Re: 250hp 300 ft/lb from a street 273? Too much to ask for?
[Re: HotRodDave]
#1051941
08/13/11 10:52 PM
08/13/11 10:52 PM
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Joined: Oct 2009
Posts: 266 Seattle Wa
PowerWagonDude
enthusiast
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enthusiast
Joined: Oct 2009
Posts: 266
Seattle Wa
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I would use an Isky Supercam 262 part #390126. It has 262 seat duration which is fairly short for torque. It has .435 lift which is more than the old 340 cam and has [Email]208@.050[/Email] lift. And best of all it is cut with a 108 LSA lobe separation which will keep compression up if you are using low compression pistons. The tight LSA keeps torque high but limits your topend rpm, not really a factor in a street truck. I would also advance that cam 2-4* also good for low rpm torque which you need in a truck with a small cubic inch engine. I know everybody likes the new modern cams like voodoo and xtreme energy comp cam but just try to find a small cam that has a 108 LSA in those modern designs. Its not so easy. IMO that would make a nice cruiser truck engine with probably as much or more power than a 318. This is an old school cam but a 273 is also old school. This cam is available from Summit Racing for about $136 ISKY - Grind No./Type 262-SUPERCAM HYDRAULICLow/Mid-Range performance cam. 9.51 compr. 3.08-3.70 axle ratio. Passenger cars and trucks. Up to 625 CFM Carb.RPM-Range 2000-5500Valve Lift - INT .435 EXT .435Valve Lash Hot - INT
Last edited by PowerWagonDude; 08/13/11 11:01 PM.
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Re: 250hp 300 ft/lb from a street 273? Too much to ask for?
[Re: PowerWagonDude]
#1051942
08/15/11 10:31 AM
08/15/11 10:31 AM
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Joined: Jan 2003
Posts: 16,123 Grand Haven, MI
patrick
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
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cam, I'd look at the lunati voodoo 60400 or 60401, use comp #901 springs. try get as much compression as you can....
IF you have to go buy new pistons, you'd be better off starting with a 318 magnum, redrill the heads to LA pattern, regrind the roller cam, and put your induction on it. you'd be looking at 300+ horse & torque with better drivability.
1976 Spinnaker White Plymouth Duster, /6 A833OD 1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!*** 2011 Toxic Orange Dodge Charger R/T 2017 Grand Cherokee Overland 2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
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Re: 250hp 300 ft/lb from a street 273? Too much to ask for?
[Re: dogdays]
#1051946
08/16/11 05:42 PM
08/16/11 05:42 PM
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Joined: Jan 2003
Posts: 16,123 Grand Haven, MI
patrick
I Live Here
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I Live Here
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Posts: 16,123
Grand Haven, MI
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Quote:
I'd start with your 273 block and bore it 0.030. Use the 4" crank, stock length rods and custom flattops. You're now at 335 cubic inches. Or the 3.58" crank right at 300 cubic inches. I'd use Magnum heads with a decent valve job and a Performer RPM. A 600-625 cfm carb would top it off. I'd suggest a single pattern cam with about 210 degrees duration and the biggest lift you can find ground on a 110 degree LSA. With headers you'd be above 300 hp and 350 lb-ft torque easily, it's pull so hard you would be amazed.
It's so much easier to make power with a slightly bigger engine and you won't have to run 4.56s to keep up on the street.
R.
anything bigger than 1.78/1.5 valves and you are notching the block for clearance. 1.88/1.60 WILL HIT
not to be Debbie Downer, but this recipie sounds like a very expensive engine (stroker crank, custom pistons) that will still get spanked by a .030 over mag headed 318....
Last edited by patrick; 08/16/11 05:43 PM.
1976 Spinnaker White Plymouth Duster, /6 A833OD 1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!*** 2011 Toxic Orange Dodge Charger R/T 2017 Grand Cherokee Overland 2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
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Re: 250hp 300 ft/lb from a street 273? Too much to ask
[Re: crlush]
#1051950
08/17/11 01:03 PM
08/17/11 01:03 PM
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Joined: Jan 2003
Posts: 16,376
dogdays
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I Live Here
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Posts: 16,376
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The stroker concept is really easy to justify. You spend more for the crank, maybe a little more for the pistons (273 pistons cost about the same as custom forgings) and save on the valvegear because you don't have to have super-dee-duper springs, etc. The stroker engine doesn't need to see 7000 rpm, the 336 will be drawing the same air at 5800 rpm, the 300 at 6400. There will be a torque increase to the torque peak proportional to the increase in displacement. After the torque peak it'll fall off faster with the same heads but as a decent set of Mag heads are good for about 400 hp I think that's no worries either. I think with the right cam, headers and a little work on the heads you're looking at a 380 hp engine from the 330, and an easy 360 lb-ft of torque.
Notching the block is not difficult, there's a pictorial on the Web by Bigblock Ranger. He did it with pistons in the block, used coffee filters to catch the shavings.
The one problem to which I have no answer is will the rods hit the bores with the piston about halfway down. This comes out of reading, I remember that when Oldsmobile stroked the 425 to 455 they used shorter rods as the stock 425 rods supposedly contacted the lower edge of the bore.
Of course you could build a 360Mag based motor for the same amount and have a better engine, but with the OP's restriction to stock 273 block this is the best way to have a streetable engine with a ton of power, short of nitrous or a supercharger.
R.
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