Hi i'm in need of help i want to build a stroker motor using an l16 block and i've got a l20b crank conrods and pistons will it fit or do i use something else any info will be much appreciated

Best thing to do is to use an L20B block. Fits in a 1200, legal with engineering and goes together like factory.

Wont fit. Use a l18 crank and rods with 240k pistons.
L18 blocks can be line bored for l20b crank but $$$$$$$$$$$$$$$$
Check out ozdat

Talk to Baz from Datsport
Go for L20b straight off or Z22 block with L20b crank or
if its for engineering reasons you will need line boring
of the L20B crank and to fit longer L20B rods you will
need block line bored as mentioned by Mick above which is
about 200-250 dollars at best but then you use L16 rods,
1mm oversize RB30E pistons, rod stroke ratio is 1.547 which
means it will be a torque monster but keep it to 7500rpm
for max with good springs on the head along with closed
chamber head with decent porting to make up for faster
air going into the engine as opposed to long rod combo.

Try the calc w/ above details RB30 slugs 1mm over = 87mm
http://www.ozdat.com/ozdatonline/enginedesign/

Good luck finding an L16 block that will take an 87mm bore!

The best stroker option for reasonable cost using an L16 block is L18 crank and pistons with L16 rods. Mill the pistons down to flat tops to achieve the deck heigh and CR desired. The longer L16 rods gives you a better rod:stroke ratio than the shorter L18 rods and gets you the CR you need cheaply. Both of those factors will help get the best performance out of a decent cam.

Unfamilia's L16 with L18crank and 240k pistons went really well and that was on LPG, And you know that it was a cheap setup if it was in his car. :) Thats if your looking for budget.

Have to use L18 block as a minimum or L16 needs sleeves that Baz has done to L16 and L18 block up to 89mm bores. However expensive but you pay for what you get, Baz has even made a deck plate from melted L series heads so he can bore and hone the sleeved blocks with the blocks tensioned up as if they have the head on them like Nissan does now to its modern engines for perfect sealing and bore trueness.

there's nothing special about 240K L24 pistons. Absolutely no sense going out and sourcing them seperately. They are the same as L16 pistons. R30 Skyline L24E engine had flat tops and fly cuts from factory but they haven't been available new for many many years.
Using the L18 85mm pistons from the engine you got the crank out of is a much better idea. With longer L16 rods you can mill the l18 pistons to flat tops anyway. You gain capacity and compression this way, and improve the rod:stroke ratio. It's a win win win situation for next to no cost. And it's perfectly safe and reliable.

Mine has flat tops but no fly cuts so who knows what they are then.
All parts are factory no machining needed when piggy put it together.

Any way heaps of advice out there I figure l18 into l16 block is easiest or l18 block with l16 rods and get pistons milled flat.

Factory bores just new rings bearings and gaskets.

So I did a slow search on "L16" and it brought me here. I am wondering if changes need to be made to the cross member mounts for it to accept an L motor as opposed to an A motor.
Gonna do some more searching, but since it brought me here...though I would ask.