I have a pacesetter header on my car right now that im planning on taking off sometime in the next week to paint. Is it worth trying to p&p the header and ports while i have it off?
I would venture to say no not worth it. Especially being n/a
~2014 New Z under the knife, same heart different body~
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2012 numbers - 4SPD AUTOMATIC!!
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Portmatching the header couldn't hurt although a ported head would help reap the rewards.
Portmatching the head and header wouldnt be a bad idea. But a P&P on a header??? Can you clarify exactly what you wanna do??
Sorry, i meant port matching and possibly a slight polishing of the ports.
So a few of you said that port matching wouldn't be a bad idea, is this going to be a noticeable gain or a fraction of a hp?
Most people willing to port match their header have gotten a ported head as well...
I was thinking about getting a spare head and do a good polish and maybe a small port job on it. Hopefully getting everything to flow alittle better.
dont port match the exhaust the exh runner port bust be atleast 1/32 smaller the header in order for your engine to run properly so no gas will come back into the engine this allows proper afr and the armour coat on pace setter headers burns and looks like crap on the header and when u put the int/exh manifold back onto the head they dont line up exactly to the port meassure and scribe an out line of the manifolds to the ports ridges create walls and will cost u power
Are you kidding me?
Technically, better flow means more more velocity in the same volume. More velocity means more exhaust scavenging. So LESS would get back to the engine.
are u forggeting that all engines produce back pressure and that u need it to make hp if u eliminate that u might as well getout and push your car
How do you come up with 1/32?
im not a machinist i just talk in redneck terms us canadiens only drink beer and fish were the beavers are ehhhh head port must be smaller than the manifold entrance in um yah just smile and nod
also the armour coat on pace setter headers burns and looks like crap if u dont remove it
I was feeling generous, so I looked up anti-reversion headers for you all.
Quote:
ANTI-REVERSION HEADERS
In our page on cylinder head porting, Henry (aka Double H) explains that the primary pipes in the exhaust manifold should match the exhaust port diameter on the cylinder head; but to reduce reversion, a primary pipe that is slightly larger than the exhaust port is better. Reversion is the flow of exhaust gasses back into the combustion chamber when the downward movement of the piston creates a vacuum in the cylinder. As we mentioned in engine tuning basics, the exhaust valves are still open when the intake stroke begins. This presents the potential for exhaust gasses to be drawn back into the combustion chamber when the piston moves down the cylinder. Any exhaust gases that are drawn into the combustion chamber will displace the air/fuel mixture being drawn in through the intakes valves and will increase the temperature in the combustion chamber, thus reducing the volumetric efficiency of the engine, as well as engine power. Preventing reversion will reduce the contamination of the air/fuel mixture by the spent exhaust gasses and will improve the efficiency of the engine. An anti-reversion header or AR header that is specifically designed to inhibit reversion would be your best choice. Anti-reversion headers have a built-in lip that restricts exhaust gas flow back into the combustion chamber.
if the primaries are larger than the exhaust ports, you get an anti-reversion effect... which is good
I would not modify a header to eliminate that feature.
to add to the above post, since a header would have to be slightly larger than the exhaust port in order to get the proper anti-reversion effect, you can't "modify a header to eliminate that feature" so yea chalk it up to being up late and tired... the header primary should be slightly larger than the port in order to guarantee anti-reversion.
Zach Reliford wrote:Are you kidding me?
Technically, better flow means more more velocity in the same volume. More velocity means more exhaust scavenging. So LESS would get back to the engine.
think of exhaust flow as a choo-choo. it puffs along, not in a steady stream.
if the piston moving up pushes exhaust out on the exhaust stroke, as the piston begins moving back down for the intake stroke the exhaust valve is still open. that means the pressure drop thats experienced by the intake manifold is also experienced by the exhaust manifold and guess what... all that sh!t you pumped out of the chamber will reverse flow while the exhaust valve is open, and like i quoted above, displace the incoming fresh air/fuel mixture.
The primary being slightly larger than the exhaust port provides an aerodynamic barrier that helps to prevent this from happening.
