Gains from boring block?

Duramaxordie

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Dec 10, 2016
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Hey guys so I'm starting the long process of building an engine. Ive search everywhere and have came up with no real results. Does anyone have numbers of gains from boring a block? I am sending my block of to have line bore checked and was going to have it bored .020 or .040 over if it was worth it in power gains. I have seen plenty of people have done it but I have seen no evidence of gains. Thanks!
 

clrussell

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Sep 23, 2013
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I don't think there is a significant power gain from boring.. It's just more to get a true cyl to put a piston into..
 

Duramaxordie

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I don't think there is a significant power gain from boring.. It's just more to get a true cyl to put a piston into..

Alright that's what I was trying to figure out. I know with 6.0s we build at the shop you can actually see a decent power gain just from boring them .020. If there is no significant gain rom boring aour block then I wont waste the money if the cylinders are in spec. Thanks!
 

clrussell

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Alright that's what I was trying to figure out. I know with 6.0s we build at the shop you can actually see a decent power gain just from boring them .020. If there is no significant gain rom boring aour block then I wont waste the money if the cylinders are in spec. Thanks!

I mean I'm not an expert by any means and I've had a few beers tonight.. But trucks have made well over 1000 hp on stock bore.
 

Duramaxordie

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I mean I'm not an expert by any means and I've had a few beers tonight.. But trucks have made well over 1000 hp on stock bore.

Oh yea I know that by no means do I expect the bore to be a big increase. I'm simply trying to find numbers so that I know when I drop the block off in the next week or so whether or not to pay the extra $$ to have it bored .020 its its not going to give me anything at all or very minimal then no point in spending the money.
 

clrussell

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Oh yea I know that by no means do I expect the bore to be a big increase. I'm simply trying to find numbers so that I know when I drop the block off in the next week or so whether or not to pay the extra $$ to have it bored .020 its its not going to give me anything at all or very minimal then no point in spending the money.

Right... .020 over Pistons seem to be easier to find though.. However Brett has some proven std bore fingers for a great proce on here
 

clrussell

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Also... If your not a vendor you'll want to take the advertising out of your signature
 

Duramaxordie

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Right... .020 over Pistons seem to be easier to find though.. However Brett has some proven std bore fingers for a great proce on here

Alright ill look into it haven't decided what I want to do for internals yet my end goal is 1000-1200 whp with a dependable build. Its gonna be a back burner project so it'll be a while before its finished. Gotta send it off to the machine shop first and have line bore checked and cylinder walls checked they looked clean but the engine is a core that had a broken crank.
 

clrussell

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Alright ill look into it haven't decided what I want to do for internals yet my end goal is 1000-1200 whp with a dependable build. Its gonna be a back burner project so it'll be a while before its finished. Gotta send it off to the machine shop first and have line bore checked and cylinder walls checked they looked clean but the engine is a core that had a broken crank.

Here Ya go..

http://www.duramaxdiesels.com/forum/showthread.php?t=74343


Brett is a stand up dude and has one of the baddest dmax trucks in the country.. Id have bought them already if I had the money and a use for them.
 

TROJAN366

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Boring .020 over would only net you 3-4 cubic inches if I remember correctly. I'd be shocked if you could tell any difference at all on the dyno.
 

ikeG

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Overboring while keeping same valve size will always unshroud your valves somewhat. But the difference would not be noticeable, just the same as you wouldn't notice the power difference from the bigger C.i. itself.
 

Duramaxordie

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It cost the same to setup and hone the cylinder which you need to anyways.


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I think that would depend on the machine shop would it not I think honing is standard when we take stuff to the machine shop but cost more if we need it bored.
 

Duramaxordie

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Overboring while keeping same valve size will always unshroud your valves somewhat. But the difference would not be noticeable, just the same as you wouldn't notice the power difference from the bigger C.i. itself.

Well I do plan on having the heads ported and valve springs but I haven't looked into options with vales yet.
 

Duramaxordie

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Not where I'm at. There's a charge for that.


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The machine shop I will be using we take all of the heads and blocks that we have to build at the shop. They "check" the blocks for us which usually consist of a line bore check and a cylinder hone, but extra if the block needs to be bored. So it will cost me more to have it bored not sure how much more but that's what I'm trying to see if it is beneficial, which if I an building heads for a larger bore seems like it will be beneficial.
 

S Phinney

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If you keep the stock bore piston you want extra clearances over stock clearances. You need to open it up some anyways. Forty over yields the best valve unshrouding. That's were you most likely will see those hp improvements


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Duramaxordie

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Dec 10, 2016
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Alright cool I will have it sent off soon and bored .040 over. Next will be finding a crank shaft haha
 

Duramaxordie

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So since I'm starting with just a block which heads would be the best to start with to build? I am a fan off the LLY to me its the best model just because simplicity before they started cramming everything in the engine bays. But since this isn't going to be a stock engine it wont have all the BS up top so what would be a good choice?
 

Awenta

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So since I'm starting with just a block which heads would be the best to start with to build? I am a fan off the LLY to me its the best model just because simplicity before they started cramming everything in the engine bays. But since this isn't going to be a stock engine it wont have all the BS up top so what would be a good choice?



You need to decide that before you get building. You need the crank and flex plate and balancer balanced together. And the heads will determine which ecm and wiring harness the engine will work with.

I'd use an lml block and crank and lbz heads. Or get Wagler heads depending how far you want to go. And I'm pretty sure you can use lb7 flexplates and balancers with the lml crank.


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