Fair enough on keeping the 4.8L Yea I think the 78mm will be a restriction, b/c the tbss intake can handle more flow than the little 78mm can give it. Look to see if you can get a used 87mm or 90mm and do a light porting on the throttle body. Those are my favorite choice of heads for the money, can't beat them. And If you ever decide to go 6.0 latter down the road, with the right set of pistons those heads and intake will work beautifully on it. I bet with the tbss you pick up 10-15 and the heads 20-30 so probably a solid 40-50whp over all.

Have you looked into/thought about traction bars to help you from spinning?

If the heads are milled to much you might have issuse will getting the intake runners lined up with the head runners. Something to look into, I know 0.03 milled shouldn't give you any problems!

What times are you running right now, and cam specs? Out of curiosity what are your mpgs with those 4.88s lol

 

yeah the 4.8 already has flat top oistons.

 

If you are pulling the motor for the heads swap, maybe think about throwing a 5.3 crank in it... with the flat tops should be real easy to reach 11.1 range also.

 

i figured thats where its hurting is up top with the 78mm tb, and the little bit of tq loss would probably help me out in the traction dept. i figured id get a ptm 92 and p&p it as for the prc's they really are the best bang for the buck and just like you said would work well with the right pistons in a 6.0 im gonna push this thing as far as itll go and once she hangs a set of rods ill be going either 370 or a 408.

as for the traction aid last time out i 60"d a 2.1 which is downright horrible, i stage go in to full preload and anything past 1/4 throttle will just ignite the tires so im pretty sure if i can get it to leave hard i can achieve the times i want on the "cam only" setup. since the last time at the track i only had rear drag shocks, now ive fabbed up mounts for the fronts(couldnt find drag shocks for clevis style lwr) installed those and my assasin bars just came in last weekend so well see what she does once shes dialed in. just like you said though im not planning on going more than .30 due to ptv and intake fitment issues but i am trying to get the most c/r out of it as i can.

times right now are 14.328 @93 with a shitty 2.1 60" cam specs are a 228/228 .588/.588 on a 112 and with the 4.88s its really not that bad lol. the 35s and the 4.88s give it a 4.10 final drive. city with the 4k converter sucks so id probably think about 10 but locked up and at 60mph its turning 1800-1900 if i remember right and probably about 14 mpg? i dont daily it anymore so i cant really remember lol

 

heres one of the 14.3 passes track video cammed silverado vs honda civic - YouTube

 

14.3 with 35's and pretty much an ext cab weight with a 4.8L. That is AWESOME MAN!!!

That is better mpg than I was thinking...nice!

Dude if you have the 228/228 then yes I would throw that nnbs intake on and ported heads, and let that massive cam "for a 4.8L" pump some serious air flow threw.

If you can't scratch the itch to port the tbss intake then why not practice on the truck intake first, and see how that goes. Then you can always port the tbss intake later down the road, which would help on a larger motor.

The max compression you are going to get to with milled heads 0.03 and stock height 0.051 gaskets is 10.1 If you throw a 5.3L crank in it with 0.03 heads and stock gaskets you will be at 11.1. cranks probably run from $150-250 and you would gain a whole point in compression and an extra 0.5L of tq, also how much better the 5.3L will responded to the larger cam and head combo.

There I go again.....not leaving you alone about more cubes haha

 

Watched another video of 20-100 that stall gear combo is dirtyyyy

 

thanks man its much appreciated. and in all honesty i already practiced on that old truck intake lol so im feeling pretty confident now. but i figured with the bigger tb and the heads it should compliment the cam pretty niceley. and correct me if im wrong but .30 on stock 64cc would be where its at 10.1 with the .51 hg. cometic does also make .27 compressed thickness and i figured with the 58s milled a little more 10.5+ was doable without ptv issues.

as for that video of the 20-100 that was with my old tune, lower shift points, without the tbss intake on, shocks and when i had less weight reduction lol. its pretty old and definitley runs quite a bit better now

 

Stock truck heads are 61.15cc and the 243/799 are 64cc. Your mill #s need to be moved over 1 decimal place for thousandth 0.03, but roughly 0.007 milled is one cc removed so 0.03 would be a little more than 4cc removed, so milling the 64cc heads will make them slightly smaller than the stock truck head cc.

stock is 9.5:1 with 61.15cc heads, so milling 64cc heads would be close to 9.6:1, 58 cc heads would make it almost 9.9:1 sense the 4.8L stroke is 3.25 gm had to use flat tops to keep the compression at 9.5 and since the 5.3L stroke is 3.62 they had to use -7cc dish pistons to keep compression at 9.5

Engine Size and Compression Calculator
here is a link to the calc I use for compression.

What weight reductions did you do?

 

so roughtly with the smallest c/t hg i should be right at about 10:1 but thanks for the info and link man its much appreciated! and in all honesty its more like what havnt i done lol. all the heat shields are removed, airbags, a/c towhooks, hitch spare tire and carrier, excess exhaust hangers were cut off, sway bar delete, sound deadning/rubber mat pulled out and the floor is all bedcoated, egr delete, converter from stock to the 10" cut out some weight as well as manifolds to longtubes, ive got a list written down here somewhere of everything and the savings but itd probably be a full page of rambling on lol. last time i weighed it i was a tad over 4600 but im hoping now itll be under although the traction bars are adding a good 30