I will be putting Tri-Y headers on this, with 2 or 2.25" exhaust, I am porting/rebuilding the head.
If I leave the intake manifold the way it is, the rest will have been done for nothing.
I cannot explain the reasoning for wanting to do it other than "feeling" that I do not have enough air, having driven this car hard for 6 months.
Okay, sure, maybe it has more to do with unmetered air entering the system due to vacuum or gasket leaks, but that is being addressed as well.
These mods have been dyno tested, and others seem to agree, from what I read, and I have been researching what to do to this car for a year.
If I eliminate any potential leak with new gaskets and seals, I will not have any unmetered air entering the system. That is what makes CIS problematic.
The air sensor plate controls the volume of fuel being sent to the injectors. If air leaks get in, it does not raise as much, thus less fuel is delivered.
When the large port on the TB is opened, more air can flow into the engine, lifting the sensor higher. A Big Bore TB allows more air in the combustion chamber, burning fuel more completely.
The shock wave of the explosion in the engine sends out waves of pressure. These bounce back and forth in the exhaust manifold, and on Rabbits, this is a bit of a problem.
Headers remove the gases in balanced length tubes, one from each cylinder, and expel them more efficiently.
Again, this is just what I have read, and many sources say the same thing.
I believe these 1.8 engines can do a lot more by breathing easier.
What is supercharging or turbo? Forcing air into the engine.
My car is NA, naturally aspirated. I just want to give it some ability to get metered air more efficiently.
I love these old VW's, I just want to do an old car justice. And, for me to want to drive it, I need just a little bit more out of it.
I am starting with the engine, exhaust and fuel because there is no point in ANYTHING cosmetic until it is driving properly. When it runs right, that is the time to think about new seats or whatever.
Your technical advice has been appreciated! I welcome all opinions!