kewlbrz

Are there any advantages to using a 5.3 Truck head over a 5.7 LS1 head when porting/polishing etc. Other than increased compression ratio?

What about combustion chamber characteristics.

Also would the advantages of the LS6 head with its raised intake runner design and D shaped exhaust port, outweigh any bennefits of a 5.3 head?

2quick4u

The only advantages of the 5.3 head is increased compression, availability, and cost. The increased compression may actually work against you on a daily driven street car.

Using the LS6 head or the 2001 and later LQ4 6.0 liter truck head would be better choices IMO. They have better flowing ports. The 6.0 truck head has the same ports as Ls6 but a slightly larger combustion chamber. This can be milled to maintain stock CR on a 346 or not milled for larger bore motors. If you are building an FI motor, you may want to go with them on a 346 to help reduce CR.

[ November 14, 2001: Message edited by: 2quick4u ]</p>

kewlbrz

[quote]Originally posted by 2quick4u:
<strong>The only advantages of the 5.3 head is increased compression, availability, and cost. The increased compression may actually work against you on a daily driven street car.

Using the LS6 head or the 2001 and later LQ4 6.0 liter truck head would be better choices IMO. They have better flowing ports. The 6.0 truck head has the same ports as Ls6 but a slightly larger combustion chamber. This can be milled to maintain stock CR on a 346 or not milled for larger bore motors. If you are building an FI motor, you may want to go with them on a 346 to help reduce CR.

[ November 14, 2001: Message edited by: 2quick4u ]</strong><hr></blockquote>

Hmmm. Are all year 6.0 liter head ports same as LS6? I assume they dont have the D exhuast port?

Seems like that head would be faboulous for an all bore motor or a stroker, with proper piston matching.

Pro Stock John

iTrader: (34)

5.3's have smaller combustion chambers.

If money were no object I would get some LS6 heads they supposedly flow like 30 more cfm with the same valves and port job (done to LS1 5.7 heads).

I have ARE 5.7 passenger heads with stage II porting, and 2.08/1.60 valves. <img src="graemlins/fluffy.gif" border="0" alt="[Fluffy]" />

CMNTMXR57

Which 5.7 heads are you talking about?

The 5.7L LS1 head?

Or since you are talking about trucks engines, are you refering to the 5.7L Vortec truck head of the previous generation.

If it is the later, they are not interchangable.

If you are refering to the LS1 5.7 vs. a 5.3, would'nt the 5.3 have slightly smaller combustion chambers, therefore increasing your compression ratio?

I don't know about differences in power between the LS6 and 5.3 heads. But aside from going to a "D" port, the LS6 heads have a different valve angle and are pretty much a modified version of the LS1 heads.

Crazyquik

The LS6/6.0 head has better swirl characteristics also doesn't it? This would mainly show itself in a power adder situation, probably not just 8-10 extra hp or so n/a. Or do LS6 heads make a bigger difference than that n/a?

J.

Matt98SS

[quote]Originally posted by kewlbrz:
<strong>

Hmmm. Are all year 6.0 liter head ports same as LS6? I assume they dont have the D exhuast port?

</strong><hr></blockquote>

the 6.0 liter aluminum heads have D exhaust ports



http://albums.photopoint.com/j/View?...126&Sequence=1

2quick4u

[quote]Originally posted by kewlbrz:
<strong>

Hmmm. Are all year 6.0 liter head ports same as LS6? I assume they dont have the D exhuast port?

Seems like that head would be faboulous for an all bore motor or a stroker, with proper piston matching.</strong><hr></blockquote>

kewl,

Only the 2001 and later aluminum 6.0 liter truck heads have the LS6 ports. Yes, they do have the D exhaust port, so they will be easy to identify. And yes they would be great heads to start with on a bored or stroked engine.

VINCE

iTrader: (1)

So are you saying that if I stroked the engine the 5.3L heads would hurt a little?

Crazyquik

Hmm, well the 6 liter head flows better and has a better short side radius, but what about combustion chamber? A smaller chamber with flattop pistons will give more performance than a big chamber with domed ones. Of course you could just mill or weld on the 6 liter heads to close down the chambers some. Then again thats more money spent.

J.

2quick4u

[quote]Originally posted by Crazyquik:
<strong>Hmm, well the 6 liter head flows better and has a better short side radius, but what about combustion chamber? A smaller chamber with flattop pistons will give more performance than a big chamber with domed ones. Of course you could just mill or weld on the 6 liter heads to close down the chambers some. Then again thats more money spent.

J.</strong><hr></blockquote>

You can mill the 6.0 heads or just leave them stock and run 9.5:1 compression. Either way, they will make more power on a 346 than 5.3 heads even at higher comression. Breathing builds HP better than slight changes in CR.

Chris G

This in an interesting thread. What would be the compression ratio with some 5.3L heads? I am looking into going this route through GTP.

So 6.0L heads flow more. Ok. Which would be better for nitrous use. I know that nitrous likes compression, but could you spray more with the "stock" milled compression of the 6.0L heads? I have no plans of going larger than 346ci, but I do want the best heads for the money.

Thanks,
Chris G

VINCE

iTrader: (1)

I have not seen any one with 6.0L heads on a 346cu dyno any higher than the usual avg 5.3L heads.. If you have who are they?

Pro Stock John

iTrader: (34)

The answer is...

It depends.

You can have small combustion chambers and may have difficulty mating those heads with a a different bottom end unless you custom spec some stuff...

I had GTP welded chamber heads from 1998/1999 and I could not use them with my new setup since my compression would have been thru the roof, 56cc chambers.

[quote]Originally posted by vmoore:
<strong>So are you saying that if I stroked the engine the 5.3L heads would hurt a little?</strong><hr></blockquote>

Y2K_WS6_T/A

I guess I am chopped liver, no one answered my QUESTION. <img src="images/icons/frown.gif" border="0">

Crazyquik

Ok, talking about nitrous. Why do people say nitrous "likes" compression? Is this because it is so cold it lowers temps in the combustion chamber, so it can help combat predetonation of a higher compression motor? What if you ran nitrous with lower compression? Wouldn't you have more physical space to pack nitrous in with slightly lower compression?

2quick4u

[quote]Originally posted by vmoore:
<strong>I have not seen any one with 6.0L heads on a 346cu dyno any higher than the usual avg 5.3L heads.. If you have who are they?</strong><hr></blockquote>

'Sporadic' (Matt) at LS1.com has dynoed very well with some TEA ported 6.0 liter heads. You might want to talk to him.

[ November 14, 2001: Message edited by: 2quick4u ]</p>

2quick4u

[quote]Originally posted by Crazyquik:
<strong>Ok, talking about nitrous. Why do people say nitrous "likes" compression? Is this because it is so cold it lowers temps in the combustion chamber, so it can help combat predetonation of a higher compression motor? What if you ran nitrous with lower compression? Wouldn't you have more physical space to pack nitrous in with slightly lower compression?</strong><hr></blockquote>

Personally I would not use high compression with nitrous. N20 builds cylinder pressure very quickly so you don't need the compression building cylinder pressure for you. Too much cylinder pressure and KABOOM!!! bye bye head gasket or worse. Remember higher compression INCREASES the chance of detonation and detonation under spray is a deadly combination for your engine. I would build an N20 motor bottom end exactly like a supercharged engines bottom end. Low compression forged pistons.

But then again I'd rather have my engine last for 100,000 miles instead of making 15 extra hp and having to rebuild it every 10,000 miles.

[ November 14, 2001: Message edited by: 2quick4u ]</p>

Speed Demon

iTrader: (14)

Are the 4.8 truck heads the same as the 5.3's?

What is needed to put the larger valves in the 4.8 or 5.3 heads?

kewlbrz

seems like the 6.0 liter head would be the ultimate for a forced induction package.

So let me understand:

GEN III has:

4.8/5.3 Truck Heads 64cc
5.7 LS1 Heads 68cc
5.7 LS6 Heads 68cc (raised intake runners and D port)
6.0 Truck Heads (2001+ Same as LS6 except for chamber size)

All heads above are same (valve angle, swirl characteristics etc...) except as noted?

Any that I am missing?

What is the chamber size for the 6.0L head?