Indy/rhs heads?

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What's referred to as "under the curve" is the actual movement of air past the valve from the moment any particular lobe begins to lift it, to the time it closes. it's like a graph of a horse power or torque result. We call it the pwer curve for that reason, and the power produced under the peak line is the whole "area under the curve". So when BJR talks about flow "under the curve", he's not talking the max lift numbers you're reading... but rather the total flow from beginning to end as one lump. An example... You have a 5 gallon bucket. You're going to fill it exactly to the 5 gal capacity thru a 5" diameter pipe that is closed off with a cone shaped plug. If you push out the plug 1" and then turn on the water, it will take 2 minutes to fill the bucket. If you push the plug out 5" so the pipe can flow it's maximum and then turn on the water, it will take 10 seconds. So you have two flow rates, and one final volume filled in that time. Well, now lets say the water is already turned on when you start to push out the plug and you go from sealed to wide open to sealed in order to fill it. Let's say it takes 25 seconds worth of pushing open to full and then closing. Why? The 5 gallons can be flowed in 10 seconds.. right? So how did the time to fill go down so much? Because very little of the flowing was done JUST at the maqx flow rate. MOST of it is done while the plug is moving. The "area under the curve" is the total amount of flow once the plug is no longer sealing to when it seals again.
Same is true with an engine's valve motion.
I think where you will get the variations in opinions... And really, they are ALL just opinions until the engine is running... Is the importance of the flow at each step along the opening and closing ramps. BJR likes small ports that flow fast at low and reeally come on hard at mid lifts. If you ask others, they will tell you that this is the formula for huge torque when the driveline is matched. As for my own opinion, I'm in the middle. I like to keep the volumes down to a point, but I'll simply match everything and let the chips fall where they may. Any decent builder can predict with decent accuracy what the particluar package will do with each change. The physics never change. Only the opinions and choices made as people push envelopes and figure out more of it.
 
All of the "area under the curve" talk takes me back to my calculus classes (who knew they would come in handy eh?). It makes total sense if you think about it, and is analagous to horsepower curves. Just as average horsepower tells more than peak horsepower, average flow (more properly described by area under the curve) better describes overall air flow. The proper way to compare heads for flow, and engines for horsepower (as has been stated) is to look at the avrage numbers/area under the curve for the RPM range that you intend to run the engine. Very interesting discussion.
 
That is EXACTLY what it is. Plot a graph for any of it and you'll see the curves. Of course, the asymmetrical cam lobes will make it a little whacked looking, but same same.
 
Very well put Moper, I agree 100%. Heres something else that the guys here can use. If you have had your heads flowed and have the actual flow #'s you can determine the HP that they are capable of making. Add the flows up from .100-.500 without the .050 numbers and divide by the total number of increments, this gives you a average flow for the head, then divide this number by 1.67 then multiply by 3.44 for the HP for the head. This would be what the tires should see if everything is right in the chassis. The peak flow number is divided by 1.67 and multiplied by 3.44 for a peak HP #, just something for you guys and gals to play with.
 
Moper, BJR..
Another good way to 'measure' the heads flow curve is to take the average flow. Just add up the flow numbers at each valve lift and divide by the total lift values up to the actusl lift of the camshaft you will be using. You will be SURPRISED at the results you will get. Best average flow is what you are after. Some heads with BIG lift flow numbers will show Much less average flow than a good street ported head most of the time. I believe this is what Moper and BJR is trying to say. Lead on gentelmen.

Terry
 
Also, wanted to add that the head with the best average flow will in most cases produce the most torque and as stated before...torque is what rules on the street.

Terry
 
Just ordered these heads for my 410 Stroker.............I changed my mind on the Edelbrocks. These should work out nice when they are done. Bought them raw.
 
Can you cut one in half accross the spring seats for us please :D? Thanks in advance... You're a peach.
 
moper said:
Can you cut one in half accross the spring seats for us please :D? Thanks in advance... You're a peach.
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Bobby at BJR is going to do the work on them. They will be at his shop on the 3rd of September along with an M1 intake for port and gasket matching.

If he can put it back together, no problem.........haaaaaaa

Bobby, I am seriously joking!!!!!!!!!!!!!!!!!!!!!!!:-D
 
I also went with the Magnum version. I had to because the last guy who had the block hogged out the oiling hole to the heads for the LA version, I pulled out the plugs and set my gaskets on to make sure.........well you can guess the rest, it would leak like a stuck pig so I put the plugs back in and back to Magnum oiling thru the push rods. I already have all the rockers, stud girdle's etc which is a good thing.
 
Mad Dart said:
I also went with the Magnum version. I had to because the last guy who had the block hogged out the oiling hole to the heads for the LA version, I pulled out the plugs and set my gaskets on to make sure.........well you can guess the rest, it would leak like a stuck pig so I put the plugs back in and back to Magnum oiling thru the push rods. I already have all the rockers, stud girdle's etc which is a good thing.
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If I'm reading this right, I would have plugged the galley at the deck and redrilled though the plug. You don't have to block the oil galley to the head on a magnum conversion cause the head blocks it for you.

Studs and girdles? good thing.
 
1wild&crazyguy said:
If I'm reading this right, I would have plugged the galley at the deck and redrilled though the plug. You don't have to block the oil galley to the head on a magnum conversion cause the head blocks it for you.

Studs and girdles? good thing.
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I didnt even think about that........good idea. But it is pretty bad, the gasket would not seal tough from what I saw if that was done. If some type of filler was used around the outside of the plug than it might have worked. If I used the LA version, I would have had to buy valve covers and NEW roller rockers cause I aint did got nun............so I saved a few bucks there.
 
Thats not the type of plug I was thinking of.

I'm talking about the kind of plugs you would use when doing a crack repair on the deck of a cylinder head, they are tapered & have no recess like a galley plug would have and once milled are as flat as the rest of the deck, so you would have to deck the block but big deal cause then you could sell all that magnum stuff and just have a good'ol reliable parts o plenty accurate shaft mount set up. :read2:

I have 2 between a couple of cylinders on one of those j heads you saw.fwiw

But if you already have things in the works don't let this throw you off corse, you have my # so call me next time, if you want, if you ever
have something like this happen again.:thumblef:
 
1wild&crazyguy said:
Thats not the type of plug I was thinking of.

I'm talking about the kind of plugs you would use when doing a crack repair on the deck of a cylinder head, they are tapered & have no recess like a galley plug would have and once milled are as flat as the rest of the deck, so you would have to deck the block but big deal cause then you could sell all that magnum stuff and just have a good'ol reliable parts o plenty accurate shaft mount set up. :read2:

I have 2 between a couple of cylinders on one of those j heads you saw.fwiw

But if you already have things in the works don't let this throw you off corse, you have my # so call me next time, if you want, if you ever
have something like this happen again.:thumblef:
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PM sent.............
 
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