Thread: Modding to 300 hp

I have a 2006 gt SC. I am going to started on my build and looking to get at or close to 300 hp at the crank (reason being I want to be as fast as the 5.3L). I am running an open cone as of now, thinking about building a CAI. Next on the todo list is headers. So, what 5hp for the intake and 15hp for the headers? That brings me to 280hp? If I follow the guide on "safely modding" to run a 3.6" pulley how much more hp could that give me or that else could I do to safely achieve my goal?

300 to the crank doesn't seem to hard to do

2-3hp for the intake, 10-12hp for the headers stock

Headers, 3.6MPS, 1.9 Rockers and #105 springs, and a good tune will get you 300 crank.

300 crank is a very realistic goal. I would add 1.9 modded rockers and be done with it. With a solid tune that should net you damn close if not spot on. From there you could start dropping pulleys to push it even further.

Agreed on the rockers. The 5.3 has a much stronger top end than the 3800 and 300hp on the 3800 isn't going to feel like 300 on the 5.3. Rockers will help that though.

id say open cone headers (proper spark plug heat range) 3.4'' pulley and a good tune should get you about 300BHP

It's not a 97-03, guy. 04+ will need to run real fat to push a 3.4 on just headers

3800 is all low/mid end power, top end is nearly non existant without valvetrain mods

Rockers help but they don't nesc really change the way the car feels.

Need a cam to really change that.

Rockers and inter-cool it.

Originally Posted by SnowFlake

300 is easy... it's over 300 where things start to get tough.
mike, what do u mean the v8 has more 'top end'? I was always confused about what people mean by that.

It doesn't fall on it's face in the upper rpm's like the 3800 does. Pit your average bolt-on modded 300 crank horsepower 3800 against against a Grand Prix GXP and the GXP will pull away every time.

But you need valvetrain mods to make 300bhp... even if it's just 1.9s, right?

Generally not with the modded stock rockers but as the cars age it's definitely smart to change the valve springs.

I changed the valve springs and seals while I was in there for my rockers.

Changed to beehive springs with my setup

Originally Posted by SnowFlake

I'm still confused, is this a gearing thing or a power curve type thing?

Power curve due to the cam.

There's no replacement for displacement