Rockin the d

I am throwing this post together to make is easier for people to get info about getting the most out of a D16 VTEC, NA, while keeping it completely streetable. I am approached every day by people who ask me about my setup, etc, and this will make things easier for sure!

The advantages of going NA with the D16 VTEC are that it is easy to work on, the majority of the OE parts can be had for less than their DOHC counterparts (since alot of these parts are laying around due to DOHC swaps) and it will get you moderate power for moderate price.

This chart is one that i compiled previously to compare swapping vs. building an NA D16 VTEC. The one thing you need to keep in mind is- if you need more than 160whp, either consider boosting or swapping, because even tho the D is a value, it has a low NA power ceiling vs. the DOHC.

stock b18c5 - 161-165 whp, 109-113 wtq, cost 5K
stock b18c1 - 140-144 whp, 103-107 wtq, cost 4K
stock b16a2 - 132-135 whp, 94 - 98 wtq, cost 3K
stock b18bX - 121-125 whp, 108-112 wtq, cost 2K
stock d16vtec - 105-110 whp, 97- 101 wtq, cost <1K
built d16vtec - 150-160 whp, 114-120 wtq, cost 3K (90% OEM parts)

You obviously need alot of compression, tuning and a severely modified intake and exhaust configuration. I will go over the combinations that i like.

bottom end

If you live in an area where 93/94 octane gas is not available, your best bet is to try to keep your compression below 12:1, in fact between to 11.5-11:1 would be ideal. The piston i prefer for all setups is the p29 from 88-89 Integra d16a1. This piston is also found under the pm7 designation in the Japanese DOHC ZC. The reason i like it is because i know it works for all setups; there are no valve relief issues re: big cams, head configuration, etc. The catch with this piston is it has a lot of dome, so you will need to tailor your compression ratio by using assorted headgasket thicknesses. This selection depends on some things-

1. Fuel quality/availability

2. Head; the z6 head combustion chamber is larger than the y8 head, enough that, all else equal, the y8 head can raise the compression ratio approximately 1/2 point vs. a z6 head.

These suggestions are assuming you have close to a stock surface level head…meaning unmilled or no more than .010 milled. If you have more than that milled, you need to adjust the headgasket choice accordingly using one of the reliable d-series compression calculators available. The headgaskets I suggest are OE Honda metal 3-layer, A’pexi 1.1mm (.043”) PN 814-h101, A’pexi 1.5mm (.059”) PN 814-h102, or Greddy 2mm (.079”)

Some baseline configurations…(ratios are approximate static compression, assuming stock bore and unmilled head)

- y8 head w/ 91 octane – 2mm HG – 11.2:1 CR
- y8 head w/ 93-94 oct – 1.5mm HG – 11:8 CR
- z6 head w/ 91 octane – 1.5mm HG – 11.3:1 CR
- z6 head w/ 93-94 oct - .037 OE HG – 12:1 CR

Please note: some of the 93/94 setups have more room for compression, so another .010 off of the head through milling would be ideal. Typically, a .5 overbore will add approx. 1/10 a point of compression. My ideal bottom end for this setup is composed of all stock components. The stock rods are capable and rather lightweight pieces which should be at minimum shot-peened, a process that is cheap and adds strength. I would even feel safe at 200whp if these rods were shot-peened and cryogenically treated, which is a deep-freezing process that even strengthens them further. A popular upgrade is installing ARP rod bolts. This stems from the fact that a high-compression D with a big cam needs some more revs than stock, and with a 90mm stroke, the stresses on the rod bolts are incredible. I recommend all new bearings, Honda OE pieces, color/ number matched to the crank and at minimum plastigauged. Cylinder treatment is up to you- I personally like to over-bore to 75.5mm…any added displacement helps a 1.6L. Nippon Manufacturing offers 76mm cast p29 pistons, however, I do not agree with going that big overbore. I believe there is a reason Honda offers a max .5mm overbore, and that is with a stock engine! At any rate, over-bore is not necessary: 75mm is more readily available used and boring cost additional dollars. Honda recommends that if there are no score marks and cross-hatch is visible, do not hone, however, I recommend to at the least check cylinders for ovalling and hone per Honda’s bore/hone specs. Honda OE rings are wonderful. Stock wrist pins are fine, but I suggest using new ones. Make sure that the piston tops are smooth: the better the polished surface, the less chance for detonation. Balance the entire bottom end to 10,000 rpm. I feel compelled to mention that there has been talk about the y8 oil pumps being inferior re: oil supply vs. z6. I have used y8 oil pump with not one issue of such starvation, however, if you prefer, manufacturer TOGA offers a higher volume oil pump for this application.

Head

People bicker about which head is supreme, however, I suggest using the head that is easiest to adapt to your chassis. If you have an EK, run a y8 head, if you have an EF/EG, run a z6 head. Whatever is easier. Besides the combustion chamber size differences, the shape of the chambers are different. The y8 chamber offers better resistance to detonation due to it having more quench area; part of the reason they made the CC smaller was to fit these areas. Make sure that all edges of the CC are smooth to prevent hot spots. Another performance difference is the ports. A z6 head has straight ports called tumble ports and a y8 head has off-set ports called swirl ports. Without getting too crazy describing them, the tumble ports can promote the best top end and the swirl port can offer better low rpm torque and better mixture and MPG with the right tune. A requirement for high-horsepower NA is porting. You NEED to have a properly ported head to eclipse 150 whp. Even a mild-port job will suffice, however, the more extravagant the porting, the more power potential. The cam to use is the Crower Stage 3 cam, hands down. Regrinds are limited (amongst other things) and other fresh billet cams are just not optimized the way the Crower profile is. It has the most advanced profile for these engines and offers the broadest power band. Again, this cam requires porting to be effective, and also you must install valve springs and Ti retainers, Crower. I use new stock keepers, however, you may feel inclined to use performance branded ones. Their Ti compound is very resistant to wear. An adjustable cam gear is necessary for tuning, I find that Crower Cams do not need incredible adjustment, however, please noteL there is a difference between z6 and y8 cam gears. The only cam gear I recommend is AEM. They have the difference between the keyways of the z6 and y8 nailed. Many manufacturers DO NOT! New OE timing belt is fine. OE valves are fine. A 3 angle valve job will assure consistent seat seal. I use OE Honda head bolts, however, they can only be used once so if you want to, ARP head studs are ideal for those of you who like to take the head on and off. Make sure to contact ARP for their recommendations on which combination or kit to get…block and head configurations cover a vast array of different ARP sets. I recommend using HYLOMAR spray gasket coating by Permatex. It is hard to find, but I do know that AEBS in CA sells it and some parts stores can special order it. Torque the head as per stock specs or ARP specs, however, if you are using an extension, remember to compensate by adding 5 ft/lbs or so on the wrench!

bolt-ons

I recommend a smooth-tract tube cold-air intake of 3” diameter. It provides a nice torque hump at low rpm and also offers access to more dense air. An upgraded throttle body is optimum, 62-65mm are popular options. The intake manifold is very important. My favor