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Ok..so i kinda blew my motor last week and i'm looking for another H22A4 for my 2001 Prelude. Now i've been looking and i found a JDM motor for $1500 w/ low miles. My concern is if i buy the motor what types of problems will i have changing out the USDM motor w/ the JDM or will it be a straight foward swap w/ no modifications of anything like the wiring and such. Any and all info would be a great help.

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yeah thats what i had intentions on doing but i re-did a compression test on the 2nd cylinder and now it has compression, very low but it's there. i think my head needs to be re-done because the stock cams are shot. they already have flat spots on the lobes and knicks in the cam itself so i'm guessing the reason my car is running like crap is the valves aren't opening and closing properly, so im looking into just freshening up the motor ie: new rod bearings, new main bearings, engine gasket set, new cams, piston rings, possibly new pistons, and head work like port and polishing and either a 5 angle or 3 angle valve job, but i need some reccomentdations for the valve job.

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right now i'ts my only ride so i dont have much of a choice, i cant keep driving it the way it is, even though i regained compression in the 2nd cylinder it's runnig like crap so i might just go a long w/ the re-build because i know a few guys who can get h22 blocks all day and they usually come across some good heads so i might just take advantage of that later down the road but for right now i need to come up w/ a parts list for the re-build

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One day, someone will combine servo technology with lathe equipment to make a machine that can create two curved surfaces (one on the head and one on the valve) that would fit together with negligible spacing in between; inexpensively.


The optimal surface of a valve is entirely smooth; i.e. curves between all flat surfaces. The smooth curve is superior to a sharp edge since edges tend to “pull” on gases flowing by them.


At present, cutting machines are heavy pieces of equipment that seem to only be able to handle either spinning the cutting bit on a fixed axis or spinning the object to be cut on a fixed axis. I am confident to say a valve could be made with a smooth curved surface with current technology, but the problem seems to be in creating the second curved surface on the head to match the valve. So, edges remain part of current valve design. Valve angling works to remedy an issue created by having edges on a valve. The fewer surfaces used to approximate the optimal curve of a valve, the more pronounced the edges. The more pronounced the edges, the more “pull” is present as a gas flows by. The more “pull” is present as a gas flows by, the slower the gas flow becomes. By increasing the number of edges between two angled surfaces, a machinist is able to reduce the edges’ impact on the gases flow by incrementally approximating the profile of a curve.


The flow issue is simplified when you consider the cross sectional profile of a valve (longwise, top to bottom). You want the gasses to flow over a smooth surface, but have the aforementioned limitations. So you design your ideal valve using curved surfaces; and like using the method of exhaustion to integrate the surface area under a polynomial of degree 2 or higher, you keep adding smaller and smaller surfaces to approximate that curve.


Also, this edge issue defeats combustion profile technology along with flow rates. The optimum gas mixture approaches homogeneity in the combustion chamber. By passing the air-fuel mixture over an edge, you provide the vapor with a nucleating surface (a place for the fuel molecules to get together and condense back into a liquid). Since your car only burns fuel vapor and not liquid fuel, the nucleated fuel particles are simply heated and expelled into the exhaust in their liquid form. This triggers your sensors to show a rich burn.


SO! 5 angles is better than 3 angles, 7 angles is better than 5 angles, and so on and so forth.


I find it VERY interesting that valve optimization is usually done with an odd number of angles as opposed to an even number (4 or 8 angles).


Perhaps someone can respond to this thread with some insight on that.

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