2 motor built choice

[shelbymonster]

im about to build my engine for the summer im gonna ditch my 87 t1 rod and pistons , i have 2 combination possible , build a t2 with cast crank , or use my t3 pistons and have a higher compression , i got a good cleaned 782 head , fwd ported exaust manifold , 2 piece intake , 3 bar set-up , 3 inch complete exaust , water meth and big fmic , and stock t2 turbo ported ,6 puck clutch

would you guys use higher compression or the good standard t2

[Speedeuphoria]

what octane gas are you going to run? This will answer your question

Most likely lower compression is your best choice

[cordes]

I would go with lower compression and more boost.

[amoparacer]

I agree low comp and higher boost.

[turbovanman²]

What is your boost target? Racer? DD? Octane availability? Are you doing your own cal?

If low boost and you can tune your own cal, higher compression.

[shelbymonster]

im using 91-94 octane gas , and it will be a dd , im realy curious with the difference of the higher compression , im planning maybe 18 psi with alky , for now rob does my cals

[Aries_Turbo]

low compression....

[tsiconquest88]

t3 higher? i thought the t3 bottom end IS the t2 bottom end lol?

[2.216VTurbo]

What is the CR with TIII pistons in a TII motor? interesting, my bro will be doing a budget build on LeRampage and I've got some TIII pistons/rods. Might be worth running a .060 shim below the HG.

[shelbymonster]

ive heard they bring the compression up to 9.5:1 , its high but not that bad when i see some cars with 10.0:1 with 12 psi of boost

[tsiconquest88]

again i thought t3 bottom ends and t2 bottom ends had the same pistons/rods, just t3 had a forged crank? and of course a distributorless ignition setup lol

[shelbymonster]

t2 an t3 got the forged crank

[tsiconquest88]

right but dont they both have the same pistons and rods?

[turbovanman²]

What is the CR with TIII pistons in a TII motor? interesting, my bro will be doing a budget build on LeRampage and I've got some TIII pistons/rods. Might be worth running a .060 shim below the HG.

I've posted this numerous times,

This is what I figured out, give a take a bit. Based on this, I would use the TIII pistons, the .020 copper shim or thicker Cometic-I don't like using the Com's and if you do some chamber deshrouding, you could get it down to 8.5:1, which would be just fine,

Ok, these are averages and not exact, I worked out that its about 1 point using a TIII head on 2.5 pistons, TBI pistons are close to TIII pistons in dish volume and TBI's are 8.9:1 so based on that-

8 valve swirl pistons, swirl head, 8.0:1
8 valve swirl pistons, G-head, 7.5:1
8 valve swirl pistons, TIII head, 7.0:1
8 valve swirl pistons, Neon head, 8.0:1

TIII pistons, TIII head, 8.0:1
TIII pistons, swirl head, 9.0:1
TIII pistons, G-head, 8.5:1
TIII pistons, Neon head, 9.0:1

again i thought t3 bottom ends and t2 bottom ends had the same pistons/rods, just t3 had a forged crank? and of course a distributorless ignition setup lol

TIII's have forged cranks, same TII rods but different bolts and forged almost flat top pistoins. TII's have dished cast pistons.

[2.216VTurbo]

Hmm, I forgot Bro's motor is a 2.5. That throws a wrench into the mix. The longer stroke and higher relative pin hieght on the 2.5 pistons would drive the CR even higher right? Or am I thinking about it backwards

[Aries_Turbo]

the pistons will be poking past the deck with the 2.5L crank. with the rods being the same length, they will poke up past the difference of 3.62" stroke vs 4.09" stroke

[butchsuppe]

Alan you're not thinking backward, but the 2.2 piston would pretrude above the deck ( I think ).

[turbovanman²]

Alan you're not thinking backward, but the 2.2 piston would pretrude above the deck ( I think ).

Correct, and if you put a 2.5 piston on a 2.2, it will be below the deck.

[black86glhs]

Can't you just round off the tops of the T-3 pistons to match the design of the swirl head combustion chamber?
Oh, and drill a hole in the piston to clear the plug?

LOL...obviously drilling a hole for the plug was not the serious part of the post, but machining the piston is a possibility. Maybe even have a slight dish machined in the top to lower the comp ratio?

[shelbymonster]

Can't you just round off the tops of the T-3 pistons to match the design of the swirl head combustion chamber?
Oh, and drill a hole in the piston to clear the plug?

someone i know got them machined , took off the dish and never got a problem ,not sure about the interference when they are not machined