Toyota supercharger pistons on 4g92

[speed2horizon]

I'm quite sure there are alot of ppl using Toyota Supercharger pistons on their GSR or 4G93 BOT. I guess there are also alot of ppl using it on reboer 4G91 and also 4G92.

There are some modification on the conrods that is needed to be done in order for the piston rods to be able to inserted to the conrod.

When used on 4G93/T I've heard that it's necessary to cut the Piston skirt because the long stroke of 4G93 will create a big angle on horizontal position causing the piston skirt to knock with the conrod.

However, I'm using an oversize 81.5mm in a rebore 4G92. It enters perfectly into the cylinder without any knocks when the crank is being turned. However, I am a little worry about the 1mm minimum clearance between the piston skirt and the crank journal along the movement path.

I am afraid that the pistons will expand when the engine is boosting and create contacts between the crank journal and the piston skirt.

Well, I personally don;t think that the piston will expand anything more than 0.5mm. If it does, the first thing that will be damaged will be the pistons and the cylinders even for stock engine. But my foreman say it's better to be safe tahn sorry...

however, I am still abit worry. Anyone have any experience on this..? Can share...?

 

[slivero]

what is the piston compression??

 

[speed2horizon]

Thanks for the concern bro... But everything done... Just need to grind the piston skirt abit to allow better clearance at the same time maintaining the V shape so that the edge of the pistons won;t wear off that much compare to flat bottom. Better strength.

I'm using the 8.9:1 compression ratio... But the compression ratio is only true in a 4agze engine in accordance to the top dead clearance volume and stock 1.0 gasket thickness.

When installing a Mitsubishi, calculations are different. cause we're not sure how the GSR heads top dead clearance differs from 4agze.

So, we can only calculate roughly... Like my set up, due to the short stroke of 4G92, if we install a low compression pistons, the outcome compression ratio will be extra low... But should be at the range of 8-9. Just nice for a 5070 ECU from a libero gt. cause gsr libero gt has a slightly higher compression ratio compare to GSR from lancer.