# Rotary Engine vs. Piston Engine - Opinions? **URL:** https://forums.speedlife.net/t/rotary-engine-vs-piston-engine-opinions/135139 **Category:** Canada Nissan Automotive **Created:** [January 15, 2008, 3:09pm UTC](https://forums.speedlife.net/t/rotary-engine-vs-piston-engine-opinions/135139 "2008-01-15T15:09:00Z") **Posts on this page:** 1 **Showing post:** 27
### Author: ![pcproa](https://avatars.discourse-cdn.com/v4/letter/p/c5a1d2/32.png) [@pcproa](https://forums.speedlife.net/u/pcproa) #### Post date: [January 17, 2008, 12:04pm UTC](https://forums.speedlife.net/t/rotary-engine-vs-piston-engine-opinions/135139/27 "2008-01-17T12:04:31Z")
> [@Nice engine swap on eBay](https://forums.speedlife.net/t/nice-engine-swap-on-ebay/2788/13): > > this is also why many high HP cars run Dual spark plugs, the spark at almost exactly the same time (depending on tuning) to get the forces directed back at the center of the combustion zone, as well as improving the “completeness” of the air/fuel mix burning and therefore not wasting any gas that could be making power… > > but this is only done in cars where they are trying to get every last HP out of them…and only worth about 10-20hp in a 1200hp motor…not much by comparison, but maybe the difference between winning and losing $10,000 or $100,000 race. Not true. Not true at all. Enter NAP-Z. Acronym for Nissan Anti Pollution. It originated on the Z22E motor. They had two spark plugs per cylinder coupled with a Hemispherical head. One spark plug fired right after the other. The ideology behind getting all of the unburnt fuel to usable power and increasing fuel efficiency while reducing carbon emissions was the driving factor behind this technology. The Z22E was in the S110 (Datsun 200SX) from 1982 up (I believe California models got it right from 1980 on the Z20E), and later found its way into the S12 (Nissan 200SX) but on the CA20E motors. The CA20E motors didn’t have Hemispherical heads. Only 2 spark plugs per cylinder. I’m not sure if there were other Nissan cars out there that used this technology as well. EDIT – I forgot to mention as well, with the Z22E, it was built with one spark plug on the drivers side of the head and one spark plug on the passenger side. The Driver side plug would spark first and pushing against the Hemi head it would start to spiral. Then the other plug would then spark further increasing the velocity of the spiraling explosion to push down the piston even harder. By the time the exhaust valve opens the spiral would be headed out the exhaust valve on the Drivers side of the engine. The CA20E lost the appropriate heads which I think can be accounted for part of the horsepower decrease. Z22E in 1982 had 102HP CA20E in 1984 had 96HP Of course there are many block differences etc --- _[View the full topic](https://forums.speedlife.net/t/rotary-engine-vs-piston-engine-opinions/135139)._