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1986, T/A, 305. Named "Bird"
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Discussion Starter · #1 ·
Is there any good power boosters for a 305? I know you can turbo a lot of things. But, what I'm really wanting is a supercharger, of some sorts. Is there any out there?
 

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Which version of the 305 does your 1986 Trans Am (info from an earlier post on increasing HP) have?

The T/A came with the LG4 305 (160 HP) standard and the optional L98 305 (190 HP)? If all you do is bolt on a supercharger kit, you will gain 25-40% more HP. The more you boost it, the more HP, and the more likely you will need internal upgrades to the rotating assembly.

Then, what transmission do you have - the 5-speed manual or the automatic? The 5-speed does not hold up well to increased torque. The auto trans might be questionable at the max possible HP.

Next, what is your budget? Here's some Weiand S/C kits:


Here’s som Vortech centrifugal kits:


And save some of the budget for upgraded fuel system, exhaust system, cooling system, etc. Maybe an upgraded rear axle assembly.
 
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1986, T/A, 305. Named "Bird"
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Discussion Starter · #3 ·
Which version of the 305 does your 1986 Trans Am (info from an earlier post on increasing HP) have?

The T/A came with the LG4 305 (160 HP) standard and the optional L98 305 (190 HP)? If all you do is bolt on a supercharger kit, you will gain 25-40% more HP. The more you boost it, the more HP, and the more likely you will need internal upgrades to the rotating assembly.

Then, what transmission do you have - the 5-speed manual or the automatic? The 5-speed does not hold up well to increased torque. The auto trans might be questionable at the max possible HP.

Next, what is your budget? Here's some Weiand S/C kits:


Here’s som Vortech centrifugal kits:


And save some of the budget for upgraded fuel system, exhaust system, cooling system, etc. Maybe an upgraded rear axle assembly.
Whats the difference between the LG4 and L98? I have the 700r4 in my car. Would that be able to handle any extra power/torque? As for budget, I dont have one just yet. I'm setting up future plans for power. Just window shopping
 

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1986, T/A, 305. Named "Bird"
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Discussion Starter · #4 ·
Whats the difference between the LG4 and L98? I have the 700r4 in my car. Would that be able to handle any extra power/torque? As for budget, I dont have one just yet. I'm setting up future plans for power. Just window shopping
Also, how do I check what engine I have?
 

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As I indicated, one is a higher performance version of the 305ci engine, with 35 additional horsepower. The engine is encoded in the VIN (vehicle identification number). The 8th digit is the engine code. H = LG4 (and it has a 4 bbl carburetor); F = LB9 (electronic fuel injection).

The engine's 3-digit code (LG4, or LB9) would also appear in the Service Parts Identification label. Label can be in the glove box, console, end of driver door panel…. not sure where they were in 1986 models. Sometimes they are illegible or completely missing in an older car.

The HP is important because the supercharger increases pressure in the intake manifold, and the HP gain is roughly proportional to the factory rated HP. Start with a higher HP engine and the S/C can add more HP with the correct pulley setup.
 

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1986, T/A, 305. Named "Bird"
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Discussion Starter · #6 ·
As I indicated, one is a higher performance version of the 305ci engine, with 35 additional horsepower. The engine is encoded in the VIN (vehicle identification number). The 8th digit is the engine code. H = LG4 (and it has a 4 bbl carburetor); F = LB9 (electronic fuel injection).

The engine's 3-digit code (LG4, or LB9) would also appear in the Service Parts Identification label. Label can be in the glove box, console, end of driver door panel…. not sure where they were in 1986 models. Sometimes they are illegible or completely missing in an older car.

The HP is important because the supercharger increases pressure in the intake manifold, and the HP gain is roughly proportional to the factory rated HP. Start with a higher HP engine and the S/C can add more HP with the correct pulley setup.
I checked the vin, finally (dont have the car at my house, so, I havent had time to check it). Its an LG4, 305. Is there any difference in the engines, besides being carbureted and efi?
 

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Did you read the first sentence of the paragraph you quoted immediately above, from my post #5? It explains the primary difference (HP). The difference is also explained in my post #2.
 

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Whats the difference between the LG4 and L98? I have the 700r4 in my car. Would that be able to handle any extra power/torque? As for budg. et, I dont have one just yet. I'm setting up future plans for power. Just window shopping
An l98 is a mid 80's corvette engine. It is a 350 with sequential port fuel injection. I have one in my 85 corvette and I had a Holly EFI with bigger injectors. I really like the engine 700R4 Trans combination. 27 mpg and smooth as silk. The holly provides the ECM function.
 

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1986, T/A, 305. Named "Bird"
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Discussion Starter · #9 ·
Did you read the first sentence of the paragraph you quoted immediately above, from my post #5? It explains the primary difference (HP). The difference is also explained in my post #2.
My fault. I meant any differences, other than horsepower. Sorry about that. Shouldve been more specific
 

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DELCO NERD
1993 Pontiac Firebird Trans Am, LT1 5.7L V8
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The LG4 is a carburetor system, so the fuel pressure will be significantly lower than that of the LB9 engine, which is fuel injected.
 
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Off the top of my head - The LG4 has dished pistons, compared to the LB9’s flat pistons = lower compression ratio = less HP. The LG4 air intake system is more restrictive, as is the exhaust system = less HP. Probably a milder camshaft. Don't know for sure about the heads but I suspect the LB9 heads flow better. At some point the LB9 engine got a knock sensor, before the LG4 did, allowing the LB9 to run more aggressive ignition timing. Not sure what year.

Beyond that I've never really been interested in the 305 engine because is can't hold a candle to the L98 (also used in the 3rd Gen Camaro/Firebird)…. or the 4th Gen's LT1 and LS1.
 
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