Honda - Which Head / Cam Combo?

[DaX]

This question is in regard to Honda heads.

For my gas-conscious commuter car that I am working on, I have a choice of heads and cams to use. The block I will be using is a D15B2, from an OBD-0 Civic DX. I have the B2 head with the stock cam in it that I can use, or I have the head from a D16A6 with the stock cam.

Remember, this car is NOT being built for power...only for gas mileage. I think that the heads are identical with the exception of the cam. The A6 head is much cleaner and in better shape than the B2 head, so I'll probably use it, but does anyone know offhand which cam I should use?

Thanks

[Matt Timion]

The b2 Cam is always going to be better for fuel economy than the a6. This is unfortunate as you said your a6 cam is in better shape.

If you want to start digging a bit, you can actually get little bit better gas mileage by putting the STD cam into your b2 (since the STD was built with gas mileage in mind). I have no idea how common STDs are in your parts (enter bad joke here) but here they hardly ever come up. In fact I saw my first one just this week at the junkyard.

hope it helps.

[DaX]

Actually it's my A6 head that is in better shape...both cams are in pretty good shape. It turns out that I also have a D15B1 [Civic STD] in my hatchback...if anything I'll just pull the cam out of this and swap it for either the A6 or B2 cam. Would you see any disadvantage to me using the B1 cam in the A6 head? I'd like to use the A6 head because of fewer miles and it has a more recent rebuild. I think [correct me if wrong] that the only differences in the heads are the cam, so unless I'm wrong, the B1 cam in the A6 head should work beautifully.

I was also thinking today about how difficult it would be to find and what kind of gains would be yielded from sleeving my motor down to, say, a 1.3L. I'd have to find a company willing to make smaller diameter sleeves, and more importantly, already existing pistons of this smaller diameter. Does anyone know what all has to match for pistons to be interchangable? It would probably be easier to design a skinnier sleeve from a pre-existing piston, kind of like how people are using Suzuki Grand Vitara pistons in their D-series engines. The pistons don't necessarily have to be high performance, because high horsepower is not what they will be used for.

[Matt Timion]

I'll talk to my friend about the b1 cam in the a6 head and get back to you. If you ever need a d15z1 head I have on in the garage collecting dust.

As for the 1.3 downgrade, have you considered using the CVCC pistons? I'm pretty certain that Honda's engines have pretty interchangable parts, so using something from a CVCC might be doable.

[DaX]

Nah, I think the Z1 head would be more trouble than it's worth. I used to have a VX, so I remember all the emissions **** I pulled of and tossed when I swapped.

That's a good idea about using CVCC pistons.

*edit*

I've found some sites with bore x stroke of older civics, but does anyone know where I can find specs like rod length, wrist pin diameter, and rod journal diameter, etc?

If I were able to use a 70mm piston from a first gen civic with the D15B2's rods, I would get exactly a 1.3L engine.

[SVOboy]

I'll look around for information now, but until then, how would a 1.3 switch over affect the power/economy these things make? Any guesses?

[DaX]

I'm guessing less displacement = more economy and less power. I spoke with Earl Laskey, and he said the sleeve blanks they get in have an ID of 73.5 mm, so finding a 70 mm sleeve will be way too expensive to justify. Assuming I could get the sleeves turned to 74 mm ID, that would still only drop my engine from 1493 cc to 1453 cc [stock bore is 75 mm], and I couldn't justify spending the money to drop less than .05 L of displacement. I guess I'll just stick to my 1493 cc unless someone comes up with something easy. It was a stab in the dark as well...the CVCC pistons probably wouldn't have worked [probably had a different wrist pin location].

[Matt Timion]

Okay, this just in. b1 on a6 head should be a "bolt on affair" as my friend told me.

He also pointed out that reducing the displacement on your engine might actually have little to no effect at cruising speeds.

but destroking that much... the Rod / stroke ratio might lessen the volumetric efficiency at cruise RPM... so the difference may be negligible

[DaX]

Cool. Then I'll just throw the B1 cam in the A6 head and drop it on the B2 block [haha, crazy alphanumeric jumble]. Don't know when I'll get on this. The block I'm going to use smoked pretty bad, so I'm going to replace all the seals & rubber, as well as have the block deck resurfaced, cylinders honed, and install new piston rings and bearings on the bottom end. Since this will be kind of costly, it's going to have to wait a few months.

[SVOboy]

Is the b1 cam actually different than the b2 cam? I heard the same thing as matt from the same person, but I was wondering if there was any difference between the two.