1 3/4ths or 1 7/8th headers for my setup
03-23-2016, 10:41 PM
#41
1 3/4ths or 1 7/8th headers for my setup I just did.the switch and the car has lost nothing......if anything it feels stronger down low and all through the rpm band. The guy posting is referring to Internet myth like another poster said for every 2 that lost power there is 20 that gained.
Last edited by Chris25; 03-23-2016 at 10:49 PM.
03-24-2016, 01:06 PM
#44
Corvette's are a different story altogether.
There's a lot being missed here. For an FBody, I'd go 1 7/8" all day, every day. The designs are all pretty much the same. 1 7/8" is a no brainer.
Now look at the Vette. Some have super long primaries (LG, Pfadt) while others are shorter (ARH). Primary length dictates a lot, as does EXHAUST VALVE SIZE, and nobody seems to mention that.
There is some science to it, but at the end of the day, most of us aren't trying to fry tires from a stoplight, we want to go fast ABOVE 3500 rpm, which is really where most cams of any significance start to build steam.
There's a lot being missed here. For an FBody, I'd go 1 7/8" all day, every day. The designs are all pretty much the same. 1 7/8" is a no brainer.
Now look at the Vette. Some have super long primaries (LG, Pfadt) while others are shorter (ARH). Primary length dictates a lot, as does EXHAUST VALVE SIZE, and nobody seems to mention that.
There is some science to it, but at the end of the day, most of us aren't trying to fry tires from a stoplight, we want to go fast ABOVE 3500 rpm, which is really where most cams of any significance start to build steam.
03-24-2016, 02:10 PM
#45
Corvette's are a different story altogether.
There's a lot being missed here. For an FBody, I'd go 1 7/8" all day, every day. The designs are all pretty much the same. 1 7/8" is a no brainer.
Now look at the Vette. Some have super long primaries (LG, Pfadt) while others are shorter (ARH). Primary length dictates a lot, as does EXHAUST VALVE SIZE, and nobody seems to mention that.
There is some science to it, but at the end of the day, most of us aren't trying to fry tires from a stoplight, we want to go fast ABOVE 3500 rpm, which is really where most cams of any significance start to build steam.
There's a lot being missed here. For an FBody, I'd go 1 7/8" all day, every day. The designs are all pretty much the same. 1 7/8" is a no brainer.
Now look at the Vette. Some have super long primaries (LG, Pfadt) while others are shorter (ARH). Primary length dictates a lot, as does EXHAUST VALVE SIZE, and nobody seems to mention that.
There is some science to it, but at the end of the day, most of us aren't trying to fry tires from a stoplight, we want to go fast ABOVE 3500 rpm, which is really where most cams of any significance start to build steam.
But i'm in it for the tire frying extravaganza's.
The gas...... more than makes up for the loss up top I may see with the smaller tubing.
Collector and back are where real power gains come from in this fbody world!
03-25-2016, 09:34 AM
#47
The smaller tube creates a scavaging process that works very well in my combination.
You said it yourself the vette platform is a totally different animal? Why? Do to the fact of what?
Collector design?
True dual?
Exhaust port velocity?
Exhaust port size?
I'd love to hear your thoughts.....you seem pretty sharp.
Old saying goes "It's not so much of what you say it's how you say it"
03-30-2016, 11:45 PM
#54
Staging Lane
Wow that went on for a while but since I’m new to the LS I’m going to jump in anyway! I just bought an LS3 376/525 GMPP crate engine/trans package. Heard some talk and by looking at the flow numbers it seems the L-92 exhaust ports are pretty weak! I think this is why header choice “could” be very important for these heads!
However I’m not really that concerned about a few pounds of low end torque because I only have about 2300 pounds to move! On the other hand I’m not concerned about a few top-end hp because I only have about 2300 pounds to move! If, if I return to my sin full ways I have an App for that, well I guess it’s a NOS button!
My little Cobra Kit Car has been down for over a year and I can’t wait to get it on the road with LS power! I WILL be cruising this summer! My plan right now is to use the stock manifolds and plumb them into my current side pipes, 3” id. Not worrying about header size until I put it up for the winter, by then I should have a better idea! The problem is we got to build them! These are my current SBC headers 1 ¾” to 1 7/8 to 3 ½ collectors and 3” id Cherry-Bombs! It was a little loud but sounded pretty good!
However I’m not really that concerned about a few pounds of low end torque because I only have about 2300 pounds to move! On the other hand I’m not concerned about a few top-end hp because I only have about 2300 pounds to move! If, if I return to my sin full ways I have an App for that, well I guess it’s a NOS button!
My little Cobra Kit Car has been down for over a year and I can’t wait to get it on the road with LS power! I WILL be cruising this summer! My plan right now is to use the stock manifolds and plumb them into my current side pipes, 3” id. Not worrying about header size until I put it up for the winter, by then I should have a better idea! The problem is we got to build them! These are my current SBC headers 1 ¾” to 1 7/8 to 3 ½ collectors and 3” id Cherry-Bombs! It was a little loud but sounded pretty good!
03-31-2016, 04:46 PM
#55
Wow that went on for a while but since I’m new to the LS I’m going to jump in anyway! I just bought an LS3 376/525 GMPP crate engine/trans package. Heard some talk and by looking at the flow numbers it seems the L-92 exhaust ports are pretty weak! I think this is why header choice “could” be very important for these heads!
However I’m not really that concerned about a few pounds of low end torque because I only have about 2300 pounds to move! On the other hand I’m not concerned about a few top-end hp because I only have about 2300 pounds to move! If, if I return to my sin full ways I have an App for that, well I guess it’s a NOS button!
My little Cobra Kit Car has been down for over a year and I can’t wait to get it on the road with LS power! I WILL be cruising this summer! My plan right now is to use the stock manifolds and plumb them into my current side pipes, 3” id. Not worrying about header size until I put it up for the winter, by then I should have a better idea! The problem is we got to build them! These are my current SBC headers 1 ¾” to 1 7/8 to 3 ½ collectors and 3” id Cherry-Bombs! It was a little loud but sounded pretty good!
However I’m not really that concerned about a few pounds of low end torque because I only have about 2300 pounds to move! On the other hand I’m not concerned about a few top-end hp because I only have about 2300 pounds to move! If, if I return to my sin full ways I have an App for that, well I guess it’s a NOS button!
My little Cobra Kit Car has been down for over a year and I can’t wait to get it on the road with LS power! I WILL be cruising this summer! My plan right now is to use the stock manifolds and plumb them into my current side pipes, 3” id. Not worrying about header size until I put it up for the winter, by then I should have a better idea! The problem is we got to build them! These are my current SBC headers 1 ¾” to 1 7/8 to 3 ½ collectors and 3” id Cherry-Bombs! It was a little loud but sounded pretty good!
If you're thinking about keeping stock manifolds, you would REALLY be surprised at just how well the factory (stainless) LS7 manifolds flow.
03-31-2016, 08:20 PM
#57
11 Second Club
One thing that keeps coming to mind, about losing tq from 1 3/4 to 1 7/8, is a post from a well known man. Tony Mamo stated, while doing a back to back header swap, that there was a tq drop at lower/mid rpm. Stating there was a trade off for better high rpm power of the 1 7/8.
03-31-2016, 08:34 PM
#58
Staging Lane
As with most "systems" it's not about just one thing it's about the "sum" of all things and how well they function together! And of course it's intended use is a big part of the system! A heavy tow rig is going to have a very different set of requirements from a feather weight 1/4 mile blaster! Most of us are somewhere in between and must find the best compromise! Mine is Fun Factor vs. Maintenance!
04-01-2016, 08:12 PM
#59
One thing that keeps coming to mind, about losing tq from 1 3/4 to 1 7/8, is a post from a well known man. Tony Mamo stated, while doing a back to back header swap, that there was a tq drop at lower/mid rpm. Stating there was a trade off for better high rpm power of the 1 7/8.
The smaller tube looked better under 4K....tied to 4500.....after that the larger 1.875 started climbing.....more peak TQ and it naturally carried better past peak (8 RWHP in this particular test).
Unless your road racing, a 1.875 tube will usually provide the most average power but like cams, there is usually a trade off when discussing primary tube diameters....not so much so on larger engines though.....a bigger motor might want the bigger tube almost everywhere. I didn't read how big the OP's shortblock is but what I said above holds true for a 383 and smaller motor. If its larger than that you really should be in a 1.875 anyway
Hope this helps!
-Tony
__________________
www.mamomotorsports.com
Tony@MamoMotorsports.com
Anything worth doing is worth doing well. Build it right the first time....its alot cheaper than building it twice!!
www.mamomotorsports.com
Tony@MamoMotorsports.com
Anything worth doing is worth doing well. Build it right the first time....its alot cheaper than building it twice!!
04-01-2016, 08:15 PM
#60
Allow me to elaborate further....
The smaller tube looked better under 4K....tied to 4500.....after that the larger 1.875 started climbing.....more peak TQ and it naturally carried better past peak (8 RWHP in this particular test).
Unless your road racing, a 1.875 tube will usually provide the most average power but like cams, there is usually a trade off when discussing primary tube diameters....not so much so on larger engines though.....a bigger motor might want the bigger tube almost everywhere. I didn't read how big the OP's shortblock is but what I said above holds true for a 383 and smaller motor. If its larger than that you really should be in a 1.875 anyway
Hope this helps!
-Tony
The smaller tube looked better under 4K....tied to 4500.....after that the larger 1.875 started climbing.....more peak TQ and it naturally carried better past peak (8 RWHP in this particular test).
Unless your road racing, a 1.875 tube will usually provide the most average power but like cams, there is usually a trade off when discussing primary tube diameters....not so much so on larger engines though.....a bigger motor might want the bigger tube almost everywhere. I didn't read how big the OP's shortblock is but what I said above holds true for a 383 and smaller motor. If its larger than that you really should be in a 1.875 anyway
Hope this helps!
-Tony
Thank You for posting that, you the Man!