318 build problems & new direction
I wouldn't get to caught up in light weight revability. A well built 440 revs quite well and those pistons are insanely heavy. But yes if you can lighten up a bit all the better.
As for the 394 hp I'd think you would need a little more. The recipe I've come understand for a 400 hp small block is 10:1 CR, 750 airgap, xe285hl or similar and 220 ish cfm heads.
With a little more head you probably can get away with xe275hl.
Just for reference;KB 107s for a 360 are 502grams. At 11.3 Scr and with a 292/108 cam the revs were nasty fast, in my first iteration.
With the current 276/286/110 and now at 10.9Scr,it has quite a bit more torque at below 3000, and didn't seem to lose much up top.
It now pulls 4% less starter gear easy enough;11.44 vs 10.97 for the 276*.The 276* would be quite happy with a 9.98 starter;which would be 13% less than the 292.
And whereas the 292* liked 8.26 second,this 276* cam is fine with 6.78. That is 18% less second gear.
The 292* liked a third gear of 6.02, whereas the 276* is Ok with 4.97. That is 17.5% less gear.
4.30s cruise at 65=3472..Whereas 3.55s cruise 65=2867, which is 17.4% slower
My conclusion was;292 cam and 4.30s suck in a DD that travels at least an hour a day on the highway; 292 needs an overdrive. Having power at 5500 to 7000, which being 40mph to 50mph is great! Having to slip the clutch out to get moving is embarrassing, and not having reasonable torque until 2400rpm/17mph also sucks.Of course while i was in that mode it wasn't all that bad, cuz i didn't know any better. I'm sure a sharp teener couldda put a hurt on me at sub 3000rpm, in a roll-on.
But after the 270/280/110 cam went in, Well,then, that was when I knew I had made the right decision for me, and my application..and when that cam dropped two lobes, I got greedy and went to the current 276/286/110. I thought to myself, it's just 6 measly more degrees it will be alright, and I wouldn't mind a bit more steam at the top.So I thought. Wrong! This cam was a lot different than I anticipated. But in the end with a bunch of tuning, It is now fabulous."course I have an overdrive now,lol.
Long story short; gearing is almost critical. But as a streeter and a DD, I learned that a bigger engine can get to 60mph faster than the littler one, and can do it with less gear and less cam, leaving you with less rpm at 60mph, and sucking less gas per mile.
So yeah, a well matched teener combo can get to 60mph likkity-split. But it will take more cam and more gear, and if an automatic, it will take more stall, than a bigger engine.It will wear out sooner and cost more to maintain, and use more gas while cruising.
I think that is an excellent case for a stroker. It can use even less cam, and even less gear, to get to that 60 mph.
And once you hit 80mph or so and start to plow air,that is when the bigger engine starts to shine. And the faster you go,the more air you push, and the bigger engine keeps going long after the little one gives up, and gearing now won't help it, only more cubes or supercharging or a lower cd, or a lot less weight, but those are another thread.
A teener with 4.30s, an automatic,and too-big-really-for-street-cam, that peaks at 5800, is gonna begin the down slide at 103 mph. By 6300 it will be gasping it's last breath and going 112 mph. The torque peak on this engine will be at about 4400, and if it musters 1.2#/cid, it will make 380ftlbs. At 4400 this is 318hp
Whereas a 360 built to the same absolute power, will only need 3.73s to keep up to the teener with a cam that is probably 2 sizes smaller.At 103mph it still has plenty of revs left, probably spinning at just 5000 rpm. It's cam will run out probably around 5400, and will be wheezing at 6000, so it will make 124 mph,before running out of Rs.This engine will torque peak at about 4100, and it will only need to make 1.055#/cid to match the teener. At 4100, this is 298hp
The 318 of course, can only dream of making as much torque below it's peak as the 360 is casually delivering.
At the starting line;
the teener is looking good with a 10.54 starter gear, while the 360 is stuck with a 9.14 starter. The 360 will need to make 15% more torque at stall to keep pace with the teener.With it's 2 sizes smaller cam, and it's 13.2% size advantage,I'll go out on a limb and say with a street TC this is all 360 territory. With 4100TCs, I can see them taking off together.But I also see the 360 pulling ahead in a very short period of time.After that it gets too complicated to see what is going on in a moment by moment basis, but I still see the 360 ahead thru the traps.
Anyway that's arm-chairing again.
I guess I should add; at 32mph, the teener will be doing 4397 in first gear, just a tic below its torque peak.It is all set to go hammer down. Whereas the 360 is only doing 3800.If they launch together, and baring wheelspin, the teener will jump ahead. The teener will be done by 46mph and will have to shift. The Rs will fall to 3740, and the poor teener has nothing left.
Whereas the 360 will pull to 50. So the smart 360 owner will call 50mph the finish-line. Cuz if he has to shift, the Rs are gonna fall to 3550. But I still think the 360 has more torque at 3550 than the teener at 3740. So while the 360 has pulled ahead, it will just maintain the lead to the next shift.And by then it will be ahead by a bit more. And so on.Right thru the traps.
But most street blasts are done by 65 mph.This will be 5588 with the teener in 2nd, and 4600 in 2nd for the 360. Ima thinking the teener might be taking this one! Nah......probably not; the teener lost too much time,fighting up from 3740;it was practically drowning down there, for just too long.
And even if the teener manages to catch up, the teener is maxed out! Whereas in 75 minutes, 3.91s can be in the 360, and bye-bye teener,bye-bye.And the 360 still has 2 or 3 cams to plow thru and two more rear end ratios before it is similarly maxed out.
I won't say it...
Ok I will; 502 gm KB107 pistons rev quicker to 6000 than they do to 7000,lol. 1969 Factory 340 pistons were 719,and nobody ever called them slo-revers,lol. Teeners were 592 and 273s were 549.Everybody brags on their 273s being snappy revers. Also in 69, all rods are listed at 726 gms, and I put 318 rods into my 360 as they already had the bushed ends, whereas my 360s were pressed. As far as I could see, the 360rods were otherwise the same even down to the casting numbers. I did not weigh them. Yes, I know the earlier 273s and 318s had lighter rods and cranks........The point is, the 360 with the 502pistons, is no slouch when it come to reving quick.Especially if you put some decent compression in it. But if you like to buzz your engine up in neutral to see how quick it revs,and it just ain't quick enough for you? well then, you can always pitch the tank oem flywheel,lol.
