Ready to build 512

[734406pk]

Check the compression ratio with the MAHLE pistons and closed chamber heads, it may too high?

[73cudabr]

I can do that - He said that these 512 combo's have been a highly requested item over the past 3-4 years and this bottom end combo has been pretty good to him in consistency and reliability. I expressed that this is a street build and 10:1 is what I was looking for. I'll double check it before the crank arrives and balancing work starts.

[734406pk]

Here is some info from Eagle:
http://www.eaglerod.com/index.php?option=com_content&task=view&id=33&Itemid=40

512 CID stroker kit works out to around 11.6:1 with a 75 cc chamber volume.  The MAHLE piston volume is +8 cc.

Check out ICON Piston P/N IC842 for example. They have a +26.7 cc dish. 10-10.5:1

[dave73chally]

Here is some info from Eagle:
http://www.eaglerod.com/index.php?option=com_content&task=view&id=33&Itemid=40

512 CID stroker kit works out to around 11.6:1 with a 75 cc chamber volume.  The MAHLE piston volume is +8 cc.

Check out ICON Piston P/N IC842 for example. They have a +26.7 cc dish. 10-10.5:1

Those icons are the exact pistons i'm running in my 512 build. They are forged and if I remember correctly made by Keith Black. My builder liked them. No issues - my compression is right at 10:1.

[734406pk]

Those icons are the exact pistons i'm running in my 512 build. They are forged and if I remember correctly made by Keith Black. My builder liked them. No issues - my compression is right at 10:1.

  Good to hear! Just sharing the research I've done FWIW. One other possibility, and maybe the best is 440source.com pistons. Check it out:
http://store.440source.com/Platinum-Series-Pistons-4375-17-Dished/productinfo/5070/

+17 cc dish, 10.5 +- CR. Also Icon pistons as far as i can tell.

[73cudabr]

Hi Guys,

Sorry for the delay. Been a stressful week at work trying to make money to pay for all of this stuff! So I'm sort of out of my comfort zone on calculating compression rations admittedly. In fact, most of this is outside of my knowledge however I'm doing my best to learn by reading Andy F's book. So this is where i'm at.

The guy doing the machine work certainly has his opinions on combinations. I'm not a technical person so I may mess some of this up. But at the end of the day, he said he would order and balance whatever combination I want, but he suggests this build as he's done them many times before and has a compression worked out to 10:3:1 with the forged flat top Mahle Pistons. He said that these pistons are designed to sit at .020 below deck which combined with a .040 gasket and an 88 CC or larger head will put me at that that compression ratio.

Now I argued that having pistons not at zero deck, and using a larger gasket would effect quench. In which case I was told again, that he will balance whatever combination I want, but said that quench isn't as big as a factor on the BB Mopar as they're not designed to leverage that as much as a high performance Chevy engine etc. He mentioned that he hears people bring it up all the time, but just does not believe in his experience it makes a giant difference. (I know from reading Chyco's posts that he would disagree)

Now after doing some research, I see both sides of that argument with very little dyno testing to show actual results (which I guess that would be hard to do?). However I'm inclined to build it in a way that gives me the most power for the money. even if I get a 1/2 HP more by leveraging the effects of quench then I'd like to do it.

_______

SO after talking to Hughes engine's when pricing heads and CNC work he mentioned ICON 613 pistons, with a 75CC Head would make 10:3:1 compression. (forgot gasket size, or piston deck height, don't know if he mentioned that)

Hughes agreed that a flat top piston would be tough to dial it in. He said the best I can get is 11:1 with a CNCed head to 89CC.

All very confusing. Sorry to rant. I just don't know enough to decide what to do. I have a builder who's made engine's his whole life, and has made many top performing engines for street and strip (trusted by lots in the area). And I'm somebody who's never even taken apart an engine before up until a few months ago, and had to buy a book to walk me through it step by step haha. So i'm not really in a place to argue too much, and do it convincingly, but do want to pick the right combination. Again, he is open to doing whatever I want, he's just making this as a suggestion.

[dave73chally]

Honestly, if he's built 512's before and you've seen his work and received feedback from past customers, I'd let him order what he wants and build it how he wants. Should be able to give him a power range, run on pump gas, ballpark figure that's realistic and let him go for it. He's an artist to a degree, let him do his thing. Then if something goes wrong, he'll more likely stick behind it.

[73cudabr]

Honestly, if he's built 512's before and you've seen his work and received feedback from past customers, I'd let him order what he wants and build it how he wants. Should be able to give him a power range, run on pump gas, ballpark figure that's realistic and let him go for it. He's an artist to a degree, let him do his thing. Then if something goes wrong, he'll more likely stick behind it.

Thats what I was thinking. He said he'd consult me to the end on the build to get me the desired result. Obviously stating that the bolt on's will be where the biggest differences will be made. I also shot a note over to Steve Dulcich who appears on Motor Trends, "road kill" "engine masters" and editor of hot rod network magazine. He is a big mopar guy. I'm surprised he wrote me back (which I thought was pretty cool), but he said not to worry about it that much.

[Chryco Psycho]

I disagree but you already no that , high compression with quench is better than no quench
 you can get a dished piston to reduce compression but maintain quench , the dish is under the spark plug
 I have seen brutal detonation on 8:1 engines as they have no quench or compression

[1 Wild R/T]

C/P is spot on...... Build for quench...    BTW I thought this was a street build.....  First off the Performer RPM doesn't have Max Wedge ports... The manifolds that do are all aimed more to the race side... Granted you can use them in a street build, & I understand the temptation, been guilty of getting caught up in it myself.. You might want to refine your focus...

[Archialfa]

Honestly, if he's built 512's before and you've seen his work and received feedback from past customers, I'd let him order what he wants and build it how he wants. Should be able to give him a power range, run on pump gas, ballpark figure that's realistic and let him go for it. He's an artist to a degree, let him do his thing. Then if something goes wrong, he'll more likely stick behind it.

If I was in your place I would listen to the guy.

I am an architect and what you're doing is what some of my clients do: they want me to design their house, but they already have so many ideas which they picked up from the internet, interior design magazines etc and all of that makes them even more confused. Just say what you want, what your budget is and let the guy do his stuff. In the end if something is not right, it will be his fault, not yours.


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[1 Wild R/T]

If I was in your place I would listen to the guy.

I am an architect and what you're doing is what some of my clients do: they want me to design their house, but they already have so many ideas which they picked up from the internet, interior design magazines etc and all of that makes them even more confused. Just say what you want, what your budget is and let the guy do his stuff. In the end if something is not right, it will be his fault, not yours.


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How about if the architect specializes in building ranch houses & your wanting a Tudor...  Yes he's built a few but he's also built a few out houses too.... Doesn't mean he knows the nuances of building an outhouse....

I've seen some builders screw together decent engines & I've seen builders who completely miss the mark... But hey it's your money roll the dice & take your chances....

[onebadfish]

Wouldn't hurt to talk to some customers who have had bb Mopar motors built by him. Quench arguments go both ways. Merit on both sides. Mine is 0.060 quench and runs like a scalded ape. My builder believed quench was over rated too. I trusted him.  I talked to a lot of people who have had motors built by him and lets face it. Anyone 60 years old making a good living building race engines....who can argue with that?


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[Archialfa]

How about if the architect specializes in building ranch houses & your wanting a Tudor...  Yes he's built a few but he's also built a few out houses too.... Doesn't mean he knows the nuances of building an outhouse....

I've seen some builders screw together decent engines & I've seen builders who completely miss the mark... But hey it's your money roll the dice & take your chances....

That's why you check out architect's portfolio first. When clients come to me asking for a Tuscany-styled home I don't have to turn them down: I just show them what kind of projects we do (high-end contemporary) and they walk away on their own.

I think the same rules applies here: if the guy is doing good work and has satisfied clients, to me that would be a good sign. Of course it's better to do the homework first, but in any kind of business there must be a level of trust involved, no?


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[73cudabr]

Thanks again for the updates. Badfish happy to hear to hear that you're running well at .060. Thats looking like where i'd end up. Either way I have a week or two before I have to make a decision on it. We're waiting for Scat to get the crank shipped out. He also said he'd be happy to supply contact information to any of his customers with his 512 builds. I appreciate the feed back. I'll talk it over with my buddy helping me build it, and get it figured out.