Is it advisable to:
port and polish my original intake manifold, instead of purchasing an aftermarket one. How much would it cost to get it done from a machine shop?
what other mods can be done to OEM throttle body, head, flywheel, etc…
BTW I have a 1990 RS (B18A1)
From what ive seen many people go with an aftermarket intake manifold over port and polishing, probably because some of these aftermarket manifolds have shorter and fatter runners to allow more air to enter the cylinders. Getting a port and polish will slightly open up your runners on your intake more and also provide a nice smooth surface for the air in your manifold to pass over. Is it adviseable to do, well it wouldn’t hurt to try. However, i would check around to find out how much for a port and polish and compare it to an aftermarket. I would say that you get more pep from your car with an aftermarket than a port and polish. But it all comes down to you and how much your wiling to shell out.
I would reccomend, a high flow air filter system if you haven’t done it already, which would take care of your intake. After that try to get a high flow exhaust. This will definitly help you take advantage of a higher flow intake. Especially since your enigine could now “breathe in” better you will want it to be able to “breathe out” better as well.
You mentioned mods such as a throttle body. If you can pick your self up a larger diameter throttle body this will also allow more air to enter your engine because the larger throttle body will have less of a restriction around the throttle plates to your intake manifold than a stock throttle body. It may also provide more crisp pedal resposes when accelerating.
If you are lightening your flywheel consider the type of driving conditions you will normally be driving in. A lightened flywheel will allow your engine to rev quicker because their is less force needed for your engine to turn the crankshaft. This will also allow you to reach that peak horsepower and torque easier. However, with every up side there is a downside. A lightened flywheel is great to have on the straight aways flat streatches of highway and mild hills, but if you travel often in areas where you will find yourself driving up a moderate to steep hill you will find that a lightened flywheel will cause your engine to struggle more than normal, trying to get up that hill. This is because that now that your flywheel is lightened and it is easier for your enigine to rotate it is also easier for outside forces to stop or slow the engine i.e. steep inclines. Think of it this way: objects in motion tend to stay in motion.
If say you had a 14lb flywheel mounted on a spindle and spun it as fast as you can with your hands and the tried to stop it. You would have a more difficult time trying to stop the 14lb flywheel than if you done the same to a 7lb flywheel. The idea is to match the amount of lightening to your flywheel with your everyday or most common driving conditions.
One thing i would suggest is to try to get an ignition system from MSD for example. If you can supply a stronger or longer spark to your ignition system (spark plugs), you can get a more complete combustion out of your air/fuel mixture. If you can get a more complete combustion from your air/fuel mixture than you will get more hot expanding exhaust gasses forcing down on the piston in the combustion chamber which can result in more HP.
I hope i’ve helped. Sorry if things may seem a bit muddled but i’ve got this terrible flu which is keeping me awake and its early morning where i’m to. I’ve reccently purchased a 92 integra RS, no mods just yet because I’m in college but there is something gonna happen soon if all goes well. Best of luck
Thank you for the response, it was a big help. I am looking into aftermarket manifolds as well. At the moment I have Hedman Chikara hedders, air intake, test pipe, muffler, spark plug wires. I have cut off the a/c and power steering belts for better response. I have a brand new msd-sci ignition module and coil, still not installed. What should I buy next? I need more power, so I was thing of getting a crank pulley first, but any advice is greatly appreciated. BTW how much will a VTEC head cost me with installation and what other changes do i need to make with an ls/vtec conversion. once again thanks for the help.
p.s: should i get rid of the testpipe and re-install a cat-converter?