I can dyno first then see what converter looks best.
That is the smart thing to do.
You can get your flex plate balanced to the engine and then run any neutral-balance TC, including the 318 ones.
For the street, with performance gears, the engine spools up so fast that it is easy to choose a stall (based on the dyno results) that is too high. You only need just enough stall to break traction. As soon as she is spinning, you can control the spin with throttle. Having a high cylinder pressure/high VP, makes this easier. Without it, it takes more throttle. If you run out of throttle/power, the tires stop spinning, and then you can begin the real work of accelerating. By 3000/3500, VP is no longer as beneficial, as the engine is now climbing the power curve.
Now consider this; with a 360 and an A body, you are looking at about 6 seconds for the zero-to 60 time-trial. You are gonna spend between 2.0 and 2.5 seconds in the 60 ft no matter what, and it will all be due to spinning. Shortly after you get past that, it will be time to shift. STALL is no longer running the show. It hasn't been, since IDK maybe the first second. So IMO, it's easy to get carried away with stall. If at any time, you have to back out of the throttle, because tirespin is running away; one of three things is wrong;
1) you have a traction issue,
2) you have too much power,
3) you have too much torque-multiplication.
If you build your 360 with those alloy heads and get 170psi with that indicated cam, and with a tight Quench, I guarantee that you will have a preponderance of bottom end torque. Without some kind of traction aid, you will have traction issues, even with those 3.23s, no matter what your stall.
Here's why;
Your starter gear is 3.23 x 2.45= 7.91. but
The TC, at zero mph is gonna multiply that by about 1.8, so;
1.8 x 7.91=14.24. So then whatever comes out of the crank is gonna be multiplied by this number..... at zero mph.
Say your 360 is stalled at 260 ftlbs; whatever rpm that might be. So then;
260 x 14.24=3700 ftlbs into the rear axle.
Say your tires are 26.5 tall. This will reduce your footlbs at the road to 3700 x (24/26.5)= 3350
This is more than enough torque, to break traction with any 255 x 26.5 tall street tire.
Now, as soon as the tire starts spinning, the Convertor will lose torque multiplication, so you gotta rev it up a lil to where the power is, to keep that starter torque high enough to continue spinning. Say by 5mph, the TC is down to 1.5 ratio; and the rpm is up to 3000. To continue spinning, and to keep the crank ftlbs at 3700, your engine will need to be making;
3700/( 1.5 x 2.45 x3.23)= 312 ftlbs. I guarantee you that your 10.5Scr 360 will be making more than this at 3000rpm. Furthermore, at 3000rpm, any stall less than 3000 is already out of the picture.
For a streeter,
there is one other time stall comes into play. Say you are cruising in Second gear at 30mph with 3.23s and still with those 26.5 tall tires. This will be 1780rpm at zero-slip, say 1840@3% slip cruise.
Now say you want to accelerate. And say you have an 1800 stall. Under these conditions, the TC is not gonna help you much. If it slips 15% at WOT, the rpm will jump to 1.15 x 1780=2047, and your torque to the rear axles will be; Crank torque(T) x 1.45 x 3.23 x 1.15=T x 5.386. If your crank torque(T) is say 260, then;
260 x 5.386= 1400 into the axles. That is Not gonna be impressive.
But say you had a 2800TC; and say under these conditions it's ratio will jump to 1.2. And say at 2800 your torque is up to 300 ftlbs. The new math is;
300 x (1.2 x 1.45 x 3.23)= 1686 which is
1686/1400=20.4% stronger. And away she goes.... without downshifting.
Now be advised that I chose these numbers as best guesses, and they may not in any way reflect your build; but the point is the same, that you are likely to put 20% more torque down, under these circumstances, switching from a stock 318TC( maybe 1800) to a 2800aftermarket.
This is why some guys swear by 3000 to 3800TCs, when running conservative street gears.
And this mirrors what I sometimes do by toe-ing the clutch instead of downshifting. Sometimes I just want a lil more acceleration than what I'm getting, in any particular cruising gear, so by slipping the clutch, I can get any power I want, to fill the slight need, without scaring the crap out of the traffic all around me, by downshifting.
For an auto-equipped streeter that also is also asked to cruise the hiway, a 3.23 is the gear of choice. So then you gotta fit your engine and stall into the combo. Since 60mph in Second gear will only be 3564 at zero slip, perhaps 4100@15% slip, I see no good reason to run a cam that makes peak-power at 5000 rpm. You want massive power at 4100! Or you want your TC to slip to a higher rpm..... You see what I mean?
To get
more power at 4100, there are only two ways to get it;
1) more airflow, or
2) supercharging, which is really just more airflow times ramming it in.
To get more naturally aspirated airflow, your options are;
1) more piston swept area (cubes),
2) better flowing heads,
3) denser air
4) more cylinder pressure,
5) a specialty cam , NOT necessarily a bigger cam.
IMO it is both easier and cheaper to just move the rpm up. If you do this right, in a streeter, you can actually give up a lot of power without losing performance; but it's hard to do with a Chrysler automatic because the gear ratios are just too far apart; especially the first two, which are the ones that count.
================
Here's food for thought;
if you could find a 4-speed trans and rear gear combo to put you at 60/65 mph in third gear, at a favorable rpm, without a crazy starter gear; you would increase your average power delivery over that window , and in so doing, reduce the time to get there.
But there is no way to do this with any bolt-on Chrysler trans...... unless you split first and second gears, with an add-on box.
The A999 ratios are 2.74-1.54-1.00 w/splits of .562/.649.. If you could at least split the 1-2 that would be great . This would require a splitter of .75; which would get you; 2.74-
2.055-1.54-
1.905; split ratios in red.
I have not heard of a .75 splitter. But there is a .78 GVod; which you can use behind the A904 for ratios of
2.45-1.91-1.45-1.13-1.00-.78 splits of
.78-.76-.78-.88-.78
Typically you would skip 1.00 ratio making overdrive .69 from Second-over
Now to hit 60mph at around 5000, would take 4.10s in 1.45 ratio; 60=4524 zero slip, say 5000 at 10.4% slip, but you got there using 3 ratios! If your power peak is at say 4900 for trapping at 60, then your shift rpm could be 5200, and then your rpm drops would have to be; to
.78 x 5200=4060, so a powerband of from;
4060 to 5200=1144 rpm. With that happening, say good-by to a wide-LSA cam, which kills absolute power, steals compression, and steals extraction. Say hello to a shorter period cam with similar or more overlap, and thus, more power over the nose.
With 4.10s and .78 overdrive 65=2636 in Lock-up, say 2720@3% slip, without a lock-up.
But it gets better.
4.10 x 2.45= a starter gear of 10.045, which is really a lil steep for an auto equipped streeter. I mean a Smoggerteen can blow those 255s off with that much starter gear. You could easily give 10% of that away; say 3.73s.
Those 3.73s will get you 65=2400 in LU/ say 2470 at 3% slip. That's looking real good.
At the other end, 60 in 1.45 Second, will get you 4730@15% slip. Say your cam peaks at 4700, and your shift is 5000. the rpm drop will be .78 x5000= 3900, now the powerband is 1100...... on the shift from First to first-over. But from First-over to Second is .76 so;
.76 x 5000=3800, so a powerband of 1200, but you're gonna trap at 4730, so; from 3800 to 4730 is.... 930rpm!
Now, in this example , the power peak is only required to be at or near 4700, which points to a small cam of around [email protected]..............
I ran a [email protected] a few years ago, and I tell you that, of the three cams I have run, that one was by far my favorite. I was very sad when it began to drop lobes, even sadder when I replaced it with a 230.
So in this exercise we see the splitter HALVING your powerband requirement. In so doing, the average power is greatly increased, so for the same zero to 60 performance, you can give up a lotta lotta power. Which usually points to the cam. By dropping the duration, and tightening up the Lsa, you can gain a lotta pressure, and very significant extraction.
Lets look at jusy one example; the XE268, This cam has specs of
268/280/110 and .050 of 224/230 which is just one size bigger, to get some more power in the Eighth mile.
In the big picture this includes;
119 compression/107 extraction/ 54* overlap.
Lets get rid of that crazy 280 exhaust duration and put the thing on a 106LSA . I get
268/276/106, and in at 104, (Ica of 58*)
122 compression/ 114 extraction/ 60* of overlap ........
Now that is a stinking nice streetable cam!
At 1368 ft elevation the Wallace spits out
Static compression ratio of 10.5:1.
Effective stroke is 2.93 inches.
Your dynamic compression ratio is 8.78:1 .
Your dynamic cranking pressure is 177.27 PSI.
V/P (Volume to Pressure Index) is 160
With that, you can raise a lil hell.
of course, this pressure will require alloy heads;
But check it out at 9.5;
Static compression ratio of 9.5:1.
Effective stroke is 2.93 inches.
Your dynamic compression ratio is 7.96:1 .
Your dynamic cranking pressure is 155.29 PSI.
V/P (Volume to Pressure Index) is 140
On the money for iron and 87gas.
Just spit-balling...............
Ok now I gotta tell you something;
I once ran my Barracuda as an 8 speed manual trans, and I can tell you that having more than 4 ratios to do the Eighth mile with, is a waste. Similarly, having more than 3 ratios to hit 60 with, is also a waste.
The biggest problem is tirespin. As soon as my 295s broke loose, with my foot in it, there was no stopping them. 325s were nearly the same. With that 224 cam and a Second gear road-ratio of 3.55 x 1.92= 6.82 , she would spin the tires from a footstomp sometimes to over 50 mph.
If you build your 360 up to 177psi with a 160VP, you will have the same or very similar problem, with your roadgear of 3.23 x 1.45 x 1.3 in the TC(guessing) =6.09..
What I'm saying is that at these numbers, you don't actually need a splitter, under 60 mph. However;
That 106 LSA cam is not gonna like the very wide 1-2 split.
To get some powerband back, would take a 110LSA , but that would change the events. on the same 267/276/ now 110 cam, to something like; 118 comp/110 extraction/ 52overlap, in at 108.
That would generate a new Ica of 62*, and I get
Static compression ratio of 9.5:1.
Effective stroke is 2.84 inches.
Your dynamic compression ratio is 7.74:1 .
Your dynamic cranking pressure is 149.47 PSI.
V/P (Volume to Pressure Index) is 131
Bummer..........
Advancing the cam a lil more will pull the numbers up, but every degree you take steals it from extraction. which is already down at 110, If you don't need the fuel economy, take some.
But you still have two options ( not including the alloy heads),
1) a slightly smaller cam; remember the size I computed earlier was only 218, or
2) a switch to a solid-lifter fast rate of lift cam.
Ok so the next smaller from a 268 is a 262
With specs of say.
262/268/110, and in at 107,(Ica of 58*) I get
122* compression/113* extraction/ 45* overlap, and
Static compression ratio of 9.5:1.
Effective stroke is 2.93 inches.
Your dynamic compression ratio is 7.96:1 .
Your dynamic cranking pressure is 155.29 PSI. runs on 89/WOT
V/P (Volume to Pressure Index) is 140 badaboom! here it is again.
However, the 45* of overlap is pointing to a powerloss over the nose, versus the Comp XE268 (54overlap). So at 9.5 Scr, this seems to be the happy spot.
Well hang on, the extraction is up to 113* I suppose we could steal a couple....
Here ya go in at 105, extraction is now 111*
Static compression ratio of 9.5:1.
Effective stroke is 2.97 inches.
Your dynamic compression ratio is 8.05:1 .
Your dynamic cranking pressure is 157.68 PSI. May require 91gas at WOT
V/P (Volume to Pressure Index) is 144 Sweet!
at 4.02 x 3.58= 744.6cc swept. 9.5scr will require a total combustion chamber size of 744.6/(9.5 less1)= 87.6cc
At .010 down, you have ~2.1 in the deck, and say 8.8cc in the .039 felPros, and 5CC in the eyebrows, so, that totals 15.9cc leaving up to 71.7 in the iron heads. Daymn that's mighty close.
