I have been told in the past that they are the same port. I would like someone who has experience with both heads to tell me the facts. Hoe do they compare in flow #'s (stock not ported) and is the port cc the same? I would really appreciate the help.
Later,
Bart

 

And I did use the search function without much success
<img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

 

So no one knows?

 

6.0 heads are lower compression.

Most of my industry contacts contend that LS6 heads are better than 6.0 heads as far as how they flow etc. I have a few contact who maintain that they flow the same.

Biggest issue with 6.0 heads is when trying to achieve high compression.

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Pro Stock John:
<strong>Biggest issue with 6.0 heads is when trying to achieve high compression.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Is that by milling only? If you go with domed pistons to achive your desired compression level, are there 'issues' with this route?

 

I measured the stock intake ports of the 6.0L heads at 210cc.

The chambers after milling 0.030, and polishing, with Ferrea valves installed were 63.5cc.

I really wish I had flow numbers since I ported them myself.

After porting, the intake volume was 214cc. I picked up 21 rwhp without tuning.

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Pro Stock John:
[QB]Most of my industry contacts contend that LS6 heads are better than 6.0 heads as far as how they flow etc. QB]</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Thank you for your response, but is there anyone who has a defintite answer? I am not trying to be an **** but I need to know before I buy, If 6.0 heads flow the same then I can mill a set of 6.0 heads. If not then it would be a waist of time. So if anyone has hard flow numebers then help me out if you can.

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by ls1290:
<strong>Is that by milling only? If you go with domed pistons to achive your desired compression level, are there 'issues' with this route?</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">NOOOOOOOOOOOOOOOO!!!!!!!!!

Yes the issues with domed pistons are many. Basically the best thing to do is make the combustion chamber smaller to increase compression, not make the dome bigger. The issue is the flame travel. Most people think that engines have an explosion. Explosions have a flame travel of 200mph or more. The flame travel in an engine is 6-7mph, so it's controled. It gets complicated but the absolute best way to have higher compression is to use a flat top piston and have a smaller combustion chamber. If you use a dome the first thing that happens is that the flame front has to travel over the piston dome to get the rest of the fuel to burn, this means that you need more timing. Timing should be thought of as the time it takes to burn the air/fuel charge. The more time it takes the less power you have. If you have 12:1 and have 31 degrees of timing vs. 12:1 and 22 and the timing is optimized for the best power then you will have much more hp with the 22 because the charge burns faster. Yadda Yadda Yadda, I could go on and on about this.

You can mill the 6.0l heads down, that will get the cc's down. To a point.

I have also heard that the 6.0L and Ls6 heads have the same ports but different chambers.

Bret

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by SStrokerAce:
<strong>NOOOOOOOOOOOOOOOO!!!!!!!!!

Yes the issues with domed pistons are many. Basically the best thing to do is make the combustion chamber .......<snip>...... the charge burns faster. Yadda Yadda Yadda, I could go on and on about this.
</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Hmmmm..... so are you saying a set of 6.0L heads with 69cc chambers along with +10.5cc Dome pistons would produce less rwhp than a set of 5.3L heads milled to 58cc chambers and flat top pistons? If so, what in the world would dome pistons be usefull for? Also, would inverted domes have this same problem?

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by ls1290:
<strong>[QUOTE]Hmmmm..... so are you saying a set of 6.0L heads with 69cc chambers along with +10.5cc Dome pistons would produce less rwhp than a set of 5.3L heads milled to 58cc chambers and flat top pistons? If so, what in the world would dome pistons be usefull for? Also, would inverted domes have this same problem?</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I would like to have some confirmation on this. I really can not see how dome pistons will produce less rwhp compaired to flat top pistons with both having the same size overall combustion chambers.

 

There have been many dyno pros through out the years that have shown that dome pistons hurt flame travel and in turn reduce horsepower. For the levels of compression that we use on the street it is stupid to even use dome piston. Domes are not totally bad though, a small one will not effect flame travel and still produce good results. A large dome will though. The dual plug hemi heads back in the sixties needed two plugs because they couldn't get them to burn because of the massive dome that was on the pistons. It blocked the flame front (remember it's traveling at 6-7mph not an explosion which is 2000 mph) so the air/fuel mixture never got entirely burned, so you had to add more igintion timing tothe system to get it to light off early enough so it will have the mixture fully burned.

You want to burn what's in there as fast as possible. The closer it is together due to chamber shape and size to the compression ratio will make it burn faster since the mixture is all in one spot. That makes more power.

Two people you might want to read who I know confirm this. David Vizzard and Smokey Yunick. I'm shure Warren Johnson and Grumpy Jenkins also have proof of this along with many other top engine builders.

Your example of Large chambers with a dome and small chambers with a flat top both giving the same compression is a good one. Yes the small chamber example will make more power because It will need less ignition advance and is less prone to knock.

Inverted domes do not have this problem. The positive dome is the problem since it blocks the flame travel. The inverted dome is one of the better wats to get lower compression and have a nice small combustion chamber.

I hope that helps.

Bret

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by SStrokerAce:
<strong>There have been ......... <snip> ....... f the better wats to get lower compression and have a nice small combustion chamber.

Bret</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Thanks Bret, it does help a lot. Would say a dome of +4cc with 58cc chamber heads be excessive? TIA.

 

well this sort of goes along with this thread but with a stock style piston and unmilled 6.0 heads what would the CR be?

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by hondakiller:
<strong>well this sort of goes along with this thread but with a stock style piston and unmilled 6.0 heads what would the CR be?</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I would like to know the answer for this question as well. I'm guessing 9.6 to 10.0 since the stock is 10.2 right?

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by hondakiller:
<strong>well this sort of goes along with this thread but with a stock style piston and unmilled 6.0 heads what would the CR be?</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">3.9" Bore x 3.62 Stroke with 0.040" gaskets and 69cc chambers = 10.22

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Thank you for your response, but is there anyone who has a defintite answer? </font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">"The LS1 already was the best overhead valve engine, and the LS6 brings it up another level. This is truly going to be a race-car grade engine perfectly suited for everyday driving. It's safe to say that it is a benchmark for the world. And the same exact heads are going to go in the 6.0-liter LQ9 for trucks. It says something about durability as well." --John Juriga, Total Integration Engineer, LS1/LS6 V8s

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by ls1290:
<strong>Thanks Bret, it does help a lot. Would say a dome of +4cc with 58cc chamber heads be excessive? TIA.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Bret, I would still like to get your $0.02 on this.

 

The 6L head placed on a C5 LS1 drops CR .7 That is why I am thinking of using them on my ATI Kit for more boost. Not sure about milling more than 35 off of them though...

 

Great post Bret, wonderfully informative. Not to hijack this thread but I got a question for you, or anyone else who can answer this. What happens if you thrwo FI into the mix? Keeping in mind I'm a novice and some of the stuff you guys are talking about is over my head at the time. but I'm trying to plan out my car logically. Rear is next then Heads/Cam and then FI(Not sure if it is super or Turbo yet). Do domed heads work better when there is boost in the chamber? Would that speed up the flash burn? Would 6.0L heads be a better investment for someone considering FI since they lower your compression ratio .7? I want to run over 10PSI of boost, is the LS1s compression ratio my enemy or is it the weak cast internals? I realize that I would not see as much rwhp gain as a set of heads that kept the same compression and increased flow, but how much would I be sacrificing?

Again excellent posts guys, I'm learning a ton <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

Mike B.

 

ttt