400 vs. 377

[Guest MegaShaft_2000]

I'm curious, I hear a lot of good things about 377's, but since you need a 400 block for it, is it worth it giving up some displacement to make a higher-revving engine? Would the extra torque the 400 has go to waste since the Z is so light, therefore making making high-rpm HP more useful?

[grumpyvette]

after building lots of both 406sbcs and 377sbcs I can tell you the 406 has a slight hp advantage (maybe 15hp)over the 377,but the 377 makes more hp per cubic inch of displacement but the 406 sbcs torque IF GEARED CORRECTLY MAKE IT THE FASTER ENGINE BY FAR

[Peternell]

OK Grumpyvette, I'll bite. Please expand on the GEARS comment. I'm building a 406 w/a TH 400 for drag racing w/stock wheel wells w/drag radials. I've got a 3.36:1 R-200 (thanks Scottie-GNZ) and a 3.90:1 R-200. Heck I could find a 3.54, 3.70 or 4.11 if need be. Also the car would see both 1/8 and 1/4 mile tracks.

 

(I know tire size thru engine torque specs are needed) but:

GENERALLY what's my best gear ratio??

Steeper gears for quicker acceleration applies to situations where tire sizes is relatively unlimited, but w/the Z wheel wells and 25" tires would a 3.90 or 4.11 car be over geared??

[grumpyvette]

ok first this is for hot street use, so you determine the rpm range and max rpm the engines work best in, now some of that is determined by the cam,etc.(Ill save you the trouble a 406 spend its most effective time (peak torque curve) in the 4200-6200 power range (if your racing a 4000rpm stall converter) and a 377 has its (peak torque range) in the 5100-6500 range (if your racing a 4500rpm converter) so figure 5200rpm for the 406 and the 377 as 5800rpm.look here

http://www.cloudmaster.com/cloudmaster/speed.html

now if you play around youll find that a 3.73 gear works well with 406 engine with the 400th trans,and 25" tires while the 3.77 can use the 4.11 rear more effectively