Post #9 near the end mentioned the idea of a 392 stroker and is the reason I went "off topic".
Further off topic , what does you 306 run on "motor only" . I am only curious as to how much you pick up with the spray as I am contemplating it. Randy
Well, the engine is kind of unique compared to what most people do. All the parts were sourced around 1995, just before all the cheap Chinese Stroker stuff started coming out, so it's still 306ci. It uses an old 1970 0.030"/0.040" Boss 302 steel crank and rods. It's built to be a STREET car, so it has a pump gas compression ratio and a solid flat tappet cam. (SFT were cheap, reliable and would rpm easily)
The cam/compression/gearing, etc are geared toward nitrous... so it's designed to be optimized for the bottle, which is an old Top Gun plate from the early 90's jetted for 200hp. A guy from Top Gun is who broke away to form Nitrous Express. I had the same kit on an old 289 headed engine jetted for 150 hp. After the engine was getting well worn, the nitrous was stepped up to 200 hp to compensate for wear, and has been there ever since. lol The current engine has been on 200 hp worth of the drugs from the beginning... which is around a dozen or so years, now. It was taken out for a freshen-up a few years ago, and showed no real signs of strain. Both engines have digested dozens of nitrous bottles without issue. The key to not killing them, is to not get greedy, and be conservative. A 'soft' tune can go a long way in regards to service life.
As for how they run off the bottle... I don't get to go to the dragstrip that often, so when I do I like to make the best of it! That means, I want to go as fast as possible, so pretty much every run is ON the bottle. With the drugs, the driver's seat is a BUSY environment! The 1/8 mile goes by in 6.29 seconds, and you're already in 4th gear before reaching the finish line. There's no time to think... It just has to be driven by instinct. OFF the bottle, it feels like everything is moving in slow motion, and I sometimes tend to shift too early. It's just not nearly as much fun, so almost every pass is a bottled one. lol
Most tracks around here are 1/8 mile. Going to a 1/4 mile track is a rare treat. The old engine was a 306 with 289 heads I ported. The best 1/8 mile times it produced were 6.73 @ 103 on the bottle, and 7.48 @ 93 naturally aspirated. For the naturally aspirated runs, a buddy with a 400 Camaro and I were really close performance wise off the bottle. (his car didn't have nitrous) so we kept making runs, and kept upping each other's best times! It kept going back and forth until I was launching my car wide open on the rev limiter at 7200 rpm! Shift point was only 6800. lol Since it was set up for the bottle, it would launch as hard as you wanted to off the bottle. Was a fun night. lol
I've only made ONE run with the current engine naturally aspirated. lol It was a warm day on a 1/4 mile track and ran 7.44 in the 1/8 and 11.66 in the 1/4. I'm sure it would do better, but with only getting to the track a couple times per year, I've always got the bottle turned on... as it's just a lot more fun and exciting. lol
The bottle is activated via a throttle switch. When the throttle is wide open, the nitrous is ON. The car is launched at 3/4 throttle. You just 'barely' lead with the clutch before going WOT, as you don't want the nitrous to come on before the clutch is released... or it tends to get violent. lol But, as soon as the clutch it starting to grab, the nitrous is on. It's all done by feel and just timing your feet. The bottle adds a MASSIVE amount of torque for launch, and improves that little 306's 60ft tremendously. The nitrous can also be switched to 'button' mode, so it's activated via a button on the shifter. This was used mostly in the street racing days, and for testing/playing around on the street. lol
I'm 51 years old, and have had the car since age 15, when it was bought as a beater first car for $1,300. We've been through a lot! lol
Well, that was a lot of rambling... Sorry for making you read all that, just to answer a simple question.