I have a 86 rx7 na, it came with the sport package and the 5 lug rims. Looks like I have the 4 piston brakes in the frt. Are my back calipers the same as the T2, since it had the sport pak?

 

Just look at the rear rotors.
If they are vented then yes, you have the same brakes as the turbo.

 

I dont have the original rotors anymore, I put slotted\vented ones on it. How can I tell by the rear caliper?

 

There is no functional/construction difference between the turbo and non-turbo rear caliper...the only difference is the rotor width the caliper will span.

Since your calipers fit the vented rotors, you obviously have the turbo calipers.

This assessment was brought to you by logic.

 

Let's clear up some nomenclature here.
These are vented rotors. Internal vanes from the center of the rotor to the outer edge. It is also slotted.


Here we have a solid rotor. No internal vanes. Also happens to be slotted and cross-drilled.


Edit: 4-piston front brakes had vented rear rotors, single piston had solid rotors. All had 'blank' faces.

 

There are only two styles of factory brake calipers for ALL FCs. The 'Turbo' brakes are the standard brake caliper for all 5 lug cars. This would include your 86 Sport. All 4 lug cars share the same smaller caliper. The two calipers are not interchangeable using factory brackets so you can't have a 4 piston caliper on a 4 lug car.

 

I do not believe this is true.
Both my '91 Coupe and '90 GTU are five lug and originally had single piston front calipers.

 

You're correct. S5 cars had 5 lugs with single piston or four piston.