305 to 350
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Junior Member
Joined: Jul 2005
Posts: 74
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From: Fayetteville, AR
Car: '89 Formula
Engine: T.P.I. 305
Transmission: Borg Warner T-5
Axle/Gears: Borg Warner 9 bolt - 3.70 posi
305 to 350
i have an 89 with a 305-5 speed. what changes would need to be made to swap with a 350, and can i keep the tpi? any info appreciated.
Joined: Mar 2000
Posts: 43,187
Likes: 42
From: Littleton, CO USA
Car: 82 Berlinetta/57 Bel Air
Engine: L92/LQ4 (both w/4" stroke)
Transmission: 4L80E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
Welcome aboard.
Do you have a 350 identified? Several changes have occurred over the years, and the specifics require knowing what you have. For instance, if the engine is pre-1985, it will have a two-piece rear main seal, which changes the crank flywheel bolt pattern, so you'd need a different flywheel. Pre-1980 have the dipstick on the driver's side, and the stock exhaust manifold gets in its way.
In general, the 350 had larger injectors (22 lb), a different fuel pressure regulator, and different knock sensor and module (as well as different PROM tuning). Depending again on the 350 you get, you may need to do all of those, or you might get away with none of them. Most reports indicate you will need to change the knock sensor and module, however.
A key to making TPI work is the cam used. Don't accept an off-the-shelf generic replacement cam, make sure it is one that is intended to be used with TPI.
About the only other thing you'll have to change is your driving habits - to give the T5 a chance to live behind a 350.
Do you have a 350 identified? Several changes have occurred over the years, and the specifics require knowing what you have. For instance, if the engine is pre-1985, it will have a two-piece rear main seal, which changes the crank flywheel bolt pattern, so you'd need a different flywheel. Pre-1980 have the dipstick on the driver's side, and the stock exhaust manifold gets in its way.
In general, the 350 had larger injectors (22 lb), a different fuel pressure regulator, and different knock sensor and module (as well as different PROM tuning). Depending again on the 350 you get, you may need to do all of those, or you might get away with none of them. Most reports indicate you will need to change the knock sensor and module, however.
A key to making TPI work is the cam used. Don't accept an off-the-shelf generic replacement cam, make sure it is one that is intended to be used with TPI.
About the only other thing you'll have to change is your driving habits - to give the T5 a chance to live behind a 350.
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