Low speed torque and driveability ?

273 said
Plus I'm questioning that big cam have poor low speed torque, now obviously we've all seen bigger cams give up torque to smaller cams but when put in perspective and especially vs a stock low powered 2bbl version of the engine bigger cams still seem to do decently down low, obviously we generally don't know what's going on under 2000 rpm.

Here's a dyno of a stock 2bbl cam to xe262h cam among other mods, as you can see all doing decent down to 2000 rpms, the one below doing well under 3000 rpms would have to look the cams up but are 390-430 hp 360, cams must be fairly decent and Richard Holdener dyno of a stock 2bbl 360 engine dyno'd 330 lbs-ft @ 2000-3000 rpm and the 380hp crate from my other post doing better than all at 381 tq @ 2500 rpm.

And the bunch of 318/340 dyno's with various cam all making decent 2000-3000 rpm torque numbers from what we can tell.

I'm just not seeing big torque drops were you could say that's why driveability suck and gonna need stall and gears to get her to be able to pull away from a stop sign, especially when there making way more torque than a stock /6 273 318 even 2bbl 360.




Torque
RPM123456
2000357.3376.9346.7356.8349.6
2200350.7370.9347.9351.3345.8
2400349.8367.5355.9353.1350.4
2600351.5367.1359.5352.6361.0353.8
2800358.8374.1367.1357.7359.7361.0
3000370.1388.0373.6363.2364.1371.9
3100371.7390.6375.9366.0369.3375.6
3200371.2390.7376.0368.7375.7381.6
3300371.3390.3377.1368.8381.0389.6
3400367.8388.9374.1368.7386.3396.1
3600361.2381.7369.2367.0390.8400.1
3700357.7375.0367.1363.3391.8400.6
3800349.9370.4363.6358.7386.9398.0
4000342.8357.8354.9348.3380.3394.0
4200331.0346.3344.9337.6383.1389.5
4400316.4329.1329.0325.1378.1385.5
4600295.7311.0313.3310.5368.2375.6
4800286.5293.8299.8290.7355.1363.3
5000270.9278.7282.0272.4342.7351.9
5200330.3337.8
5400311.8321.7

360 build

Dyno Test
HorsepowerTorque
RPMTest 1Test 2Test 3RPMTest 1Test 2Test 3
2600172.7N/A166.12600348.9N/A335.6
2800190.6196.6183.92800357.7365.8345.1
3000204.3207.51973000357.7363.3345
3200190.1226216.23200359.6370.7354.9
3400237.6242.4235.33400367374.5363.5
3600258.3267.7253.13600376.8390.6369.3
3800281.4281.8274.93800388.9389.4379.9
4000299.6310.1297.14000393.5407.2390
4200319.1313.8314.44200399.1392.3393
4400320.8329.4328.54400383.8393.1392
4600354.5352.73524600404.8402.7401.6
4800359.5379.4375.44700397.2420.2408.4
5000377.4392.3389.44800393.4415.2410.7
5200378.8396.5401.64900399.8410.6412.2
5400390.3401411.75000396.4412409.1
5600384399.14205200382.6400.4405.7
5800387392.3426.55400379.5390400.5
6000369.2391.8430.25600360.2374.3394
6200370.2377423.35800350.5355.3386.1
Click to expand...
Now there was the qualifier, "among other mods". To properly compare and assert something you need as direct a comparison as possible.
About 25 to 30 yarns ago, PHR magazine did a series of tests to compare 383 Chev builds. They rebuilt a 350 and dyno'd it. Then they put a stroker crank in with 400 rods. Now you could use the 350 pistons, but compression would be up a bit so they had pistons to keep the compression as close as possible installed. The cam was the same, and they tested it this way.
Then they pulled it apart to install 5.7" rods instead of the 400 engine 5.565" rods. Of course the piston pin location had to be changed, so new pistons with the crowns identical to the second set. It was dyno'd again.
The increase in displacement provided a modest increase in torque and power, but not what you would expect. Changing rod length had virtually no effect on torque or power.
What did make a big improvement was to change the cam to one more suited to the 383. This mainly involved LSA and valve lift with a very small duration increase. The main increase was the LSA change to match the cylinder displacement and intake valve diameter and the bit more lift. In a 350 engine the LSA would not have been correct, so any benefit from the minor increase in duration and lift would have been less than what would be expected.
The one thing they did note was that the longer 5.7" rods made the 383 quieter due to less piston slap.