TB42 engine re-bore to fit TB45 pistons

Post by **create** » Fri Nov 13, 2009 10:41 am

Has anyone bored out a TB42 block to fit TB45 pistons. This would mean a bore out of 3.5mm. Is this taking out too much "meat"?

Post by **nastytroll** » Fri Nov 13, 2009 3:26 pm

:oops:

Post by **MUNGA GQ** » Fri Nov 13, 2009 4:22 pm

i fitted the 4.2efi head and intake to a 4.5 block.
some rooting around but it is on and running great.
took it out on the beach, has a bit more power that the old 4.2L with 500,000km on it, but that may only be that the new 4.5L motor has only done 200,000km.

very happy with it.

Post by **brad-chevlux** » Fri Nov 13, 2009 6:56 pm

i doubt nissan would have put enough metal in the block to allow for a 3.5mm over bore and still have enough left to have any strength.

I'd say they would have revised the block to fit those pistons.

you can't get a 4.5 engine from a wrecker?

Post by **create** » Fri Nov 13, 2009 6:57 pm

I have a 4.5 head and inlet manifold and plan to fit it to a TB42 block. I would like to make it a 4.5l and wanted to know if any one has bored out the TB42? How far can it go?
I also have the TB45 block and complete engine but dont want to fit this engine as it means I would need to engineer the car.

Post by **brad-chevlux** » Fri Nov 13, 2009 8:38 pm

ACL list a piston that is 1mm over. beyond that you would have to use a custom piston, or pray that a 3.5mm over bore won't kill it.

They other option is to have the block sonic tested to know exactly how thick the walls are.

In the end it would probably be both cheaper and easier to buy a TB45 short motor

Post by **grinch2** » Sat Nov 28, 2009 1:46 pm

i would personaly just drop in the 4.5l motor a lot less hassel and probably a lot cheaper, i wouldn,t think there would be much involvec in getting it engineered, in qld all it would need is a $50 mod plate

Post by **awill4x4** » Sat Nov 28, 2009 2:23 pm

If your old 4.2 isn't going to used anywhere and just junked some people "may" suggest machining the engine number off the 4.5 and restamping it with the old 4.2 number

. (There's not a lot of difference visually)
Not that anyone could ever condone such actions though.
Regards Andrew.

Post by **create** » Mon Nov 30, 2009 2:12 pm

awill4x4 wrote:If your old 4.2 isn't going to used anywhere and just junked some people "may" suggest machining the engine number off the 4.5 and restamping it with the old 4.2 number . (There's not a lot of difference visually)
Not that anyone could ever condone such actions though.
Regards Andrew.

Yes I have had several PM's suggesting this. I think that in an accident situation my insurance company may use this as an "out" and not pay up. So for now I am going to stick with a TB42 block and a TB45 head. When I can save the cash I will get the TB45 block engineered.

Post by **badger** » Mon Nov 30, 2009 8:53 pm

here in qld it would cost between $50 and $75 to engineer that swap. its 100% bolt in right down to exhaust

Outer Limits 4x4 Board

TB42 engine re-bore to fit TB45 pistons

TB42 engine re-bore to fit TB45 pistons

Who is online