over the stock 5.996 rod length?

I believe it may be related to piston speed at high rpm. using a chart and spreadsheet found here http://e30m3performance.com/tech_articles/engine-tech/rod-ratio/kin2.htm

Stock Crank stroke of 87 mm (3.40in) and stock 351 rods of 144.25mm (5.956in) you get a max velocity for the piston of 28.86 and acceleration of the piston max at 23m/s^2

Go to the 6.2" rod and you get max velocity of 28.81 and acceleration of 22.8m/s^2

Now I'm not knowlegeable enough to know if this spreadsheet applies directly to our engine. Crank design may play a role in the calculations. These are numbers at 6200rpm as well.

So should I be thinking the longer rod to help control piston speed at higher rpm? This motor will likely get the Autorotor with plans for sustained visits slightly above 6000k.
 
Note found a great explination of rod length preferences from Vernon back in 2003 ... kinda miss that guy.

http://sccoa.com/forums/showthread.php?s=&threadid=23811&highlight=deck+height

I'm planing on 6.2 rods then. I'll pickup some H-beam rods later. Just a couple more questions. (I'll send money via paybal I guess)

How do the Diamond coatings compair to Swain Tech? I've only heard of Swain Tech talked about very positively.

If I'm going to go .030 over, what kind of issues are there related to skirt coatings regarding sidewall clearance?

And rings...not being a engine builder, what's the difference between the two items, and what are your thoughts on how these may compare with a set from Total Seal?

Will the pistons come with lock rings?
 
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People who are actively responding include Mike, Scott, Scott, and myself. That's 4. I need another or it won't happen. We have to have 5 people before I can take any money.

I don't know about the coatings. As with the whole "Whipple vrs. Autorotor" discussion I'm sure there are people who could present an argument for either one. I have no idea but I think the a ceramic coating would be a big plus if you plan to run nitrous or extreme boost or WOT for a sustained period of time.

I can ask about the skirt coatings and clearance concerns.

I think for my money I'm going with Total Seal rings. Just my .02. The more expensive rings from Diamond are thinner low tension rings which I would probably not use in a forced induction motor.

FYI

Stock rods are 5.915
351W rods are 5.955

Both are good rods, longer is better but the shorter the piston gets the less stability in the bore. I don't think there is a huge advantage one way or the other. I'm planning to go 6.125" but I could go with the 5.955 just as easily.

I'm sure the pistons will come with the locks, but I'll check.

David
 
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