hey guys!

I have a 03 rcsb with 5.3. I bought the on3 76mm kit and have accumulated a yank 2800 converter with trans cooler, walbro 400lph fuel pump, and siemens 60# injectors. ill be going to e85

After doing a lot of research my goal of 500/500 seems likes it will be halted by the stock 5.3 valvesprings floating around 10-12psi. That leaves me to have to change to a set of comp 918's, blue ls6 springs or like. While having the valvecovers off, im curious if going to a 1.8rr would be advantageous. Now I don't want to tear the accessories off and in to the motor to do a cam swap as this is completely budget and I will be using a 6.0 for a build if this doesn't suffice. I know everyone will say "save your money, just do a cam" but if I can find a set of full roller rockers for $200 on ebay LS1 LS2 LS6 Stainless Steel Roller Rocker Arms Rockers Adjustable 1 8 Ratio | eBay
and slap them on while I have the stock components off during the valve spring swap; it seems like a no brainer if their will be any gains as im dead set on keeping the stock cam.

Dropping the trans and gas tank, removing the front facia, and removing the oil pan to tap for lines is the extent of heavy labor. The rest should be bolt on and that is why I don't want to do a cam swap. I would rather start with a 6.0 and replace rod bolts, head bolts, and do a turbo cam instead and start with a good budget motor then risk going with a cam and pushing outside the limits of the stock 150k 5.3


Does 500/500 on e85 with the 76 kit seem too far fetched?

 

500/500 on e85 can be done. You will need around 15lbs. LS6 springs are a great idea as they can be had for around $60. However, don't worry about the 1.8's its basically the same idea as adding a little bit of lift to your cam. It's not worth it. You would gain about 10-20hp which won't really make much of a difference in hitting your 500/500 goal. A cam along with the supporting mods needed for it won't push the limits of your stock 150k 5.3 the opposite is true. Most of the weak valvetrain parts are replaced in a cam swap(springs, pushrods, etc) which means swapping cams won't only make your 500hp goal easier it will also strengthen your motor.

 

I'm running the isky 165A springs in my 4.8L. Stock48 has run them in his turbo application up to 900rwhp. They are pretty cheap too. I don't think you will need to run 15psi to hit 500/500, especially on E85.

 

Ok I wasnt sure if the 10-15hp claimed by RR were amplified when going FI.

If I were to tear the motor apart for a cam swap I would want to do rod bolts and head bolts along with oil pump and timing set etc and if I did that id rather start with a 6.0.
Its a great running motor and the less disassembly the better I feel at this point. And I should be able to hit my goal without doing so.

 

You won't need e85 to hit your 500/500 goal. Your 60lb'ERS won't get you there on the corn. FWIW I have 65lb injectors and a 340lph fuel pump and I'm at 65% IDC on 10psi running 93 octane

 

im slowly inching up on 500 and have stock springs and cam. currently im at ~12 psi and ive shown 20-21 rwhp per psi on 93 pump with my trick setup.

I know im pushing it but a dyno with 501rwhp would be something worth printing.

 

I think your making a cam swap out to be much harder then it is. Changing the valve springs takes longer then the cam swap does, The heads don't have to come off, just the water pump, timing cover and stuff. You can reuse the stock lifters and everything. It's not very hard at all.

 

I do not recommend changing the rockers. The stock ones are just fine after you do the comp trunion upgrade.

 

Yeah a cam swap isnt hard at all, the hardest part is probably the crank pulley but everything else is easy

 

I agree the cam swap would be better all around if you were going to do anything.