GMR head port vs full race port
11-25-2012, 09:47 AM
#1
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GMR head port vs full race port
What are the bennefits to a full port job by say Euthanasia ( just for the example of this thread ) over just a exhaust gasket GMR style port matching?
One better than the other?
If so why?
Looking for comments by people who have done the head builds.
One better than the other?
If so why?
Looking for comments by people who have done the head builds.
11-25-2012, 09:50 AM
#2
I cant really speak for the LSJ crowd but i had my head ported and polished. Basically just a gasket match and SLIGHTLY opening things up. Nothing too crazy. I noticed my spool time got slightly better but that could also be from a few other things during the engine build.
I would say a full port job would be better as it opens up alot more air flow and really smooths stuff out tho
I would say a full port job would be better as it opens up alot more air flow and really smooths stuff out tho
11-25-2012, 10:34 AM
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Most places don't port anything bigger than the manifold runners. it would be pointless. Everyone ports the same match the manifolds, and if you want an angle valve job they do that also.
Last edited by MP Cobalt; 11-25-2012 at 11:58 AM.
11-25-2012, 11:23 AM
#5
the balance on an s/c LSJ between inlet and exhaust, led the GM racing guys to only do the exhaust port. I am thinking they had the engineering capability, the science, testing and money to know whats best.
LNF is very different and its been said many times, leave the ports alone. Check ZZP posts on this, they may not have GM engineering etc, but they have done a lot of dyno runs and engine work.
LNF is very different and its been said many times, leave the ports alone. Check ZZP posts on this, they may not have GM engineering etc, but they have done a lot of dyno runs and engine work.
11-25-2012, 11:27 AM
#6
the balance on an s/c LSJ between inlet and exhaust, led the GM racing guys to only do the exhaust port. I am thinking they had the engineering capability, the science, testing and money to know whats best.
LNF is very different and its been said many times, leave the ports alone. Check ZZP posts on this, they may not have GM engineering etc, but they have done a lot of dyno runs and engine work.
LNF is very different and its been said many times, leave the ports alone. Check ZZP posts on this, they may not have GM engineering etc, but they have done a lot of dyno runs and engine work.
11-25-2012, 11:44 AM
#8
leave the LNF head ports alone. seems reasonable to me. Zoomer says porting for more port flow on an LNF loses power in reality. Hard to challenge that without doing your own research.
This is an LSJ thred/question however.
from Omega5 on redline forums back in early 2009, he is a very knowledgeable and thinking guy from Saskatchewan:
"Before going into too much detail, there are a few things about SC'd engines that you need to know.
1) Higher exhaust flow in an SC'd will yield more power. That can be achieved in three ways; higher port flow, higher valve lift, or longer lobe duration.
2) The power delivery of the combustion cycle actually happens later than in a turbo or NA engine. Opening the exhaust valve too soon, can actually hurt performance, as a majority of the energy is being lost out the exhaust.
3) .... I won't go into that now.... it's a camshaft thing.
With that said; we know that a longer duration can potentially hurt performance. Therefore we should achieve maximum exhaust flow via higher lift and higher port flow.
It has been shown in the past (with other SC'd engines) that the ideal exhaust flow (rule of thumb) should be ~80% of the intake flow... for higher boosted engines, that can be upward of 85%. It has also been shown that to get the optimal exhaust flow ratio, it can be beneficial to sacrifice intake flow.
Of course there are various factors that come into play when finding the optimal port flow, so don't take the above numbers to heart.
Now... I know that some people call BS on the I/E ratio stuff.... however think of it like this; what goes in, must come out. Properly balancing your intake and exhaust is very critical.
"
This is an LSJ thred/question however.
from Omega5 on redline forums back in early 2009, he is a very knowledgeable and thinking guy from Saskatchewan:
"Before going into too much detail, there are a few things about SC'd engines that you need to know.
1) Higher exhaust flow in an SC'd will yield more power. That can be achieved in three ways; higher port flow, higher valve lift, or longer lobe duration.
2) The power delivery of the combustion cycle actually happens later than in a turbo or NA engine. Opening the exhaust valve too soon, can actually hurt performance, as a majority of the energy is being lost out the exhaust.
3) .... I won't go into that now.... it's a camshaft thing.
With that said; we know that a longer duration can potentially hurt performance. Therefore we should achieve maximum exhaust flow via higher lift and higher port flow.
It has been shown in the past (with other SC'd engines) that the ideal exhaust flow (rule of thumb) should be ~80% of the intake flow... for higher boosted engines, that can be upward of 85%. It has also been shown that to get the optimal exhaust flow ratio, it can be beneficial to sacrifice intake flow.
Of course there are various factors that come into play when finding the optimal port flow, so don't take the above numbers to heart.
Now... I know that some people call BS on the I/E ratio stuff.... however think of it like this; what goes in, must come out. Properly balancing your intake and exhaust is very critical.
"
11-25-2012, 12:00 PM
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leave the LNF head ports alone. seems reasonable to me. Zoomer says porting for more port flow on an LNF loses power in reality. Hard to challenge that without doing your own research.
This is an LSJ thred/question however.
from Omega5 on redline forums back in early 2009, he is a very knowledgeable and thinking guy from Saskatchewan:
"Before going into too much detail, there are a few things about SC'd engines that you need to know.
1) Higher exhaust flow in an SC'd will yield more power. That can be achieved in three ways; higher port flow, higher valve lift, or longer lobe duration.
2) The power delivery of the combustion cycle actually happens later than in a turbo or NA engine. Opening the exhaust valve too soon, can actually hurt performance, as a majority of the energy is being lost out the exhaust.
3) .... I won't go into that now.... it's a camshaft thing.
With that said; we know that a longer duration can potentially hurt performance. Therefore we should achieve maximum exhaust flow via higher lift and higher port flow.
It has been shown in the past (with other SC'd engines) that the ideal exhaust flow (rule of thumb) should be ~80% of the intake flow... for higher boosted engines, that can be upward of 85%. It has also been shown that to get the optimal exhaust flow ratio, it can be beneficial to sacrifice intake flow.
Of course there are various factors that come into play when finding the optimal port flow, so don't take the above numbers to heart.
Now... I know that some people call BS on the I/E ratio stuff.... however think of it like this; what goes in, must come out. Properly balancing your intake and exhaust is very critical.
"
This is an LSJ thred/question however.
from Omega5 on redline forums back in early 2009, he is a very knowledgeable and thinking guy from Saskatchewan:
"Before going into too much detail, there are a few things about SC'd engines that you need to know.
1) Higher exhaust flow in an SC'd will yield more power. That can be achieved in three ways; higher port flow, higher valve lift, or longer lobe duration.
2) The power delivery of the combustion cycle actually happens later than in a turbo or NA engine. Opening the exhaust valve too soon, can actually hurt performance, as a majority of the energy is being lost out the exhaust.
3) .... I won't go into that now.... it's a camshaft thing.
With that said; we know that a longer duration can potentially hurt performance. Therefore we should achieve maximum exhaust flow via higher lift and higher port flow.
It has been shown in the past (with other SC'd engines) that the ideal exhaust flow (rule of thumb) should be ~80% of the intake flow... for higher boosted engines, that can be upward of 85%. It has also been shown that to get the optimal exhaust flow ratio, it can be beneficial to sacrifice intake flow.
Of course there are various factors that come into play when finding the optimal port flow, so don't take the above numbers to heart.
Now... I know that some people call BS on the I/E ratio stuff.... however think of it like this; what goes in, must come out. Properly balancing your intake and exhaust is very critical.
"
11-25-2012, 04:03 PM
#10
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This shouldnt be too expensive then if thats all thats being done is opening up the exhaust ports.
John what are your thoughts on doing exhaust ports only, supertechs, new timing chain and tensioner (100kmiles) and neutral balance shafts, along with new head studs, and oem headgasket?
Mess with pistons too while the heads off or no?
John what are your thoughts on doing exhaust ports only, supertechs, new timing chain and tensioner (100kmiles) and neutral balance shafts, along with new head studs, and oem headgasket?
Mess with pistons too while the heads off or no?
11-25-2012, 05:18 PM
#12
This shouldnt be too expensive then if thats all thats being done is opening up the exhaust ports.
John what are your thoughts on doing exhaust ports only, supertechs, new timing chain and tensioner (100kmiles) and neutral balance shafts, along with new head studs, and oem headgasket?
Mess with pistons too while the heads off or no?
John what are your thoughts on doing exhaust ports only, supertechs, new timing chain and tensioner (100kmiles) and neutral balance shafts, along with new head studs, and oem headgasket?
Mess with pistons too while the heads off or no?
Its a dd car why fool around with the balance shafts, its not like u are trying to get the last 2% of the total available power that can be extracted from the engine. The NBS change is a lot of time and some money. Better spend ur money elsewhere in my opinion.
11-25-2012, 05:41 PM
#13
This shouldnt be too expensive then if thats all thats being done is opening up the exhaust ports.
John what are your thoughts on doing exhaust ports only, supertechs, new timing chain and tensioner (100kmiles) and neutral balance shafts, along with new head studs, and oem headgasket?
Mess with pistons too while the heads off or no?
John what are your thoughts on doing exhaust ports only, supertechs, new timing chain and tensioner (100kmiles) and neutral balance shafts, along with new head studs, and oem headgasket?
Mess with pistons too while the heads off or no?
nbs shafts arent hard to put in with the engine in the car
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