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Discussion Starter #1
I only had one ride in a 70 Boss 302, out in the country on wide open roads. The engine was pretty lame until about 3500 then the power came on pretty heavy. In fact it was so lame it was nearly boring. Would a hemi headed big block provide enough torque at low RPM's to provide better drivability? Who would make the best aftermarket heads that would give awesome power for the street on pump gas? I plan on about 500 cubic inches and would like about 500 carbureted horsepower at 6500 RPM. I don't know much about the aftermarket hemi headed motors, where would I learn more? Right now I am still prepping my D1VE block. Want to start thinking about high RPM hemi heads soon. If I keep everything on it aluminum I will still have a nice handling car, with better drivability than the Boss 302. Before I choose piston's I will need to know what heads I will be running. I would like a very reliable motor with smooth power from 1500 RPM to redline about 7500... No drag racing intention, may end up doing a little road racing with it. Thanks, Roy
 

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Heads?

I had a Boss 302 and yes they didnt make torque until 4000 rpm.
This engine was a solution to the SCCA racing rules and not meant for drag racing. My Boss at the track could turn low 13's relatively stock with polyglass tires back in the mid 70's.

Your comments about making 500 hp with a stroker does not require exotic heads and in fact DOVE or D3VE's will work to achieve 6500 rpm.
You should be able to make 500 hp at 5,500 and have massive low end torque for the street.

If you look into the engine build section you will find some combo's that might shock you.
 

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Even if a big block has oversized heads, say in the same relation as a 302...it will make more torque simply because of the additional cubes.

IMO, holding a boss headed 460/514 to 500hp is sort of counterproductive. The heads aren't really geared to low speed torque, and "neutering" them to 500hp (through manifold, cam, carb, etc) won't uncork the potential that makes them worthwhile.
 

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Discussion Starter #4
I don't think I was clear about the purpose of this engine. I am looking for a high RPM engine with a strong torque band from 2000 to 7000 RPM. What heads would let the motor breath at sustained high RPM's? I like driving fast out on open country roads and the car will be run at PIR some on the road race circuit I won't use iron heads due to weight consideration. Again this combo will never likely see a drag strip. Probably more like 600 horsepower, I was just being conservative. Torque is what I'm after not peak horsepower. My hydraulic 460 runs out of cam at about 4000 RPM and the valves would probably float soon after that. I was thinking a Boss type engine because I want the high RPM use, but with more low end guts (ie the big cubic inches the 302 Boss engine lacks). Maybe this isn't possible with the 460 block? Surely the Boss 9 type engine could be suited to road racing conditions or would I be better off with the SOHC engine? The Cobra 4.6 modular would do it but that defeats the purpose of having a simple engine that I can work on myself and wind the p%[email protected]##@ out of sometimes. I am looking for simplicity on steroids. I would like a 460 block that would run all afternoon at 4-7,000 RPM. Can it be done?
 

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I would think a 460 CI engine cammed appropriatedly would serve your needs very well. I would invest in some good rods and a good set of ported Aluminum heads. Something like the new P-51's. Top that off with a good single plane intake and a bigger carb and you should easily be at your goals.

You may also consider the 514 (4.15) stroker since buying rods will be a must. The added stroke will help your bottom end and give you the needed torque out of the corner.

460 block, ARP studs, stroker kit, and P-51's, Victor, 1050 carb, 2" headers, etc. 600 HP no problem and it should live all day.
 

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heads

If you're willing to spend the money for Boss heads then just go with a set of worked TFS A460 heads with the 2.35 intake valve. You have to get a matching intake, pistons, and headers but in my opinion you can't beat the A head for permance when related to overall cost. They have large ports/valves to support a high rpm motor and with the right combo you will still have a ton of low end also. I'd look at a 532 or 557 kit since they have tons of torque and can be made from a production block. Just my opinion. Chris
 

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I would think you might want to go with a big bore short stroke deal. According to my simulator program a 4.440 bore A head motor with a good cam and 3.85 (429) stroke would make power through 6500 rpm.

Install a 4.15 stroke crank and you pick up a few cubes and some hp but the rpm level drops down to 6200 or so.

Try to keep the rotating assembly as lite as you can and there should be no reason it cant run 7k all day like you say.

dkp
 

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Why turn the motor so high if you don't have to? You say you are wanting torque instead of horsepower, but at the same time want to spin it regularly to 7500rpm. I can't think of any reason to hold it at that high of a rpm unless that's where the motor makes its torque (horsepower being a figure based on torque and time). Is it just geared so that you have to run that high to get the speed you need? If that's it and you only want 500hp or a bit more, how about a CHI 3V headed 400"+ clevor? Otherwise, how about a 429 with 2.2" offset to 460 stroke and either TFS street or the P-51 heads as suggested? If you've got the cash though, a hemi headed 500+" big block that can happily rev and make power to 7500rpm would be nice... but a lot more than 600hp.
 

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I have a 1969 Boss 429,stock cubic inches,11.5 comp,roller cam,dual quads,4:11 rear.
Very streetable,power band from idle to 7000,dyno at 600 hp.Yes,hemi heads work.
 

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I think a 4.150 stroke with good heads will easily make power at 7000+ rpm. For a road course vehicle I don't think it'd hurt to have the extra inches to help get you out of the turns.
 

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I was concerned...

I was concerned about the same thing. Blue-thunder heads with the big exhaust valve option comp-ported on top of 435" 385 with a dominator victor intake and EFI and a cam that makes peak power at 7500rpm on paper. And, 7.88:1 compression with a centrifugal blower that doesn't make boost until 3000rpm. I was worried it would be a pig off idle to about 3000rpm due to the low compression, big ports, big valves, small stroke, etc.

I'm happy to report that is NOT the case. It has more torque/power off idle than I know what to do with. It doesn't drive like a boss 302 at all.
 

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69boss429 said:
I have a 1969 Boss 429,stock cubic inches,11.5 comp,roller cam,dual quads,4:11 rear.
Very streetable,power band from idle to 7000,dyno at 600 hp.Yes,hemi heads work.
niiiiiiiccceee! Pencil, I think youll find that any 500 inch motor worth building that is a collection of matched parts designed to run 7500 rpm is gonna make a LOT of power. And like the others have said, at 500+ inches a "loss" in low end torque may just mean a little less wheelspin. :lol:
 
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