Possibly, let's see what one of the head porters says... But you'd have to open up the chambers for the bigger bore and that might offset the point of using them? Would you want to use them for the 62cc chambers?

 

Would 5.3L heads with with 2.1 & 1.6 valves flow enough for a 4xx+ block? TIA.

 

Why would the chambers need to be widened?

 

4.??? bore right for a 4xx motor?

5.3 is like a 3.85 bore motor stock. You'd want to open up the chambers to work with a 4.000+ bore.

 

To match the bore of the block. If the combustion chamer isnt the same of the bore, all your port work is usless. Imagine a lid for the jelley jar that was too small. It dosent directly realte to this but it does kinda. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

 

If the 5.3 head is running a 2.1 intake, the area around the seat had to be enlarged some for good flow.

What would the effects be of running non-port matched 5.3 heads on a stock 6 liter bottom end?

The difference in the diameters of the bore are about .25", so the chamber radius bore mismatch is .125" on each side. Is that enough to make a huge difference?

 

I think it would depend on how much power you want to make. I think you could make up to 500 RWHP with that type of set up, but if more is desired then you would have to step up to a head that will deliver more port volume, like the LS6 or 6.0L. The 4.8/5.3/5.7 head is safe from water leakage at 225-230cc, the 6.0/LS6 is safe at 250cc.

 

I think it would depend on how much power you want to make. I think you could make up to 500 RWHP with that type of set up, but if more is desired then you would have to step up to a head that will deliver more port volume, like the LS6 or 6.0L. The 4.8/5.3/5.7 head is safe from water leakage at 225-230cc, the 6.0/LS6 is safe at 250cc.

 

I still dont understand how port work with a smaller chamber and a bigger bore is a total
waist.I would understand if there was more to
be gained from opening the chamber.You are still
opening up the ports and valves.I just thought
it only effected squish.If i am way off i would
like to learn.

 

Think about it, man. Which setup would all you to get more MIXTURE (air and fuel) into the combustion chamber:?
1> A cylinder head that has the bore circumfrence the same size as the head's combustion chamber or...
2> A large bore with a smaller cylinder head combustion chamber?

The correct answer is number 1. If you have a large bore with a cylinder head chamber that isn't the same size as the bore you're giving up all of that volume that you could be fitting MORE mixture in thus less combustion and less power.

If you have a large bore with the cylinder head chamber the SAME size as the bore size then you can fit the MAXIMUM amount of mixture in that volume thus maximum combustion and more power.

Refer to the picture to clarify:
<img src="http://home.insightbb.com/~l.proctor1/bore.JPG" alt=" - " />

 

Nasty c5 take you now i get it.But i am still
wondering if you have a 4.00 chamber and a 4.100
bore will the added compression make up for the
lose in chamber volume.

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by jkane33:
<strong> Nasty c5 take you now i get it.But i am still
wondering if you have a 4.00 chamber and a 4.100
bore will the added compression make up for the
lose in chamber volume. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Now that I don't know <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" /> , I only stick to the basics <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by jkane33:
<strong> Nasty c5 take you now i get it.But i am still
wondering if you have a 4.00 chamber and a 4.100
bore will the added compression make up for the
lose in chamber volume. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">O.k. think about this.........

The swept area of the larger bore engine is going to be more so the compression ratio formula is going to give you more compression anyways. A 383 with a 60cc head will be more compression than a 346 with a 60cc head.

On the other hand. The flow you will gain from unshrouding the head is going to be where the gain is. Head flow is much more important than chamber shape or compression ratio, they are important but not as much. I've worked on this in my head for awhile in a much differen context (flow vs. chamber shape) and hands down 402cfm of flow (vs. 360cfm) is more valuable then 70cc chamber vs a 110cc chamber. (If you get what I am talking about just from these specs then you NEED to e-mail me about this!)

The compression ratio is really limited by Octane, and if you wanted it back a unshouded chamber that is milled back down to size will get you alot farther ahead!

I hope that makes sense!

Bret

 

These statements are all correct to a point but there is no power loss from mismatch of chamber and bore. It is strictly about flow in chamber around valve. If flow is unimpeded by valve and chamber shape than that fact is where power is made. The mismatch actually helps promote mixture
turbulence on compression stroke and this adds power. If you flow test on a clear bore you can also see at .500"+ lift valve is clear of chamber and is intruding in to bore. This is where peak cylinder filling in running motor is happening ,
because peak piston velocity should happen around this cam timing event if cam is properly sized and timed in motor. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

 

Everyone thank you for explaining this to me.
The thing that really got my attention was
when stangkiller said ALL your port work is
useless.I figured ther would be more to be gained
but i just didn t understand how it would be
totally useless.I just replaced my 5.7 with a
6.0 escalade motor.Took my stage 2 heads and
every thing else off of the 5.7 and put them on the 6.0.I measured the chamber diameter and it
was 3.9 and the bore is 4.0 so when i heard port
work was useless i got worried,even though traction in 3rd is no longer exsiting. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

 

no longer exist (sorry)