421 stroker 243/799 or 317 heads?
02-20-2017, 12:26 PM
#41
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My dad's 08 2500 HD has 823 heads on it from the factory. IMO, that's either too much port volume or not enough cam because it's kind of a dog at low rpm. Once it hits 3000 it starts to pull hard.
Contrarian viewpoint...Hot Rod(IIRC) did a cathedral vs rectangular shootout on a large engine and found down low the cathedral heads were stronger and gave up very little up top.
Contrarian viewpoint...Hot Rod(IIRC) did a cathedral vs rectangular shootout on a large engine and found down low the cathedral heads were stronger and gave up very little up top.
02-22-2017, 08:16 AM
#43
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No the truck isn't lifted. Much easier to hook a gooseneck to a near stock hight truck or load/unload from the bed standing on the ground. No plans of lifting either but if I were too it would be geared accordingly. Plus it's an automatic so torque at 1500rpm is basically useless. My torque on the stock top end and 421 bottom with an "RV" cam style peaked at 3800rpm. Be a different story if it were boosted then would gain significant torque at highway cruising rpm OD lockup 2200-2300rpm.. It will make plenty of TQ with this build. 65mph 3rd gear lockup is 3200rpm I think maybe 3500. I'm pretty confident in it making power where I want it to with the 235 heads.
02-22-2017, 09:56 PM
#44
For a truck, low end torque rules. As said above, my dad's 6.0 doesn't really start to pull until 3000 rpm. My F150 3.5 Ecoboost has a flat torque curve coming in at 1800 rpm. It will outpull the 6.0 from a dead stop and will pull a 20 ft trailer better because it doesn't need to rev to get into the powerband.
02-23-2017, 12:31 PM
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I'm not arguing the realy low end torque is better in a truck at all. I've had my 2500hd for 10 years and 7 years with the 421 bottom end. Also had a 2013 3.5 ecoboost f150 and it pulled amazingly well. I also drive semi for a living and have done heavy haul/ oversize for a while and grew up living and working on farms. I'm very familiar with the benefits of bottom end. I'm just stating that in my application it's not as needed. Also will still make more than it did stock @1500rpm. My next build will be a twin turbo LSX built for bottom end and flat torque as similar to the 3.5 eco as I can get just a bigger V8 version.