turning a 5.3 vortec into an LS1

[camarofanarmy]

I have the heads, cams and the intake manifold for an LS1, what mods will I have to do to make it work.

[E. Haskell]

LS1tech.com - they know it all.

[CRBoyd91]

Have fun with that.

[nailhead425]

The 5.3 has a smaller bore, 96mm vs 99mm, so while the heads might help, you'll need a cam change to really wake up your 5.3.

If you're interested in a Gen III, don't fool around, get the 6.0 truck block and enjoy the fat 4.0" bore.

[05ChevySilveradoSS]

I have the heads, cams and the intake manifold for an LS1, what mods will I have to do to make it work.

Dont Listen To Anyone. . .You Can Tune That 5.3L To Outspec An LS1 5.7L. Its Capable! I Promise Ya. . .stick With The 3.78Bore x 3.62Stroke. The 5.3L Is Well Capable!

[nailhead425]

The 5.3 bore is 3mm smaller than the LS1 and does not offer any breathing advantages over the larger bore. With the same stroke as the LS1 the piston speed is the same so you'll need more cam timing for the same cylinder filling. So essentially, to beat an LS1 you'll need more compression, more cam, and more tuning.

I'm not saying that there isn't alot of potential in the 5.3, I'm saying there is buckets of potential in the 6.0. Since it bolts in and we're talking about changing heads...

It's very similar to building a 305 vs a 350. Sure, you can do it and even make some good power, but the 6.0 is a much better option.

Oh yeah, I've built 2 5.3s, 3 6.0s and a 6.6 stroker for side jobs. Guess which one people like most?

[smith7629]

Nailhead which generation of block did you use to make the 6.6L? I initially assumed you meant the 400c.i. from years past but then I thought maybe you modified a new generation such a 6.0L. Also have you built any Buick engines? I'm guessing so from your name.

[nailhead425]

I used a Gen III truck block because it was cheap and had less than 10k miles. I bought the components from SLP and used AFR heads. All it took was a slight bore to fit the forged pistons along with the rest of the machine work. Standard 4" bore with after market 4" stroke.

Old school 400s aren't that great. Unless you get expensive aftermarket heads you'll never get the full potential of the large bore.

Most people have no idea how well the Gen III/IV small blocks were designed. The new L92 heads are very good factory heads. Big power is available in a small, light package.

I've built a "few" Buicks. Mostly Nailheads.

[05ChevySilveradoSS]

The 5.3 bore is 3mm smaller than the LS1 and does not offer any breathing advantages over the larger bore. With the same stroke as the LS1 the piston speed is the same so you'll need more cam timing for the same cylinder filling. So essentially, to beat an LS1 you'll need more compression, more cam, and more tuning.

I'm not saying that there isn't alot of potential in the 5.3, I'm saying there is buckets of potential in the 6.0. Since it bolts in and we're talking about changing heads...

It's very similar to building a 305 vs a 350. Sure, you can do it and even make some good power, but the 6.0 is a much better option.

Oh yeah, I've built 2 5.3s, 3 6.0s and a 6.6 stroker for side jobs. Guess which one people like most?

The 5.3L Has Higher Flowing Heads Than The LS1.
But Camaro, The 5.3L Is Just As Capable As The 6L And 5.7L Displacement Engines. Which I Can See where Nail Is Coming From In The Displacement Department, But Ive Seen Some 5.3L's And Worked On A Few That Will Make An A** Out Of An LS1

[howpeculiar]

DId that LS1 have the same exact modifactions done to it as the 5.3L? Mod for mod, bigger displacement always gives a bigger return. Period. Not knocking the 5.3L in any way, but if you change the CR, Cam, heads, exhaust and intake to build more power, and perform the same mods (adjusted to take advantage of displacement), the larger bore wins. Look at the potential in the LS7. 427 CI returns a lot more torque than 325 CI.

[05ChevySilveradoSS]

DId that LS1 have the same exact modifactions done to it as the 5.3L? Mod for mod, bigger displacement always gives a bigger return. Period. Not knocking the 5.3L in any way, but if you change the CR, Cam, heads, exhaust and intake to build more power, and perform the same mods (adjusted to take advantage of displacement), the larger bore wins. Look at the potential in the LS7. 427 CI returns a lot more torque than 325 CI.

Well Yes True! But Stock For Stock The 5.3L Has Higher Flowing Heads. And The 5.3L Is Detuned From He**. Id Put The 5.3L Against The LS1 Anyday, Thats How Much Potential This Engine Has. . .Not Saying The LS1 Doesnt Either. Its Just That The 5.3 Is An Capable Engine. Not Many People Know This, Which Is Why I Preach Everyday About It.

[nailhead425]

The 5.3L Has Higher Flowing Heads Than The LS1.
But Camaro, The 5.3L Is Just As Capable As The 6L And 5.7L Displacement Engines. Which I Can See where Nail Is Coming From In The Displacement Department, But Ive Seen Some 5.3L's And Worked On A Few That Will Make An A** Out Of An LS1

yeah, okay. I've built them. I'm not trying to be a jerk, but the larger the bore, the better the results. All the Gen III/IV heads flow well, but which "5.3" heads are you talking about? Also, don't forget chamber size, valve size, etc. Break out the flow bench numbers for the 5.3 head on a 96mm bore and a 99mm bore. We can get into a bench racing match if you'd like but the truth of the dyno is that you can build a 5.3 to whomp a LS1, but anyone who is remotely serious doesn't mess with the 5.3 or the 5.7 (LS1/LS6), they go for the larger bore blocks. The 5.3, 5.7(LS1/LS6) and 6.0 have the same stroke. Smaller bores, with the same stroke, produce much higher port veolicities. Larger bores allow for more efficient cylinder filling, which results in more power. GM isn't stupid, that's why the L92 is so incredible and why the L92 heads on a 6.0 make it brutal.

[05ChevySilveradoSS]

yeah, okay. I've built them. I'm not trying to be a jerk, but the larger the bore, the better the results. All the Gen III/IV heads flow well, but which "5.3" heads are you talking about? Also, don't forget chamber size, valve size, etc. Break out the flow bench numbers for the 5.3 head on a 96mm bore and a 99mm bore. We can get into a bench racing match if you'd like but the truth of the dyno is that you can build a 5.3 to whomp a LS1, but anyone who is remotely serious doesn't mess with the 5.3 or the 5.7 (LS1/LS6), they go for the larger bore blocks. The 5.3, 5.7(LS1/LS6) and 6.0 have the same stroke. Smaller bores, with the same stroke, produce much higher port veolicities. Larger bores allow for more efficient cylinder filling, which results in more power. GM isn't stupid, that's why the L92 is so incredible and why the L92 heads on a 6.0 make it brutal.

Well Spoken. Good Post!

Well Im Talking About The L33 Vortec Heads, And The LM7 Heads (Both Higher Flowing Than The LS1 5.7L) Ive Worked On LS1 Powered Camaros (Rear Differentials) Mostly, But I Look Under The Hood (When There In The Shop) And I See Alot Of 5.3L Heads On Top Of The LS1 5.7L Engines (Which Someone Has Put On It Of Course). Yes I Understand The Bigger The Bore The More Power, Thats Just A Given, All Im Saying Is That The 5.3L Is Capable Of Producing Pretty Serious Numbers. It All Just Depends On How Much $ Your Wanting To Dump Into It. Just Like Now You Can Go Buy A Brand New Turn Key Naturally Inspirated 650Hp 5.3L, Were Not Talking With The Supercharger And All, Im Talking All Motor. ITs A Capable Engine Nail, Which Im Sure You Know That. I Just Dont Think The 5.3L Gets The Credit It Deserves Like Its Bigger 6L Brothers. Oh And Yes No Doubt The L92 Heads Are Great, And Would Wake The 6L Up Astoundinly, But It Would Also Increase The Power Amazingly On The 5.3L.

And Yeah Ive Worked On Several LS Engines Myself, And Im Sure That Will Continue. There Great Engines. Its Amazing How Well The Heads Are On Those Things. Even The Block Is Just Amazing How Well Built They Are.

[Corr69]

I don't think you understand what Nailhead is saying.

The more displeacement, the more results with less money. Its that simple.

You'll have todo more mods to a 5.3L to make it as fast as a 6.0L. Because if u did everything to both, the 6.0L would be faster.

[05ChevySilveradoSS]

I don't think you understand what Nailhead is saying.

The more displeacement, the more results with less money. Its that simple.

You'll have todo more mods to a 5.3L to make it as fast as a 6.0L. Because if u did everything to both, the 6.0L would be faster.

I Understand Exactly What He's Saying, And I Understand What Your Saying, But All Im Saying Is That Its A Very Capable Engine. Its Capable Of Some Serious Power.

Its Another Reason Why I Preach So Much About How Capable This Engine Is Because I Love The Characteristics Of It, And How So Many People Dont Have A Clue How Much Potential this "Small Displacement" Engine Is Capable Of.