taro2413

hey guys im thinkin real hard on this one i know i want to swap out the cam for either a 212/218 or a 220/220 in my 4.8 thats a certainty. But where im havin the problem is heads. i cant seem to find any with smaller intake valves than 2.02 or 2.04 and that will work with the smaller bore...the heads i was leanin more towards are the texas speed 5.3 1.5s only cuz i think the 2.5s would be overkill on it and would hurt perf rather then help it. I was readin somewhere that on the 5.3s you want to stay at a 2.0 intake valve cuz any larger and it will hit the piston. but with the 4.8 i don see this bein a problem as it has a shorter stroke, am i on track here or am i way off?...anyone runnin these heads on here? id like to here your input on them. Any other suggestions on heads would help too....

Also what kind of lift numbers would be the max on a 4.8 as i already have 1.85 rr on the truck and don want to go over wat i need.

Also wat kind of power numbers can i expect to gain out of this head\cam combo? out of a 4.8 in general?

Kinda new to the ls world i like the old bbc myself lol so a lil behind on the times sorry fellas.

InchUp

iTrader: (2)

243 heads off an LS6, milled down for 10:1 compression and a 212/218 cam will do nicely. CompCams has a high lift XR265 camshaft that is a .558/.563 but with your 1.85:1 rockers you're looking at a 212/218, .607/.613 on a 115 LSA. You'll need to invest in dual springs for sure. In a 293 cubic inch V8 you're looking at maxing out the rev range with this cam, as the truck intake manifold will start taking a **** on you before the camshaft runs out of breath. The high lift XR265 is a 1750-8000 rpm camshaft in a 4.8L. Make sure to check piston to valve clearances! 243 heads are now being put on stock 5.3L's so the head will work and flow very well but make sure to check before tossing a cam that big in there with your 1.85's.

http://store.summitracing.com/partde...1&autoview=sku

Truckshop

iTrader: (17)

if you do look into this pm me. i will be removing some 243 heads off my truck very soon. they are milled .040 and have patriot dual springs on them already.

InchUp

iTrader: (2)

PM me with price?

taro2413

koo thx for the advice....do you know wat kinda power gain thats gonna make?

InchUp

iTrader: (2)

THIS MUCH!



No one can say for sure so let us know after you're finished. If I had to guess, I'd figure you'll gain enough to hang with a stock LS1's numbers in horsepower but a little less in torque. When all is said and done, probably 335hp, 330lb-ft torque or somewhere in there...all upper RPM of course with a very 'peaky' torque curve.

taro2413

would that be rear wheel numbers? i already got it baselined and came up with 305-315 flywheel hp and bout the same torque with no tune still on stock tune.

InchUp

iTrader: (2)

Unfortunately no, those numbers were flywheel hp only. I did however forget to factor in the bump in compression so you may see 340-345hp and 335-340lb-ft of torque. The numbers themselves mean very little though. It's the overall gain across the entire power band that means everything, which this setup will provide. Just don't go too hog wild with the cam duration otherwise you'll only be gutting the 4.8L of it's low end torque and throttle response for slight high RPM screaming power.