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Need a piston recommendation

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Need a piston recommendation

Postby mitchmc » Wed Nov 23, 2011 12:45 pm

Hey guys, building a new motor for my car this winter and need a recommendation on some pistons for it. Its a 4.310 bore x 4.000 stroke combo bbc. Steel crank and eagle H-beams. Using 990 casting heads, bone stock with manley valves. Not looking to do any work with them because I will be selling them later on to replace with a set of nice aluminum ones. Haven't decided on camshaft yet, but was looking at a Howards 121313-12. Intake is a big dart single plane, not sure of the exact model or number on it yet. What I am looking to get out of the motor for compression is about 10.5-1 for now, maybe a little higher with about a 0.037 quench (can I go tighter with this? Or too tight already?), but still maintain decent piston to valve clearance for future modifications to it. Then maybe get a set of the AFR 114cc chambers later on and bump the compression a little. Would like to make 550-600hp, with 550 being more realistic. I'll probably be running a quick fuel 950 on this motor as well. Running on 91 octane pump gas with possible mix of C16, but with the tight quench I think I may get away with this compression on the iron heads.
Any input appreciated!
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Re: Need a piston recommendation

Postby dfree383 » Wed Nov 23, 2011 12:52 pm

Something from Probe is a good value, seeing that what your doing doesn't require anything trick.
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Re: Need a piston recommendation

Postby mitchmc » Wed Nov 23, 2011 1:50 pm

Looked at some probe ones, they go straight from 18cc dome to a 39cc dome, I could get what I want with the 39cc, but kinda big might make some piston to valve clearance problems. sorry I forgot to mention in the post above that I'd like them to be forged, just for the sake of knowing that I can put more power to the bottom end if need be. Seems like its a really tough piston to find. Also forgot to mention I have 6.135 rods. Thanks!
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Re: Need a piston recommendation

Postby needforspeed66gt » Wed Nov 23, 2011 3:25 pm

The Icon(KB) forged line is really nice for the price.
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Re: Need a piston recommendation

Postby ProPower engines » Wed Nov 23, 2011 5:59 pm

Mahle power oak pistons are another good choice. Although at first they appear to be more than the KB pistons they do come with a real good file fit ring set where thats a needed item in the build anyway.
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Re: Need a piston recommendation

Postby Nitrousknob » Wed Nov 23, 2011 6:28 pm

When you shop for your pistons make sure they will work with AFR heads. All pistons will work with the 990s but not with the AFRs, combustion chambers are shaped different. Had that problem once before. Changed from brodix to AFR
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Re: Need a piston recommendation

Postby rustbucket79 » Thu Nov 24, 2011 12:47 am

X2 for the Mahle Power Paks. We used the .030 version in a build a while back, nice looking pistons, fairly light too. FWIW, our pistons did not have the 1/16 rings, it had the thinner metric rings.

http://www.summitracing.com/parts/MLE-BBC645310D28/
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Re: Need a piston recommendation

Postby needforspeed66gt » Thu Nov 24, 2011 1:17 pm

ProPower engines wrote:Mahle power oak pistons are another good choice. Although at first they appear to be more than the KB pistons they do come with a real good file fit ring set where thats a needed item in the build anyway.


Yep - forgot about those because I have not used them in a BBC yet, have done dozens of sets for the SBC, Ford Mod, and GM LS motors though - great piston kits.
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Re: Need a piston recommendation

Postby mitchmc » Thu Nov 24, 2011 1:42 pm

Ya the mahle ones do look nice, little bigger dome than I was looking at previously that would give me 10.67 cr with 0.037" quench, right where I want to be. Question is would they fit all or most aftermarket aluminum heads like AFR or brodix? Anyone have experience? Thanks!
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Re: Need a piston recommendation

Postby Alan Roehrich » Thu Nov 24, 2011 1:48 pm

At about 6500 RPM, maybe lower, you'll find that 0.037" total deck clearance will most often result in problems. I've found that 0.042" is about as tight as you can go, safely. About there, the pistons are close enough that carbon won't form in places, and you may even see shiny spots where the piston actually touches. I've seen pistons hit hard enough at 0.039" total clearance to close up the top ring groove. I could run 0.036" in my 427, according to the rules, but I have had the ring pinch slightly at 0.040", even though I'm running just barely 0.002" vertical oil clearance on my steel rods, with stiff pins and tight piston to cylinder wall clearance.

I have successfully used closed chamber pistons in open chamber heads for mid 10:1 compression engines. For example, JE has part number 258206 that fits your application, with a 33cc dome, it will get close to 10.9:1 in your application, depending on how close your 990 castings are to 119cc, they're often closer to 121 to 122cc, unless valves with thick margins are used and some milling is done. You could mill a little dome off the top to drop the compression further, if needed.
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Re: Need a piston recommendation

Postby ProPower engines » Thu Nov 24, 2011 5:53 pm

mitchmc wrote:Ya the mahle ones do look nice, little bigger dome than I was looking at previously that would give me 10.67 cr with 0.037" quench, right where I want to be. Question is would they fit all or most aftermarket aluminum heads like AFR or brodix? Anyone have experience? Thanks!


The nice thing about the Mahle piston kits is they are available for a wide range of chamber designs for most head manufactures. A call to their tech guys will en-lighten you as to choices that are not always in the cataloge and they do have lots that are not which is the reason I mention it and they can modifiy stock as well.
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Re: Need a piston recommendation

Postby mitchmc » Fri Nov 25, 2011 6:27 pm

Thanks for the info on the quench Alan. I thought maybe that was a little tight but wasn't totally sure. The JE's you gave a part number for are nice, but where I am located they are $880 for the set, and thats just the pistons I think, little more than I wanted to spend. The mahle's are still my best bet here as the whole kit with rings and pins is $700. Problem is I might not need the pins because I already have a set. (This motor was a turbo'd unit with low comp pistons, just swapping for higher comp.) So the pins that I have are nice I'm assuming, haven't looked too close. Does mahle have a part number for just the pistons that come in that set? I would have phoned them today and asked about it and the clearance for AFR heads, but I can't find a phone number to contact them at. Does anyone have a phone number which I can reach them at? Thanks again!
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Re: Need a piston recommendation

Postby Alan Roehrich » Fri Nov 25, 2011 6:35 pm

The Mahle pistons will most likely not work with your current pins, unless the current pistons are Mahle. When using pins that are retained by locks in the pistons, it is necessary to use pins made for the pistons and the locks.

I look at what fits best and works best, then look at price second. It's a lot cheaper and easier to buy something that fits and works well with the least amount of work. I'm not a huge fan of the rings Mahle uses, in fact, I'm not a fan of buying "package" sets of pistons and rings, I prefer to select my own ring package, from my preferred supplier.
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Re: Need a piston recommendation

Postby mitchmc » Fri Nov 25, 2011 7:06 pm

Ya that was stupid thinking on my part about the pins, but I'll have to check maybe they are mahle ones. Anyway does mahle have a part number for just the pistons and pins? Also what about these icon ones
http://www.summitracing.com/parts/UEM-IC782-060/

Don't know anything about them really, good choice maybe? I know they were mentioned earlier in the post and with a 27.00cc dome would do the trick.

And I know what you mean about the price thing, and if it comes down to it I will spend the money, it would just throw my budget out a little is all so if I can possibly avoid going over budget I will. Thanks for all the advice!
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Re: Need a piston recommendation

Postby ProPower engines » Fri Nov 25, 2011 7:09 pm

Alan Roehrich wrote:The Mahle pistons will most likely not work with your current pins, unless the current pistons are Mahle. When using pins that are retained by locks in the pistons, it is necessary to use pins made for the pistons and the locks.

I look at what fits best and works best, then look at price second. It's a lot cheaper and easier to buy something that fits and works well with the least amount of work. I'm not a huge fan of the rings Mahle uses, in fact, I'm not a fan of buying "package" sets of pistons and rings, I prefer to select my own ring package, from my preferred supplier.



Thats right the Mahle pistons have a special length and lock so the pin design from an other brand will not work,
besides the cost of the pins is so minimal why chance a used pin.You can also get different pins from them as well. The pin that comes with the piston can be swapped for a lighter/heavier pin for balancing corrections or to keep the current balance the same or close as possible. The ductile file fit ring set that comes withthe pistons is very good quality and will stack up to most any engine application needs.
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