Let's talk TORQUE

[BUCKETOBOLTS]

Its easy to find secrets to build a high HP engine. But I'd like to talk torque monsters. What have you found to build massive bottom end torque? A square engine(bore=stroke), over-square(bore>stroke), or under-square(bore<stroke) design engine? What spec cams? What size and volume heads? How about rod ratio? Any exhaust secrets?

 

[bmc69]

I'm getting pretty outrageous torque numbers with the 408s I build..at very low RPM. We have been refining the design of the engines over time. Couple of 'secrets' included:

1. The 408 is 4.030 x 4.0 bore and stroke. Stroke length is important, obviously. And while increasing the bore size would help too, the blocks can't take much more than .040 overbore

2. Comp Dual-Energy (265 DEH) cam grinds really produce at low RPM. Typically end up with the cam advanced 4-6 degrees from straight-up.

3. Intake runner CSA is very important to keep velocity high at low RPMs. They are getting harder to find, but the oft-dengrated Edelbrock SP-2P intakes are the best choice I have found for building a low-moderate RPM 'torque monster'.

The 'downside' (I don't think it is a downside, but to each his own..) is that you end up with a motor that breaks the 300 ft-lb ceiling at less than 1500 RPM and peaks at almost 500 ft-lb below 4500. And then runs out of 'juice' very quickly after that.

 

[wildbill]

%) %) %) The quick way low $ is a 351W a good RV cam stock heads and small long tub headers. This will make a lot of torque. Other wise you will need a big one 400 to 427 W and the same goodies good luck and have fun. To get the #'s get ahold of the cam co of your choice and tell them what you want and they will help you with the right cam and all the other goodies. I deal with erson have had good luck with them. ;D ;D ;D Bill %)

 

[Broncobowsher]

Don’t forget our good friend ion. While having too much might cost you at the pump for the needed premium to keep him happy. A little in the compression ratio side sure helps a lot. My basic little 11:1 91 octane pump gas 351 makes 200 ft-Lbs just off idle all the way up to 300 then back to 200 at redline, and that is at the rear tire, not the engine.

 

[76Broncofromhell]

Play with the flywheel weight and that will affect your low end significantly. I would run a 408W with some decent heads (not super high-flow) and a nice roller cam with a reasonable torque curve. Then lighten the rest of the rotating assembly (pistons, rods, crank) and that thing will be a torque monster.

My 408 right now is a torque monster while also pulling a whole bunch of horsepower so you can have both. I can let the clutch out in second gear at lights and pull away without stalling. So I would tend to advise towards more HP on a stroker.

 

[swa0330]

Go Diesel ;D

Don't want to start a war here though. I am expecting my 4BT cummins to be putting out 450 lb ft at 1300 rpm. That is with some slight mods though. I should have the number from a dyno in 6-9 months.

 

[ginwisconson]

Its easy to find secrets to build a high HP engine. But I'd like to talk torque monsters. What have you found to build massive bottom end torque? A square engine(bore=stroke), over-square(bore>stroke), or under-square(bore<stroke) design engine? What spec cams? What size and volume heads? How about rod ratio? Any exhaust secrets?

More the better ;D