Re: 250hp 300 ft/lb from a street 273? Too much to ask for?
[Re: 78asprin]
#1051925
08/13/11 11:08 AM
08/13/11 11:08 AM
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Joined: Feb 2007
Posts: 1,025 Las Vegas, NV
dodgeboy11
super stock
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super stock
Joined: Feb 2007
Posts: 1,025
Las Vegas, NV
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Ahh, well that being the case, I would pick up a set of 302 casting heads and use the largest intake valve you can fit to your bore. The top of the cylinder may need to be relieved just a bit, but hopefully not. You'll want to run flat top pistons at zero deck. For a cam I'd consider something similar to this: http://www.summitracing.com/parts/CRO-31241/though I'd rather see 110 or 108 lobe separation. Port the heads, gasket match the intake to the 360 gasket size and run a Perf RPM intake. A set of headers and I would think this combo would easily meet your goals.
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Re: 250hp 300 ft/lb from a street 273? Too much to ask for?
[Re: 78asprin]
#1051927
08/13/11 12:27 PM
08/13/11 12:27 PM
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Joined: Jan 2005
Posts: 12,478 Kalispell Mt.
HotRodDave
I Live Here
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I Live Here
Joined: Jan 2005
Posts: 12,478
Kalispell Mt.
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The 4bbl 273 made 230HP from the factory so you are only asking 20 more HP, not aiming very high in my opinion. A set of headers and modern cam and you will easily surpass that with out pulling the heads. If you are building a 273 from scratch get flat top pistons made or buy the cheapie ones and deck the block, get some 273 specific gaskets from summit so you can get .030 quench (very small bores and tall pistons can run even tighter but that should be safe and effective). Run a good quality small tube header, SCAT I beam rods, back cut the stock valves(even 360 size valves are gonna be pretty shrouded), do a little basic port clean up and an XE265HL cam on a 110 LSA. You would easily make 300 hp 300#TQ
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: 250hp 300 ft/lb from a street 273? Too much to ask for?
[Re: 78asprin]
#1051929
08/13/11 12:47 PM
08/13/11 12:47 PM
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Anonymous
Unregistered
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Anonymous
Unregistered
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As others have said, headers and a mild cam will get you there.
Err on the mild side in cam selection since it's going in a truck.
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Re: 250hp 300 ft/lb from a street 273? Too much to ask for?
[Re: HotRodDave]
#1051932
08/13/11 02:51 PM
08/13/11 02:51 PM
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Joined: Nov 2009
Posts: 2,275 Desert Tracker
HYPER8oSoNic
top fuel
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top fuel
Joined: Nov 2009
Posts: 2,275
Desert Tracker
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Quote:
The 4bbl 273 made 230HP from the factory so you are only asking 20 more HP, not aiming very high in my opinion. A set of headers and modern cam and you will easily surpass that with out pulling the heads.
If you are building a 273 from scratch get flat top pistons made or buy the cheapie ones and deck the block, get some 273 specific gaskets from summit so you can get .030 quench (very small bores and tall pistons can run even tighter but that should be safe and effective). Run a good quality small tube header, SCAT I beam rods, back cut the stock valves(even 360 size valves are gonna be pretty shrouded), do a little basic port clean up and an XE265HL cam on a 110 LSA. You would easily make 300 hp 300#TQ
Nice tips on this build Dave!! Quite effective too, especially with the quench issue. The cam issue is questionable though, there are so MANY (grinds) ways to exceed this goal as well as being efficient by todays' standards.
"Stupidity is Ignorance on Steroids" "Yeah, it's hopped to over 160" (quote by Kowalski in the movie Vanishing Point 1970 - Cupid Productions)
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Re: 250hp 300 ft/lb from a street 273? Too much to ask for?
[Re: HYPER8oSoNic]
#1051933
08/13/11 02:58 PM
08/13/11 02:58 PM
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Joined: Jan 2005
Posts: 12,478 Kalispell Mt.
HotRodDave
I Live Here
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I Live Here
Joined: Jan 2005
Posts: 12,478
Kalispell Mt.
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The advantage in the cam I mentioned in a small engine vs the ones you mentioned are huge. The small engine will make very little TQ and the mopar cams will not help at all, a short duration high lift cam will help a bunch over the old mopar stuff with long duration short lift. It keeps you from loseing what little TQ they have but still allows them to breath at higher RPM where the small motor has to go to make any respectable HP.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: 250hp 300 ft/lb from a street 273? Too much to ask for?
[Re: dart4forte]
#1051936
08/13/11 03:25 PM
08/13/11 03:25 PM
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Joined: Jan 2005
Posts: 12,478 Kalispell Mt.
HotRodDave
I Live Here
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I Live Here
Joined: Jan 2005
Posts: 12,478
Kalispell Mt.
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The 302 head has a much smaller port, in order for them to flow the same then the 302 has to have more velocity, very simple physics. The 315-920 heads have bigger ports and flow more than the 302 but they are slightly lower velocity.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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