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Tech Q and A

Aaron Bonk
Feb 11, 2013
Sstp 1301 01 o+tech q and a+super street logo Photo 1/1   |   Tech Q and A

Q My friend just bought a BB2 Honda Prelude Si. It doesn’t have V-tec, but it does have the H23A1, which is in great shape. I have an extra H22A V-tec head that I want to give him. My friend is awesome and never gets a break! So how do I run the V-tec solenoid on a non-V-tec block? Where do I tap the block for good oil flow?

Croydon, PA

A For the love of all that is holy—it’s called “VTEC” – not “V-tec,” “Vtech,” or even “Vtek”. Lucky for you, though, it all pretty much means the same thing and, lucky for you, with the H-series you can skip all of that oil tapping nonsense you may have heard about when converting B-series, non-VTEC engines to VTEC. It’s almost as if Honda wanted you to take that extra head you’ve got, give it to your friend and do the conversion for him. Before swapping over the VTEC head and head gasket, though, be sure to remove the oil control plug from the deck of the block. If you don’t, VTEC will never work. You’ll also need all sorts of H22A bits, like the thermostat housing, rear water pipe, water pump, timing belt, lower drive pulley, head bolts, spark plug wires, complete intake manifold assembly and timing belt covers.

Q Is there any hope for my sorry excuse of a 2006 Mazda 5 Sport? Are there any decent aftermarket parts available? Can I use the same aftermarket parts from the Mazda 3? I looked, and the engines are the same size, I think. I’m just looking for some extra oomph. I’ve always wanted a nice import ride, but this is what I have for now.

Nathan Post
Sacramento, CA

A You’re right, the engines are virtually the same between the two, but there are still a few options specifically for your 5. K&N currently offers an intake system for the Mazda 5 and, last we checked, 5Zigen had developed a version of its Border S exhaust system that’ll fit. You could play around with bolt-ons but, the truth is, at over 3,300 lbs, a 10 or 12hp gain won’t feel like much. You might consider a turbocharger system originally designed for the 3. There are at least a couple out there. We suspect that with a little bit of intercooler pipe fabbing most any of those kits will also fit the 5.

Q I’m about to pick up an FC chassis RX-7 that has 110k miles on it. I wanted to swap in a 13B twin-turbo engine from the FD RX-7. What would I need to complete the swap (e.g. ECU, wiring harness, and such)? Will it be an easy changeover or are there other factors involved besides just bolting the engine up?

Carmon Falls
Afghanistan, but from Oklahoma City, OK

A Mazda’s 13B-REW from the ’92-’02 RX-7 is arguably the best piece of internally combusted machinery ever to be sold without pistons. The heresy of yanking one out in favor of a V8 or some other monstrosity might seem like a punishable offense but, as it turns out, it makes you being able to find your donor engine that much easier. The fact that conversion mounts are available for exactly what you have planned might lead you to believe that this swap is straightforward, but it isn’t. Unlike the Honda swaps that you’re used to, you’ll run into compatibility issues with the electronics, A/C, power steering, exhaust, throttle linkage, cooling system and more. You’ll also likely have to abandon the sequential turbo configuration. We should also mention that aftermarket mounts aren’t the only way to get this swap done. By retaining your FC’s oil pan along with its mounts, and modifying the REW’s center housing to accept your existing brackets, you can accomplish the same thing for less money. Finally, you’ll want to consider some sort of standalone engine management system. Adapting the older wiring harness and sensors to play nicely with the FD’s ECU rarely ends well.

Q I recently installed Toda Spec B camshafts with Skunk2 cam gears into a B16B, both set at zero degrees. I had my CTR head milled 0.015-inch and I also installed a Mugen two-layer head gasket for a higher compression bump. I took my car to be tuned at a local tuner and he told me that my VTEC is not kicking in as hard as it’s supposed to. Before the Toda cams were in, I tuned it with stock internals with basic bolt-ons and it made 175 whp. After the cams went in, it only made 170 whp. Did I do something wrong or is my B16B just not up to the cams’ expectation? My timing was correct, set to OEM specs, and I did my valve adjustment correctly, just like how my tuner told me to. My cam gears weren’t touched at all during the tuning process. I don’t know if it’s necessary to adjust them. After the tune I put my CTR cams back in and now my VTEC is kicking hard like before. I don’t know if my tuner is just stupid and doesn’t know anything about Toda cams or if he just wants more money. He’s tuned a lot of Hondas before, so I know that he has enough experience.

Tou Yang
Via email

A What exactly were you doing on the dyno if your cam gears were never adjusted? Although your milled head and two-layer head gasket raised your compression ratio, they’ve also made your life a whole lot more complicated. Together those changes have positioned your cams slightly closer to the crank, which essentially retards everything they do, like when they open and close their valves. All of that can be fixed, though, and, as it turns out, that’s what cam gears are for. But you’ve got work to do before visiting the dyno again. In light of those deck height changes, you really need to degree those cams. Cam degreeing is all about locating a cam’s centerline and positioning it so that it occurs—in crankshaft degrees—exactly where the cam manufacturer says it should. Toda should’ve provided you with each cam’s recommended centerline—the fixed point on any given lobe that occurs exactly halfway between when the valve opens and when it closes. That information will allow you to adjust each cam gear so that each of those cams is doing exactly what it’s supposed to be doing exactly when it’s supposed to do it. Degreeing cams isn’t simple; you’ll need some specialized tools and a pretty good understanding of the four-stroke cycle, so if you’re not sure how to do it, read up on the subject or find someone who does.

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