[whtpny]

Alright.. I've been delving deep into the fathoms lately and reading old threads regarding all sorts of topics. Something I've seen in a few is the topic of a big bore "3.700." It is actually something that ACMillr suggested to me a while back. I understand, it is a larger than stock bore that increases the cubic inches to 302 with the stock stroke. My question is what is the advantages or disadvantages of the big bore setup. I've seen some guys saying that high 300rwhp numbers are not out of the question with this setup. I've seen plenty of people praising them as good options, I am just trying to learn the specifics of what makes them better or worse than any of the other options for people looking to build their motor for power and durability. Enlighten me if you guys don't mind.

[whtpny]

bump

[adrenaline=lifeline]

a disadvantage is thinner cylinder walls

[whtpny]

that's why i'm wanting to learn all the ins and outs.. what i've read said that they are just as or even more reliable than some other options

[BWAL]

sleeves?

[adrenaline=lifeline]

Originally Posted by whtpny that's why i'm wanting to learn all the ins and outs.. what i've read said that they are just as or even more reliable than some other options

n/a yea sure its great but u hook up some juice or some high psi fi and ur asking for hole in the block. my question would be wat if u did the big bore plus a stroker

[adrenaline=lifeline]

Originally Posted by BWAL09 sleeves?

good idea i forgot about those

[Boomer]

Advantages of a big bore are endless. First the obvious add cubic inch, you also unshroud the crampped valves. Anyone who tells you the cylinder walls are weak or thin has no clue. A big bore will handle just as much as a stock block, no worries about any power adders at all. The choice of a dry or wet sleeve can make a big difference as well, I prefer wet myself.

Stroking a big bore can get you upwards of 324 C.I., factoring in rod ratio and piston speed it is not my preference to do both but it has been done. If I were going to do another modular bigbore for myself it would be a destroked 5.4. The advantage would be more reliable, stronger, with the ability to spin higher rpms with less stress on the internals.

[Boomer]

Just to add increasing the stroke will generally require a offset piston pin. On a engine that has a long stroke from the get go this will add to the side load on the piston and can cause premature wear. Choosing the correct set up can make all the difference on a combination, be prepared to spend 3000+ on a properly built shortblock (big bore) and figure more for stroker. Piston choice is very, very important as well as a connecting rod that will not grenade.

[whtpny]

so more cubic inches and more room to breathe is the big kicker that results in the extra power.. wet vs dry sleeves.. someone told me wet sleeves were more prone to leaking oil.. is this true or only if they are not done correctly.. also.. rad ratio and piston speed, i guess these numbers are not very optimal if both stroked and bored? why is it that this doesn't seem to be a popular road for people (doing a big bore)?

[limited]

I agree with the destroked 5.4l. When I was seriously looking into the big bore,I was finding out a lot of people having head gasket sealing issues. the big bore option was not that much more money,the sleeves from ford (SVT)was around 50 and my machinist would install for 400 and piston cost was really no more$$. but the head gasket thing stopped me

[Boomer]

Originally Posted by whtpny so more cubic inches and more room to breathe is the big kicker that results in the extra power.. wet vs dry sleeves.. someone told me wet sleeves were more prone to leaking oil.. is this true or only if they are not done correctly.. also.. rad ratio and piston speed, i guess these numbers are not very optimal if both stroked and bored? why is it that this doesn't seem to be a popular road for people (doing a big bore)?

Wet sleeve can be a problem , having someone that does them regularly helps there. Big bores are usually more in cost and people choose to go stroked for this reason maily. You can expect 400rwhp with a well thought out build using a big bore, if you have the money do it.

[blackstang2004]

you could get the boss block. it has a 3.7 bore

[Boomer]

Originally Posted by blackstang2004 you could get the boss block. it has a 3.7 bore

This is probably the easiest route and honestly the smartest.

[whtpny]

so the boss block is something i should look at? the ~400rwhp is that with mad high compression or something around 10-11 with full bolt ons heads and cams, the whole nine yards?

[whtpny]

i've seen the teksid aluminum block as a suggestion, as well.

[blackstang2004]

im thinking of doin the boss block an stroking it. my setup would be n/a. maybe a 100 or 125 shot for the track.

[DiZzyBonne]

Sorry for taking this a bit off topic, but what's the difference between stroke and bore, besides the obvious of stroke being a longer cylinder wall vs bore being a wider cylinder wall? If I'm not mistaken, a longer stroke is generally for more torque, vs a bigger bore being generally for more top end? Either that, or will a bigger bore give you a better overall torque curve? Whatever, just what's the difference between the two lol.

[acmillr]

Originally Posted by adrenaline=lifeline a disadvantage is thinner cylinder walls

Wrong, the walls are siamesed in the Cleveland cast blocks...

Originally Posted by BWAL09 sleeves?

The new ones are not sleeved.

Originally Posted by adrenaline=lifeline n/a yea sure its great but u hook up some juice or some high psi fi and ur asking for hole in the block. my question would be wat if u did the big bore plus a stroker

WRONG

Originally Posted by Boomer Advantages of a big bore are endless. First the obvious add cubic inch, you also unshroud the crampped valves. Anyone who tells you the cylinder walls are weak or thin has no clue. A big bore will handle just as much as a stock block, no worries about any power adders at all. The choice of a dry or wet sleeve can make a big difference as well, I prefer wet myself. Stroking a big bore can get you upwards of 324 C.I., factoring in rod ratio and piston speed it is not my preference to do both but it has been done. If I were going to do another modular bigbore for myself it would be a destroked 5.4. The advantage would be more reliable, stronger, with the ability to spin higher rpms with less stress on the internals.

Right, but I think the 3.7" bore/ stock stroke 302 would be the high revver of choice.

[acmillr]

Originally Posted by whtpny so the boss block is something i should look at? the ~400rwhp is that with mad high compression or something around 10-11 with full bolt ons heads and cams, the whole nine yards?

I think you could knock on the door of 400 with a big bore set up, 11:1+ compression, big bumpsticks, a great set of heads, and a solid intake.