ready to drop in HP 300

[F-250 restorer]

On the weekend of the 11th I have scheduled to drop in my baby. Since October 08, I've been researching and buying parts for my 390 to 300 swap, and now I'm just about ready. What I finally ended up with is this: 1978 block. with a 1981 head .030 over bore with hypereutectic pistons at 8.5:1 compression. .010 under on the crank and mains, shaved the block .020 shaved the head .020. Shot for 9.2:1 compression. ARP rod bolts. Isky mild cam with lifters, double springs, and new rocker arm studs. Head: ported and polished with matching runners to DP Offy intake and Hedman dual header. Head also has sbc over size valves! Ignition: MSD 6a stand alone box with MSD TFI coil, and DuraSpark 11 dizzy, completely rebuilt with new 'bearings!' and recurved Carb: a newly rebuilt Pony Carbs Autolite 4100, 1.08 venturi Exhaust: 2.25" dual, through generic turbo mufflers. Polished cast aluminum valve cover (adds at least 10 hp, also hides the roller rockers I'm going to tell everyone are there, but aren't.) The people on this forum have been invaluable. I say 'thanks' to one and all. I'm sure I'll have many more questions. What sold me on the 300: I read somewhere: A straight 6 will produce 30--40% more hp than an equivalent size v8.

[9.ford.5]

Originally Posted by F-250 restorer

What sold me on the 300: I read somewhere: A straight 6 will produce 30--40% more hp than an equivalent size v8.

HAHAHA yeah....no! a 302 ci inline 6 vs. a 302 ci v8...the inline with produce more torque then the v8 but the v8 will produce more hp., the 300 will show its peak performance at a much lower rpm than the v8

a straight six might produce 30-40% more TORQUE than a similar size v8 but the v8 will probably produce 30-40% more HP


nice build though

[F-250 restorer]

Horsepower is calculated with a mathimatical formula translating TORQUE into an idea that people can get their minds around. It is the same thing with a different name.

I don't want to beat a dead horse and get into a dialogue about what produces more power, a v8 or I6. Do the research. If you have the same carb, ignition, etc., the I6 produces more.

[9.ford.5]

any way you figure it if you were to dyno the two engines setup as you mentioned my bet is a 300 would hit higher TQ and the v8 would still hit higher HP within their individual most efficient rpms, 6 cylinders firing vs 8, 8 will obviously have an advantage at higher rpms because there are 8 of them to spin the flywheel vs 6...then you get frictional advantages, 6 cylinders will have less friction and larger pistons therefore will do more work with less thermal loss as a result producing more HP/TQ PER CYLINDER but the v8 has 2 more cylinders to make up for that...we should try this sometime it would definitely yield interesting results

[F-250 restorer]

blah blah blah

[Harte3]

Great build F-250. Gotta get it running and post some pics/vids Don't be afraid to lean on Jon at Pony if you have any problem with the carb.

[91Bronc300]

I think rather thank comparing the two different peak RPMs of an I6 to a V8, Restorer is referring to a comparison of the exact same RPM range between the two engines. And in that sense, yes, horsepower is simply a math formula away from torque. At any point where an engine is producing more torque at a certain RPM than another engine at THE SAME RPM, then that engine is also producing more horsepower, AT THAT RPM. I think that's what he meant.

[91Bronc300]

Ok, so I just did a mock up math problem to figure out if I was talking truth or not in that last post.

This is the TQ to HP conversion formula:

(Torque x Engine speed) / 5,252 = Horsepower

So if we assume that F-250 Restorer's 300 build is going to make 350 ft/lbs at 2500 RPM then:

350 x 2500 / 5252 = 166.6 HP @ 2500 RPM

Then assuming a comparable high performance 302 build will make 35% less torque (350 x 0.65 = 227.5) at the same RPM we have:

227.5 x 2500 / 5252 = 108.3 HP @ 2500 RPM

And 35% less horsepower than 166.6 (166.6 x .65 = 108.3 HP) is 108.3 HP.

So even though the inline will have a peak torque higher than anything the 302 ever produces and the 302 will have a greater peak horsepower than anything the 300 ever produces, that is simple the nature of their native happy RPM ranges. But if comparing two different engines at the EXACT SAME RPM, then a percentage difference in torque makes the very same percentage difference in horsepower.

[6CylBill]

Originally Posted by F-250 restorer

What sold me on the 300: I read somewhere: A straight 6 will produce 30--40% more hp than an equivalent size v8.

Nope, sorry. Fail.

The 300 makes more power per piston than the 302, but the 302 has more pistons. There motors are the same size. Why doesn't the 300 make 220 horse then?

As you said to my buddy above; "Blah blah blah".

[dwrestle]

Now wait just a minute if we are comparing a 300 to a 302 then I agree that the 302 will have more top end power, but the two engines are only close in the fact that they are both 300 cubes and built by Ford, pretty much everything the stock 302 has is way better than the stock 300 flow wise, and the 302 is a short stroke big bore motor which is already very condusive for high RPM power, and the truck 302 only made 170-205 HP.

However if we are going by Inline 6 vs V8 in general then thats another story, not all I6's act like the 300. The Jeep 4.0 revs to 5500 RPM with no problems and has a very broad flat torque cure(which most I6's do), and it makes 175-195 HP from the factory, and look what happens when you stroke it. The Chevy Trailblazer 4.2 make 290 HP, and also has an awesome torque curve(so does the 5 cylinder for that matter). BMW uses some I6's that I'm sure rev really high and like most I6's make good torque at all RPMs.

I don't think that an I6 will produce 30-40% more HP than a V8 in the same size range. I am willing to bet that it will have more torque at all RPMs, and be a better engine overall, especially when your talking about old tech like 302's and 350's, but I'd take a good I6 anyday. Just wish the 300 had some better stuff available for cheap, like a sweet head or something.

[F-250 restorer]

Originally Posted by Harte3

Great build F-250. Gotta get it running and post some pics/vids Don't be afraid to lean on Jon at Pony if you have any problem with the carb.

Thanks, Harte3. You helped me through quite a bit of it. I certainly appreciate it.

And yeah, I'm sure I'll be calling Jon at Pony when going through the joy of getting the carb dialed in. It's pushing up the hill that makes the peak so enjoyable.

I'll be sure to post some video on youtube, painting the engine compartment, hanging the mufflers with coat hanger to get it to the muffler shop, cutting out the old engine mounts, etc.

[F-250 restorer]

Originally Posted by 9.ford.5

any way you figure it if you were to dyno the two engines setup as you mentioned my bet is a 300 would hit higher TQ and the v8 would still hit higher HP within their individual most efficient rpms, 6 cylinders firing vs 8, 8 will obviously have an advantage at higher rpms because there are 8 of them to spin the flywheel vs 6...then you get frictional advantages, 6 cylinders will have less friction and larger pistons therefore will do more work with less thermal loss as a result producing more HP/TQ PER CYLINDER but the v8 has 2 more cylinders to make up for that...we should try this sometime it would definitely yield interesting results

I agree. I remember reading about an I6 dragster. They guy had taken 3 351 heads, cut them up somehow, and welded them together to come up with one head for a 300. I can't remember is it was W or C heads.

Regarding the 302 and the 300: I wonder what torque/hp results we would get if the 300 was flowing the same volume of air through the head as the 302. Then the playing field would be a bit more even.

[dwrestle]

If the 300 matched the 302 in flow in every category, then the 300 would be better in everything except maybe the very top end, really the 302 can be way better than it is from the factory too. I would bet the 300 would have put out 180 to 210 HP and 300-330 TQ in EFI form. If the carb version was as good as the 302 carbed(2bbl intake and carb with the head flowing the same) it would probably put out the same numbers as the EFI 300 did.

The 300 would really compare to a 350 or 351 if that were the case, and we probably wouldn't have a bunch of threads about how to beat the V8, because it already would.

[dwrestle]

Yeah I read somewhere about a guy cutting up Chevy LS1 heads and putting them on a 300, don't remember where I read that at though, sounded cool, and expensive.

[dustybumpers]

make sure the starter is bolted up before you put the headers on. been there, done that, found out the hard way. it's also easier to sneek the headers in while motor still on the lift, you need the room. you don't have to bolt them up, just get them in there before you bolt up the motor mount.