Building a Jet boat. Pretty set on a 5.3 L33 due to weight and cost. Boat will cruise at 3200 rpm. Boat will have exhaust manifolds to 3" to atmosphere (only about 24" of exhaust after manifolds). My goal is to hit 380-400 ft lbs at 3000-3200 rpm. What is the best way to do this? Is this realistic? BUDGET BUILD!

Does anybody have an actual power curve of the L33? Everything I search seems different and it's tough to trust anything. I've done a TON of searching on here regarding this motor, however, my application is a little different.

All feedback is greatly appreciated.

 

The L33 is pretty close to the GM 5.3 crate motor. You're probably not going to get there with a NA 5.3. Check out the links below for the 5.3 torque curve and a real dyno test of the the higher compression LQ9 6.0.
http://www.chevroletperformance.com/...5628&engCat=ls
http://www.hotrod.com/techarticles/e...#ixzz21ehbAsre

 

what is a realistic gain at 3000-3200 rpm with cam swap and some tuning?

 

look at comp cam 54-455-11.it is good for low end torque.

 

I checked it out on the Comp Cams website. No dynosheets specific to the L33 though. Anybody have realistic dyno sheets with their mods?

The GM dynosheet for a stock L33 says peak torque of 335 lb ft. Is this at the crank, or rear wheel?

 

try camquest 6 to play around with cams.a fast truck intake is good for torque if you have the room .that dyno number is most likely a crank reading.what wiring harness will you use ?

 

Have not yet decided on EFI or Carb'd. The carb thing for marine application is much simpler but not sure if I'll be leaving power and fuel economy on the table - probably?

 

Depends on how good you are with a screwdriver. Most people that can't get good power or fuel economy out of a carb don't know much about them.

That being said, generally, you can do better fine tuning on injection which helps out tremendously with fuel economy. Power wise, if you know what your doing, it's negligible.

 

I think the cam grind on most truck motors is optimized for low end, same with the intake. You might get some more torque at 3000 rpm with more lift, but getting 400ft lbs is probably not realistic in a 5.3.
btw, the carb intakes flow much more top end than the efi. With a cam you'll make more hp with a carb.

 

The performer rpm is a dual plane and will retain good low end torque without giving up much on the top.

 

performer dual plane with a carb and a Zo6 cam or prefferably this one
http://www.engpwrsys.com/index.php?a...od&productId=4
should get you close to what you are looking for. what fuel will you be using

 

91 octane - purple

 

With a small cam with little overlap and about 10.5 compression should get you where you wanna be. Just keep your dynamic below 8.5 and you should be good on 91.