Hybrid mi16 -6

[mmt 15]

Hi guys

Would it be possible to mate together a GTI 6 bottom to a mi16 head ? What kind of compression Would GTI 6 pistons and mi16 head make? Has it been done before? 

 

Thanks

[petert 586]

There's no reason why you can't. Use an XU10J4 cam belt and an XU9T head bolt over the water pump. CR is probably 10.4-10.5:1.

Edited May 5, 2019 by petert

[Andy 105 1 Cars]

Slight hijack. Is it possible to do this the other way around.? That is , XU9J4 bottom end and xu10j4R head ?

 

[welshpug 1,657]

yes, has been done on here before, albeit gti6 head, same basic casting ss the j4r

[mmt 15]

Thanks Peter. I’m worried if the CR is good enough for a race engine. 

[welshpug 1,657]

only just high enough for a road engine really

[petert 586]

Deck the block, or fit a thinner head gasket and you'll get into high 11's. That's essentially what I use.  ie Mi16 head, XU10 block, flat top piston and 1mm (or less) head gasket.

[mmt 15]

Great. Thanks (again). Which gasket would you recommend? 

[petert 586]

I think Cometic make one in 87mm but you're better off getting the block o-ringed after you deck it and use a copper gasket. Then you have choices of 0.5, 0.7 and 1.0mm. If ordering through Ridgecrest, ask for Mi16 XU9J4 pattern with a bore 0.5mm larger than your piston size.

 

https://coppergasket.com.au/

 

What pistons are you going to use?

 

 

[mmt 15]

Thanks. 

Std. GTI6 pistons(In stock). 

 

I’ll be starting hoarding parts and begin the build come vinter. 

Edited May 8, 2019 by mmt

[petert 586]

How will you manage valve to piston clearance? The pockets will need deepening, a lot.

[mmt 15]

Don’t know. Might just have to find some Mi pistons. 

[petert 586]

Even they won't be deep enough when you add some decent cams. Thus you may as well factor in cutting the GTi6 pistons deeper. Still a cheap build.

[mmt 15]

Thanks Peter. Great input. How deep should the pockets be? I already have a High lift cam in stock. 

[petert 586]

What cam(s)? Sorry, it's something you really need to measure during a trial build.

Edited May 15, 2019 by petert

[welshpug 1,657]

the gti6 piston crown can't match the standard cutouts of the MI16, you can only safely add 1mm to them, which makes cams like the PH" safe but nothing much more.

though I haven't compared them directly, there looks to be a lot more to play with in the older heavier piston.

[petert 586]

@Welshpug are you saying the GTi6 piston crown is too shallow to deepen the pocket more than 1mm? Surely someone has a dud piston they can cut open and measure?

[wicked 103 3 Cars]

Does anyone know if the hybrid the other way around will work with respect to the OEM piston pockets; xu9j4z / DFW with Gti6 head? 
And then specific the outlet valves pocket diameter: RFS has slightly larger outlet valves compared with the mi16 (30.8mm vs 29.5mm), so the valve might not fit the pocket. Or is there enough margin?

 

[welshpug 1,657]

2 hours ago, petert said:

@Welshpug are you saying the GTi6 piston crown is too shallow to deepen the pocket more than 1mm? Surely someone has a dud piston they can cut open and measure?

yeah, Bridgecraft engineering who offer a service to deepen the cutouts on the gti6 piston checked how far they could take it and 1mm was safe.

[mmt 15]

Mi pistons then! 

@peter, I don’t know the exact lift of the cam. Enough to require cut puts in the head for them to be able to turn: HIGH LIFT!  

How Would the 1.9 mi16  crank and its pistons sit in the 2.0 GTI6 iron bottom with a mi 16 head? 

 

[petert 586]

If you choose Mi16 pistons, you'll also need XU10J4 Mi16 rods as well. Unless you can find some cheap, 2nd hand parts, your bill will become expensive. Add new rod bolts, reco' the big ends and cut the pockets deeper, and you've spent some coin.

[welshpug 1,657]

If you have cams and a head with that much lift then there really is no other option than some high compression pistons.

 

for one you'll never fit them over a standard piston even modified, secondly you need a lot more than 10.4-1 (minus whatever you lose from enlarging the valve cutouts...)

[petert 586]

It's easy to make 12:1 with flat top pistons. I told you how above.

[mrmut 0]

hi guys

one winning combination

XU10J4RS block (the block is lowered 0.5mm) , crankshaft 86mm , connecting rods on xu10j4 , flat pistons (fiat engine 1,6 16v) 86,4mm , head mi16 , camshaft adjusting while on DW8 diesel engine

 

Edited May 17, 2019 by mrmut

[xy8 4]

       XU10J4R block 

      87mm fiat pistons 

      xu10j2   rods

      dw12 crankshaft 

       mi16 head

       cr 12+  was too much  as I found out 1.5 years later.