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Old 08-14-2003, 07:42 AM   #1 (permalink)
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building a 454 to tow with

i am in the search now for a 454 BBC for my 1950 GMC dually. I will be towing on occasion 14,000 lbs or so, but typically, just 7,000 lbs. My question is, what RPM should I be targetting to cruise at when I build the motor? I want the peak torque farily low so I can cruise at 65 mph or so without screaming the engine. right now, my rear end has what i believe to be 5.14 gears. I am going to be running a gear vendors OD unit so I will have the .73:1 overdrive. i figured with 32" tires, i will be at 2500 RPM's at 64 mph with the 5.14's. I will be running a sm465 tranny. I can swap out the rear end to 4.10 gears if need be, but would it be necessary? Is 2500 RPM's too much for a BBC to cruise at? Should I target it in the lower 2k?

ok, now for the building questions:
This is a slow project so I have some time to build the motor when I get one, my goal is 600 lb ft. of torque, not really concerned with HP as that will come with torque and the main focus of this engine is towing. how feasable is 600 lb ft. of tq. from a BBC? i know it's not unheard of, but with a good build through heads, cam, pistons (higher compression), what do I need to look for to get that kind of power from it? I want to try to keep the tq. peak low so that it is right in my cruising range. thanks

mods....wasn't sure where to put this, a mixture of questions, move if need be
greg


edit: the gearvendors is a .78:1 OD so i have to refigure my RPM's....
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Old 08-14-2003, 08:11 AM   #2 (permalink)
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600 FT LBS IS DOABLE BUT ONLY WITH MORE COMPRESSION. MORE COMP. ALSO YOU HAVE A BETTER CHACE OF DETINATION. LOWER COMP. AND A GOOD CAM IS THE BEST CHOICE. FOR GAS REASONS IF YOU WANT TO RUN HIGH COMP. I.E 9.5 AND HIGHER YOU WILL HAVE TO RUN HIGH OCTANE FUEL. AS FAR AS THE HEADS FOR TQ AT LOW RPM THE SMALLER THE PORT THE BETTER FOR VELOCITY. IF YOU RAISE THE RPM THEN YOU NEED BETTER FLOWING HEADS AT THAT RPM LEVEL. MY BBC IS 9.0 COMP. SMALL CAM AND EFI HEADS ( SMALL PORT ) AND MAKES TONS OF TQ
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Old 08-14-2003, 08:16 AM   #3 (permalink)
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i guess more importantly than the numbers (amount of tq), is where the tq is at. basically i just want the most power i can get at a low RPM for towing comfortably with. i don't want to have to keep the engine running at 3000+ RPM's everytime i tow with it. thanks
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Old 08-14-2003, 12:59 PM   #4 (permalink)
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Re: building a 454 to tow with

Quote:
Originally posted by bignissan

This is a slow project so I have some time to build the motor when I get one, my goal is 600 lb ft. of torque, not really concerned with HP
600 is not out of the question without real high compression, but it will take a roller cam and 9.5 cr with iron heads. You can go to aluminum heads and 10.5, which would be a little better.

Check out the rollers that Camcraftcams (tried to link it, but can't copy and paste anything right now)grinds. They have a reputation of making lots of torque and Charles will work with you to get what you need.
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Old 08-14-2003, 01:00 PM   #5 (permalink)
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Old 08-14-2003, 01:04 PM   #6 (permalink)
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Quote:
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Thanks for the fix, newbie!
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Old 08-14-2003, 02:28 PM   #7 (permalink)
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thanks! sounds good! 'm not worried about running high octane, this will be a tow rig only. i plan on filling up with about 120 gallons of gas and just taking off to wherever i am going. I have a 108 gallon cylinder gas tank that will go in the bed, then feed into a stock type in the cab(on the old 50's).
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Old 08-14-2003, 02:41 PM   #8 (permalink)
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Thanks for the fix, newbie!


Been around a while, just quiet most of the time.

back at ya!!

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Old 08-14-2003, 03:20 PM   #9 (permalink)
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mlclark has been here about 1 year and half longer!!! a not so newb newbie thanks!
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Old 08-15-2003, 07:29 AM   #10 (permalink)
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600 ft lbs.... Hmmm.

Just a FYI on the Vortec 8.1 (2003 Suburban 3/4ton spec):
340 hp at 4200 rpm and 455 lb-ft/torque at 3200 rpm

Just wondering about a USED but reliable diesel engine? With the chassis and planned towing weight, seems like there should be a surplus diesel you could find to drop into that chassis. Trying to remember how wide the engine bay is on that thing.

Still a really cool project two rig!

Tom
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Old 08-15-2003, 07:32 PM   #11 (permalink)
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the 454 in my '99 3/4 ton burb (4l80E, 4.10s) cruises at LOW rpm's. around town it will lug happily away at 1200rpm in 3rd gear, just cruising along. on the highway it is under 3000 up until you hit 85-90mph. The motor in my truck makes 290hp and 400ft lbs stock, but with the little tweaks its got (banks 4" exhaust, K&N filter) i would assume it to be up around 300hp and 415ft lbs. it tows GREAT. super awesome up the steep ass hills at 80mph with 7000lbs great. but great can always be better

as to how to build one for towing, get a desktop dyno program and play with it from there. it will give you a good idea of how certain parts work together to make power at a specific RPM range.

But in short, think big cubes. its the only way to make more power without having to get into the tricky stuff. Get a stroker kit, think 500ci plus. and still run pump gas and low comp. to make crazy power. sure, you will get shitty mileage, but you will anyways towing 14k.
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