Mild 6.0L Build Suggestions?

[Matthew Jeschke]

Not bad but, I want to see you get them mirror finish......






JK that would take forever, I assumed it would be difficult which is why I just sent a set to get CNC ported and polished. I'm just too lazy, I also remember reading somewhere that overly polished intake runners are actually a bad thing. But, since I have no source to site don't take it as fact.

Great point haha I like that mirror finish isnt ideal... I will take that as I am feeling lazier each day.

I am still going to have the machine shop port match the combustion chambers.

I don't want to spend big $$ though for port matching the runners tho.

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[fasteddy]

I would go with LS3 heads, seem to be the gold standard right now. I got my 317s from a guy upgrading to the LS3 heads.

Nah....you're going the right way for your requirements. Small 317 heads will make more TQ at low RPM with a small cam....like around .500 lift......dual springs are kinda overkill.
LS3 heads make less TQ at low RPM but ramp quickly after 3500 rpms.....but you need 60lbs of fuel pressure and are harder to tune....and suck more gas.

I like the small heads on a tahoe 6.0 build......Lots of TQ under 4000 rpms which is where my tahoe is 95% of the time.
I just prefer the 862 heads (unported) because you get more compression and smaller intake volume which means more power under 5000rpms.

 

[Matthew Jeschke]

Nice, I assumed smaller runners / lower flow heads were of benefit to lower end power but was unsure. Most info I find and ppl I talk to know how to build a hotrod motor. Very few know about low end power for a truck so good info has been hard to come by.

Roger sold me new dual valve springs for price of single ones. He has some awesome stuff and I think he customized the springs for my cam somehow.

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[1BADI5]

Nice, I assumed smaller runners / lower flow heads were of benefit to lower end power but was unsure. Most info I find and ppl I talk to know how to build a hotrod motor. Very few know about low end power for a truck so good info has been hard to come by.

Roger sold me new dual valve springs for price of single ones. He has some awesome stuff and I think he customized the springs for my cam somehow.

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No, longer runner = torque

For proof of concept, look at a Gen4 rec port truck intake compared to a LS3/L99 car intake. Then compare the torque numbers and where they fall on the graphs.

 

[Matthew Jeschke]

No, longer runner = torque

For proof of concept, look at a Gen4 rec port truck intake compared to a LS3/L99 car intake. Then compare the torque numbers and where they fall on the graphs.

I presume, more specifically, the ratio of runner length to diameter?

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[fasteddy]

No, longer runner = torque

For proof of concept, look at a Gen4 rec port truck intake compared to a LS3/L99 car intake. Then compare the torque numbers and where they fall on the graphs.

I was referring to the heads, the 862 vs LS3......the volume of the intake runner of the head. Not the intake manifold.

200cc on the 862 vs 257cc on the LS3. Air travels faster through a smaller chamber, velocity. Better throttle response, more TQ at low RPMs.

Trust me, I've done it both ways.....spent 4X the money on Big heads, big valves and nothing but disappointment under 4K rpms.

If the application is a vehicle that will live from 4-6K, like a vette or race mobile then bigger is better. But on a heavy vehicle that lives under 5K I prefer unported cathedral heads.

 

[Matthew Jeschke]

good advice. You are piecing together some thoughts I had had but couldn't find information on.

I finished polishing the combustion chambers... did the whole second head in one session.

It isnt mirror finish but knocked off all the high points and gave it a smooth finish.

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[Matthew Jeschke]

Ha, just read why mirror polishing is bad (except on exhuast)... The fuel doesn't atomize / mix with the air as well. It tends to stick to walls of combustion chamver and or intake runner walls if they are too smooth.

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[Matthew Jeschke]

Slowly but surely. Got the crank shaft in double checking machine work and fitment. Everything is to factory spec! Saving all my measurements as well. It's not too tricky although I had one thing that baffled me for a bit...

Crankshaft end play. Spec is 0.0015" minimum. I couldn't even fit that feeler gauge. I second guessed difficulty with this so I kept checking it as I did the 15 ft/lb pass on the main bolts, and didn't do the TTA pass. I took out the #3 main with thrust bearing.

I had put on a bunch of assembly lube. I put it on the sides of the thrust bearing too. This was preventing it from moving in the crankcase for the thrust test. I wiped off the excess lube, re torqued and everything was perfect!

I also had some issue sealing those M10 side bolts. I used high temp RTV spec'd for oil pan. I had to take them out and put them back in... I put a HEALTHY amount of RTV on back side / head of bolt. I finger tightened them with the socked such that I could see RTV come out all 360 degrees around the bolt head.

I'm now waiting for RTV to set up a bit before I do the 18 ft/lb torque pass on them. Otherwise this is REALLY simple.

 

[fasteddy]

Looking Good!
You should plan on a set of long tube headers and free flow exhaust (doesn't have to be loud).
That will help you with your plan to maximize TQ and fuel mileage.