New '92 Civic DX (soon to be VX)

[GasSavers_TomO]

Originally Posted by first350

I plan to shave it to increase compression for FE...I'm having a little trouble finding good info on what kind of compression ratio to aim for that will still allow me to run 87 octane, but at least 1 person is saying 10.5...so I'll probably aim for 10 to be a bit conservative.

10.5 is all the higher I would go and still be able to stay with 87 octane.

Originally Posted by first350

I'll do all the other easy stuff too: smooth out casting lines, port match,...I had thought of increasing compression by going w/ longer rods (you can usually get a higher compression ratio w/out detonation this way), but opted not to b/c I'm trying to keep costs low.

-Peter

You don't really want to mess with the stroke on the D15Z1, it sits right at a rod/stroke ratio of 1.62 which is perfect for low resistance rotating as well as lateral pressures of the piston.

If you really want to increase the FE of a VX, invent and aperture style throttle body. It would offer better, less restricted flow of air into the intake manifold.

[first350]

Originally Posted by TomO

10.5 is all the higher I would go and still be able to stay with 87 octane.


You don't really want to mess with the stroke on the D15Z1, it sits right at a rod/stroke ratio of 1.62 which is perfect for low resistance rotating as well as lateral pressures of the piston.

If you really want to increase the FE of a VX, invent and aperture style throttle body. It would offer better, less restricted flow of air into the intake manifold.

aperture style TB - similar to a camera shutter? sounds like a good idea if you could get it to flow like a velocity stack for all throttle positions...I should start tinkering with this idea...

*wonder if smaller multiple throttle bodies would work...have them open up sequentially;

say you have 4 TB's:
full throttle - all 4 full open
freeway 65 MPH partial throttle - 1 full open, 3 full closed

you would choose how many TB's by sizing them such that 1 TB fully open would match power for freeway cruising.

[GasSavers_vxhatch]

Originally Posted by first350

i plan to run taller/thinner tire if I can find one...so the final ratio will be even taller!

Ah, taller/thinner - great qualities in a............................ tire. My car has 155/80/13 Kumhos. Taller/thinner than stock. iirc, max rated pressure is 42psi, wish it were higher. I bought the car with these tires, so I can't say whether they are a benefit to FE or not. I'll likely go back to the stock size, if I can find em, once these wear out.

Doug

[first350]

Originally Posted by vxhatch

Ah, taller/thinner - great qualities in a............................ tire. My car has 155/80/13 Kumhos. Taller/thinner than stock. iirc, max rated pressure is 42psi, wish it were higher. I bought the car with these tires, so I can't say whether they are a benefit to FE or not. I'll likely go back to the stock size, if I can find em, once these wear out.

Doug

lol - I actually just bought the same tires...$130 shipped to my door - FTW! (I'm accustomed to paying $200+ per tire for my 350Z...I luv this civic!)