There’s a big factor!!!
Boy do I wish I knew all this when I had the engine out!! I’d love to swap converters now, but I’m not sure it’s worth the trouble at this point in time. That’s great information, it’s helping me understand the concept behind torque multiplication.The 1973 318s were advertised at 8.0 Scr, but generally. come in around 7.8 after a reman. The closed-chambers will bump that up, but I think 8.3 is about where yours might be. At 2700ft elevation, that's gonna hurt the bottom end power. The Wallace calculator predicts about 124 psi cranking cylinder pressure.
I had a freshened 1973 smogger , that I used to use as my winter engine, stock long-block, with a small-port intake, a 4bbl,fresh-air,and headers. I put that engine in every winter 5 or 6 years running, and it never had the same trans or gears in it. But when it had a a 904, then it also had a 2800TC. and when it had the 2800, then it usually had 3.23s. And in that combo, she was a ripper. and here's why; Below is a 5.2 Magnum graph, so much more powerful than either of our engines. But look at the shape of the curve. At 1800, it shows about 270 ftlbs. Let's arbitrarily drop that to 70% for your combo; so 189. And your TC is gonna multiply that by say 1.6 at Zero mph, so 302. Now the trans has a first gear multiplier of 2.45, so now 741. With the rear at 2.76, then 2045 into the rear axles.
But with 3.55s then 2630. Checkmark that.
Lets up the TC to 2800
On the graph, that looks like 295 ftlbs. Again at 70%=207ftlbs. But this time I'll estimate 1.7 in the TC@zero mph, and still 2.45 low and back to the 2.76s; I get 2374 ftlbs. So now with the TC alone, you are half way between 2.76 and 3.55, as compared to the 1700 stall. With 3.55s, this combos to 3054! and now 49% greater than where we started.
Ok but I know you're thinking, that don't sound like all that much,right? Well hang on; 189ftlbs at 1700rpm is 61hp. Whereas 207 at 2800 is 110hp, using the estimated numbers, this is an increase of 80% in horsepower.
Ok now I'm not saying the 2800TC will increase your delivered power to 110hp@2800. I'm saying you could be looking at a power increase of 80%@zero mph, over an 1800TC. And that is a really big deal. You understand the difference?
This is the bandaid for the low cylinder pressure.
View attachment 1715673960
what is your tire size?
IMO: It absolutely will be worth it.but I’m not sure it’s worth the trouble at this point in time.
So far I'm doing pretty good; I got the tires right on, but overstated the intake duration @.050 by 3 degrees, which will not affect the Ica; So all my calcs are spot on. I even called the shift rpm within 100rpm. So, on a roll;Okay, my rear tires are 245/60R15, which works out to 26.6". I'm gonna get after doing a compression test later today and will report back the results.
OK...it's not your 30" tires!Okay, my rear tires are 245/60R15, which works out to 26.6". I'm gonna get after doing a compression test later today and will report back the results.
So far I'm doing pretty good; I got the tires right on, but overstated the intake duration @.050 by 3 degrees, which will not affect the Ica; So all my calcs are spot on. I even called the shift rpm within 100rpm. So, on a roll;
you wanna hear about my Theory of the Enclosed Earth System? Go to; AJ's Opinion; the shape of the Earth in the Search bar..
https://www.forabodiesonly.com/mopa...he-shape-of-the-earth.480916/#post-1973272310
OK...it's not your 30" tires!
There you go!I was going to comment on how closely you nailed the shifting in post #31, because punching it in 1st around 25mph gets some good response, then mediocre performance until I hit higher speeds.
If you don't notice night and day, it wasn't running right to begin with.
It's funny, I saw an 833 for sale last night and started researching what it would take for the conversion. After all, I really do prefer manual vehicles - last 20 years that's all I've had. But, it's a little more money and effort I'm willing to invest at this point, especially since there are so many other points that need to be dialed with this car. I don't want to complicate things even further.There you go!
The only cure for that hole, long after stall, is more pressure, as described in the post. Or.... closer spaced gearing; like a 4 speed; which will prevent the rpm from dropping so far, and, since your average power in each selected gear will be higher, that points to quicker thru the gears. So there is another option, but pressure is better and probably less money too.
The higher stall, streetable stall, only helps you get off the line, and if you happen to downshift into a sub-stall rpm. Once you are accelerating past stall rpm, it'd pretty much all on the motor. The stator is still giving you something, but the shape of your power-curve remains the same, and if there is a hole in the power delivery, that will not go away.
But you can change the size of the hole.
With say a 2000 stall, and the start of the powercurve being say 3400, that is a mighty big 1400rpm hole.
With a 2800TC the hole is reduced to 600rpm.
With a 3400TC, the hole goes away.
Same goes for the A833 4-speed, with average drops to 72.5%. Shifting at 5200 The Rs drop to 3770, hole G-o-n-e.
Sorry for your loss...haha.I broke a 3.55 7.25 SG friday night and had to replace with a 2.76 open to get to school on Monday :-( ...went from a rocket off the line to a freight train on the freeway, with as much acceleration......neutered!
If this is the case, I hope I can figure it out. I will say that the car IS faster. Definitely. With the 2.76s it really didn't even want to spin one wheel, now with the 3.55's it'll smoke both tires. However I'm getting some wheel hop and I'd like to get these weak springs off the car before going too far.I'm goin' with this right here
With the new numbers, The Wallace predicts ~132 psi, and the new V/P is 106, better than 99, but still pretty weak. We'll see how your Compression test compares.
Average 1331 - 130, 133
2 - 135, 134
3 - 131, 129
4 - 134, 133
5 - 136, 136
6 - 140, 139
7 - 122, 122, 120
8 - 137, 137