I've got a set of 5.7 heads gettin' worked on. I'm thinkin'about putting 'em on my 5.3. The guy is saying that they may flow too much for the small bore engine and I may not see much gain from it. Has anybody tried this?

 

you can have heads that flow TOO much? i can understand you would see larger gains on a big cube with huge flowing heads but i dont see how it could hinder performance on a smaller cube <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" /> am i wrong?

 

5.7 heads have larger combustion chambers which will yeld a lower copression ratio. whitt1

 

less compression, weaker low end and stronger top end, that's what I'm hearing. This could end up with little or no improvement at the end of the track.Is the pain worth the gain?

 

If you want to run those heads, you can mill them .030 and get about a point of compresion back. If it were me I would put bigger valves in the 5.3 heads. You can use the valves out of the LS1 heads.

 

I had a set of LS6 heads on my 5.3. I did not dyno my engine before the heads, plus I did the cam at the same time. However, I do not believe a head can flow to much.
All I can think of is that the small bore size will act as a shroud with the larger intake valve. The exhaust valve is the same size. I do not think this will hurt power any, which is why I have 5.7 valve in my current 5.3 heads.

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by whitt1:
<strong> 5.7 heads have larger combustion chambers which will yeld a lower copression ratio. whitt1 </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">WooHoo! We get the point! <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" /> <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

 

Some heads can flow too much for certain motors. If the bottom end isnt built to work with a good set of flowing heads then you will loose your bottom end power. Alot of people think if you just throw a set of hawged out heads on a motor it will run like a beast right off the bat. You need a cam with enough lift and dur. to work with such heads. If you ran a set of stage three heads on a stock bottom end, stock cam, and etc.., you wont get full use of these heads. Your cam would die off right when the heads are starting to work best. Just by putting bigger valves in a head wont help unless you do other things like bowl work and maybe a pocket port job. I learned my lesson on this with a set of AFR heads. I ended up selling them and buying a set of dart iron eagles and starting over. {roundy round motor}

 

yeah i understand you would have to change cams. i was thinking it was implied that if you put some good flowing heads on somewhere you at least put A cam in, hopefully one suited to the flow patterns of the heads.

i was under the assumption that the guy was saying that because its a smaller engine than an ls1 you wont see any (or as large of) gains from the heads.

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by red53gmc:
<strong> </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by whitt1:
<strong> 5.7 heads have larger combustion chambers which will yeld a lower copression ratio. whitt1 </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">WooHoo! We get the point! <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" /> <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Fixed the echo <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />