How much more power can a 5.3L make without hurting road manners or gas mileage?

[PhotonFanatic]

I want to do the 5.3L swap, but I'd like to add some power and torque before it goes in the truck. But there's two conditions: I don't want it to hurt the road manners, and I don't to harm the MPG. By road manners, I mean I don't want it to shake the truck at all. Just feel totally smooth like a factory engine.

Are these things too limiting, to allow for making any more power? I think they would probably rule out the standard heads/cam/intake swap. So what does that leave? If I'm building the engine from a bare block, would lighter rods free up power? How about using roller rockers instead of the factory ones? Electric water pump, and electric cooling fans? There's a few things you can do that free up power by increasing efficiency. What's on that list?

But maybe I'm wrong about the heads, cam and intake. Maybe there's some room to grow, but it still won't jiggle the truck or harm MPG much. Any ideas?

Thank you

 

[Camar068]

The easiest increase in power is going to be a cold air intake. If you decide to go headers, make sure you go long tube. Short tube headers are just as good as stock manifolds....so your paying for looks when you go shorty.

hopefully I'll be building a 5.3 from the ground up. Be about $2,200. I've got the Brian Tooley Racing Torque cam on my list because it increases HP/TQ below 2,500 rpm's. I don't need a thumper cam as I don't spend much time over 5,000 rpms.

For the BTR torque cam you need to upgrade your valve springs, but your stock converter will be fine. I've not done springs but watched enough videos to see that it's easy.....that and I stayed at a Holiday Inn last night lol.

What's your gear ratio and trans?

Of course, in the end....gas mileage is all up to your foot. I can get 17 mpg's out of my swap if I want to, but I don't

 

[PhotonFanatic]

I believe my truck has 2:73's, but I could be wrong about that. It's the stock gearing. It will do 80 mph at around 1,800 RPM so it's probably the 2:73's.

I currently have the 700R4 transmission. But that may become a 6L80e when it's time for the 5.3L swap. I still want to do 80 or 85 mph at 1800 RPM. Don't wanna lose that, for highway. I like to keep RPM's low on the highway.

I was considering the 6.0L or even 6.2L conversion, but I can't see any reason it would be necessary. A few minor tweaks to a 5.3L gives you the same power they make when stock. I'd like to do an extra 150 hp and tq over the stock TBI 350 that's in the truck now. Should be more than one of these old trucks will ever need.

And I do still want to use it for light towing, as one would with a half ton truck.

 

[SquareRoot]

Cost- Power- Reliability. You only get two.

 

[Ricko1966]

You do know the 5.3 only has 25lb more torque than your 350? So just my opinion trying to make 1.5 times torque that your 5.3 made factory,without hurting gas milage is going to be a tall order. IMHO turbocharge the 350 power when you want it,mpg when you want it. Yep you could just turbocharge the 5 3,now your out the cost of the ls swap and the turbo.

 

[SquareRoot]

Pro Charger. I've wanted one forever. Now with the PF4, the tunes are already in the ECU just waiting to add the gun factor. Centrifugal blowers intrigue me.

 

[SquareRoot]

I believe my truck has 2:73's, but I could be wrong about that. It's the stock gearing. It will do 80 mph at around 1,800 RPM so it's probably the 2:73's.

I currently have the 700R4 transmission. But that may become a 6L80e when it's time for the 5.3L swap. I still want to do 80 or 85 mph at 1800 RPM. Don't wanna lose that, for highway. I like to keep RPM's low on the highway.

I was considering the 6.0L or even 6.2L conversion, but I can't see any reason it would be necessary. A few minor tweaks to a 5.3L gives you the same power they make when stock. I'd like to do an extra 150 hp and tq over the stock TBI 350 that's in the truck now. Should be more than one of these old trucks will ever need.

And I do still want to use it for light towing, as one would with a half ton truck.

If you're really running 2.73's and overdrive you can't get what you're asking for with that combination. That's a horrible combination. I doubt your getting better mpg limping along at 1800 rpm than if the engine were in it's powerband at 2300-2500. From experience, 3:73 is a great gear with the typical .27 OD.

 

[Ricko1966]

If you're really running 2.73's and overdrive you can't get what you're asking for with that combination. That's a horrible combination. I doubt your getting better mpg limping along at 1800 rpm than if the engine were in it's powerband at 2300-2500. From experience, 3:73 is a great gear with the typical .27 OD.

Yea but with 3.73s he won't be able to go 160
My next build is going to be similar to this but much milder. Turbo that wont spool up in 4th at highway speed. You can't beat boost for power.

A 305ci Engine Makes Big Horsepower Using a TorqStorm Supercharger

Old-timers who were around back during the original muscle car era will look back longingly on the engines that ruled the streets then: the 290hp 302, the 350hp

www-motortrend-com.cdn.ampproject.org

 

[618Syndicate]

Yea but with 3.73s he won't be able to go 160
My next build is going to be similar to this but much milder. Turbo that wont spool up in 4th at highway speed. You can't beat boost for power.

A 305ci Engine Makes Big Horsepower Using a TorqStorm Supercharger

Old-timers who were around back during the original muscle car era will look back longingly on the engines that ruled the streets then: the 290hp 302, the 350hp

www-motortrend-com.cdn.ampproject.org

That build has over 2k in parts before he even boosted it. Bang for the buck you can't beat an LS. Sure, you can do other stuff, stuff that might even be cooler than an LS, but in terms of HP/$ a modded LS will win every time.

 

[Grit dog]

You do know the 5.3 only has 25lb more torque than your 350? So just my opinion trying to make 1.5 times torque that your 5.3 made factory,without hurting gas milage is going to be a tall order. IMHO turbocharge the 350 power when you want it,mpg when you want it. Yep you could just turbocharge the 5 3,now your out the cost of the ls swap and the turbo.

And 75 hp more. A stock early 5.3 will walk a 5.7tbi all day long.

 

[Grit dog]

@PhotonFanatic, your best bet would be to do a 6.0 Uhaul swap.
Buy ya a running 4.8 junker engine for cheap, rent a Chevy Uhaul van for 2 days. Swap the 6.0 in the van for the 4.8 laying on your floor. Return Uhaul van with a full tank of gas!
Presto, low buck 6.0 for your squarebody!

 

[Termite_Delight]

If you insist on a 5.3, start with a L33, Aluminum block 320hp stock.

 

[Ricko1966]

And 75 hp more. A stock early 5.3 will walk a 5.7tbi all day long.

Not arguing that pointat all,and you are right it does have 75 more horsepower stock. I was just saying I don't think making another 125 lbs of torque without hurting milage or drivabilty,which is O.Ps numbers and goal is going to be an easy deal.

 

[Ricko1966]

That build has over 2k in parts before he even boosted it. Bang for the buck you can't beat an LS. Sure, you can do other stuff, stuff that might even be cooler than an LS, but in terms of HP/$ a modded LS will win every time.

Oh yeah the NA aspect of that motor was way overkill,and way over spent. A turbocharged mostly stock 305 with a turbo would do. But boost is going to make anything better,and what I think is most bang for the buck. Just my opinion.

 

[Grit dog]

Not arguing that pointat all,and you are right it does have 75 more horsepower stock. I was just saying I don't think making another 125 lbs of torque without hurting milage or drivabilty,which is O.Ps numbers and goal is going to be an easy deal.

Oh, I agree…cheap fast or good…pick 2. Haven’t found a situation yet that that adage doesn’t apply to.