Streetable 340 making 450 hp… meh… I suppose I will post my combo in my 340 Duster.
10.5:1 flat top pistons
284/484 purple cam (241 duration at .050) hydraulic flat tappet.
Rebuilt X cylinder heads
1.5 Harland sharp rockers
LD340 intake
Edelbrock 750
3200 stall FTI converter
727 transmission
3.91 sure grip
I found a very detailed dyno simulator calculator online that took into account cylinder head flow, multiple cam specs, and dynamic compression and found all those specs thru this forum and calculated inputs on the low end. Final result for my engine was 390 horsepower.
Do I believe that number, sure, I believe it’s at least 350 hp and not quite 400 hp. But also this is fairly streetable. 72blunblu has specs just ever so slightly higher than mine and daily drives his duster. I don’t quite daily drive mine but I drive it between 30 degrees and 90 degrees outside as I please wherever I want.
Things to think about, I have 12 inches of vacuum, which is the low end for decent power disc brakes but acceptable. On the highway I turn 3600 rpm, tolerable to me because it’s in the power band of the engine’s cam specs. It has plenty of power to have fun, but not so rowdy that it’s impossible to idle thru town at 15 to 25 mph. Requires 93 octane pump gas to not detonate on shut down. Fuel mileage is 12 mpg out of the secondaries, 6 mph in the secondaries. And uphill gravel road is its enemy without proper planning to commit to a little momentum to not spin out trying to idle it up the gravel road.
While I agree 450 hp from a 340 is not impossible with todays cam grinds, cylinder head options, etc, I think it will put the car out of daily driver contention by requiring a little extra warm up time to get out of the grouchy cold engine mode and to remember to commit to throttle inputs etc when navigating stop and go traffic. Based on 72blunblu’s response I believe if not for the extra OD gears of the aftermarket transmission he fitted it would be a lot less enjoyable to daily. I don’t even daily mine and have thought about OD transmission options… but not worth the hassle for me. I am in top gear by 35 mph, after that rpm is speed lol.