OEM headers restriction damage pistons/rods? (DE)
10-19-2016, 08:51 AM
#1
OEM headers restriction damage pistons/rods? (DE)
I was watching this tune video of a local tune shop that supposedly is fairly respected for tuning Z's and G's and they mentioned they highly reccomend replacing the headers due to their restriction.
Normal but what the tech focused was that with higher power, the headers on the DE's actually help blow rings and rods with these motors due to the restriction.
That and the oil temp and burning issues are the only draw backs to these motors in his eyes. But the headers kind of had me curious as to why and how..
Does anyone know anything more about what/how and why and how true this is? I know a lot of FI applications reccomend good flow headers for performance but this is the first I've ever heard of them damaging or hurting the engine in some type of way.
Normal but what the tech focused was that with higher power, the headers on the DE's actually help blow rings and rods with these motors due to the restriction.
That and the oil temp and burning issues are the only draw backs to these motors in his eyes. But the headers kind of had me curious as to why and how..
Does anyone know anything more about what/how and why and how true this is? I know a lot of FI applications reccomend good flow headers for performance but this is the first I've ever heard of them damaging or hurting the engine in some type of way.
Last edited by CK_32; 10-19-2016 at 11:23 AM.
10-19-2016, 11:00 AM
#2
Registered User
Interesting question. I myself still run the stock exhaust manifolds and HFCs on my Z with boost north of 13psi. Haven't had any issues or signs Yet of premature wear of piston rings or internals, oil consumption/burning even when I was NA.
Only restriction I believe he was talking about was the lack of exhaust scavenging because of how small the manifold runners are inside. When you are pushing boost at the mid to high rpm you need better flowing headers to help remove all the burnt up gas and fumes from the cylinders, think of it as comparing blowing air thru a drinking straw or a garden hose. They both can flow air fine under normal load, but once you blow harder on the straw ( simulating higher rpms) you start to feel lots of resistance as all that air you are trying to blow out can't leave as fast as it wants, a garden hose with a much bigger diameter can handle the demanding force to help move air better with the same effort you did with the straw with little to no resistance.
I'd love to hear any one else's answer to this. I hope I made some sence with my example.
Only restriction I believe he was talking about was the lack of exhaust scavenging because of how small the manifold runners are inside. When you are pushing boost at the mid to high rpm you need better flowing headers to help remove all the burnt up gas and fumes from the cylinders, think of it as comparing blowing air thru a drinking straw or a garden hose. They both can flow air fine under normal load, but once you blow harder on the straw ( simulating higher rpms) you start to feel lots of resistance as all that air you are trying to blow out can't leave as fast as it wants, a garden hose with a much bigger diameter can handle the demanding force to help move air better with the same effort you did with the straw with little to no resistance.
I'd love to hear any one else's answer to this. I hope I made some sence with my example.
10-24-2016, 05:19 PM
#3
350Z-holic
iTrader: (13)
^yeah...
CK - is this video public? Can you (legally) share a link?
It make sense (in my head) when you consider the engine is simply an air pump and at the end of the day you're only as efficient as the amount of air you can move in and the amount of air you can move out of your engine ...
FI forces a higher volume and a denser volume of air through the engine...if you're doing this to a exhaust system that wasnt designed for it of-course you'll get resistance and push-back.
The exhaust gas has to go somewhere ... if it can't scavenge out of the inefficient exhaust system it'll pushback into the pistons/rings...
I like the thread...interested in what others have to say...
CK - is this video public? Can you (legally) share a link?
It make sense (in my head) when you consider the engine is simply an air pump and at the end of the day you're only as efficient as the amount of air you can move in and the amount of air you can move out of your engine ...
FI forces a higher volume and a denser volume of air through the engine...if you're doing this to a exhaust system that wasnt designed for it of-course you'll get resistance and push-back.
The exhaust gas has to go somewhere ... if it can't scavenge out of the inefficient exhaust system it'll pushback into the pistons/rings...
I like the thread...interested in what others have to say...
Last edited by bealljk; 10-24-2016 at 05:21 PM.
10-26-2016, 05:53 AM
#4
Very unlikely that the headers cause piston / rod damage on these applications. One thing that needs to be remembered that in a turbocharged application the exhaust is pressurized, typically on an OE application this can be a back pressure ratio of around or exceeding 2:1 (10psi of boost, 20psi in the turbo manifold).
On a naturally aspirated application typically some back pressure in the exhaust is required top get good low and mid range power. This pressure usually will only be 1-3 psi at most however.
Neither of these will have an effect on the massive amount of cylinder pressure created when the fuel ignites in the cylinder. Typically the only downside to higher back pressure (besides lower power) would be premature valve float, which is especially a big problem on a higher power turbo application.
Usually the cause of oil burning is an ineffective piston / ring design or a poor pcv system.
On a naturally aspirated application typically some back pressure in the exhaust is required top get good low and mid range power. This pressure usually will only be 1-3 psi at most however.
Neither of these will have an effect on the massive amount of cylinder pressure created when the fuel ignites in the cylinder. Typically the only downside to higher back pressure (besides lower power) would be premature valve float, which is especially a big problem on a higher power turbo application.
Usually the cause of oil burning is an ineffective piston / ring design or a poor pcv system.
The following users liked this post:
CK_32 (10-26-2016)
10-26-2016, 08:46 AM
#5
Registered User
Very unlikely that the headers cause piston / rod damage on these applications. One thing that needs to be remembered that in a turbocharged application the exhaust is pressurized, typically on an OE application this can be a back pressure ratio of around or exceeding 2:1 (10psi of boost, 20psi in the turbo manifold).
On a naturally aspirated application typically some back pressure in the exhaust is required top get good low and mid range power. This pressure usually will only be 1-3 psi at most however.
Neither of these will have an effect on the massive amount of cylinder pressure created when the fuel ignites in the cylinder. Typically the only downside to higher back pressure (besides lower power) would be premature valve float, which is especially a big problem on a higher power turbo application.
Usually the cause of oil burning is an ineffective piston / ring design or a poor pcv system.
On a naturally aspirated application typically some back pressure in the exhaust is required top get good low and mid range power. This pressure usually will only be 1-3 psi at most however.
Neither of these will have an effect on the massive amount of cylinder pressure created when the fuel ignites in the cylinder. Typically the only downside to higher back pressure (besides lower power) would be premature valve float, which is especially a big problem on a higher power turbo application.
Usually the cause of oil burning is an ineffective piston / ring design or a poor pcv system.
10-26-2016, 11:58 AM
#6
Thank for your explanation, even though I am Supercharged I can understand how that works now in a turbo application. Since my exhaust is not directly impacted by my Vortech, my guess is that it would still fall under an NA application with maybe more than necessary back pressure with the OEM exhaust manifolds due to the linear boost delivery.