how much can you bore a f54 block

[zr240]

I was just wondering how far anyone had succesfully bored a f54 block out to as I want to go to 3L without changing stroke

Thanks

Ash

[2ManyZs]

I don't have any books with the F-54 listed but all the rest of the L series can be bored .060 oversize with no problem. According to the book I have it is possible to go .080 oversize, but make sure you can get the right pistons and rings before you do it....

I think I would limit it to .060 and see how it goes. Besides, you might need a re-bore or a good honing in the future and if you were to go .080 over you might not be able to do it for a rebuild due to the amount of material taken out with a .080 overbore.

.080 would be probably be nearly the limit you can go without major problems if it can be done in the first place.

According to the L engine calculator a .060 will give you about 2850cc, and the .080 will give you about 2880cc. Of course the head selection and the pistons will also contribute to the overall displacement.

[ZmeFly]

the standard pitson is 86mm, from what i know you can go to a 88mm piston, now not know exactly what that is in over bore that is the safest.

you could go to a 89 mm piston, but thats reallly pushing it and you should have your block checked first before attempting such a great leap

make sure your starting out with a good block first then decide exactly what you want and go from there

[onemore240]

As you know, F54 blocks came with flat top pistons from the factory =)

You'd have to get your block sonic tested to see if it can take the abuse you're about to dish out to it.

If everything is good and the block can hold up, then bore it 3mm -- in doing so allow enough room so you can run 89mm KA24 pistons which are also flat top so there will be no compression drop, in fact, it should go up.

I believe with this combo it gives you +-0 deck making the piston drop at top dead center w/ no contact with the head and allowance for maximum combustion inside the cylinder.

Also, as aforementioned, your head makes a big difference. With an early E88 head...the ones with the skinny uniform casting stamp on it...you'll come away with 3 L which is your goal. With an N-42 you should be about 2940cc +- some...I think minus. If you can find it, the E31 head will give you a bit MORE than 3 L with higher compression...put 280Z valves in it and port polish and balance the whole blockand you'll have a killer stroker motor.

-- Daniel