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Old 12-02-2009, 10:09 AM   #16
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Default Re: Bore & stroke combos

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Originally Posted by Radical540 View Post
That only leaves (1) potential rebuild, if we consider .030+ standard protocol.
Pistons over that are all custom anyways.... so it's VERY easy to do rebuilds in .005" steps (or less)... unless you are doing something stupid it leaves room for 5 rebuilds. Standard practice in drag race motors and circle track motors.
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Old 12-02-2009, 10:10 AM   #17
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Default Re: Bore & stroke combos

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I wanted to leave more room for rebuilds thats why the 4.500 bore. I see nobody suggested the 4.500 stroke why is that? I figured since the cranks cost the same why not go bigger but I was leaning more toward the 4.375 then the local engine builder said he didnt like that combo but never told me why. Looking to make around 900+ but not go over 7500 Im thinking 555 or 565 is the way to go. Anymore info/personal combos is greatly appriciated.
Thanks

Mine is 4.375/4.600bore (bought car turnkey is only reason for bore) and it makes 1013 peak 980 avg hp... it never goes over 7100-7200 ever. I myself have never been a fan of a 4.50x4.50 to much stroke IMO you have a pm also
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Old 12-02-2009, 10:10 AM   #18
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Default Re: Bore & stroke combos

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Originally Posted by nonracer View Post
I wanted to leave more room for rebuilds thats why the 4.500 bore. I see nobody suggested the 4.500 stroke why is that? I figured since the cranks cost the same why not go bigger but I was leaning more toward the 4.375 then the local engine builder said he didnt like that combo but never told me why. Looking to make around 900+ but not go over 7500 Im thinking 555 or 565 is the way to go. Anymore info/personal combos is greatly appriciated.
Thanks
A lot more work and planning to put that much arm in a 9.8" deck block.

Get as many easy cubes as you can....
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Old 12-02-2009, 10:12 AM   #19
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Default Re: Bore & stroke combos

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I believe the 4.375 option is the longest stroke you can go with a short deck block.

Also, don't plan on off the shelf pistons for any stroke over 4.250.

you can make a 598 4.600 bore 4.500 stroke in a short deck block, 582 pistons are not custom order from everything I've used. Lots of builders do not like 598 in a short deck but its do-able.
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Old 12-02-2009, 10:14 AM   #20
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Default Re: Bore & stroke combos

I had a 4.600 bore block that went through 4 freshens and a blowup and it was only at 4.610. The second blowup killed the block but the reason it isn't salvagable again isn't because of the bore size.

Big Blocks love Bore. I would always go with the most you can while leaving a bit of room for freshening in the future. Also, the Dart block can go 4.650 easily for a NA combo as well.
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Old 12-02-2009, 10:22 AM   #21
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Default Re: Bore & stroke combos

Thanks guys I think the local builder did say he didnt like the 4.375 in a low deck but I was thinking of a 10.2 block the car is a sbc so I need everything to change over anyway.
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Old 12-02-2009, 10:48 AM   #22
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Default Re: Bore & stroke combos

A few questions based on the last few posts:
1) Hammertime: WHO makes non-customer order 582 pistons? I've yet to find a reputable Mfg. that has off-shelf pistons for this combo.
2) MattG: Dart specifies in their spec sheet that Big M max bore is 4.625
3) nonracer: Are any of these alleged builders specifing WHY they don't like this low-deck combo? Just curious.
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Old 12-02-2009, 10:53 AM   #23
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Default Re: Bore & stroke combos

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2) MattG: Dart specifies in their spec sheet that Big M max bore is 4.625
Yup they do and at that Bore, they still have more material between the cylinders than the World blocks at 4.600".
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Old 12-02-2009, 10:55 AM   #24
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Default Re: Bore & stroke combos

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Yup they do and at that Bore, they still have more material between the cylinders than the World blocks at 4.600".
Agreed!

However where World blocks surpass Dart is in the maincap bulkhead thickness...especially the main. Compare a Dart block against a World block in the main area, and you'll see what I mean.

(Dart is still my preference though)
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Old 12-02-2009, 11:17 AM   #25
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Default Re: Bore & stroke combos

If your thinking about going with a 10.2" deck then hell go 4.560" bore with a 4.375" stroke. That should easily make 900+ HP. My oldman ran that same combination but with a 14-71 and it ran well. Pistons are off the shelf and you have plenty of material to work with..
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Old 12-02-2009, 11:38 AM   #26
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Default Re: Bore & stroke combos

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Originally Posted by SStrokerAce View Post
Pistons over that are all custom anyways.... so it's VERY easy to do rebuilds in .005" steps (or less)... unless you are doing something stupid it leaves room for 5 rebuilds. Standard practice in drag race motors and circle track motors.
This is common practice up here. I started with a 540 combo, and the first time that I wanted to up the compression ratio, I was talked into a 4.6 bore. The story was that there was lots of of the shelf pistons at this size. For what I was charged, I could of had custom pistions anyway.
But the big bore does help the airflow and bigger valves.
BTW -It is possible to fit 4.5" stroke into a low deck block, but if you're starting from scratch, go tall deck if you want to put that big of a crank in it.
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Old 12-02-2009, 12:04 PM   #27
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Default Re: Bore & stroke combos

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Originally Posted by SStrokerAce View Post
Pistons over that are all custom anyways.... so it's VERY easy to do rebuilds in .005" steps (or less)... unless you are doing something stupid it leaves room for 5 rebuilds. Standard practice in drag race motors and circle track motors.
X2!

Good engines that are properly maintained should only need .0003-.0005 of material removal during a normal freshen. I am surprised that so many hone the shit out of them and replace the rings. A typical good ring set will run better the 2nd or 3rd run. If you are wearing out rings before then, I would question your tune up, hone schedule, builder or all of the above.

10.2 deck, 4.600 bore, 4.5 stroke and a 6.800 rod is a great combo............As long as you can afford to feed it!
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Old 12-02-2009, 02:52 PM   #28
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Default Re: Bore & stroke combos

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Originally Posted by Radical540 View Post
A few questions based on the last few posts:

3) nonracer: Are any of these alleged builders specifing WHY they don't like this low-deck combo? Just curious.
No. Thats why I asked here.Maybe rod ratio or he didnt like comp height I dont know.All builders have their own thoughts but this is just one guy.
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Old 12-02-2009, 03:14 PM   #29
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Default Re: Bore & stroke combos

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No. Thats why I asked here.Maybe rod ratio or he didnt like comp height I dont know.All builders have their own thoughts but this is just one guy.
Exactly why!

Unfavorable rod ratio and comp height. It is doable for sure, and it's done all the time, but it is a less than optimum combo in my opinion.
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Old 12-02-2009, 03:25 PM   #30
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Default Re: Bore & stroke combos

4.5 bore 4.5 stroke. 572. my bud did that combo and its a torque puking tranny killer


i just have a little 4.310 bore 4.00 stroke motor
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