The world of LS1/LS6 head flow #'s
07-12-2002, 02:21 PM
#1
Re: The world of LS1/LS6 head flow #'s John, truth be told:
</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Flowbench used:
Test bore for both:
Exhaust tube extension/length:
Before/after #'s:
Intake Runner Volume:
Port velocity:
</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">The vast majority of head purchasers have very little interest in learning or knowledge of these terms. They simply see: "ported heads = go faster", and tend not to question or worry about the in depth technical stuff involved. Most of their research involves finding a reputable shop, price shopping/negotiating, and slapping down the plastic.
Only a few of us are actually nerdy engine spec customers LOL!
I received before/after numbers on my first set of Stage 2 heads. Never asked since then <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />
Tony
</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Flowbench used:
Test bore for both:
Exhaust tube extension/length:
Before/after #'s:
Intake Runner Volume:
Port velocity:
</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">The vast majority of head purchasers have very little interest in learning or knowledge of these terms. They simply see: "ported heads = go faster", and tend not to question or worry about the in depth technical stuff involved. Most of their research involves finding a reputable shop, price shopping/negotiating, and slapping down the plastic.
Only a few of us are actually nerdy engine spec customers LOL!
I received before/after numbers on my first set of Stage 2 heads. Never asked since then <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />
Tony
07-12-2002, 02:37 PM
#2
Staging Lane
Join Date: May 2002
Location: Grand Rapids, Michigan
Posts: 81
Likes: 0
Received 0 Likes
on
0 Posts
Re: The world of LS1/LS6 head flow #'s Here's your data, with before and after on same line, and a column added with "after" divided by "before", shown as a percent:
</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">code:</font><hr /><pre style="font-size:x-small; font-family: monospace;">Intake:
before after
0.1 67.1 65.1 97.0%
0.2 127.6 142.4 111.6%
0.3 181.3 206.6 114.0%
0.4 218.8 242 110.6%
0.5 236.4 257.3 108.8%
0.6 242.3 269.6 111.3%
Exhaust:
0.1 55 56 101.8%
0.2 99.6 111.9 112.3%
0.3 136.2 148.1 108.7%
0.4 157.6 178 112.9%
0.5 170.4 200.2 117.5%
0.6 178.1 216.3 121.4%</pre><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">That's the first thing I'd do with before and after numbers, look at % increase.
It's still possible that the same heads will have a different % increase, depending on the bore size, or other factors. A good example will be if you put in larger valves. Big valved heads vs stock on a 3.9" bore won't gain as much (so maybe you'd have 110%), but put before and after both on a 4" bore, and maybe the big valved heads gain more (might be 115%).
<small>[ July 12, 2002, 02:41 PM: Message edited by: Miles in Michigan ]</small>
</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">code:</font><hr /><pre style="font-size:x-small; font-family: monospace;">Intake:
before after
0.1 67.1 65.1 97.0%
0.2 127.6 142.4 111.6%
0.3 181.3 206.6 114.0%
0.4 218.8 242 110.6%
0.5 236.4 257.3 108.8%
0.6 242.3 269.6 111.3%
Exhaust:
0.1 55 56 101.8%
0.2 99.6 111.9 112.3%
0.3 136.2 148.1 108.7%
0.4 157.6 178 112.9%
0.5 170.4 200.2 117.5%
0.6 178.1 216.3 121.4%</pre><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">That's the first thing I'd do with before and after numbers, look at % increase.
It's still possible that the same heads will have a different % increase, depending on the bore size, or other factors. A good example will be if you put in larger valves. Big valved heads vs stock on a 3.9" bore won't gain as much (so maybe you'd have 110%), but put before and after both on a 4" bore, and maybe the big valved heads gain more (might be 115%).
<small>[ July 12, 2002, 02:41 PM: Message edited by: Miles in Michigan ]</small>
07-12-2002, 06:14 PM
#3
Re: The world of LS1/LS6 head flow #'s </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by John@PACE:
[QB]Another question, CNC is very repeatable from port to port right. On hand ported heads, what is the average flow variance from port to port on a finish head?
QB]</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">This is something I have often wondered as well. When have you ever seen someone show what all the ports did before and after. How do they rate their numbers? Is it on the averages from each port? Or do they rate it off the "best port" on the intake and exhaust side. I highly doubt each port flows exact same numbers as the other before and after work is done.
I'm sure it would not amount to much, but If I am paying someone to port heads, I sure would like to know what ALL of the ports did before and after.
[QB]Another question, CNC is very repeatable from port to port right. On hand ported heads, what is the average flow variance from port to port on a finish head?
QB]</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">This is something I have often wondered as well. When have you ever seen someone show what all the ports did before and after. How do they rate their numbers? Is it on the averages from each port? Or do they rate it off the "best port" on the intake and exhaust side. I highly doubt each port flows exact same numbers as the other before and after work is done.
I'm sure it would not amount to much, but If I am paying someone to port heads, I sure would like to know what ALL of the ports did before and after.
07-13-2002, 12:00 AM
#5
On The Tree
Join Date: Jan 2002
Posts: 111
Likes: 0
Received 0 Likes
on
0 Posts
The world of LS1/LS6 head flow #'s I see flow #'s from various heads all day long. Most of them list the final CFM #'s and what bore and valves these numbers came with. Few give the new intake runner volume or list max velocity on intake port in ft/sec.
Since comparing flow bench from someone else flow bench always raises an eyebrow, do you guys ever get a baseline set of numbers for what the heads flow stock and then the final numbers?
Example: This is a set of our LS1 CNC heads with stock valves, stock bore test and no chamber work.
Stock LS1 Flow #'s
Intake:
.100 67.1
.200 127.6
.300 181.3
.400 218.8
.500 236.4
.600 242.3
Exhaust:
.100 55.0
.200 99.6
.300 136.2
.400 157.6
.500 170.4
.600 178.1
Modified CNC LS1 Stage I (stock valves) flow #'s
Intake
.100 65.1
.200 142.4
.300 206.6
.400 242.0
.500 257.3
.550 264.1
.600 269.6
Exhaust
.100 56.0
.200 111.9
.300 148.1
.400 178.0
.500 200.2
.550 210.0
.600 216.3
The bench used to flow these heads before and after is said to be conservative compared to others in the industry.
So, how do we acurately compare flow numbers from one vendor to the next?
John
www.PACEPerformance.com
Since comparing flow bench from someone else flow bench always raises an eyebrow, do you guys ever get a baseline set of numbers for what the heads flow stock and then the final numbers?
Example: This is a set of our LS1 CNC heads with stock valves, stock bore test and no chamber work.
Stock LS1 Flow #'s
Intake:
.100 67.1
.200 127.6
.300 181.3
.400 218.8
.500 236.4
.600 242.3
Exhaust:
.100 55.0
.200 99.6
.300 136.2
.400 157.6
.500 170.4
.600 178.1
Modified CNC LS1 Stage I (stock valves) flow #'s
Intake
.100 65.1
.200 142.4
.300 206.6
.400 242.0
.500 257.3
.550 264.1
.600 269.6
Exhaust
.100 56.0
.200 111.9
.300 148.1
.400 178.0
.500 200.2
.550 210.0
.600 216.3
The bench used to flow these heads before and after is said to be conservative compared to others in the industry.
So, how do we acurately compare flow numbers from one vendor to the next?
John
www.PACEPerformance.com
07-13-2002, 12:06 AM
#6
Re: The world of LS1/LS6 head flow #'s </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">So, how do we acurately compare flow numbers from one vendor to the next?</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">You can't. Unless all heads are flowed on the same bench by the same operator on the same day with the same test procedure. Not likely to ever happen.
Providing before/after flowbench numbers and graphs seems like the best idea.
The same can be said about comparing dynojet numbers from various shops.
Tony
Providing before/after flowbench numbers and graphs seems like the best idea.
The same can be said about comparing dynojet numbers from various shops.
Tony
07-13-2002, 12:20 AM
#7
On The Tree
Join Date: Jan 2002
Posts: 111
Likes: 0
Received 0 Likes
on
0 Posts
Re: The world of LS1/LS6 head flow #'s Tony. I agree. However, how many vendors supply before and after #'s? Also, the example I listed is simple since the only change to the heads was the port work. But, I guess if you have the before #'s for your heads, then at least the finish head # gains can be seen.
So, what do you think vendors should list?
Flowbench used:
Test bore for both:
Exhaust tube extension/length:
Before/after #'s:
Intake Runner Volume:
Port velocity:
Another question, CNC is very repeatable from port to port right. On hand ported heads, what is the average flow variance from port to port on a finish head?
Obviously, there are a ton of variables. I would like to discuss what information can make comparisons simpler.
<small>[ July 12, 2002, 12:21 PM: Message edited by: John@PACE ]</small>
So, what do you think vendors should list?
Flowbench used:
Test bore for both:
Exhaust tube extension/length:
Before/after #'s:
Intake Runner Volume:
Port velocity:
Another question, CNC is very repeatable from port to port right. On hand ported heads, what is the average flow variance from port to port on a finish head?
Obviously, there are a ton of variables. I would like to discuss what information can make comparisons simpler.
<small>[ July 12, 2002, 12:21 PM: Message edited by: John@PACE ]</small>
Trending Topics
07-13-2002, 01:56 AM
#8
On The Tree
Join Date: Nov 2001
Location: Gold Coast Australia
Posts: 164
Likes: 0
Received 0 Likes
on
0 Posts
Re: The world of LS1/LS6 head flow #'s This is one of the things that annoys me when they (head shops) list figures they don't always say 25"/28", 3.9"/4.0"/4.03"bore etc.
Just knowing these will make a difference in ability to choose a head for the application.
eg. the CNC LS6 heads from SDPC are flowed on a 4.030" bore @ 28" so you have to keep that in mind when looking at someone elses figures.
On another note I would rather invest my money in a set of CNC heads, or CNC hand blended than hand ported heads just so I know each cylinder is =.
Just knowing these will make a difference in ability to choose a head for the application.
eg. the CNC LS6 heads from SDPC are flowed on a 4.030" bore @ 28" so you have to keep that in mind when looking at someone elses figures.
On another note I would rather invest my money in a set of CNC heads, or CNC hand blended than hand ported heads just so I know each cylinder is =.
07-13-2002, 02:18 AM
#9
D(irecto)r Pepper
Join Date: Nov 2001
Location: Houston Raceway Park...in TEXAS.
Posts: 1,952
Likes: 0
Received 0 Likes
on
0 Posts
Re: The world of LS1/LS6 head flow #'s </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by v8 ute:
<strong>This is one of the things that annoys me when they (head shops) list figures they don't always say 25"/28", 3.9"/4.0"/4.03"bore etc.
On another note I would rather invest my money in a set of CNC heads, or CNC hand blended than hand ported heads just so I know each cylinder is =.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I agree, the main shops "should" strive to have some kind of "standard".
If every one used 28" on a 3.9" bore would do me fine. If it's different than that and you dont tell me.....
P.S., Buyer beware.
<strong>This is one of the things that annoys me when they (head shops) list figures they don't always say 25"/28", 3.9"/4.0"/4.03"bore etc.
On another note I would rather invest my money in a set of CNC heads, or CNC hand blended than hand ported heads just so I know each cylinder is =.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I agree, the main shops "should" strive to have some kind of "standard".
If every one used 28" on a 3.9" bore would do me fine. If it's different than that and you dont tell me.....
P.S., Buyer beware.
07-13-2002, 02:27 AM
#10
Re: The world of LS1/LS6 head flow #'s I have worked with several different brands of flow benches over the last twenty years and have found the JKM benches to be the MOST conservatitive of them all. (See the latest issue of GMHT about the Buick GN head tech article). The durability of the bench is ok, but the science is a bit off, however once corrected, the benches work very well. <img border="0" alt="[judgement]" title="" src="graemlins/gr_judge.gif" />
Can you tell us what brand flow bench your CNC heads were flowed on? <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />
</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif"> Few give the new intake runner volume or list max velocity on intake port in ft/sec. </font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Do you have any port volume or area stats you want to give?
IMO if you want to know what stock ports really flow, test one or two ports on several different heads with the same casting number. Average the flow among them and then you will see a trend line appear. Head core shift can be a real problem. I have seen some castings shifted so much that the intake bowl mismatched the bottome edge of the seat ring by over .060" . Needless to say these ports didn't flow well at all. <img border="0" title="" alt="[Sad]" src="gr_sad.gif" />
On the other hand, lots of head castings are built within tolerance and produce great flow. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />
</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif"> Another question, CNC is very repeatable from port to port right. On hand ported heads, what is the average flow variance from port to port on a finish head? </font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">You are completly right about CNC ports being repeatable. One thing about a CNC is it will make a bunch of great ports or bunch of lousy ports depending on the programming. <img border="0" alt="[judgement]" title="" src="graemlins/gr_judge.gif" />
Hand finished ports can be very closely matched depending on the individual who ports them and what kind of day they are having. <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" />
I haven't seen much difference in test bore size to make a real issue.
Hope this answers your question. <img border="0" title="" alt="[Razz]" src="gr_tounge.gif" />
Richard
Can you tell us what brand flow bench your CNC heads were flowed on? <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />
</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif"> Few give the new intake runner volume or list max velocity on intake port in ft/sec. </font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Do you have any port volume or area stats you want to give?
IMO if you want to know what stock ports really flow, test one or two ports on several different heads with the same casting number. Average the flow among them and then you will see a trend line appear. Head core shift can be a real problem. I have seen some castings shifted so much that the intake bowl mismatched the bottome edge of the seat ring by over .060" . Needless to say these ports didn't flow well at all. <img border="0" title="" alt="[Sad]" src="gr_sad.gif" />
On the other hand, lots of head castings are built within tolerance and produce great flow. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />
</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif"> Another question, CNC is very repeatable from port to port right. On hand ported heads, what is the average flow variance from port to port on a finish head? </font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">You are completly right about CNC ports being repeatable. One thing about a CNC is it will make a bunch of great ports or bunch of lousy ports depending on the programming. <img border="0" alt="[judgement]" title="" src="graemlins/gr_judge.gif" />
Hand finished ports can be very closely matched depending on the individual who ports them and what kind of day they are having. <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" />
I haven't seen much difference in test bore size to make a real issue.
Hope this answers your question. <img border="0" title="" alt="[Razz]" src="gr_tounge.gif" />
Richard
07-13-2002, 03:20 AM
#11
On The Tree
Join Date: Jan 2002
Location: Australia.
Posts: 107
Likes: 0
Received 0 Likes
on
0 Posts
Re: The world of LS1/LS6 head flow #'s </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by headbam:
<strong>
</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif"> Another question, CNC is very repeatable from port to port right. On hand ported heads, what is the average flow variance from port to port on a finish head? </font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">You are completly right about CNC ports being repeatable. One thing about a CNC is it will make a bunch of great ports or bunch of lousy ports depending on the programming. <img border="0" alt="[judgement]" title="" src="graemlins/gr_judge.gif" />
Hand finished ports can be very closely matched depending on the individual who ports them and what kind of day they are having. <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" />
I haven't seen much difference in test bore size to make a real issue.
Hope this answers your question. <img border="0" title="" alt="[Razz]" src="gr_tounge.gif" />
Richard</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">couldn't agree with the CNC thing more...funny how CNC is meant to give this magical consistency that a hand porter can't get when most of the CNC heads I flow will have a variation of 10% from good to bad off the same programme...core shift? CNC can fix anything <img border="0" title="" alt="[Roll Eyes]" src="images/icons/rolleyes.gif" />
my advice is to select a good porter and regardless of whether he uses CNC or hand methods...spend the extra and get him to tune EVERY port...not just a before and after on ONE port...I always test 4 ports before sending out a job...that way I have gone atleast halfway to making sure there are no dogs in amoungst them...don't assume that because it is CNC it is guru...I see alot that aren't!!
A good start for the industry would be to show test pressure as a standard...I notice John from Pace doesn't list this is his criteria of standards <img border="0" title="" alt="[Embarrassed]" src="gr_emb.gif" /> I copped a real flogging on this Forum for asking what test pressure some test were made at....the concensus was "what does it matter? **** off and get a life!"
Max port velocity is going to be over the short side radius....where do you want to map the average from? <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" /> Port volume pretty much sums up the equasion...the highest flowing head with the smallest port will always make the nicest street power...
</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by v8 ute:
<strong>
On another note I would rather invest my money in a set of CNC heads, or CNC hand blended than hand ported heads just so I know each cylinder is =.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">but are they? Only a flow test will tell...let's face it CNC is a cost effective way of removing material quickly...no CNC come with the knowledge of what makes a cylinder head port flow... <img border="0" title="" alt="[Roll Eyes]" src="images/icons/rolleyes.gif" /> and when most of what happens is an inch either side of the valve seat (45deg) the CNC's talents are somewhat deminished.
<small>[ July 13, 2002, 03:37 AM: Message edited by: HOWQUICK ]</small>
<strong>
</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif"> Another question, CNC is very repeatable from port to port right. On hand ported heads, what is the average flow variance from port to port on a finish head? </font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">You are completly right about CNC ports being repeatable. One thing about a CNC is it will make a bunch of great ports or bunch of lousy ports depending on the programming. <img border="0" alt="[judgement]" title="" src="graemlins/gr_judge.gif" />
Hand finished ports can be very closely matched depending on the individual who ports them and what kind of day they are having. <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" />
I haven't seen much difference in test bore size to make a real issue.
Hope this answers your question. <img border="0" title="" alt="[Razz]" src="gr_tounge.gif" />
Richard</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">couldn't agree with the CNC thing more...funny how CNC is meant to give this magical consistency that a hand porter can't get when most of the CNC heads I flow will have a variation of 10% from good to bad off the same programme...core shift? CNC can fix anything <img border="0" title="" alt="[Roll Eyes]" src="images/icons/rolleyes.gif" />
my advice is to select a good porter and regardless of whether he uses CNC or hand methods...spend the extra and get him to tune EVERY port...not just a before and after on ONE port...I always test 4 ports before sending out a job...that way I have gone atleast halfway to making sure there are no dogs in amoungst them...don't assume that because it is CNC it is guru...I see alot that aren't!!
A good start for the industry would be to show test pressure as a standard...I notice John from Pace doesn't list this is his criteria of standards <img border="0" title="" alt="[Embarrassed]" src="gr_emb.gif" /> I copped a real flogging on this Forum for asking what test pressure some test were made at....the concensus was "what does it matter? **** off and get a life!"
Max port velocity is going to be over the short side radius....where do you want to map the average from? <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" /> Port volume pretty much sums up the equasion...the highest flowing head with the smallest port will always make the nicest street power...
</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by v8 ute:
<strong>
On another note I would rather invest my money in a set of CNC heads, or CNC hand blended than hand ported heads just so I know each cylinder is =.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">but are they? Only a flow test will tell...let's face it CNC is a cost effective way of removing material quickly...no CNC come with the knowledge of what makes a cylinder head port flow... <img border="0" title="" alt="[Roll Eyes]" src="images/icons/rolleyes.gif" /> and when most of what happens is an inch either side of the valve seat (45deg) the CNC's talents are somewhat deminished.
<small>[ July 13, 2002, 03:37 AM: Message edited by: HOWQUICK ]</small>
07-13-2002, 04:46 AM
#12
On The Tree
Join Date: Nov 2001
Location: Gold Coast Australia
Posts: 164
Likes: 0
Received 0 Likes
on
0 Posts
Re: The world of LS1/LS6 head flow #'s </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Howquick...no CNC come with the knowledge of what makes a cylinder head port flow... </font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">This knowledge obviously comes with the person who puts in the R&D to get the programme right. It is a pity that there is soo much core shift in these castings and without discussion like this someone (like myself) could very well make a poor investment.
</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Howquick
my advice is to select a good porter and regardless of whether he uses CNC or hand methods...spend the extra and get him to tune EVERY port...not just a before and after on ONE port...I always test 4 ports before sending out a job...that way I have gone atleast halfway to making sure there are no dogs in amoungst them...don't assume that because it is CNC it is guru...I see alot that aren't!! </font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">This good advise and something that without industry knowledge you have to have some figures that are compareable to help sort out which head (LS6, LS1-5.3,5.7,6.0) to use and where you will go to get these heads.
I personally am not after the meanest baddest heads I'm after the best to suit my current application with out waisting money (this doesn't mean they're the cheapest) , if at all possible that they be adaptable for my future short block.
P.S. Howquick, did you get my PM on LS1.com about your Oil control thingy? Mel (1surfer)is interested too. Could you PM me about it?
<small>[ July 13, 2002, 04:53 AM: Message edited by: v8 ute ]</small>
</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Howquick
my advice is to select a good porter and regardless of whether he uses CNC or hand methods...spend the extra and get him to tune EVERY port...not just a before and after on ONE port...I always test 4 ports before sending out a job...that way I have gone atleast halfway to making sure there are no dogs in amoungst them...don't assume that because it is CNC it is guru...I see alot that aren't!! </font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">This good advise and something that without industry knowledge you have to have some figures that are compareable to help sort out which head (LS6, LS1-5.3,5.7,6.0) to use and where you will go to get these heads.
I personally am not after the meanest baddest heads I'm after the best to suit my current application with out waisting money (this doesn't mean they're the cheapest) , if at all possible that they be adaptable for my future short block.
P.S. Howquick, did you get my PM on LS1.com about your Oil control thingy? Mel (1surfer)is interested too. Could you PM me about it?
<small>[ July 13, 2002, 04:53 AM: Message edited by: v8 ute ]</small>
07-13-2002, 10:25 AM
#13
TECH Regular
Join Date: Feb 2002
Location: the moon
Posts: 414
Likes: 0
Received 0 Likes
on
0 Posts
Re: The world of LS1/LS6 head flow #'s looking at John's head numbers I would guess around 45FLWHP is to be gained over stock N.A.
But for instance in his application IF they are going on a supercharged motor, the extra flow really only means it'll make the power with around 2psi less boost than a set of stock heads.
Not much talk about what happens with a port is under pressure either.
Anyhow,it's all in the application.
John, What are your port CC #'s?
Velocity will of course vary through the port, so you can forget ever comparing this parameter between head porters IMO.
That's some nice head tech to discuss for us nerds but not practical to think we can get that sort of info from everybody.
I have seen the CNC Heads John mentions. Very nice.
I could see getting a bit more flow from them by a final hand finish. Mainly in the chambers as the port work is about as good as any hand job I have seen.
But then that would be more work which means more money for the customer.
The amount of manual work saved with cnc machines is tremendous.
Don't a lot of pros now begin with a cnc job and then finish by hand?
I can't see doing heads 100% by hand anymore with the machines available now.
I am just glad I can do this stuff myself and save a bundle of cash, even though it takes a lot of manual labor hours with the ol' grinder.
I don't think cnc offers any tremendous port equity advantage over hand.
When I port heads( I am not a Pro) I do one area on a port and then do the same to the other 7.
I don't just do 1 entire intake port and then move to the next. I would think a Pro, a guy who does it for a living will be extremely close from port to port.
Steve
But for instance in his application IF they are going on a supercharged motor, the extra flow really only means it'll make the power with around 2psi less boost than a set of stock heads.
Not much talk about what happens with a port is under pressure either.
Anyhow,it's all in the application.
John, What are your port CC #'s?
Velocity will of course vary through the port, so you can forget ever comparing this parameter between head porters IMO.
That's some nice head tech to discuss for us nerds but not practical to think we can get that sort of info from everybody.
I have seen the CNC Heads John mentions. Very nice.
I could see getting a bit more flow from them by a final hand finish. Mainly in the chambers as the port work is about as good as any hand job I have seen.
But then that would be more work which means more money for the customer.
The amount of manual work saved with cnc machines is tremendous.
Don't a lot of pros now begin with a cnc job and then finish by hand?
I can't see doing heads 100% by hand anymore with the machines available now.
I am just glad I can do this stuff myself and save a bundle of cash, even though it takes a lot of manual labor hours with the ol' grinder.
I don't think cnc offers any tremendous port equity advantage over hand.
When I port heads( I am not a Pro) I do one area on a port and then do the same to the other 7.
I don't just do 1 entire intake port and then move to the next. I would think a Pro, a guy who does it for a living will be extremely close from port to port.
Steve
07-13-2002, 11:19 AM
#14
TECH Resident
Join Date: Nov 2001
Location: Chattanooga,Tn
Posts: 917
Likes: 0
Received 0 Likes
on
0 Posts
Re: The world of LS1/LS6 head flow #'s Well here are some 5.3 heads from tea
STK INT STK EX TEA INT TEA EX
0.050 32.7 25.5 34.2 27.3
0.100 65.4 51.0 68.3 54.5
0.150 94.4 76.4 102.0 80.9
0.200 123.3 101.7 135.7 107.2
0.250 151.5 124.5 167.5 132.7
0.300 179.7 147.2 199.2 158.2
0.350 199.2 160.0 226.3 181.9
0.400 218.8 172.7 253.4 205.6
0.450 223.0 179.8 274.2 221.3
0.500 227.2 186.8 295.0 236.9
0.550 230.5 191.8 310.6 245.4
this was done with clay on intake port to simulate
an intake and 1 5/8 pipe on the exhaust
flow at 28in of water on a 4.00 bore
This was done a computerized flowdata bench
<small>[ July 13, 2002, 11:22 AM: Message edited by: H82BBad ]</small>
STK INT STK EX TEA INT TEA EX
0.050 32.7 25.5 34.2 27.3
0.100 65.4 51.0 68.3 54.5
0.150 94.4 76.4 102.0 80.9
0.200 123.3 101.7 135.7 107.2
0.250 151.5 124.5 167.5 132.7
0.300 179.7 147.2 199.2 158.2
0.350 199.2 160.0 226.3 181.9
0.400 218.8 172.7 253.4 205.6
0.450 223.0 179.8 274.2 221.3
0.500 227.2 186.8 295.0 236.9
0.550 230.5 191.8 310.6 245.4
this was done with clay on intake port to simulate
an intake and 1 5/8 pipe on the exhaust
flow at 28in of water on a 4.00 bore
This was done a computerized flowdata bench
<small>[ July 13, 2002, 11:22 AM: Message edited by: H82BBad ]</small>
07-13-2002, 01:03 PM
#15
On The Tree
Join Date: Jan 2002
Posts: 111
Likes: 0
Received 0 Likes
on
0 Posts
Re: The world of LS1/LS6 head flow #'s Joe (JPR) - Thanks for the info!
Testing from what I know was at stock bore @ 28" . I'll have to confirm this on Monday.
Richard (Headbam) - I will find out the flowbench type on Monday. cc's I believe 8 above stock. Head core shift was discussed quite a bit. Worst core shifting heads are the LS6's and that's why a lot of guys mess up the ports on them from what several people mentioned. Core shift is corrected for before CNC'ing from what I understood. Will have to confirm this. Intake port velocity at the popular new cam lift levels messured 1.5" from intake flange are a tick away from 300 ft/sec.
HowQuick - I disclosed info here you asked about, care to do the same so we can compare? <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> Yes, like anything, CNC head is only as good as the program (porter). These heads are entry level with stock valves, I don't know if I would even call them stage I. These heads were testing against another "famous" CNC equivalent head on an engine dyno and produced more power across the board. Quite a few iterations before a final port geometry was selected. However, that is not the point here. It was just what made me think of how people derive at different flow #'s.
One thing that I rarely see anyone discuss is the fact that when you put on a LS1 or LS6 intake, the numbers drop like a rock, especially for the high number claiming heads (I think Chris E did a comparison way back when?). I know someone discussed the intake head flow limits, does anyone remember the numbers?
H82BBAD - That's what I'm talking about. Look at the numbers. How can we even begin to compare those to any other head? Not enough data that is critical for comparison right? What would you do if a set of "less flowing" heads dynoed better?
I think it's like Tony said about Dyno #'s. Except with a dyno, everyone tries to correct to a standard.
So, how do you correct flow #'s for different exhaust extensions used, bore sizes used, valve sizes, intake additions, etc?
Well, at the end of the day, I guess the track tells the tale. I guess I was just being one of those nerdy engine spec guys. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />
Testing from what I know was at stock bore @ 28" . I'll have to confirm this on Monday.
Richard (Headbam) - I will find out the flowbench type on Monday. cc's I believe 8 above stock. Head core shift was discussed quite a bit. Worst core shifting heads are the LS6's and that's why a lot of guys mess up the ports on them from what several people mentioned. Core shift is corrected for before CNC'ing from what I understood. Will have to confirm this. Intake port velocity at the popular new cam lift levels messured 1.5" from intake flange are a tick away from 300 ft/sec.
HowQuick - I disclosed info here you asked about, care to do the same so we can compare? <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> Yes, like anything, CNC head is only as good as the program (porter). These heads are entry level with stock valves, I don't know if I would even call them stage I. These heads were testing against another "famous" CNC equivalent head on an engine dyno and produced more power across the board. Quite a few iterations before a final port geometry was selected. However, that is not the point here. It was just what made me think of how people derive at different flow #'s.
One thing that I rarely see anyone discuss is the fact that when you put on a LS1 or LS6 intake, the numbers drop like a rock, especially for the high number claiming heads (I think Chris E did a comparison way back when?). I know someone discussed the intake head flow limits, does anyone remember the numbers?
H82BBAD - That's what I'm talking about. Look at the numbers. How can we even begin to compare those to any other head? Not enough data that is critical for comparison right? What would you do if a set of "less flowing" heads dynoed better?
I think it's like Tony said about Dyno #'s. Except with a dyno, everyone tries to correct to a standard.
So, how do you correct flow #'s for different exhaust extensions used, bore sizes used, valve sizes, intake additions, etc?
Well, at the end of the day, I guess the track tells the tale. I guess I was just being one of those nerdy engine spec guys. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />
07-13-2002, 01:06 PM
#16
TECH Resident
Join Date: Nov 2001
Location: Chattanooga,Tn
Posts: 917
Likes: 0
Received 0 Likes
on
0 Posts
Re: The world of LS1/LS6 head flow #'s what else would you need John?
I gave bore size for both test,28 in for both test,ports clayed for both test.etc
what more would you want?
BTW it flows less than your head in the stock form because it is a 5.3 head
I would also add that TEA has very much improved the midlift numbers on these since these test as they are almost 2 years old.
<small>[ July 13, 2002, 01:10 PM: Message edited by: H82BBad ]</small>
I gave bore size for both test,28 in for both test,ports clayed for both test.etc
what more would you want?
BTW it flows less than your head in the stock form because it is a 5.3 head
I would also add that TEA has very much improved the midlift numbers on these since these test as they are almost 2 years old.
<small>[ July 13, 2002, 01:10 PM: Message edited by: H82BBad ]</small>
07-13-2002, 01:41 PM
#17
On The Tree
Join Date: Jan 2002
Posts: 111
Likes: 0
Received 0 Likes
on
0 Posts
Re: The world of LS1/LS6 head flow #'s H82BBAD - I was just using this CNC head as an example. I'm not trying to "compare" it to anyone elses head or discuss that. This discussion curiosity was merely if and how do you standardize how people flow their heads and derive the numbers so there can be a level ground comparison. This may not be a feasible idea, but none the less the discussion interests me. Your question of what else would I like to see for those heads is exactly what we are trying to get at. What exactly do we need to "equally" compare #'s? As Miles in Michigan pointed out, % differences may show better gains, that's why I inquired about before and after #'s. However, do you know your runner cc volume before and after, is there any type of port velocity data at various lifts, etc? We didn't discuss if these are vital or would help in the comparison, but they are another variable.
Like I said, I definitely don't want the thread to turn into, vendor a flows is better then vendor b, vendor a heads are better then vendor b, etc. I was just interested in the "nerdy" aspects (as Tony put it <img border="0" alt="[chug]" title="" src="graemlins/gr_chug.gif" /> ) of comparisons and standards. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
<small>[ July 13, 2002, 01:43 PM: Message edited by: John@PACE ]</small>
Like I said, I definitely don't want the thread to turn into, vendor a flows is better then vendor b, vendor a heads are better then vendor b, etc. I was just interested in the "nerdy" aspects (as Tony put it <img border="0" alt="[chug]" title="" src="graemlins/gr_chug.gif" /> ) of comparisons and standards. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
<small>[ July 13, 2002, 01:43 PM: Message edited by: John@PACE ]</small>
07-13-2002, 01:46 PM
#18
On The Tree
Join Date: Jan 2002
Posts: 111
Likes: 0
Received 0 Likes
on
0 Posts
Re: The world of LS1/LS6 head flow #'s Eek... I completely neglected milling the heads! Add that to the variable of how much power a head will produce and make this comparison more complex. Chamber work another.
FWIW, my example above was not milled.
<small>[ July 13, 2002, 01:48 PM: Message edited by: John@PACE ]</small>
FWIW, my example above was not milled.
<small>[ July 13, 2002, 01:48 PM: Message edited by: John@PACE ]</small>
07-13-2002, 02:02 PM
#19
TECH Resident
Join Date: Nov 2001
Location: Chattanooga,Tn
Posts: 917
Likes: 0
Received 0 Likes
on
0 Posts
Re: The world of LS1/LS6 head flow #'s well I am of the thinking that you cant compare one flow bench to the other also.
1. Some use clay,this is the method I prefer as it makes the port tested and the runner opening
2.I also like to see the flowed with a pipe on the head just personal preferance.
3 I dont know how most shops do it but we used flow heads before milling them,cause if the numbers wernt up to snuff they would go back to the port room.no since nicking a freshly milled deck up <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
1. Some use clay,this is the method I prefer as it makes the port tested and the runner opening
2.I also like to see the flowed with a pipe on the head just personal preferance.
3 I dont know how most shops do it but we used flow heads before milling them,cause if the numbers wernt up to snuff they would go back to the port room.no since nicking a freshly milled deck up <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
07-13-2002, 11:38 PM
#20
Re: The world of LS1/LS6 head flow #'s Thanks for bringing up this topic. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
Could you tell us what portion of the intake and exhaust ports are machined by the CNC? Chambers worked on too?
Miles points out an interesting fact about percentage gains. I notice that they are in the useable lift curve for most hyd. roller cams. Very potent. <img border="0" alt="[judgement]" title="" src="graemlins/gr_judge.gif" />
As for consistency among each CNC finished head, there should be very little change in flow from port to port. We see the biggest variable is the profile of the valves. Backcut angles will produce two very different flow curves.
How that translates to power to the ground has yet to be determined. <img border="0" alt="[Burnout]" title="" src="graemlins/burnout.gif" />
Cheers,
Richard
Could you tell us what portion of the intake and exhaust ports are machined by the CNC? Chambers worked on too?
Miles points out an interesting fact about percentage gains. I notice that they are in the useable lift curve for most hyd. roller cams. Very potent. <img border="0" alt="[judgement]" title="" src="graemlins/gr_judge.gif" />
As for consistency among each CNC finished head, there should be very little change in flow from port to port. We see the biggest variable is the profile of the valves. Backcut angles will produce two very different flow curves.
How that translates to power to the ground has yet to be determined. <img border="0" alt="[Burnout]" title="" src="graemlins/burnout.gif" />
Cheers,
Richard