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Discussion Starter #1
Just wondering how much power can be had by going with a bigger bore on a forced induction setup? Small block ford 8.2 currently 4.030 thinking about going 4.125 bore will keep the same stroke which is 3.25 so with the bigger bore i would have 347 ci as of right now im 331 ci. is it worth spending $2000 for for the extra 16 ci
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I have no experience with your particular application, but I know there is a noticable difference in the power of a 5.3 LS with a 3.780 bore vs and 6.0 with a 4" bore. The larger bore opens up around the valves and usually lets the heads breathe better in most applications.
 

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Does the 331 need a rebuild yet? I thought about doing this on my last rebuild but decided against it just because I want the additional sealing surface for the HG's and the extra meat for future rebuilds. But then again mine is just a toy and I don't need a maxed out combo. Just my opinion but I can't imaging the power gain being worth doing it unless it's time for new pistons/freshen up anyways.

Guess it all depends on how bad you need the power and if you have already hit all the lower hanging fruit?

Assuming you are making 3 hp per cu/in now I would think you could plan on another 48hp (plus more if the valve shroud issue was really a hold back.
 

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Not worth doing. Keep the HG sealed by running a smaller bore. Spool up is about the only gain that I've seen from more CI. The turbo limits HP..
 

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Discussion Starter #5
I have no experience with your particular application, but I know there is a noticable difference in the power of a 5.3 LS with a 3.780 bore vs and 6.0 with a 4" bore. The larger bore opens up around the valves and usually lets the heads breathe better in most applications.
Hmm thats interesting, i would like to un shroud the valves
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Discussion Starter #6
Does the 331 need a rebuild yet? I thought about doing this on my last rebuild but decided against it just because I want the additional sealing surface for the HG's and the extra meat for future rebuilds. But then again mine is just a toy and I don't need a maxed out combo. Just my opinion but I can't imaging the power gain being worth doing it unless it's time for new pistons/freshen up anyways.

Guess it all depends on how bad you need the power and if you have already hit all the lower hanging fruit?

Assuming you are making 3 hp per cu/in now I would think you could plan on another 48hp (plus more if the valve shroud issue was really a hold back.
No the engine does not need to be rebuilt, Ive heard also you will have better head-gasket sealing with a smaller bore. 48 hp is pretty good, i would think the smaller bore is holding back the potential of my cylinder heads which are ported to the max. Also i dont need the power that bad as im running 5.25 @ 136 in the 1/8
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Discussion Starter #7
Not worth doing. Keep the HG sealed by running a smaller bore. Spool up is about the only gain that I've seen from more CI. The turbo limits HP..
Im supercharged seems like you get a better response if u post in the turbo section.
I need all the head gasket sealing as possible as im running 30+lbs of boost, Also heard that turbo and superchargers like big bores with small stroke is this true?
 

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4.100 is the max bore under boost .
I’d do 4.06 then step to the 4.1 for block life if you’d like to unshroud the valves.
there are many 4.125 that survive .
best thing is there is no law but only restrictions placed on you by a forum.
 

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I have successfully used Fuel Hoops on SBF's up to 4.145" bore but I would much rather keep them to 4.125" or smaller if at all possible. The hoops are not the limiting factor, the receiver groove that needs to be .010" - .020" wider than the Hoops is the problem. I am considering making some SBF hoops that are only .040" wide to help with this issue. Every thousandth counts on these SBFs.
 

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Discussion Starter #10
I have successfully used Fuel Hoops on SBF's up to 4.145" bore but I would much rather keep them to 4.125" or smaller if at all possible. The hoops are not the limiting factor, the receiver groove that needs to be .010" - .020" wider than the Hoops is the problem. I am considering making some SBF hoops that are only .040" wide to help with this issue. Every thousandth counts on these SBFs.
What are fuel hoops and how do they work?
 

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Like o-ringing on steroids. This is the current system used in Top Fuel. One piece SS hoops that press into machined grooves in the heads approximately .065" deep with receiver groove in the block that the copper gasket gets swedged into. Cylinder pressure has to make it thru four 90* turns to escape. The receiver groove depth is roughly double that of a conventional o-ring setup. It is the most reliable head gasket setup IMHO as well as many others.
 

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No not with Fuel Hoops. However in many cases the new receiver groove cut will clean up a previous o-ring/groove in the block. Even if you could put them in the block you would give up an important feature of the Hoop being embedded so deeply in the head it can never leak on the head side of the Hoops vs an o-ring receiver groove only being about .010" - .012" and much more likely to fail on the head side.
 

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Can the ss wire be in the block not head
It can, but is not as reliable. With the head being aluminum, the receiver groove will get rounded edges over use and eventually be prone to failure.
 

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Discussion Starter #15
Thanks guys seems like when you are using top fuel hoops you can only use copper head-gasket i have a wet block so would be hard to seal up.
Thanks.
 
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