Max Torque Big Block

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mbaird

mbaird

mbaird
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What would you build for a max torque BB ?
My daughter bought a 77 MH with a 440 and I got thinking about it.
I am not doing anything at the moment but rather curious about It.

B or RB ? Stroked ? Heads and portwork ? Cam profile ? Headers or Manifolds ?

Lets hear your recipe and reasoning.
 
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mbaird said:
What would you build for a max torque BB ?
My daughter bought a 77 MH with a 440 and I got thinking about it.
I am not doing anything at the moment but rather curious about It.

B or RB ? Stroked ? Heads and portwork ? Cam profile ? Headers or Manifolds ?

Lets here your recipe and reasoning.
Click to expand...

I just finished a 496 for my '65 Coronet and it has 630 torque and 610 hp. It is a pump gas engine with Trick Flow heads, a small hyd roller cam, small headers, and a Holley Sniper EFI setup. I designed it to lug my 4000 lb Coronet around town while still having enough power to pull me down the 1/4 mile in low 11's.

If I was doing a motor home engine I'd shorten the cam up a little more and probably use a different cylinder head but I'd stick pretty close to this same design. Maybe shoot for 600+ torque and 500 hp.
 
AndyF said:
I just finished a 496 for my '65 Coronet and it has 630 torque and 610 hp. It is a pump gas engine with Trick Flow heads, a small hyd roller cam, small headers, and a Holley Sniper EFI setup. I designed it to lug my 4000 lb Coronet around town while still having enough power to pull me down the 1/4 mile in low 11's.

If I was doing a motor home engine I'd shorten the cam up a little more and probably use a different cylinder head but I'd stick pretty close to this same design. Maybe shoot for 600+ torque and 500 hp.
Click to expand...
Single plane ? What were the cam specs ?

I had a 65 Coronet 500 with a bigblock . Loved that car!
Ran 12.90 with a freshened New Yorker 440 headers and a 284/484 cam.
 
Nope, final answer, lolol! But in all seriousness, if you get on the HD/motor home forums and research it, your going to pay the price now or later... the efficiency and extreme long term reliability of the diesel route pays for itself in fuel consumption over the long term. But yes, diesels are an expensive option, it’s advisable to upgrade the transmission and rear axle in a high load diesel application, Diesel harmonics (especially in six cylinder versions) oftentimes match the running rpm of the drive train, effectively multiplying harmonic vibration, and a good 6BT would bring a premium. It depends on how much your going to use it, but any real long distance and long term use will come out cheaper by going diesel. But, with only moderate usage, Andy’s plan would be the route to take.
 
A mild 440 would work fine. Low compression, small carb & cam and a gear vendors OD. Don't build a motor that costs 50 times the value of the motor home.

My very mild 460 puts down around 500 Ft/lbs and moved my short box 4x4 easily.
 
I have to say that although deisel power sounds attractive the reality is nobody puts enough miles on a motorhome to pay off.
The early 6BTs only put out around 400 ft/lbs and at such a low rpm it would require a rear gear change.
Then consider how hard they are on A/T and that pushes the price up even further. Then you have to cool that beast !
For around 5 grand you could build a stroker BB easily... Its the head requirements and cam profile that are in question.
And just how much torque can you get out of a BB that would survive motorhome conditions.
 
Yes... Andys build sounds impressive ! I wouldnt have guessed that much torque with a mild cam.
 
505 CI. Edelbrock MW Victor heads. 12.7 CR. Soilid Roller. 670L. 274/282 @ .050. Indy cross ram, 750 eddies. 720 HP, 677 TQ.
 
I was at the dyno shop today with a 540 inch big block that made 700 ft-lbs of torque at 4000 rpm and 600 hp at 5800 rpm. It is going in a mud bogger truck. Probably too hard core of a build for a motor home but it gives you some idea of the torque you can make. We tested a 520 inch BB Ford that was built for a motor home late last year. That engine made 600 ft-lbs of torque at 2500 rpm. It had a very small hyd cam in it and stock cast iron heads. I think it made around 400 hp peak since it was built for low speed grunt not high speed power. Something like that would move a big motor home down the road pretty well.
 
Theres a difference between max torque and low speed torque (off idle powerband).

Torque on a NA engine is mainly a product of cubic inch.
Race engines can produce more than 1.4 lbs-ft per cid but a low rpm idle-4500 is gonna be 1.1 to 1.15 lbs-ft per cid. So if you want more than 500 lbs-ft in MH powerband of idle to 4500 you need to stroke it.

For parts selection you want cam intake etc.. the works off idle basically stock or a mild upgrade.
 
You're not going to build an engine like Andy's for $5K. In fact I'd say you wouldn't get a stroker capable of 600lbs feet together for twice that. Lower your expectations, and do a simple flat tappet 440 with factory heads and enjoy. The stroker route - I'd use the 470 recipe. Taller piston, a little more grunt.
 
Torque is almost a pure function of displacement, NA, as said. Buy the largest stroker you can get if you want torque. A 4.25 or 4.5inch crank in the 440 block with a cleaned up set of factory heads, good exhaust valves, HR or hydraulic flat tappet cam and you should be happy, except at the gas pump. S/F....Ken M
 
You don't need a stroker. Dad had a 30' Vogue motorhome in the 70's w/ a 440. Stock bottom end, some ported iron heads and a custom Camonics hydraulic camshaft that used stock rocker arms.

Once while he was standing with a group of men he mentioned he could easily run 80 mph up the grade heading up to Twin Lakes in California. One of the group called BS and bet him $500 he couldn't do it. They set a date to meet at the grade with witnesses. Before the day, the disbeliever met one of my Dad's fishing buddies and was told, "That bet is a bad idea. I rode with Bill in that motorhome at 85 mph up that grade."

Bet date cancelled.

Plumbing contractor had one of Dad's stock stroke 440's in an even larger motorhome. The contractor kept a a framed picture of his ticket from the CHP for racing a Jaguar on a California interstate...........115 mph.

I'd have Pop give you the particulars but he passed some 20 years ago.
 
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In the case of a motor home, it's going to be more about usable torque than maximum torque, rpm range of idle to 5500 rpm. Stay with stock stroke and rod length just rework the iron 452 heads by the MP templates, polish and unshroud the chambers to minimize detonation, and add hardened exhaust valve seats. Use a set of inverted dome pistons and set the quench for .038 and target no more than 8.9:1 compression (Do you really want to be limited to premium gas in a motor home? Better own stock in Exxon...) Use a Lunati Voodoo 262/268 hydraulic and Edelbrock performer with functional EGR, H.E.I. conversion ignition, F.I. Tech self tuning fuel injection. The best option for exhaust appears to be Hedman ceramic street mid-length headers and three inch duals with Dynomax dual inlet/outlet stainless motor home muffler.
 
mbaird said:
How much a 6BT and whats entailed in installation?
Click to expand...
depends on your skill level. and what year 6B you start with.

mbaird said:
I have to say that although deisel power sounds attractive the reality is nobody puts enough miles on a motorhome to pay off.
The early 6BTs only put out around 400 ft/lbs and at such a low rpm it would require a rear gear change.
Then consider how hard they are on A/T and that pushes the price up even further. Then you have to cool that beast !
For around 5 grand you could build a stroker BB easily... Its the head requirements and cam profile that are in question.
And just how much torque can you get out of a BB that would survive motorhome conditions.
Click to expand...
I used to work for a diesel performance shop and truck pulled for several years before all the high school kids with their mommy's money ruined it.

Anyway, that 5 grand stroker in a confined environment like a motorhome is not only going to run hot, but be very hard to cool. 2nd. you can get a late 90s, I'd go 99-00 non-HP Cummins for less than 1000, in running order. Those truck are rusting out badly and you can get the whole truck usually for not much more if you look hard enough. Then you have two options, you can stay with the electronic injection pump and run something along the lines of a TST PowerMax 3 or similar tuner. a a stock 99, with the TST tuner, we saw an increase of 167 hp and 350 ft lbs at the rear wheels. putting you around 400 hp and 750 ft lbs at the tires, reliably. and stayed under the exhaust temps that wreck havoc on pistons. Add 4-5 hundred for the tuner. As for the transmissions. my pulling truck was putting 1350 ft lbs to the rear tires, in 10 years of pulling, dyno runs, drag races, somehow I never blew the transmission. Granted it was a NV4500 5 speed manual with a Southbend dual disc clutch. And guess what, they did put that very manual into a few motor homes. even school buses.

your other option would be to swap to a mechanical P7100 injection pump, then you can simply turn the power up and down with a simple screw driver.

If you source your parts right, you could do it and make more power at a more usable RPM with better fuel economy for near the same or LESS than a big block stroker. For comparison, I'm gonna have about 6500 in my darts 440 drive train, I'll only be making my 500-550 and 550-600 ft lbs. at the flywheel. Just the heads alone for a stroker BB are gonna set you back 1000-1500, cam kit- 500, stroker crank, rods and pistons 2000-3000. intake 2-3 hundred.

RB stroker: 3700 engine alone
Trans upgrade to handle that power: 1000-2000 plus converter.
Total 5-6 grand for maybe 650 hp and 700 ft lbs flywheel

Cummins, 1000-1200 is the going rate for a good used running motor
Tuner: 4-5 hundred (mechanical injection pump if you went that route would be a 1000.
NV4500/NV5600: 1000-1500.
Aftermarket injectors: 500
HX40 turbo: 500
Clutch: 900

Total for cummins swap with transmission: 5500-6000 for 650 hp and 1350 ft lbs at the rear wheels (I essentially gave you my truck's combo, it was also my daily driver and was featured in 8 lug diesel magazine years ago). Add 1500ish if you went automatic trans. (could go with an Allison swap for less). Oh and I averaged 18.6 mpg city/highway combined. a motorhome would be less but more than a big block stroker for sure.
 
not sure a motorhome can be set up easily for a manual. I sold Dodges when the Cummins came out and they were hard on autos at the time... Dodge finally came out with a TSB to install a giant *** cooler below the cab.
The thing about a low rpm torque motor is that is doesnt require expensive valve train or high flow heads.
 
mbaird said:
not sure a motorhome can be set up easily for a manual. I sold Dodges when the Cummins came out and they were hard on autos at the time... Dodge finally came out with a TSB to install a giant *** cooler below the cab.
The thing about a low rpm torque motor is that is doesnt require expensive valve train or high flow heads.
Click to expand...
yeah, at the time. You're talking circ 1989--1993. Vast improvements have been made and really, unless you're doing stupid power, both the 46 series and the 48 series autos hold up okay, iggest weakness if valve bodies but easily upgraded and cheaply. And manuals can be used in a motorhome just fine, depending on WHAT motor home model. And to get max power out of an RB, you're gonna have to upgrade the heads and valve train. especially with a cam. Whether that's stock heads ported and polished or aftermarket aluminum ones, you're still looking at 1000 in heads easy.
 
I’d do something like:

8.5-9.0cr
Good quench
Very mildly reworked stock heads
Pretty small cam, not real fast rate, slow bleed lifters
Really good ex valves and seats
 
If you crank the performance up, definitely going to have to upgrade the cooling too. Also, since no one has asked the question... Does it have the industrial medium duty413/440 with the commercial municipal water pump and the gear driven reverse rotation cam or is it a standard 440 truck engine? I mentioned Cummins 5.9 litter first, but I think the best upgrade would be an IH DT466 with a six or seven speed Rockwell from a medium duty International truck. All kinds of those on the market in municipal or utility auctions. Rest of the trucks are worn slap out but the powertrains are slant 6 reliable.
 
PRH said:
I’d do something like:

8.5-9.0cr
Good quench
Very mildly reworked stock heads
Pretty small cam, not real fast rate, slow bleed lifters
Really good ex valves and seats
Click to expand...

I would agree if there was a better option than 50 year old heads. Cast iron heads are good for an application like this but it would be even better if there were brand new thick wall castings with quench. That doesn't exist so you have to use 50 year old parts which is a crap shoot. We had an engine on the dyno recently that was a full rebuild using all stock parts (number matching type of engine) and one head let go after a few pulls. That head had been fully rebuilt, pressure checked, magnafluxed, etc. and it still let go after it got a little bit of stress. So the owner had to go find another casting and pay for another head rebuild.
 
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