Convertor/Gear Ratio Advice

[canadian duster]

I am looking for advice on a convertor stall and gear ratio for my Dana 60. The engine will be a 408" topped with a 6v71 blower. expecting ~600hp. The transmission is a 727 and then a dana 60 out back.

Driving condition will be 70% street and 30% cruising (some longer trips hopefully in the future). I'm thinking of a 3.54 or 3.73 due to the high low end torque this engine will be pushing. Id like 4.10's but suspect cruising at 60-70 mph would be +4000 rpm. 275/70/15 tires.

Thanks

 

[roccodart440]

Those tires and 4.10 gears will turn 2,750RPM at 60MPH.

If you aren't going to run an OD I'd want to be in the 3.55 or 3.73 range for your rear gear.

 

[ScampMike]

Those tires and 4.10 gears will turn 2,750RPM at 60MPH.

If you aren't going to run an OD I'd want to be in the 3.55 or 3.73 range for your rear gear.

seeing as we're on the subject - I have a 408 (300 RWHP), a 727 - full manual kit with a 5k spragless converter backed by 4.10's - 305/15's - I want to "back it off" some to make it more street friendly without loosing too much performance.. for now the 4.10's stay - I am thinking 3800ish on the stall...? yay, nay?

 

[roccodart440]

3800 should work really nice. I run a 3500 in nearly the same combo

 

[jbc426]

I am looking for advice on a convertor stall and gear ratio for my Dana 60. The engine will be a 408" topped with a 6v71 blower. expecting ~600hp. The transmission is a 727 and then a dana 60 out back.

Driving condition will be 70% street and 30% cruising (some longer trips hopefully in the future). I'm thinking of a 3.54 or 3.73 due to the high low end torque this engine will be pushing. Id like 4.10's but suspect cruising at 60-70 mph would be +4000 rpm. 275/70/15 tires.

Thanks

My daily driver spins out around 500 hp from an EFI'd Magnum based 408" motor. I chose 3.91's out back with 275/60-15 Nitto 555's. The power is transferred through an Extreme Automatic's Stage 2 modified 200R4 with a 4000 rpm stall high-end torque converter with a triple disc carbon fiber lock-up clutch. First gear is 2.76 to 1 and overdrive is .67 to 1. Locking up the torque converter is like having a fifth gear. I spin 2500 rpm cruising at 80 mph, and nothing I've encountered on the street has beat me yet. I know there are faster quicker cars out there, but most people don't choose their combination of parts to suit the actual type of driving they are going to do.

Getting 5 mpg can tend to keep the car off the road more often than not. My combo pulls down 14mpg around town and 18mpg on the freeway at 70 mph.

There are lots of quicker faster cars around but many are sitting in garages, because they missed the combination of gears, transmissions and engine mods to make their cars both fast and efficient enough to drive daily. That's fine for a lot of guys, but I like driving my junk. If you want to build a car you can enjoy on a regular basis, be sure and do your homework on matching your driveline combination to your desired end result. What ever you choose to do, have fun.

I know because I have a garage queen too. I don't drive it nearly as much what with race gas being nearly $8 a gallon. If they beat me in the '68, I pull out the 700+ hp '70.

 

[canadian duster]

Thanks guys.