Whats The Difference Between Mi And 1.9gti Pistons

[vern 0]

As title what is the difference between the Mi and 1.9 pistons apart from having a different pin, and valve cut outs. Are they interchangable, any benift for using one or the other?

[DamirGTI 342]

The Mi16 conrods are lighter/stronger or something i can't remember which is of these two , but PeterT will know for sure , me thinks that using Mi16 pistons in 1.9 8v engine or vice versa is not so good idea because of the different shapes of the piston crowns - the piston crown squish area wont match to the head/combustion chamber squish area if you swap them like if you fit the Mi16 pistons in 1.9 8v engine , and this will affect combustion process ..

 

Regards !

Damir

[Sandy 191]

Mi16 pistons are flat topped with small valve cutouts. They use a floating pin with circlips.

 

1.9GTi pistons are dished and use interference fit pins.

[nick 3]

Also the 8v rods are crank located while the Mi rods are piston located. So if you put and Mi piston on an 8v rod you won't have any "play" (it will be located on both crank and piston)

 

Nick

[petert 587]

So if you put and Mi piston on an 8v rod you won't have any "play" (it will be located on both crank and piston)

 

Someone thought of that by choosing different pin sizes, making it physically impossible.

 

You can use Mi16 pistons AND rods in an 8v however, which makes a very nice combination, with heaps of compression.

Edited March 11, 2008 by petert

[vern 0]

Thanks for replies people.

Should have said what I am doing, I am using an Mi bottom end and an 8v head in a turbo engine, just wondering which pistons to use as going to get some forged pistons.

[DamirGTI 342]

Someone thought of that by choosing different pin sizes, making it physically impossible.

 

You can use Mi16 pistons AND rods in an 8v however, which makes a very nice combination, with heaps of compression.

 

But what about the squish area of the piston/head Peter ? aren't they must be (ideally) a "mirror image" ?

 

Regards !

Damir

[nick 3]

Someone thought of that by choosing different pin sizes, making it physically impossible.

 

Not impossible, just difficult. We have just done it on my Mi engine.

 

Nick

[tony perks 1]

Got Mi rods and pistons in my rally car and yes the compression is a bit high at 12.2:1 but with the cam i run its lovely, got to use 100 octane tho or she pinks a bit at low rev high load situations, not a problem if you run mapped ignition.

[Miles 331 1 Cars]

You want just some Forged dished piston's then, You could run them with the pin moved to reduce compression so you can up the boost a bit more which I wish I did with the one I;ve just done