S16 And Gti-6 Block Interchangeable?

[Anthony 1,003]

Going to shortly be rebuilding a 2.0 Mi16/S16 (XU10J4) bottom end, but the original block has some visible wear in the usual place at the top of the bore, and also slight scoring on one cylinder but that should largely hone out OK. Useable, but not ideal.

 

I also have a GTi-6 (XU10J4RS) bare block that is in excellent condition with no visible wear/scoring and would thus be a much better starting point, but the question is whether there's any significant difference between the two blocks that'll stop me building a GTi-6 block with S16 pistons/rods/crank?

 

Visually there's no obvious major differences between the two and they both appear to be roughly the same height and all the important holes and fixings appear to be the same. The GTi-6 block has the dipstick on the front whereas the S16 is at the back (the hole is there on the GTi-6 block, but has a bung in it), and the S16 has an additional breather point at the front (3 on the S16 and 2 on the GTi-6) although it's not too much of an issue to adapt the breathers to suit. The mounts for the cambelt cover are different, but the threads are there to change from one to other, and I know from experience that the sleeve the tensioner goes over is fractionally longer on the GTi-6 so needs swapping.

 

Is there anything that I've missed that's likely to cause a problem that anyone knows of / has experienced?

 

I do also have a 2.0 8v (XU10J2) block buried at the back of the garage which from memory is also in excellent condition, but I know that doesn't have the piston spray bars on it (I guess that's not really an issue for a sub-200hp NA application though) and without going to the hassle of pulling it out I don't know whether that has all the required holes and fixings on it - I'm assuming that it probably does though.

[welshpug 1,657]

I believe most if not all 2.0 iron Blocks are near identical, main difference is in the conrods and pistons between the S16 and the gti6.

 

You need to match the conrod/piston assembly with whichever head you use as the chamber in the head is a different size (IIRC gti6 is 36cc, Mi16 40cc)

 

dont know the specifics of making the breathers fit, but as you said they appear to all be the same but blanked in some places.

[ablister 31]

does anyone know if a gti6 head can be put on a xu10j2 bottom end. Reason i ask is that i have a 306 xsi phase 1 (2.0 8v xu10j2) and would like a gti6 engine in there. I know it would be just as cheap to replace the engine but would be easier for me to just swap head over. Looked on service box and pistons/rods are different but crank is the same. Can i leave std block on (with, i assume, a loss of power over std gti6?) or should i replace pisons + rods?

[Richie-Van-GTi 71 2 Cars]

ablister yes you can use the bottom end with any xu10 head other than the turbo 8v head due to the compression issues required for a turbo. The only issues you get are small changes in CR, this seems to vary from 8.8 to 10.4 depending on head/piston combo.

[welshpug 1,657]

you'd need gti6 pistons and rods to make it work, they have cutouts for the large valves used and a compression height that works well with the standard cams.

 

would be far easier to use a complete gti6 engine, unless you go the way of re-boring to take some new pistons as I've read that the iron blocks do wear.

[ablister 31]

will the 86mm bore in my engine not be suitable for gti6 pistons then if boring is required?

[Anthony 1,003]

All the XU10 blocks have the same 86mm bore.

 

What Welshpug means is that because the iron XU10 blocks seem to suffer bore wear worse than alloy XU5/7/9 engines, it might not be worth using the block you have to swap over the GTi6 pistons/rods and use new piston rings. The only "cure" for a worn block is to replace it with an unworn one, or to rebore it and use corresponding larger pistons (which will require removing the engine anyway, so you might as well just stick a complete GTi6 engine in there in the first place IMO)