LS4 Performance - How to get 400hp?

I have searched but only see this question for the 94-96 Impala SS.

I am a mobile detailer with a F-150 and want a car(need a decent sized car b/c of that), want to spend around 10k in a few months. It was either a Charger R/T or a SS, I like the viper inspired seats of the charger but unless its a SRT8 I don't like the exterior. So I have been thinking about the SS for a bit.

Well I will probably get a 06/07, whats the best way to get 400hp? I don't have enough money for a SC and prefer NA anyways. I'm talking 400 crank, but 430 crank or 400 WHP would be great! Don't really want to spend more than 1.5k to 2k..figure it can't be to bad considering this car already has 300 stock.

I don't care about mpg because I am getting 12mpg right now, and I want a dependable vehicle.

turbo is the only way to get to that number, outside of nitrous, and that will cost much more than your budget.....then if you did get it turbo'd, you would grenade the trans in less than 6 months...

...if you are looking for "reliable" don't an LS4 w-body, if you want car that is 400hp AND reliable....definitely don't get an LS4 w-body, get an LS2 GTO...

Well like I said I need a larger vehicle because I do mobile detailing.
So pretty much these cars sucks? haha
How can there tranny's be so weak? Well I was thinking a cam, intake, exhaust, programmer and a dyno tune. How much do you think that would get me?

A friend has a 08 Impala but with the V-6, no issues whatsoever. Different cars?

$2000 for a trans, another $1000 for spray. That's the easiest way to 400 WHP.

You could do a turbo or heads and cam to get there, but it ain't gonna be cheap.

$2000 for a trans, another $1000 for spray. That's the easiest way to 400 WHP.

You could do a turbo or heads and cam to get there, but it ain't gonna be cheap.

I'm talking 400 crank, haha. 400WHP would be nice but right now I am more aiming 400-430 crank. Mods? And best ways to preserve transmission failure? I'm a DIY guy, but wouldn't flush a tranny but I would drain it

A friend has a 08 Impala but with the V-6, no issues whatsoever. Different cars?

the problem is that they basically have the same transmission....

Well like I said I need a larger vehicle because I do mobile detailing.
So pretty much these cars sucks? haha
How can there tranny's be so weak? Well I was thinking a cam, intake, exhaust, programmer and a dyno tune. How much do you think that would get me?

A friend has a 08 Impala but with the V-6, no issues whatsoever. Different cars?


When I had my 06 Impala SS my transmission went on me twice and i rarely if ever beat on the car. My mechanic that did my transmissions told me he would have these cars in his shop quite often and its always for a transmission job. He also pointed out to me that even though the transmission is supposedly "Heavy Duty", they share the same torque converter as all the other v6 models. If you're looking for a more reliable car that will get 400 hp easily and wont have to worry about it breaking down on you, get a G8 GT/GXP or a Charger R/T or SRT8. Sorry.

i'm not sure what these guys are talking about with doing turbo or giving it a bottle...DavidGXP runs 450+ crank HP with basically a cam (dod delete), LS6 intake, headers, CAI and tune. dude's in the mid 12s. but you have to drop the motor to do the cam. be prepaired to do a trans.

I'm planning on a similar setup as soon as my trans goes, which it will in every LS4 car. I'm going to swap in the 6T75 trans with either a 5.3 alum truck block or if I'm lucky an LS2. using the LS4 accessory drive and crank to make it fit. ported and milled stock heads (they're the LS6 castings) 10.x:1 compression ratio, a water meth kit, a high rpm screamin cam (loss in unusable low end). If displacment doesn't change from 5.3 im looking at an easy 475 horse, with a 6.0 more like 550. I wanna break 12 eventually with an N/A motor and maybe a 75 shot or somthing.

best mods for these cars, after the trans, really is suspension. they handle like crap from the factory. the ZZP tubular control arms really sharpened the car up and got rid of torque steer. the Bilstein HD's are also awesome but beware of sag with lowering springs. my sig lists all of my current major mods and besides my bad front hubs, the exhaust noise with dod on, and trans I'm really happy with my car. be prepaired to spen about 3-5k on mods to be as happy as me.

check out this thread http://ls1tech.com/forums/showthread.php?t=1535015&goto=newpost

Or you can buy my car if you live close.
Im thinking about letting it go.
Built trans and engine with suspension mods.

i'm not sure what these guys are talking about with doing turbo or giving it a bottle...DavidGXP runs 450+ crank HP with basically a cam (dod delete), LS6 intake, headers, CAI and tune. dude's in the mid 12s. but you have to drop the motor to do the cam. be prepaired to do a trans.

I'm planning on a similar setup as soon as my trans goes, which it will in every LS4 car. I'm going to swap in the 6T75 trans with either a 5.3 alum truck block or if I'm lucky an LS2. using the LS4 accessory drive and crank to make it fit. ported and milled stock heads (they're the LS6 castings) 10.x:1 compression ratio, a water meth kit, a high rpm screamin cam (loss in unusable low end). If displacment doesn't change from 5.3 im looking at an easy 475 horse, with a 6.0 more like 550. I wanna break 12 eventually with an N/A motor and maybe a 75 shot or somthing.

best mods for these cars, after the trans, really is suspension. they handle like crap from the factory. the ZZP tubular control arms really sharpened the car up and got rid of torque steer. the Bilstein HD's are also awesome but beware of sag with lowering springs. my sig lists all of my current major mods and besides my bad front hubs, the exhaust noise with dod on, and trans I'm really happy with my car. be prepaired to spen about 3-5k on mods to be as happy as me.

check out this thread http://ls1tech.com/forums/showthread.php?t=1535015&goto=newpost

OP is on a budget, so your monster build isn't gonna help him.

My bad on reading his first post...I assumed he meant 400 WHP, not crank. You gotta spend some money on a 5.3 to get to 400 CHP without spray or a turbo (and that ain't cheap, either!). DavidGXP is there now, but he spend more than $2k to get there reliably, and he's already been through one short block.

Pick two: Make it fast, make it cheap, or make it reliable. You simply can't have all three.

Or you can buy my car if you live close.
Im thinking about letting it go.
Built trans and engine with suspension mods.

Why are you considering selling?

these cars dyno 240-250 whp stock so a 150whp gain is going to take alot of money.

He's looking for 400 crank HP.

On a side note, I toyed with the idea of getting a Charger R/T before I bought the GXP. If you find one with the Road and Track package (not just R/T) you will have the SRT8 seats and upgraded suspension. Prior to the '11, getting an SRT 8 seemed bogus to me. The 6.1 was not worth the $ to buy an SRT over the 5.7l R/T's. The 5.7 was very close to the 6.1 in power.

He needs about at least 100hp gain at the wheels to be close to 400crank hp without nitrous, to gain about 100 hp is going to cost around 3grand.

Thinking of selling cause I bought a suv and now I don't need the gxp.
Its a want not a need.

Going to get it detailed and multi point inspected by Cadillac if I put it up.

Looking for 15k. Awesome car and it just dusted a 2012 srt8 charger from 55 to 140. I had to make a hard right, and the car took the corner with ease doing 120. The charger went way..over the line.

I have already told everyone how to make 400+ hp

Use the tfs 5.3 top end package with
Ls7 lifters, and buckets. Then get the katech tray with the Opsu adapter. Headers, 3" exhaust and a ls6 intake swap. Total will cost around 4500.00
Run the trans till it blows! My trans cost me about 3500 when it was all said and done. Suspension was arpond 500.00 for springs, bars, and alignment.

I have pieced this car together and nothing was done all at once, so I have around 6000.00 invested.

He needs about at least 100hp gain at the wheels to be close to 400crank hp without nitrous, to gain about 100 hp is going to cost around 3grand.

Wut? He's already at a little over 300 crank hp, so why would he need at least 100 wheel hp to gain a 100 crank hp?

A better statement would be that he needs about 70 wheel hp to gain 100 crank hp and make his goal of 400 crank hp.

I have pieced this car together and nothing was done all at once, so I have around 6000.00 invested.

Which isn't bad at all considering the sticker price and the cars that it can run with now...

He's looking for 400 crank HP.

On a side note, I toyed with the idea of getting a Charger R/T before I bought the GXP. If you find one with the Road and Track package (not just R/T) you will have the SRT8 seats and upgraded suspension. Prior to the '11, getting an SRT 8 seemed bogus to me. The 6.1 was not worth the $ to buy an SRT over the 5.7l R/T's. The 5.7 was very close to the 6.1 in power.

The 2009 and up R/T's are closer to the 6.1 Hemi because of the increase in HP and better gearing. Stock they can run mid 13's. If I was the OP I would get a G8 GT or GXP or a Charger R/T with the Road and Track package from
The years 2009 and up. These LS4 cars are very expensive to mod.

Yeah, forgot they added VVT in 09.

All you guys need is a intake swap. The ls1 intake makes a huge difference compared to the stock ls4.
The ls6 isn't really needed unless one wanted to make power up to 6500.

With a intake and I am positive low 13's is possible

All you guys need is a intake swap. The ls1 intake makes a huge difference compared to the stock ls4.
The ls6 isn't really needed unless one wanted to make power up to 6500.

With a intake and I am positive low 13's is possible

I remember reading that on one of the threads here on this forum. A lot of guys are using either the ls1, ls6, or ls2 intakes if I remember correctly.

Well on may 5th ill let everyone know what the impala goes with ls1 intake, catless dp, and diablew tuned. Should have it all done this weekend.

David you would miss the car after all the headaches and time that have been invested in it. But if you do decide to sell it please make it to the track first. I am really curious to see how your setup does.

Well I'm not looking to buy a car until Aug/Sep.
Glad I checked here first, the LS4 cars are no longer a option. I couldn't buy a car knowing id have 2k+ because the tranny will be going out.

I'd like to spend around 10k and 13k max, 10k would be better.
So I need a decent performance vehicle with good amount of space..so far this is what I'm thinking

A 06/07 R/T and I would get the once with the Viper inspired sets, guess that also comes with the suspension. Get that a new bumper, SRT spoiler and new hood, and I would really love it!

Or a TBSS, probably RWD. I like them but have detailed a stock TB and really didn't like the interior to much. Anything better on the SS?I do love the exterior and engine

My "dream" vehicle for now would be like a 2005 Porsche Cayenne Turbo. They are 100k SUVs, great off-road, amazing interior, quick, roomy and pretty dependable. But..a used one cost around 20k(lower price).

Any other good vehicles? I looked at the Jeep SRTs but they are 20k and I would just get the porsche for that...So a R/T usually around 11ish, a TBSS, or wait until..like Jan or Feb and the Porsche? Probably longer tho. I'm a senior in HS working at publix and doing auto detailing but don't want to go crazy on a car.

I also probably have around 300lbs of supplies, how do you think that will effect performance?

Dude you dont want a high milage porsche anything. If something breaks and you cant afford the repairs your gonna be SOL...sometimes you have to make a compromise betwern performance and practicality. Id say the TBSS is your best option, faster than the charger and more room. But the interior does suck big time. My suggestion is a 99 to 06 denali, its got a 6.0 and hauls ass for what it is and has a nicer interior than the TBSS and you couldnt ask for more room.

Obviouslly weight will slow you down, eat gas, and impair handeling.

Well I'm not looking to buy a car until Aug/Sep.
Glad I checked here first, the LS4 cars are no longer a option. I couldn't buy a car knowing id have 2k+ because the tranny will be going out.

I'd like to spend around 10k and 13k max, 10k would be better.
So I need a decent performance vehicle with good amount of space..so far this is what I'm thinking

A 06/07 R/T and I would get the once with the Viper inspired sets, guess that also comes with the suspension. Get that a new bumper, SRT spoiler and new hood, and I would really love it!

Or a TBSS, probably RWD. I like them but have detailed a stock TB and really didn't like the interior to much. Anything better on the SS?I do love the exterior and engine

My "dream" vehicle for now would be like a 2005 Porsche Cayenne Turbo. They are 100k SUVs, great off-road, amazing interior, quick, roomy and pretty dependable. But..a used one cost around 20k(lower price).

Any other good vehicles? I looked at the Jeep SRTs but they are 20k and I would just get the porsche for that...So a R/T usually around 11ish, a TBSS, or wait until..like Jan or Feb and the Porsche? Probably longer tho. I'm a senior in HS working at publix and doing auto detailing but don't want to go crazy on a car.

I also probably have around 300lbs of supplies, how do you think that will effect performance?


Get the Charger R/T with the Road and Track package. You honestly won't be disappointed.

you could suck it up and go with the LS4. transmission issues can be tentatively fixed for about a grand. decent performance potential and decent mileage out of the box.

if you want true reliability you're looking at the wrong 3 options.

if you want true performance you're looking at the wrong 3 options

fast, cheap, reliable. pick any 2...

i doubt youll be able to pick up a 06/07 r/t anything for 10k unfortunetly..

The trans really isnt that big of a deal imo.. gm will just keep giving you new ones for free lol. And the mileage is amazing, after my cai exhaust and tune im getting between 28-32mpg @ 65mph... pretty amazing if ya ask me, especially with the way gas prices are headed over $5 this summer, ugh!!

Well I'm not looking to buy a car until Aug/Sep.
Glad I checked here first, the LS4 cars are no longer a option. I couldn't buy a car knowing id have 2k+ because the tranny will be going out.

I'd like to spend around 10k and 13k max, 10k would be better.
So I need a decent performance vehicle with good amount of space..so far this is what I'm thinking

A 06/07 R/T and I would get the once with the Viper inspired sets, guess that also comes with the suspension. Get that a new bumper, SRT spoiler and new hood, and I would really love it!

Or a TBSS, probably RWD. I like them but have detailed a stock TB and really didn't like the interior to much. Anything better on the SS?I do love the exterior and engine

My "dream" vehicle for now would be like a 2005 Porsche Cayenne Turbo. They are 100k SUVs, great off-road, amazing interior, quick, roomy and pretty dependable. But..a used one cost around 20k(lower price).

Any other good vehicles? I looked at the Jeep SRTs but they are 20k and I would just get the porsche for that...So a R/T usually around 11ish, a TBSS, or wait until..like Jan or Feb and the Porsche? Probably longer tho. I'm a senior in HS working at publix and doing auto detailing but don't want to go crazy on a car.

I also probably have around 300lbs of supplies, how do you think that will effect performance?

Look for a LS1 GTO.

Look for a LS1 GTO.

Truthitude.

Look for a LS1 GTO.

If I remember correctly, he said he needed a larger car because of his work. A GTO would be an excellent choice in my opinion but he needs something with 4 doors. The sad thing is, there aren't many sports sedans with good performance with in his price range and HP requirements ala Impala SS, Pontiac Grand Prix and Dodge Charger/Chrysler 300

If I remember correctly, he said he needed a larger car because of his work. A GTO would be an excellent choice in my opinion but he needs something with 4 doors. The sad thing is, there aren't many sports sedans with good performance with in his price range and HP requirements ala Impala SS, Pontiac Grand Prix and Dodge Charger/Chrysler 300

Actually when I compared my GF's GXP to my buddies GTO, the GTO actually had more back seat room, althought the trunk space was a bit smaller. For being a HS kid needing to transport supplies, I think a GTO has plenty of room.

I have already told everyone how to make 400+ hp

Use the tfs 5.3 top end package with
Ls7 lifters, and buckets. Then get the katech tray with the Opsu adapter. Headers, 3" exhaust and a ls6 intake swap. Total will cost around 4500.00
Run the trans till it blows! My trans cost me about 3500 when it was all said and done. Suspension was arpond 500.00 for springs, bars, and alignment.

I have pieced this car together and nothing was done all at once, so I have around 6000.00 invested.

If you had to do it again would you invest in a turbo kit instead ?

No to the turbo, because the kit is around 6000 after being shipped and the trans upgrades would cost a little more. Plus I would still have the crappy intake, exhaust, and the dod b.s
Mid 12's is plenty fast for a street car and reliable.

If I had all of the money up front, then, I would sell my heads and go with the tfs heads and 3.29 gears.

The tfs heads will raise the compression to 11:1 iirc (search my old threads) and use a smaller 205cc intake runner vs 212cc for the 243 heads. Port volicity from low to mid lifts kick the crap out of our heads.


Nothing wrong with turbo builds. Especially if you have fab skills.
Stuff just adds up real quick, and your tune better be spot on!

No to the turbo, because the kit is around 6000 after being shipped and the trans upgrades would cost a little more. Plus I would still have the crappy intake, exhaust, and the dod b.s
Mid 12's is plenty fast for a street car and reliable.

If I had all of the money up front, then, I would sell my heads and go with the tfs heads and 3.29 gears.

The tfs heads will raise the compression to 11:1 iirc (search my old threads) and use a smaller 205cc intake runner vs 212cc for the 243 heads. Port volicity from low to mid lifts kick the crap out of our heads.


Nothing wrong with turbo builds. Especially if you have fab skills.
Stuff just adds up real quick, and your tune better be spot on!