87 firebird 305 carb to 94 3.4 destroked to 3.0L with bw s475 80mm turbo
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Joined: Apr 2008
Posts: 10,401
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From: Utah
Car: 89 RS 89 iroc 87 firebird
Engine: 3.1 Turbo/ 355 twin turbo
Transmission: a4 w/ 4500 stall/ a4 / t5
Axle/Gears: strange s60 /w 3:42's
87 firebird 305 carb to 94 3.4 destroked to 3.0L with bw s475 80mm turbo
im sure im going to get alot hell for this but i dont care its what i want and its what im doing
ive been searching for another 6 car to swap this motor into but i havent been able to find any and as luck has it i just picked up an
89 iroc w an l98 thats been converted to carb and an
87 firebird 305 carbed auto car for 1500 bucks including the 300 mile tow for both cars
the car as it sits now






the interior is going into my iroc once i get the tear on the ds fixed
im goin to make my own solid motor and trans mounts to swap the v6 in instead of using stick rubber mounts
as far as the trans im still deciding between a turbo 350 with trans brake or a close ratio 6 speed
specs on the motor are
94 3.4 with a 2.8 crankshaft for 3.0L of high reving fun
custom j.e pistons for 11.01-1 cr
solid roller cam
fuel system as it is now is dual intank 255's but swaping those out to dual intank 340lph pumps as the walboros are on edge already for e85
custom t4 flanged bw s475 with an 80mm wheel
engine managment is being handled by a megasquirt ecu
anyways lots of pics to come
ive been searching for another 6 car to swap this motor into but i havent been able to find any and as luck has it i just picked up an
89 iroc w an l98 thats been converted to carb and an
87 firebird 305 carbed auto car for 1500 bucks including the 300 mile tow for both cars
the car as it sits now






the interior is going into my iroc once i get the tear on the ds fixed
im goin to make my own solid motor and trans mounts to swap the v6 in instead of using stick rubber mounts
as far as the trans im still deciding between a turbo 350 with trans brake or a close ratio 6 speed
specs on the motor are
94 3.4 with a 2.8 crankshaft for 3.0L of high reving fun
custom j.e pistons for 11.01-1 cr
solid roller cam
fuel system as it is now is dual intank 255's but swaping those out to dual intank 340lph pumps as the walboros are on edge already for e85
custom t4 flanged bw s475 with an 80mm wheel
engine managment is being handled by a megasquirt ecu
anyways lots of pics to come
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Engine: Vortec 4200 Inline 6 PT70 Turbo..
Transmission: 4L65E
Axle/Gears: 3.73
Re: 87 firebird 305 carb to 94 3.4 destroked to 3.0L with bw s475 80mm turbo
Why not! I'll watch. Any idea who will make a torque converter to make it all work? Trial and error cam specs or has this been done a few times? I remember a 4th gen 3.4 turbo that ran well but It's been a long time. Maybe it was in GMHTP magazine? Goodluck!
Thread Starter
Supreme Member
iTrader: (1)
Joined: Apr 2008
Posts: 10,401
Likes: 5
From: Utah
Car: 89 RS 89 iroc 87 firebird
Engine: 3.1 Turbo/ 355 twin turbo
Transmission: a4 w/ 4500 stall/ a4 / t5
Axle/Gears: strange s60 /w 3:42's
Re: 87 firebird 305 carb to 94 3.4 destroked to 3.0L with bw s475 80mm turbo
motors already built and been dynoed was pleased and not so pleased with the results destroking the motor made me lose more tq then i thought i would
example my 3.1 makes over 100 ftlbs more tq then hp this new motor is down about 80 ftlbs from hp.
i expected some loss of tq but not as much as i did
custom solid roller cam 278/268 on 114lsa .550/.550 lift
if i do an auto trans ill be getting a neal chance converter
as far as this bein done a few times,lets just say ive put together a few of these motors for myself, and done some turbo stuff for other board members
and thnx
Thread Starter
Supreme Member
iTrader: (1)
Joined: Apr 2008
Posts: 10,401
Likes: 5
From: Utah
Car: 89 RS 89 iroc 87 firebird
Engine: 3.1 Turbo/ 355 twin turbo
Transmission: a4 w/ 4500 stall/ a4 / t5
Axle/Gears: strange s60 /w 3:42's
Re: 87 firebird 305 carb to 94 3.4 destroked to 3.0L with bw s475 80mm turbo
my iroc is close to being finished so ill be starting on this soon, if anyone is going to be doing a v6 to v8 swap soon id be willing to trade the v8 mounts,springs and engine specific parts for v6 mounts, springs ,front brake line etc
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