99 Firebird-3.8 to ls1 swap questions - Fourth Generation Pontiac Firebird (1993 - 2002) - Firebird Nation

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99 Firebird-3.8 to ls1 swap questions


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#1 Noesparks

Noesparks

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  • Interests:Fixing up this 99 firebird i just purchased with no rust and kept in reletively good conditiom
  • Year: 1999
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  • Engine: 3.8 v6
  • Transmission: 5 speed

Posted A week ago

So I just purchase myself a 99 firebird with 246k miles about a month ago. It actually ran really nice once I changed the manifold gaskets/plugs/wires/coils. Wanted to beef up the engine and try to hit 300hp. but i just wanna stay NA and I'm reading a 3800 wont really get much better without some boost. Now one of the rod bearings has gone out and i got some knock(sad day). I wasn't thinking about swapping engines so soon but if I gotta drop the engine out I figure I might aswell just swap it now rather than later even if it might be a bit of a hassle. I want to try to hit at least 400HP. Anything more than that will be icing on the cake. I want to be able to have the car reliable and daily driven yet also survive a day at the track(mainly drifting/circuit).

 

 

 

What I'm trying to figure out is what parts exc should i us to achieve this. Should I stroke it, bore the cylinders, both, or neither. I've read a ls6 heads are good and to get a aftermarket camshaft rather than using a ls6 cam. I've read that they can have oil starvations problems at times, anyway to combat this? been seeing stuff about gen4/ls2 lifters aswell.


Literally any info would be appreciated greatly as I've never done a swap or engine build before. I've only ever just fixed what broke on my vehicles with new stock parts. 

 

 

(sidenote. i do understand the 5spd will have to be swapped for the 6spd aswell. probably the dif too.)



#2 Injuneer

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  • Year: 1994
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Posted A week ago

Are you aware, to swap in an LS1 you will need the engine, the PCM, the engine wiring harness, the K-member that supports the engine, a new clutch and transmission (T56) as well?  The T5 can't handle the torque from an LS1 and won't bolt up to it.

 

If so, the easiest thing to do is pull the complete engine/trans/K-member/suspension out of a wrecked 99-02 LS1 Camaro or Firebird, drop the corresponding complete V6 assembly out of your car and drop the front end of the chassis over the LS1 assembly.  That way you have all the right parts, including the correct coil springs for the weight of the LS1 engine.

 

Rear axle depends on whether your car has a limited slip differential (RPO G80 on Service Parts label).

 

Are you looking for 400 HP at the flywheel (the way the factory rates the engine), or at the rear wheels?  Makes a significant difference.


1994 FIREBIRD FORMULA
FRED

 
381ci all-forged stroker (Callies Stealth, Oliver billet rods, BME 2618-T61 nitrous pistons) - 10.8:1 - CNC LT4 heads/intake - Comp Cams solid roller - MoTeC M48 Pro engine management - 8 LS1 coils - 58mm TB - 74#/HR injectors - 300-shot dry nitrous - TH400 - Gear Vendors 0.78:1 O/D - Strange 12-bolt - 4.11 Pro-Street gears - AS&M headers - true duals - Corbeau seat - AutoMeter gauges - roll bar - Spohn suspension - QA1 shocks - a few other odds 'n ends. 800HP / 800lb-ft at the flywheel, on a 300-shot. 11.5 @ 117 MPH straight motor
 
https://www.firebird...9_698_32777.jpg

 


#3 tom99

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Posted A week ago

There is a extensive post on swapping at the top of the “all things v6 section “ the ideal would be to find another v8 car of the same year wrecked and go to town


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#4 Noesparks

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  • Interests:Fixing up this 99 firebird i just purchased with no rust and kept in reletively good conditiom
  • Year: 1999
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  • Model: Firebird
  • Engine: 3.8 v6
  • Transmission: 5 speed

Posted A week ago

Are you aware, to swap in an LS1 you will need the engine, the PCM, the engine wiring harness, the K-member that supports the engine, a new clutch and transmission (T56) as well?  The T5 can't handle the torque from an LS1 and won't bolt up to it.

 

If so, the easiest thing to do is pull the complete engine/trans/K-member/suspension out of a wrecked 99-02 LS1 Camaro or Firebird, drop the corresponding complete V6 assembly out of your car and drop the front end of the chassis over the LS1 assembly.  That way you have all the right parts, including the correct coil springs for the weight of the LS1 engine.

 

Rear axle depends on whether your car has a limited slip differential (RPO G80 on Service Parts label).

 

Are you looking for 400 HP at the flywheel (the way the factory rates the engine), or at the rear wheels?  Makes a significant difference.

 

 

oh yes i do know about all the extra things i gotta do to make it work. I am looking to find a wrecked v8 to get most of that stuff. also i am trying to have to hp at the wheels not flywheel. but if it isnt possible then getting as close as i can is just as good. i also may have found a wrecked trans am only 10 hrs away. waiting to hear back atm.

 

 

 

 

 

There is a extensive post on swapping at the top of the “all things v6 section “ the ideal would be to find another v8 car of the same year wrecked and go to town


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oh thanks. i did not know about this. still learning the site and finding new info everyday. thanks. i will be sure to check that out.


What im most worried about figuring out atm is what mods i need to do to the engine for the HP. 


Edited by Noesparks, A week ago.





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