5.7 carb or 5.3

[SubLo]

Wrong, forced induction.

That's what I said man.

 

[silverado_lover]

Turbos or SC don't make a truck un-streetable

 

[90lsx]

Turbo 5.3 or 4.8 are making well over the 450 HP mark that he is looking for

 

[454SSguy]

For a 5.3 to make 450hp, it would be unstreetable. You'd be torturing yourself as a DD. Reason being, you'd have to choose a crank, piston, and head combo to put you in the @10.5 - 11:1 or greater compression ratio with all sorts of supporting mods like 4-bolt main, 750 - 800 cfm carb or equivilent efi, raised runner/intake, high-pressure fuel pump, blueprint/balance, and relatively large/lopey/poor-street-idling cam, etc. Otherwise, a supercharger might put you close to there on a more or less stock 5.3.

The 5.7 with it's slightly larger displacement could put you there with an ever so slightly lower compression ratio albeit with extensive mods as well.

If you're looking at a brand new long-block swap and are shooting for that power level, i'd look at a 406 (bored/honed 400) for streetable power.

That's my 2 cents. Other opinions may vary.

<flame_on>

Not to dump on your post but, the stock LS 5.7's are already around that compression ratio after a smaller headgasket, and the cam profiles are the same for the 5.3 and the 5.7. I think with a decent cam, set of 243 heads and decent intake (LS6, Fast, Vic Jr, EFI PRO Flo) you could reach your power goals. You could even go carb if you got that kit from edlebrock, probably loose a little gas mileage but a 5.3 would still be a nasty little motor. Or you could do all that and run a small procharger or novi on top of it. Then your def making your power goals.

 

[DieselPower]

Driving 450 hp on the street gets a bit interesting. I had a carb'd corvette that was pushing the high side of 400 hp. Without traction control, it could be a bit hairy at times. I could not start from a stoplight without squeaking the tires. A 2cd gear shift was good for another chirp - and I'd barely touch the throttle. It was a bit nerve-racking if there were any cops at the intersection. That much fun was on a dry road, toss in a little rain and the back end would get squirrely - and it had a much better weight balance than a truck does. With 4 wheel disk brakes, it was able to bleed off the speed that the engine had - aren't most GMT400's equipped with drum rear brakes?

If you are going to be that ambitious with power, you'll want to build everything to make it streetable. Otherwise you'll find that you have an occasional weekend/sunny weather driver that becomes a white-knuckled driver when the weather deteriorates. Getting sideways may be fun when you are alone on a back road, but if you are commuting in traffic it's a problem.

The carburetor isn't the problem. Fuel injection is nice from the standpoint of warm up times, but if something goes wrong - a carburetor will get me home, the FI vehicle will need a tow. The LS series makes good power, but it is far more complex and likely to have mechanical/electrical failures.

 

[silverado_lover]

I agree with the first 2/3 of that post...OP even doing a cammed/stalled 5.3 will probably be plenty of power. There comes a point when all that extra power is useless because you can't put it down.

 

[DRAGGIN95]

I love the power my 6.0 has!

 

[90lsx]

6.0 243 heads a custom grind cam tuned and injectors. 475-500hp easy all day also how does driving 450 on the street get interesting?? Try driving a 800 HP vette on the streets and then you are finally getting to have some fun bro

 

[454SSguy]

just to give you an idea, my LS1 GTO made 455 to the wheels, with torquer V.3 cam, and ported and polished 243's on a nitrous tune (4 or 5 degrees of timing pulled). A 5.3 would not be far off that with the same mods.

 

[DieselPower]

Try driving that 800 hp vette on the streets without traction control. Now toss in a car on one side of you, another in front, another in back - and a guardrail for that "boxed in" effect. Add a light dusting of rain on the road. It gets interesting trying to keep the vehicle going in a straight line when you have lots of power and no technology controlling it. Power is fun, but a daily driver needs to be driveable. A 400+ hp truck is going to be a bit of a handful in the same circumstances. Even a GTO has traction control to make the vehicle "civilized".