YAMAHAGUY

iTrader: (6)

Ahhhh, you are up in Canada.

N20addiction

iTrader: (1)

Damn thanks for the list of parts and info! My parts list is getting longer and longer lol

N20addiction

iTrader: (1)

Honestly I've just started looking into that, the heads I have laying around at the moment are 706's. Not sure what they flow stock but I'm sure it's not too Impressive. Where should my flow numbers be for this set up since it's a small 5.3?

Kinda sucks I have a set of all pros laying around as well but I assume that would be wayy to much head for that motor.

N20addiction

iTrader: (1)

We'll if that 80e is still for sale next month I may take it off your hands, otherwise funds are tied up at the moment

bobfig

just a list of flow per head design stock. may be a little variance but here it is. GM Head Casting Info with flow numbers

*knuckles*

Casting Number 706 and 862
Head: 1999+ 4.8L / 5.3 Liter Truck
Material: Aluminimum
Part Number:
12559862
12561706
Combustion Chamber Volume: 61.15cc
Compression Ratio: 9.5:1
Intake Port Volume: 200cc
Exhaust Port Volume: 70cc
Intake Valve Diameter: 1.89 inches
Exhaust Valve Diameter: 1.55 inches

Stock Head Flow Numbers
Chamber 61.15 cc----0.100--0.200--0.300-- 0.400--0.500---0.550---0.600
Intake 200 cc----------63 ---128----179-----210----218----221-----226
Exhaust 70 cc----------54 -- 93 ----121----145-----163----168----174



Estimate Horsepower from Head Airflow

Enter Depression of Airflow in Inches of Water:
(The pressure your heads were flowed at) 28 in/H2O
Enter Head Air Flow in CFM: 226
(for better results use total cfm including intake manifold)
Engine CID: 325
Select Type of Engine Work: Typ Street/Strip Eng
Typ Race Eng
SuperStock
ProStock/Comp
Mountain Engines
Enter Number of cylinders: 8

The HP for your Cylinder Head Flow of 226
is 429 at a RPM Range of 5,749 to 7,249
for your engine size of 325 CID


that is from
Wallace Racing - Automotive Calculators

there are all kinds of calculators to mess around with to give you a rough idea of the potential your engine could make. As for the 706 heads they seem to flow best @ .600 lift and that matches the cam your interested in. they have the flow good enough for 429hp and where made for the 4.8/5.3l. there are numerous threads about those heads cracking but someone may chime in with better knowledge. try a castech 706 head search. If you have used them for quite sometime chances are good there okay.
It really depends on what you use your truck for most and picking a combination of parts to match. you want to go flat tops so that will up your compression with those heads over 10 to 10.5 to 1 so if you use larger heads it will drop it so again it all depends on what you have in mind.

here is another calaulator I use to get a rough idea as well as a few from above link.
Rough Engine Horsepower Determination Program

not sure how accurate it is but again it is just an idea when you start try to build a combination.

later

bobfig

i have been effected by the castech crack, they lasted about 135k miles before they cracked. i did catch it early tho so i didn't have too much of a problem. ended up getting some 799 heads and getting them milled for cheap. i just didn't feel like i wanted to run another 706 head that could potentially crack later so that's why i went with the 799 and also that i can't say no to more power

N20addiction

iTrader: (1)

Okay well What do you guys think about putting some prc 5.3 stage 2.5 heads and a tbss intake? I'm sure it would flow much better with that setup

Also thinking about changing to a torquer v2 or v4

bobfig

looks like for those prc stage 2.5 heads you have to supply the heads as that's just a mill job. as for more power yah it may make more power but its all about how much you want to spend.

as for a cam imo that's starting to get too big unless its going to be a race truck.

*knuckles*

^^^^ i agree, i think your first cam choice with some sort of stall would do better for a truck. those v3, v4 cams mentioned automatic cars in the description. are you planning on a complete rebuild or repair and replace?

check this out if you haven't yet

https://www.performancetrucks.net/fo...o-here-523548/


that is impressive. he has other video's of it in action but he put the flat tops in and had his heads intake valve size increased and ported them after. that is out of my skill set at the moment but totally changed my approach to my build gonna keep it simple with minimal down time. just to give you an idea and visual of what your trying to achieve in action.