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Piston Selection

Methanol may require different metering, problematic if you don't know how much, I certainly don't. Need adjustable system, methanol is also very poisonous, be careful using it. It burns with invisible flame too, no fun there. We caught some on fire once while racing the pro stock car, if it hadn't been close to dark we wouldn't have even known it.

More compression you run you should be able to drop timing advance. You seem to know that already.................

Although I have heard engines with noisy cold startup pistons, by and large I don't really remember it being a given that forged were noisier even though I too had heard that a lot. Can't remember any customers griping about it.
 
Heywood said:
Diamond at NPG are listed at 995 now. Wiseco price was through my machinists contact, but is canadian price - so might be a little higher.
I have heard good things about Arias also but haven't investigated them further.
All prices I listed are with rings, pins and locks. I would love to get them cheaper. I called ross again today and I need to take a moulding of the head if I want them domed for 11:1 CR but still same price.

Don't forget its been a couple of years since you started your build :laugh:
Click to expand...

Yea I realize it's been a couple of years, but prices have not inflated that much. I personally wouldn't buy through NPG for pistons, the markup is quite large. The price from ROSS included rings, wrist pins, and locks. However for my application they recommended the upgraded wrist pins and rings.
 
Did you have a contact at Ross or was that their standard rate? It seems there's a big difference if you know someone who can get them wholesale.
 
Nope, I just called their main line and ended up being directed to the custom products guy. He was pretty cool and was interested in my project.
 
So I am sending off the mold of the combustion chamber to Ross today so that they can make me some 11:1 pistons.

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Yeah I will be replacing the rods. Probably K1 but open to suggestions. Haven't found anything else in the same price range. Not interested in going to Pauter or cunningham in the 12-1400$ range.
 
I would document your order and share it with everyone here. That way should anyone else care to order the same pistons they could reference your order and have ROSS recreate your pistons.

On another note did you really have to make a mold? I would have thought you could have just gotten them a volume measurement and called it a day. That's all I provided to Diamond Racing to have my pistons made.
 
Weren't you dropping CR where as I am increasing it? They have to dome the top of the piston so they need to know the exact valve arrangement. For lower CR its dished so it doesn't matter the shape, just the volume.
 
The noise issue with the Forged pistons had to do with the inability to control expansion rates well as with the HE, or Cast type that are more common throughout the Auto industry; generally more cylinder to piston clearance is required with forgerd. If you're building a track car or one you are going to put a power adder on or beat on, best to spend the money on replacemant rods and Forged pistons. If you are keeping the stock cams, either 3.0 or SVT, bumping the compression should be considered with caution. If you are adding different cams with more overlap then compression will need to be raised to recover the cylinder pressure lost by the increased valve overlap common to most performance cams. Forged pistons in a performance rebuild are a no brainer. The 4 valve heads on the Duratec series flow very well. The 4 valve pentroof arangement (thank you Cosworth)lends itself to very high flow rates and high output from small displacement, consequently they respond very favorably to increased RPM so build it to accept the increased RPM or you'll be picking up the pieces and doing it again. Lastly, use proper fuel if you're tracking it 100 octane minimum.
 
Thanks for the input Rick.

I have sent a mold to Ross and am awaiting a call to finalise the order for the pistons. I plan to go with 11:1 CR.
I have read alot and talking to my machinist, who builds almost exclusively race engines, higher RPM is generally a losing game. I did think about it, but it didn't seem to make sense. Engine will handle a bit higher than stock I'm sure but from what I've seen the power flattens off around redline anyway.

PS - I am using SVT cams for now.

PPS - This is a ported 3l head build - so I expect flow to be limited somewhat at higher rpms by the split to oval transition.
 
Looking for the combustion chamber volume if anyone knows what it is for the 3L heads.

Thanks!
 
OK for all to see/correct:
Swept volume (bore 89, stroke 79.5) = 494.6 cc

Compression ratio of 10:1 => Combustion chamber + deck clearance + head gasket thickness volume = 55 cc

But
Combustion Chamber = 52 cc from link above
Deck Clearance (Deck ht - piston ht - rod length - 0.5 stroke = 208 - 30 - 138 - 79.5/2 = 0.25 mm) => 1.6 cc
Head Gasket (1 mm in link above) => 6.2 cc with no oversize on the gasket
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52+1.6+6.2 = 59.8 cc or compression ratio of only 9.3:1

Based on these numbers I think I'll specify a dome volume of 6 cc
Will give CR between 11.1 and 10.2
 
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