Ls3
GM has a 3 valve head for the ls9. (due in production 2009 model year).It has bean in development and testing for the last couple of years.It is not central injected. there are several of them in our shop. It is not any thing like the drawing you guys are looking at. I cant tell you mutch about it but think of one shaft mounted rocker moving a short push rod that moves another shaft mounted rocker that opens 2 intake valves at once. The combustion chamber is hart shaped with with the int. valves at the top of the hart I will ask my boss how mutch I can tell you about it.
Originally Posted by its scot
GM has a 3 valve head for the ls9. (due in production 2009 model year).It has bean in development and testing for the last couple of years.It is not central injected. there are several of them in our shop. It is not any thing like the drawing you guys are looking at. I cant tell you mutch about it but think of one shaft mounted rocker moving a short push rod that moves another shaft mounted rocker that opens 2 intake valves at once. The combustion chamber is hart shaped with with the int. valves at the top of the hart I will ask my boss how mutch I can tell you about it.
Originally Posted by Bud M
You guys are making this way too complicated. 4 valves flow more than two because they have significantly more valve circumference so they flow better, especially at low lifts. They are less susceptible to valve float because the typical OHC has significantly less reciprocating weight. Why do you think that virtually all recent race engine designs and every recent sportbike design has 4 (or more) valves per cylinder? The LSx motors were designed with being applicable to a wide range of vehicles being a priority. Sports cars to Trucks had to use the same basic engine to keep costs where GM wanted them. And they have produced an excellent engine working around that necessity. But don't kid yourselves, a 4 valve engine with the same displacement could be more powerful in every aspect without any insurmountable drawbacks. And the argument that they won't fit in an F body doesn't work either. I have pix of a Northstar in a 4th gen. It fits. And if the car was designed around it, it would fit even better.
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Teching In
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Originally Posted by its scot
GM has a 3 valve head for the ls9. (due in production 2009 model year).It has bean in development and testing for the last couple of years.It is not central injected. there are several of them in our shop. It is not any thing like the drawing you guys are looking at. I cant tell you mutch about it but think of one shaft mounted rocker moving a short push rod that moves another shaft mounted rocker that opens 2 intake valves at once. The combustion chamber is hart shaped with with the int. valves at the top of the hart I will ask my boss how mutch I can tell you about it.
First of all, I assume it is the single cam version, not the dual cam version ...
http://www.freepatentsonline.com/6505589.pdf [ Single camshaft design ]
http://www.freepatentsonline.com/6505591.pdf [ Dual camshaft design ]
http://www.freepatentsonline.com/6668546.pdf [ Combustion Chamber shape in Figure 5 ]
Those pictures showed a valvetrain that appeared to allow room for a
central injection DI set up. The newer patent shows a revised set up
that doesn't appear to offer enough room for central injection DI.
http://www.freepatentsonline.com/6962134.pdf
So, are you telling us that neither of these are the current design?? If the
central injection airblast design from Orbital Engineering/Synerject is
not being used, are they using a high pressure, side injection DI set up
on the LS9??
The 2v vs 4v debate needs to be stopped by the moderators. It's jacking this thread and it's already been done to death in the thread linked by J-rod. Complete with Brits who worship OHC for some reason and everything. (seriously, you need to realize that your displacement-limited racing is not comparable to the street) Oh, and the OHC people lost. There isn't anything being said here that hasn't already been said there.
...With one exception: nobody was stupid enough to claim that OHV was "old tech" over there. (OHC was invented first, and is the more primitive. OHV was an innovation that came later to save weight, money, size, etc...) So the OHC is actually the old tech. You people need to deal with the fact that the future is here!
...With one exception: nobody was stupid enough to claim that OHV was "old tech" over there. (OHC was invented first, and is the more primitive. OHV was an innovation that came later to save weight, money, size, etc...) So the OHC is actually the old tech. You people need to deal with the fact that the future is here!
Launching!
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From: Exton, Pennsylvania
Originally Posted by black_knight
The 2v vs 4v debate needs to be stopped by the moderators. It's jacking this thread and it's already been done to death in the thread linked by J-rod. Complete with Brits who worship OHC for some reason and everything. (seriously, you need to realize that your displacement-limited racing is not comparable to the street) Oh, and the OHC people lost. There isn't anything being said here that hasn't already been said there.
...With one exception: nobody was stupid enough to claim that OHV was "old tech" over there. (OHC was invented first, and is the more primitive. OHV was an innovation that came later to save weight, money, size, etc...) So the OHC is actually the old tech. You people need to deal with the fact that the future is here!
...With one exception: nobody was stupid enough to claim that OHV was "old tech" over there. (OHC was invented first, and is the more primitive. OHV was an innovation that came later to save weight, money, size, etc...) So the OHC is actually the old tech. You people need to deal with the fact that the future is here!
Do you have a source for your claim that OHC came first? I am not saying it didn't, but I would like to see some evidence.
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Originally Posted by RussStang
Do you have a source for your claim that OHC came first? I am not saying it didn't, but I would like to see some evidence.
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From: Dallas, North Mexico
Originally Posted by Bud M
You guys are making this way too complicated. 4 valves flow more than two because they have significantly more valve circumference so they flow better, especially at low lifts. They are less susceptible to valve float because the typical OHC has significantly less reciprocating weight. Why do you think that virtually all recent race engine designs and every recent sportbike design has 4 (or more) valves per cylinder? The LSx motors were designed with being applicable to a wide range of vehicles being a priority. Sports cars to Trucks had to use the same basic engine to keep costs where GM wanted them. And they have produced an excellent engine working around that necessity. But don't kid yourselves, a 4 valve engine with the same displacement could be more powerful in every aspect without any insurmountable drawbacks. And the argument that they won't fit in an F body doesn't work either. I have pix of a Northstar in a 4th gen. It fits. And if the car was designed around it, it would fit even better.
Given the same space, weight, cost and BSFC requirements; 4 valves are not always more powerful (assuming it requires OHC). If a bigger engine fits in an engine bay, the engine bay was too big.
Originally Posted by treyZ28
While the output potential of the 4 valve over the 2 valve cant be argued, its output in application can. 4 valves require more space, more money, more complexity, more cost, more weight and provide a lower efficiency (BSFC).
Given the same space, weight, cost and BSFC requirements; 4 valves are not always more powerful (assuming it requires OHC). If a bigger engine fits in an engine bay, the engine bay was too big.
Given the same space, weight, cost and BSFC requirements; 4 valves are not always more powerful (assuming it requires OHC). If a bigger engine fits in an engine bay, the engine bay was too big.
Show me documentation proving that lower BSFC is inherent in multi valve head designs. I'll be very surprised if you can.
If an engine bay is just barely big enough to hold an engine, its not big enough to work on one. That's how you cars where mechanics charge for 6 hours of labor to replace a water pump.
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From: Dallas, North Mexico
Originally Posted by Bud M
BS arguments. The size and weight differences are minor factors. Complexity? A 4 valve head is too complex for who? There are millions of them on the road.
Show me documentation proving that lower BSFC is inherent in multi valve head designs. I'll be very surprised if you can.
If an engine bay is just barely big enough to hold an engine, its not big enough to work on one. That's how you cars where mechanics charge for 6 hours of labor to replace a water pump.
Show me documentation proving that lower BSFC is inherent in multi valve head designs. I'll be very surprised if you can.
If an engine bay is just barely big enough to hold an engine, its not big enough to work on one. That's how you cars where mechanics charge for 6 hours of labor to replace a water pump.
Ok fine. Make it big enough to fit this OHV engine and enough room to work on it. Now there isn't enough room for an OHC engine. While it may fit, its not big enough to work on one. That's how you cars where mechanics charge for 6 hours of labor to replace a water pump.
Have you ever seen a 4.6 DOHC ford engine? Its huge compared a 6.0 GM OHV engine with 25% less displacement! And those engines have very small bores and long strokes. If that thing was even square, it would be much bigger.
I never said OHC was "too" complex; I said it was "more" complex.
All things equal, BSFC is worse with DOHC, which is what I said if you read the fine print. "4 valves... (assuming it requires OHC) "
Originally Posted by treyZ28
While the output potential of the 4 valve over the 2 valve cant be argued, its output in application can. 4 valves require more space, more money, more complexity, more cost, more weight and provide a lower efficiency (BSFC).
Given the same space, weight, cost and BSFC requirements; 4 valves are not always more powerful (assuming it requires OHC). If a bigger engine fits in an engine bay, the engine bay was too big.
Given the same space, weight, cost and BSFC requirements; 4 valves are not always more powerful (assuming it requires OHC). If a bigger engine fits in an engine bay, the engine bay was too big.
Originally Posted by RussStang
Do you have a source for your claim that OHC came first? I am not saying it didn't, but I would like to see some evidence.
I'm really just making fun of that whole "old-vs-new" argument anyway. I don't care which is older or newer, just how they work.
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Originally Posted by black_knight
I don't recall the source, but consider the fact that V-type engines weren't developed until some decades after the invention of the internal combustion engine.
I'm really just making fun of that whole "old-vs-new" argument anyway. I don't care which is older or newer, just how they work.
I'm really just making fun of that whole "old-vs-new" argument anyway. I don't care which is older or newer, just how they work.
Originally Posted by treyZ28
not to mention, they are both old as dirt. who cares which dirt is older?
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ok i have a question, why is GM doing this?? what do they intend to use this engine in?? why didn't thye just use the LS7 in a detuned version??
also on a more technical note what do you guys think GM could get out of the LS7 heads in term of flow?? are they at their limits now as far as a production unit is concerned??
just trying to figure what tempted GM to push with these heads.
thanks guys.
Chris.
also on a more technical note what do you guys think GM could get out of the LS7 heads in term of flow?? are they at their limits now as far as a production unit is concerned??
just trying to figure what tempted GM to push with these heads.
thanks guys.
Chris.
Originally Posted by chuntington101
ok i have a question, why is GM doing this?? what do they intend to use this engine in?? why didn't thye just use the LS7 in a detuned version??
Launching!
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From: Exton, Pennsylvania
Originally Posted by black_knight
I don't recall the source, but consider the fact that V-type engines weren't developed until some decades after the invention of the internal combustion engine.
I'm really just making fun of that whole "old-vs-new" argument anyway. I don't care which is older or newer, just how they work.
I'm really just making fun of that whole "old-vs-new" argument anyway. I don't care which is older or newer, just how they work.
Launching!
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From: Exton, Pennsylvania
Originally Posted by black_knight
Or, more importantly, what meaning does the term "advanced" have apart from the attributes of the engine itself (i.e. size, weight, cost, power, etc). Oh, and HP/L is for morons.