Torque estimate?
Thread Starter
Melting Slicks
Joined: Mar 2004
Posts: 2,965
Likes: 419
From: Melbourne FL
Torque estimate?
I'm considering ordering one of the new RS 5 speeds from Keisler and was wondering which one based on the motor I'm building. It started out to be a mild 406 to be used as a daily driver. Initially it was just going to be a 406 shortblock with all my current L79 components bolted to it but that's changed slightly and it may be a little stronger than I first was projecting.
Basically, it's a .0.030" over SBC 400 with a calculated 10.25:1 compression running a set of Trick Flow Twisted Wedge aluminum heads. It has a Comp hydraulic roller cam, p/n 12-432-8. That's .510/.520 lift with 282/288 duration and LSA of 110. Exhaust is under the chassis Hedman headers with N11 mufflers out the back. On top is a dual plane manifold with a BG 650 DP.
I was thinking the 400 ft-lb rated RS400 would be adequate and if I go with the 2.80 first gear, it will probably bump that rating slightly. I won't be banging the gears all the time or doing full throttle launches but certainly won't baby it either!
So what do those with similar motors estimate for torque and HP?
Basically, it's a .0.030" over SBC 400 with a calculated 10.25:1 compression running a set of Trick Flow Twisted Wedge aluminum heads. It has a Comp hydraulic roller cam, p/n 12-432-8. That's .510/.520 lift with 282/288 duration and LSA of 110. Exhaust is under the chassis Hedman headers with N11 mufflers out the back. On top is a dual plane manifold with a BG 650 DP.
I was thinking the 400 ft-lb rated RS400 would be adequate and if I go with the 2.80 first gear, it will probably bump that rating slightly. I won't be banging the gears all the time or doing full throttle launches but certainly won't baby it either!
So what do those with similar motors estimate for torque and HP?
Instructor
Joined: Sep 2009
Posts: 222
Likes: 55
From: Chico California
I second that. A well built 400 with good heads like you decsribe should easily be in the high 400 lb/ft range. Also, you don't mention what rear end gearing you're running. Unless you have tall gearing (3.08 or taller) I would strongly recommend that you stay away from the RS 400 or 500 with the 3.37 first gear. That's simply too deep a gear for the amount of torque your motor should be putting out. I've run a big block with an older TKO running a 3.27 first gear with 3.50 rear gearing, and first gear was almost useless. If you're going to run an RS tranny go with the 600.
Thread Starter
Melting Slicks
Joined: Mar 2004
Posts: 2,965
Likes: 419
From: Melbourne FL
Rick, the whole first gear/differential ratio situation has been discussed in the Keisler 5 speed thread. They are now offering an optional 2.80 first gear for the RS400 (and probably RS 500 as well). I am running a 3.70 rear and was going to take advantage of this option but responses to my query seem to indicate I'm underestimating the torque of my new motor and have to re-think my transmission choice. Frankly, I didn't realize the ZZ383 put out that much torque! I'm probably one of the few that underestimates the output of their motor 
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