Ebay cheap headers question
10-24-19, 01:25 PM
#1
Ebay cheap headers question
Hey guys I want to ask about some cheap headers I saw on eBay (sorry I don't know how to saw you the link).The price is just 100 $ and I want to ask if anyone has install those.Acording to Mr Paul from PPE and RRracing review the PPE headers don't give any gains at all to a supercharged IS like mines and I m thinking that the only think I want to do is free the OEM manifolds from the restrictive cats so the cheap ones could do the same job wright?They have short tubes not like the PPE ones and I contacted them but they told me that these headers are not made for supercharged IS .PPE headers for NA IS and supercharged are the same so I don't understand the diference.A help from exchast guru s will be much apreciated.
Thank you
Thank you
10-24-19, 03:54 PM
#2
How would PPE headers not help? That doesn’t seem right.
10-25-19, 07:07 AM
#3
The OEM log style manifold is OK up to a point but at higher RPMs the back pressure increases in the log and cat hurting performance. Read on.
Long tube primaries into long tube collectors help the bottom and mid-range while shorter collectors are better suited for high rpms.
The key take away is smooth transitions and/bends bends take away less heat and maintain exhaust gas velocity while sharp angles like those in the OEM manifold create back pressure.
In the ideal world the primaries are grouped in pairs by firing order so the departimg gasses help scavenge pulls the combustion gases along as they dump into the collector. Our chassis does not allow headers to be configured in the most beneficial manner as we can't pair cylinder 1 and 2 or 3 and 4 as they reside on opposite sides of the block.
Mind you this is where *equal length primaries* matter. When firing order is paired so the cylinder can extract combustion gasses in order by volume. If we had an I4 with all exhaust ports on one side, great. A huge win with equal length but We Don't so equal length primaries don't do **** for us. Here is where less bends is better. A smooth radius is better than equal length.
On the forced side of things exhaust bends matter even less as you are pumping the cylinder full of the air fuel mixture and spent gasses left in the combustion chamber get pushed out regardless of pipe bends and equal length.
So, if the $100 headers have form, fit, and durability = win! Use them! If the N/A guys extend the collectors 16 in or so, they would likely work fine for them too. Just saying all this talk about equal length is crap for our cause and its why some don't report gains.
Last thing. For SS 304 it only needs to contain about 9% chromium (think anti rust part) to qualify as SS304 while the rest of the material is whatever blend of steel (iron ore) they throw in there. Point is just because it says SS it can still rust until the chromium content goes higher.
Long tube primaries into long tube collectors help the bottom and mid-range while shorter collectors are better suited for high rpms.
The key take away is smooth transitions and/bends bends take away less heat and maintain exhaust gas velocity while sharp angles like those in the OEM manifold create back pressure.
In the ideal world the primaries are grouped in pairs by firing order so the departimg gasses help scavenge pulls the combustion gases along as they dump into the collector. Our chassis does not allow headers to be configured in the most beneficial manner as we can't pair cylinder 1 and 2 or 3 and 4 as they reside on opposite sides of the block.
Mind you this is where *equal length primaries* matter. When firing order is paired so the cylinder can extract combustion gasses in order by volume. If we had an I4 with all exhaust ports on one side, great. A huge win with equal length but We Don't so equal length primaries don't do **** for us. Here is where less bends is better. A smooth radius is better than equal length.
On the forced side of things exhaust bends matter even less as you are pumping the cylinder full of the air fuel mixture and spent gasses left in the combustion chamber get pushed out regardless of pipe bends and equal length.
So, if the $100 headers have form, fit, and durability = win! Use them! If the N/A guys extend the collectors 16 in or so, they would likely work fine for them too. Just saying all this talk about equal length is crap for our cause and its why some don't report gains.
Last thing. For SS 304 it only needs to contain about 9% chromium (think anti rust part) to qualify as SS304 while the rest of the material is whatever blend of steel (iron ore) they throw in there. Point is just because it says SS it can still rust until the chromium content goes higher.
10-25-19, 11:37 AM
#4
Thank you for the reply.I just want to get rid of the primary cats.Thats what mr Paul from PPE advised me to do also.
The cheap headers from eBay are short.You have a lot of knowledge about exchast .I m not sure if I will buy them.I just wanted to ask another opinion.I don't want to much noise also.
The cheap headers from eBay are short.You have a lot of knowledge about exchast .I m not sure if I will buy them.I just wanted to ask another opinion.I don't want to much noise also.
10-25-19, 02:05 PM
#5
You could retain your existing exhaust manifold and just break the catalytic converter material out of the manifold. It is easy to do
and should take less than an hour with a hammer and long pry bar. Its done often in the ISF community as a cheap alternative
to $1800 headers.
and should take less than an hour with a hammer and long pry bar. Its done often in the ISF community as a cheap alternative
to $1800 headers.
10-26-19, 10:34 AM
#6
Thank you for the reply.I just want to get rid of the primary cats. Thats what mr Paul from PPE advised me to do also.
The cheap headers from eBay are short.You have a lot of knowledge about exhast .I m not sure if I will buy them.I just wanted to ask another opinion.I don't want to much noise also.
The cheap headers from eBay are short.You have a lot of knowledge about exhast .I m not sure if I will buy them.I just wanted to ask another opinion.I don't want to much noise also.
This still have secondary cats?
You could retain your existing exhaust manifold and just break the catalytic converter material out of the manifold. It is easy to do
and should take less than an hour with a hammer and long pry bar. Its done often in the ISF community as a cheap alternative
to $1800 headers.
and should take less than an hour with a hammer and long pry bar. Its done often in the ISF community as a cheap alternative
to $1800 headers.
10-26-19, 11:51 AM
#7
Thank you for the reply guys.No I haven't the secondary cats on 2013Fsport.I actually don't believe in power gains from the exhast(gains that you can actually see on the street not imagine because of the noise like most people do).My buddy Elias was the first who bought JUN-TW full exhast which claimed gains up to 34hp.He bought it for 6000$ and he thought that the car was faster but when we tested the cars (mine was completely stock then) half fender in front and he couldn't believe it.I ve spend a lot of money on my car but I think that they worth it.After I saw RRracing saying that the PPE headers didn't gain anything to the 2IS and mr Paul himself (and a big thanks for his honesty)adviced me to get rid of the OEM manifold cats I m thinking that I don't want to spend so much for headers.
Perhaps I m wrong but I believe that if I delete the primary cats and leave the rest of the exhast OEM with no cats at all the gains will be the same to someone who has PPE headers and full exhast.
Perhaps I m wrong but I believe that if I delete the primary cats and leave the rest of the exhast OEM with no cats at all the gains will be the same to someone who has PPE headers and full exhast.
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10-27-19, 10:34 AM
#8
I was disappointed in the lack of gains from headers on my car, I had no measurable increase in peak maf readings and I swear the midrange felt weaker. I did however have quite noticable gains by switching over to a dual 2.5" exhaust. I'd have to go back and check but going with a larger diameter exhaust might have given me the largest gains over any thing else.
If you want more power, why not just do a pulley swap?
If you want more power, why not just do a pulley swap?
10-27-19, 01:32 PM
#9
I was disappointed in the lack of gains from headers on my car, I had no measurable increase in peak maf readings and I swear the midrange felt weaker. I did however have quite noticable gains by switching over to a dual 2.5" exhaust. I'd have to go back and check but going with a larger diameter exhaust might have given me the largest gains over any thing else.
If you want more power, why not just do a pulley swap?
If you want more power, why not just do a pulley swap?
My first thought was to buy headers as the price is way better. Rather than buying one expensive cat from the dealer. I've had good luck with aftermarket cats on my old GS400.
I'd rather buy aftermarket than headers for the reason that they will probably crack over time, and cost more in the end to add cats for smog testing yearly.
If the header gains are marginal then I'll stick with stock setup for now, and get a custom mid pipe done down the road.
10-27-19, 03:20 PM
#10
I did change the pulley to a very small one and manage to raise boost from 0.4 to 0.5 bar.The procharger C2 is a small supercharger as i understand now so i cant do much about performance except switch to a Rotrex.The file i have now on the car from OV is lean at high RPMs and i m waiting for a new one.The guy from the dyno advised me to change all the exhast and i ll see great gains but i doubt it.I just thought of these headers just to get rid of the primary cats.
10-28-19, 09:21 AM
#11
Here is what we have found over the years testing headers on supercharged motors. In general, just bolting on headers to a supercharged motor with no other changes, will make less difference than bolting them onto an NA motor.
when adding headers to a supercharged motor, the major concerns are.
1. removing the catalytic converters
2. increasing flow with larger runners/collector
On this application, equal length runners make less of a difference as scavenging is less important when the exhaust is pressurized.
Tube length will still play a roll in the power band. You will still get more midrange power with the longer runners, more high rpm power with the shorter runners.
We have made IS350 headers with larger outlets for some customers in the past. I don't have dyno data showing the difference though. We have made them with 2.5" outlets instead of the 54mm OEM size outlet which they matched up to a 2.5" cat-back. It is also possible to increase the runner diameters to increase flow even more if running a lot of boost. Only testing would tell if this would be advantageous or not.
We have seen on the Nissan VQ37VHR motors that bolting on headers and retuning will produce the same power at a lower boost pressure. After changing the pulley size to increase the boost back to where it was, more power is made. So additional changes had to be made to take full advantage of the headers' increased flow.
when adding headers to a supercharged motor, the major concerns are.
1. removing the catalytic converters
2. increasing flow with larger runners/collector
On this application, equal length runners make less of a difference as scavenging is less important when the exhaust is pressurized.
Tube length will still play a roll in the power band. You will still get more midrange power with the longer runners, more high rpm power with the shorter runners.
We have made IS350 headers with larger outlets for some customers in the past. I don't have dyno data showing the difference though. We have made them with 2.5" outlets instead of the 54mm OEM size outlet which they matched up to a 2.5" cat-back. It is also possible to increase the runner diameters to increase flow even more if running a lot of boost. Only testing would tell if this would be advantageous or not.
We have seen on the Nissan VQ37VHR motors that bolting on headers and retuning will produce the same power at a lower boost pressure. After changing the pulley size to increase the boost back to where it was, more power is made. So additional changes had to be made to take full advantage of the headers' increased flow.
10-28-19, 11:50 AM
#12
Intermediate
The Ebay headers are clones of the Megan headers. When the clones showed up, it seems Megan stopped making them, which is why the "de-smoggers" or HFCs for this mid-length-style seems so easy to get, until you start looking for them. I got a set of un-installed Megans years ago and ran into the cat-less problem, so I never installed them. Will be hacking down a set of used Berk HFCs from a '10 G37S and giving them the flanges I need to mate to my Ebay special midpipe (godsnow, IIRC, the box is in my shed still, if anyone wants part #s) then will be running the factory axle-back because it's easier than fabbing a mud shield for inside the rear bumper cover. Also the chinesium mufflers are fairly ricey.
In a static-cam world, the longer the primary tubes, the more radical of duration and lobe separation angle you can get away with. Separating each cylinders' intake and exhaust paths for as long as possible, and keeping their energies relatively equal throughout the length, is why you see crazy-long 32" primaries on side-piped C2/C3 corvettes with straight-up ignorant cam profiles. Also why you see zoomie headers in the racing classes that allow them. No backpressure is good backpressure, the only exhaust anyone "needs" is a few inches of header primary to keep oxygen away from the bowl area so you don't blowtorch the seats. Beyond that, your exhaust is sacrificing power for other gains, like moving sound, heat, and fumes away from you.
In a dynamic camshaft profile world, the volume of air being moved with each stroke is changing significantly more dynamically than just atmospheric inertia does in the static-cam world. While there's significantly fewer dynamic cam examples for me to gather from, it seems that primary length isn't as critical as with a static-cam, but the volume of the primaries still is...which kinda makes sense to me, since the dynamic cam's able to optimize scavenging and minimize short-circuiting. The latter being more productive than the former, magazine articles selling you stuff be damned.
I mean, a stepped long-tube primary like PPE's is generally always going to be "better". The crazier your cams get, the more better it'll be. We can grind something around 20mm of lift into our cam geometry, by just changing base circle and valve length. While most of us, right now, will probably be happier with some chinesium headers and a couple hundred extra bucks to spare, if someone adds lift and duration to their cam profile, the PPE's will start showing their value to those who balk at their price by making up power that couldn't be found elsewhere.
In a static-cam world, the longer the primary tubes, the more radical of duration and lobe separation angle you can get away with. Separating each cylinders' intake and exhaust paths for as long as possible, and keeping their energies relatively equal throughout the length, is why you see crazy-long 32" primaries on side-piped C2/C3 corvettes with straight-up ignorant cam profiles. Also why you see zoomie headers in the racing classes that allow them. No backpressure is good backpressure, the only exhaust anyone "needs" is a few inches of header primary to keep oxygen away from the bowl area so you don't blowtorch the seats. Beyond that, your exhaust is sacrificing power for other gains, like moving sound, heat, and fumes away from you.
In a dynamic camshaft profile world, the volume of air being moved with each stroke is changing significantly more dynamically than just atmospheric inertia does in the static-cam world. While there's significantly fewer dynamic cam examples for me to gather from, it seems that primary length isn't as critical as with a static-cam, but the volume of the primaries still is...which kinda makes sense to me, since the dynamic cam's able to optimize scavenging and minimize short-circuiting. The latter being more productive than the former, magazine articles selling you stuff be damned.
I mean, a stepped long-tube primary like PPE's is generally always going to be "better". The crazier your cams get, the more better it'll be. We can grind something around 20mm of lift into our cam geometry, by just changing base circle and valve length. While most of us, right now, will probably be happier with some chinesium headers and a couple hundred extra bucks to spare, if someone adds lift and duration to their cam profile, the PPE's will start showing their value to those who balk at their price by making up power that couldn't be found elsewhere.
10-28-19, 12:27 PM
#14
This is the link from eBay seller guys.I really respect PPE for his honest reply and I m sure their headers are the best in the market.I just can't afford it right now and I m looking for other alternatives although I haven't decided yet what I should do.Perhaps headers and leave the rest of the exhast OEM so that it won't get to loud!
10-28-19, 12:31 PM
#15
Intermediate
This is a Megan header that got hit with hi-temp black years ago. It's effectively the same as the ebay specials in function, and, IMO, is all any of us need until we start swapping stuff that spins fast.. then we have PPE ahead of the game to go to.