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need lil more getup

247 Views 3 Replies 4 Participants Last post by  theghosttanker
i got a 83 280zx n/a and was wonderin if it would be alright to portnpolish my head to gain up some power. if i were to do this how much would i gain, how much would my 1/4 times drop? and what else should i do along with it. i would like to get a hotter cam to but dont have the $$ right now. i would like to know how it went for all u do it your selfers out there. thank u for any advice i can give me.

intake, sidepipe exhaust, clutch, 60mm tb with turbo amf and thats about it
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Pretty useless mod at this stage of the game. Save some money and do some other stuff first. The stock head on import cars is pretty clean already and the stock EFI intake is more of a restriction than the head is on these cars.
Well there are things to do that are cheaper than doing head work. Also if you don't have enough for a cam how do you have enough for head work. A good port and polish job will require machine work that you won't be able to do at home. If you mean do a very mild port job then yes you could do it but you probably won't gain much, maybe 5hp. A good reworked head is only good for about 20-30hp depending on how it's set up. As you have probably read the 60mm tb and turbo AFM does nothing on a stock engine such as yours so basicly all you have is intake and exhuast. I would start with some little things like a header, high flow cat, lighter flywheel. Also if you are willing to get rid of the power steering and a/c system you could go with a euro damper. It's basicly a lighter single groove crank pulley. If you are looking for just a little more power and don't want to go all out then a cam would probably be the last step as well as an adj. FPR to help tune for it. On the other hand if you want to go all out I would hold off on the cam until you had enough to do the cam, head work, and stand alone fuel system all at once. You only want to open the engine up once and do it right the first time so if thats your goal save up and do it at once. As for the stand alone you could do it before hand and maybe pick up a few hp with basic bolt ons but it really won't do much until you do internal engine work like the cam and such. As for 1/4 mile times a lot has to do more with how you drive and how you tunned the car rather than what mods you have. Also the more mods you have the better the system will work to make you faster. For example just the head work alone would probably only be good for about .2 secs or less depending on how much was done. However you add a good cam, stand alone system, and tune the car properly you might be able to drop a full second with good driving skills. Right now it sounds as if you need to take a step back and design a plan for your car before you mod any further. Make a long term goal for the car and then make a plan that meets that goal. At that time start researching and pricing what it's going to take to get it there. Then you can decide if this is the plan you want to follow and can afford to follow. At that point is when you should start buying parts and modding the car. If you don't do this you could end up throwing on useless parts or parts that counter act other parts such as bubble did on this site with his cam ordeal. Good luck
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Actually, with a die grinder and a little patience you can easily and cheaply make a noticeable improvement in your power. All by yourself....Match the plenum intake to your larger throttle body and smooth and polish that throat as best you can. On the other side, open up the intake runners as best you can,as far back in as you can, and grind off the big bumps where the injector screws go in. You may have to put the injectors in and trim the screws where they protrude into the runners. Polish the runners too, as deep into the plenum as you can reach. Now smooth out the intake ports in the head, going after casting bumps and sharp edges. With the stock manifold, port matching or enlarging the ports won't help you much, but smoothing bumps definitely will. Polish the intake ports and then rough them up again with 100 grit after you get the bumps out. Pay particular attention to getting all rough spots, sharp edges, and bumps off the short side radius of the port...(the inside of the bend that the air has to flow through) In the valve area, being very careful not to knick the seats, smooth the transition from aluminum to valve seats, and in the combustion chamber, unshroud the valves so you have 3/16"clearance between the edge of the valve and the side of the chamber. (Be careful not to grind too far; use a head gasket to mark the limit of grinding.)Mirror polish and smooth as much of the exhaust ports as you can reach, but don't try to get the liners out...they don't harm flow as much as you would think, anyhow. Mirror polish the tops of the pistons, and the inside of the combustion chamber, and smooth any sharp edges, and extra threads for the spark plug holes. (Put a plug in and see where there are extra threads caused by the tap at the factory, past where the plug protrudes into the chamber.) Since you have the head off, see about having a new valve job done.....SI hi performance swirl polished valves cost about 14 bucks apiece, and a modern shop with CNC equipment often does a 5 angle grind for about the same cost as a 3-angle. Anyhow, if you are trying to do this on a tight budget, lap the valves lightly by hand, and put it all back together with a felpro gasket set, which will raise your compression slightly over stock. Replace your valve seals, they come with the felpro set. Borrow a scale from a drug dealer and lighten, balance and polish your rocker arms. Finally, if you are not putting on a header, do what you can with the exhaust manifold, smoothing and polishing the ports and runners. Do not try to port match your exhaust.
You can do all this work yourself, and all it will cost you is time and abrasives and a gasket set. it's hard to say how much you get from every little bit....but after you are done, you will definitely see a power improvement. With the polishing of the chambers and piston tops, and the removal of threads and sharp edges in the chamber, you will be able to advance your ignition timing more without getting pinging problems. If you don't do this, then you won't see all the power increase you are looking for!
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