rebuilding D15Z1 1.5L Civic VX engine...what to change??
I just picked up a '92 civic HB w/ 155K miles as a commuter car...I'm in the process of buying a D15Z1 1.5L Civic VX engine to rebuild myself, then swap into the civic.
*I've been searching this forum (and google too) regarding my questions...found lots of great info, but still have questions: what internal engine modifications should I do for FE? here's what I was thinking: 1) shave head (this should increase compression ratio, and FE, right? any ideas of what compression ratio to aim for?) 2) smooth out all casting surfaces and port match (intake/exhaust manifold, ...) 3) lightweight pistons/rods...is this worth it? any other ideas (or comments on my ideas) would be great! *I'm coming from the opposite side of FE...I autoX a BSP 350Z...so I understand most of the ideas for FE, just haven't thought about it enough! thanks! |
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Look at that, 2 members on this forum with civic hb 92-95 https://www.gassavers.org/showthread.php?t=774 https://www.gassavers.org/showthread.php?t=5614 |
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thanks for the response...I saw those threads, and have started a long list of "To Do Aero Mods"...I feel weird getting so excited about modding the civic for FE . |
Remember that you want turbulence after the injectors leading into the combustion chambers to encourage atomization of the fuel mixture. IIRC most everything is already port matched on the D15Z1.
I'll have to check since I'm in the middle of rebuilding a spare Z1 that I have. the only thing that I am making sure I do is to radius the oil passages and rebuild the oil pump. Other wise replace the valve stem seals, piston rings and other gaskets and call it a day and spend just around $100 to have a mighty mighty gas saver engine. |
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thanks! |
I've also seen those ebay rebuild kits with pistons, but I would use the factory pistons before an ebay piston. I would go with new rings, main and rod bearings (maybe get the crank rebalanced), and replace the valve guides and seals. Other than that I don't see how you could improve the VX much more.
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The pistons are fine on my motor, don't need to replace them. Things I am replacing:
That is all I can remember at the moment. The sleeves were in perfect shape along with the pistons and crank. I will be inspecting the condition of the oil pump while I'm radiusing the oil passages and such. I've spent right around $130 for all the gaskets, rings, bearings, and parts. It's good to know the right people. ;) |
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As for compression, increasing compression will indeed increase fuel economy. BUT, you could end up having to buy midgrade or premium fuel to prevent detonation. This could result in increased fuel cost, despite imroved fuel economy. So increasing compression might not be a good idea. |
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2) Any idea of what compression ratio to aim for that will allow me to still run 87 octane? thanks for all the help guys, this forum is great!:thumbup: |
Well, my experience with Honda engines is in 100% favor of TomO's recommendation. I have several engines I have done exactly what he described and from my experience it has just greatly extended the engine life, increased the oil pressure and worked great.
I did rings, rod bearings, main bearings, valve guides, new oil pump and new gaskets. I honed the piston walls and reused the original pistons. It doesn't seem to use any oil and runs fine. |
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