Generation III Internal Engine - 5.3 vs 5.7 shortblock.......

Would there really be much of a difference in power output for similar parts installed on both these shortblocks? I have a 5.7 LS1 with a spun rod bearing and I got a 5.3 LM7 shortblock that I was going to harvest the crank and connecting rods from and put my 5.7 pistons on it to make my LS1 go again. But is that really needed? The 5.3 is fine and I'd hate to spend money getting all this done if the 5.3 shortblock would work fine with everything I want to put in. I figure that way I'd just save the LS1 block for a forged build later on down the road. Anyone have any advice?

It's probably not worth the hassle of swapping the crank and having the pistons swapped onto the 5.3 rods if you plan on building a forged motor down the road. The 5.3 can make enough power to hold you over until you're ready to build something better. The main issue is the loss of torque from the drop in cubic inches, but with the right parts you can minimize this. Cam selection and boosting the compression are key to maximizing torque output. Mill the heads to 58cc's and keep the cam at or below 220 degrees duration with a narrow LSA to move the powerband down in the revs.

Well that's where my problem is though, I already have a set of 5.3 heads that have been fully ported and an MS3 spec cam which is a lot more than 220! I'm guessing the cam is a tad on the big side for the smaller cubes?

There are guys on the performance trucks website and some use camshafts that large you might want to do some seachn there too?

btw the link is at the top of the page

haha, it's funny you mention that because I'm searching through it right now! Before the only truck forum I knew of was some 4x4 forum and that search netted me exactly squat on 5.3 builds.

My cam specs are 236/242 @ .050 and all I've found is that my cam choice would be overkill....hardcore overkill for the 5.3. I guess I'll just suck it up and swap the parts into my 5.7 because I'd hate to buy another cam and rework the heads to boost compression (which is the main reason I went with the 5.3 heads, to boost compression on my LS1) when I can spend that same money on getting the parts balanced and put back in my LS1 block. :cry: My wallet is really going to hate me, it's been losing a lot of weight already over this car!

i made 395 to the tire with a 5.3 in a 2000 SS camaro.

i made 395 to the tire with a 5.3 in a 2000 SS camaro.

That's a nice horsepower number with a 5.3. Would you care to share the details of the setup?

bbk intake manifold

ported t-body

228in 232ex 113 lsa
595 lift 595 lift

1-3/4to 1 7/8 steped headers

slp air lid

dual valve springs

If you put the pistons from a 4.8L it ups the CR as well since the stock 5.3 are dished and the 4.8 are flat tops.