Cam and valvetrain longevity....??? low duration high lift...
09-19-2016, 04:57 PM
#171
Registered
Okay, did a work around to edit above.
I just figured out that the posts I can't edit are one's I have two sets of quotes in.
edit in:
Intake Duration at 050 inch Lift: 244
Exhaust Duration at 050 inch Lift: 256
Duration at 050 inch Lift: 244 int./256 exh.
Advertised Intake Duration: 306
Advertised Exhaust Duration: 318
Advertised Duration: 306 int./318 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.632 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.632 in.
Valve Lift with Factory Rocker Arm Ratio: 0.632 int./0.632 exh.
Lobe Separation (degrees): 114
I just figured out that the posts I can't edit are one's I have two sets of quotes in.
edit in:
Intake Duration at 050 inch Lift: 244
Exhaust Duration at 050 inch Lift: 256
Duration at 050 inch Lift: 244 int./256 exh.
Advertised Intake Duration: 306
Advertised Exhaust Duration: 318
Advertised Duration: 306 int./318 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.632 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.632 in.
Valve Lift with Factory Rocker Arm Ratio: 0.632 int./0.632 exh.
Lobe Separation (degrees): 114
Last edited by SB; 09-19-2016 at 05:02 PM.
09-19-2016, 05:20 PM
#172
Registered
Tim posted a question on facebook, asking if anyone ever dynoed with dry race style dyno headers, vs wet marine exhaust back to back. A guy replied with these sheets. His "wet" exhaust, was stainless marine wet manifolds.
At 3500RPM, the wet exhaust gave up 36 ft lbs of torque.
At 5100RPM, the wet exhaust gave up 39 horsepower.
For some reason, we argue over 10cc on intake runner volumes, 1/2 point of static compression, a couple degrees of cam duration, 100cfm of carb airflow. Everyone is so scared to add duration to a camshaft, worried that it will lose too much torque down low. Everyone is scared to be a few cc to large on an intake runner, fearing a loss of torque. We'll spend thousands on CNC ported heads, custom roller cams, and all kinds of stuff to make more HP and torque. But when the exhaust subject comes up, there's crickets. Seems like everyone has the mindset, that headers and good exhaust, is only for top end power. For the past 50 years, one of the best , simplest, and most effective mods, to almost any hot engine, heck, even a 454 in a motorhome, was a set of free flowing headers, and see torque gains.
I've seen quite a few engines come off the dyno, and need major jet changes, because the engines were installed with wet exhaust manifolds, when they were originally tuned on the dyno with 2.25 ID race car headers. Just water in the pipes alone, can be a big restriction. The average marine manifold has 3.5" inner pipe. Then you dump huge volume of water in that 3.5" pipe, and that pipe diameter becomes even smaller, as well as the water hindering airflow. I really don't see a good reason these days, to be running a wet performance exhaust. There's plenty of sound solutions that can keep the noise down. Not only is wet exhaust a hinderance on power, its also the limiting factor on camshaft choice. My tails are dry until the end. I have gaffrig air operated mufflers on them. At idle, theres water dumping into the muffler, and even with the mufflers open, its not too loud. Close them, and my 800hp engines sound like 330's with wet merc exhaust. At WOT, I have about 4 inches of the 4.5" pipe where water is entering. Basically, the back half of the mufflers see water. They don't get hot.
I think we should line up a few exhaust systems, and use full forces engines as test mules.
At 3500RPM, the wet exhaust gave up 36 ft lbs of torque.
At 5100RPM, the wet exhaust gave up 39 horsepower.
For some reason, we argue over 10cc on intake runner volumes, 1/2 point of static compression, a couple degrees of cam duration, 100cfm of carb airflow. Everyone is so scared to add duration to a camshaft, worried that it will lose too much torque down low. Everyone is scared to be a few cc to large on an intake runner, fearing a loss of torque. We'll spend thousands on CNC ported heads, custom roller cams, and all kinds of stuff to make more HP and torque. But when the exhaust subject comes up, there's crickets. Seems like everyone has the mindset, that headers and good exhaust, is only for top end power. For the past 50 years, one of the best , simplest, and most effective mods, to almost any hot engine, heck, even a 454 in a motorhome, was a set of free flowing headers, and see torque gains.
I've seen quite a few engines come off the dyno, and need major jet changes, because the engines were installed with wet exhaust manifolds, when they were originally tuned on the dyno with 2.25 ID race car headers. Just water in the pipes alone, can be a big restriction. The average marine manifold has 3.5" inner pipe. Then you dump huge volume of water in that 3.5" pipe, and that pipe diameter becomes even smaller, as well as the water hindering airflow. I really don't see a good reason these days, to be running a wet performance exhaust. There's plenty of sound solutions that can keep the noise down. Not only is wet exhaust a hinderance on power, its also the limiting factor on camshaft choice. My tails are dry until the end. I have gaffrig air operated mufflers on them. At idle, theres water dumping into the muffler, and even with the mufflers open, its not too loud. Close them, and my 800hp engines sound like 330's with wet merc exhaust. At WOT, I have about 4 inches of the 4.5" pipe where water is entering. Basically, the back half of the mufflers see water. They don't get hot.
I think we should line up a few exhaust systems, and use full forces engines as test mules.
09-19-2016, 05:32 PM
#174
Registered
For an off the shelf cam, they work very well. With that being said, it basically is a supercharger /nitrous cam. If I were building a N/A 540, with good exhaust, good cylinder heads, it wouldn't be my pick of cams.
The 651, with 12 degrees of split, can kinda hurt the torque. It will hold on better in the upper rpm, vs say a 244/248 cam, but will more than likely give up some midrange power. Single pattern cams can make great street cams. They really build some torque. But they tend to die off in the upper rpms, as the blowdown phase is simply not as good. Works great with a blower, when you need that extra time to evacuate the cylinder.
With that being said, that 651 cam, might have worked substantially better in tims build, where if in fact, his exhaust system, isn't up to par. I think you SB, had mentioned that scenerio before. You can really dial an engine combo in, when the engine has the proper designed exhaust. You can then take advantage of scavenging, overlap, and so on. But if the exhaust is crap, the cam really needs to be adjusted for it.
09-19-2016, 06:12 PM
#176
Gold Member
Gold Member
Tim posted a question on facebook, asking if anyone ever dynoed with dry race style dyno headers, vs wet marine exhaust back to back. A guy replied with these sheets. His "wet" exhaust, was stainless marine wet manifolds.
At 3500RPM, the wet exhaust gave up 36 ft lbs of torque.
At 5100RPM, the wet exhaust gave up 39 horsepower.
For some reason, we argue over 10cc on intake runner volumes, 1/2 point of static compression, a couple degrees of cam duration, 100cfm of carb airflow. Everyone is so scared to add duration to a camshaft, worried that it will lose too much torque down low. Everyone is scared to be a few cc to large on an intake runner, fearing a loss of torque. We'll spend thousands on CNC ported heads, custom roller cams, and all kinds of stuff to make more HP and torque. But when the exhaust subject comes up, there's crickets. Seems like everyone has the mindset, that headers and good exhaust, is only for top end power. For the past 50 years, one of the best , simplest, and most effective mods, to almost any hot engine, heck, even a 454 in a motorhome, was a set of free flowing headers, and see torque gains.
I've seen quite a few engines come off the dyno, and need major jet changes, because the engines were installed with wet exhaust manifolds, when they were originally tuned on the dyno with 2.25 ID race car headers. Just water in the pipes alone, can be a big restriction. The average marine manifold has 3.5" inner pipe. Then you dump huge volume of water in that 3.5" pipe, and that pipe diameter becomes even smaller, as well as the water hindering airflow. I really don't see a good reason these days, to be running a wet performance exhaust. There's plenty of sound solutions that can keep the noise down. Not only is wet exhaust a hinderance on power, its also the limiting factor on camshaft choice. My tails are dry until the end. I have gaffrig air operated mufflers on them. At idle, theres water dumping into the muffler, and even with the mufflers open, its not too loud. Close them, and my 800hp engines sound like 330's with wet merc exhaust. At WOT, I have about 4 inches of the 4.5" pipe where water is entering. Basically, the back half of the mufflers see water. They don't get hot.
I think we should line up a few exhaust systems, and use full forces engines as test mules.
At 3500RPM, the wet exhaust gave up 36 ft lbs of torque.
At 5100RPM, the wet exhaust gave up 39 horsepower.
For some reason, we argue over 10cc on intake runner volumes, 1/2 point of static compression, a couple degrees of cam duration, 100cfm of carb airflow. Everyone is so scared to add duration to a camshaft, worried that it will lose too much torque down low. Everyone is scared to be a few cc to large on an intake runner, fearing a loss of torque. We'll spend thousands on CNC ported heads, custom roller cams, and all kinds of stuff to make more HP and torque. But when the exhaust subject comes up, there's crickets. Seems like everyone has the mindset, that headers and good exhaust, is only for top end power. For the past 50 years, one of the best , simplest, and most effective mods, to almost any hot engine, heck, even a 454 in a motorhome, was a set of free flowing headers, and see torque gains.
I've seen quite a few engines come off the dyno, and need major jet changes, because the engines were installed with wet exhaust manifolds, when they were originally tuned on the dyno with 2.25 ID race car headers. Just water in the pipes alone, can be a big restriction. The average marine manifold has 3.5" inner pipe. Then you dump huge volume of water in that 3.5" pipe, and that pipe diameter becomes even smaller, as well as the water hindering airflow. I really don't see a good reason these days, to be running a wet performance exhaust. There's plenty of sound solutions that can keep the noise down. Not only is wet exhaust a hinderance on power, its also the limiting factor on camshaft choice. My tails are dry until the end. I have gaffrig air operated mufflers on them. At idle, theres water dumping into the muffler, and even with the mufflers open, its not too loud. Close them, and my 800hp engines sound like 330's with wet merc exhaust. At WOT, I have about 4 inches of the 4.5" pipe where water is entering. Basically, the back half of the mufflers see water. They don't get hot.
I think we should line up a few exhaust systems, and use full forces engines as test mules.
At some point, one has to draw the line and clearly define what compromises you are willing to make and what you will give up by doing so.
In our world, we have to decide if we are ok with losing substantial power in exchange for increased reliability and much lower cost.
09-19-2016, 06:31 PM
#177
Registered
With that being said, that 651 cam, might have worked substantially better in tims build, where if in fact, his exhaust system, isn't up to par. I think you SB, had mentioned that scenerio before. You can really dial an engine combo in, when the engine has the proper designed exhaust. You can then take advantage of scavenging, overlap, and so on. But if the exhaust is crap, the cam really needs to be adjusted for it.
Anyway, if you have a potatoe in your exhaust pipe you are just going to contaminate the combustion chamber with unburnable spent exhaust gases. Some will make it into the intake tract too. Suks. Anyway, bringing these from say a Crane type 8-10 degree spread, too a Comp Cam type 6 degree spread helped a lot. Wouldlove to try a single pattern in these, but you know how it goes....time and $$$$ stops. The two Gill exhaust deals, by the time the 2nd happened, I was pretty adimant on just replacing the Gills and getting a set of mufflers like the GGB's (straiht thru mostly) but the cam change route was taken because labor was free and the cam a lot cheaper.
On the car frt, wow do I have a lot of stories on those. Some where self induced and some where because of rules.
You can only beat your head against cement for so long, with no help from others at those times, where once you realize exhaust can be that important, you start to study and play with it more. Thus why I keep bringing up exhaust type criteria and questions.
09-19-2016, 06:39 PM
#178
Registered
MT, my Db limit is like 82 or 84dB. If someone cane prove to me a totally dry exhaust with non restrictive muffles can get even real close. I'm all ears. That could change things greatly. Won't help our speed limit law, but duck and hide + no super fast on Saturday's has all but eliminated tickets for most.
Moving is not an option so I don't want to hear anyone comment on that. Thanks.
Moving is not an option so I don't want to hear anyone comment on that. Thanks.
09-19-2016, 07:19 PM
#179
Registered
MT, my Db limit is like 82 or 84dB. If someone cane prove to me a totally dry exhaust with non restrictive muffles can get even real close. I'm all ears. That could change things greatly. Won't help our speed limit law, but duck and hide + no super fast on Saturday's has all but eliminated tickets for most.
Moving is not an option so I don't want to hear anyone comment on that. Thanks.
Moving is not an option so I don't want to hear anyone comment on that. Thanks.
09-19-2016, 07:32 PM
#180
Registered
Am I dead. Or dreaming ? Awesome !
