Intake runner size for 582 BBC -tech help-
11-21-2007, 03:42 PM
#11
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I talked to quite a few people about the same thing, and for that size of engine they recommend a 335 - 355 with a dynamic of about 7.5 - 8.0 for pump gas, thats why I asked you earlier what your dynamic was? you have a small cam but we don`t know all the specs. but it should still be close to the 8.0 . lots of different heads out there, that are really good, you just need to have someone sell you,on a set, that they are running. I`m sure you already have a manufacturer in mind. my opinion for what you have would be the 325- 335 with that size of cam
11-21-2007, 06:57 PM
#12
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Originally Posted by superstreeter
I talked to quite a few people about the same thing, and for that size of engine they recommend a 335 - 355 with a dynamic of about 7.5 - 8.0 for pump gas, thats why I asked you earlier what your dynamic was? you have a small cam but we don`t know all the specs. but it should still be close to the 8.0 . lots of different heads out there, that are really good, you just need to have someone sell you,on a set, that they are running. I`m sure you already have a manufacturer in mind. my opinion for what you have would be the 325- 335 with that size of cam
Thanks for your advise.
11-21-2007, 07:57 PM
#13
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Dynamic Compression Ratio
The calculated compression ratio, as given above, presumes that the cylinder is sealed at the bottom of the stroke (bottom dead center - BDC), and that the volume compressed is the actual volume.
However: intake valve closure (sealing the cylinder) always takes place after BDC, which causes some of the intake charge to be compressed backwards out of the cylinder by the rising piston at very low speeds; only the percentage of the stroke after intake valve closure is compressed. This "corrected" compression ratio is commonly called the "dynamic compression ratio".
This ratio is higher with more conservative (i.e., earlier, soon after BDC) intake cam timing, and lower with more radical (i.e., later, long after BDC) intake cam timing, but always lower than the static or "nominal" compression ratio.
The actual position of the piston can be determined by trigonometry, using the stroke length and the connecting rod length (measured between centers). The absolute cylinder pressure is the result of an exponent of the dynamic compression ratio. This exponent is a polytropic value for the ratio of variable heats for air and similar gases at the temperatures present. This compensates for the temperature rise caused by compression, as well as heat lost to the cylinder. Under ideal (adiabatic) conditions, the exponent would be 1.4, but a lower value, generally between 1.2 and 1.3 is used, since the amount of heat lost will vary among engines based on design, size and materials used, but provides useful results for purposes of comparison. For example, if the static compression ratio is 10:1, and the dynamic compression ratio is 7.5:1, a useful value for cylinder pressure would be (7.5)^1.3 × atmospheric pressure, or 13.7 bar. (× 14.7 psi at sea level = 201.8 psi. The pressure shown on a gauge would be the absolute pressure less atmospheric pressure, or 187.1 psi.)
The two corrections for dynamic compression ratio affect cylinder pressure in opposite directions, but not in equal strength. An engine with high static compression ratio and late intake valve closure will have a DCR similar to an engine with lower compression but earlier intake valve closure.
:roll: :roll: :roll:
The calculated compression ratio, as given above, presumes that the cylinder is sealed at the bottom of the stroke (bottom dead center - BDC), and that the volume compressed is the actual volume.
However: intake valve closure (sealing the cylinder) always takes place after BDC, which causes some of the intake charge to be compressed backwards out of the cylinder by the rising piston at very low speeds; only the percentage of the stroke after intake valve closure is compressed. This "corrected" compression ratio is commonly called the "dynamic compression ratio".
This ratio is higher with more conservative (i.e., earlier, soon after BDC) intake cam timing, and lower with more radical (i.e., later, long after BDC) intake cam timing, but always lower than the static or "nominal" compression ratio.
The actual position of the piston can be determined by trigonometry, using the stroke length and the connecting rod length (measured between centers). The absolute cylinder pressure is the result of an exponent of the dynamic compression ratio. This exponent is a polytropic value for the ratio of variable heats for air and similar gases at the temperatures present. This compensates for the temperature rise caused by compression, as well as heat lost to the cylinder. Under ideal (adiabatic) conditions, the exponent would be 1.4, but a lower value, generally between 1.2 and 1.3 is used, since the amount of heat lost will vary among engines based on design, size and materials used, but provides useful results for purposes of comparison. For example, if the static compression ratio is 10:1, and the dynamic compression ratio is 7.5:1, a useful value for cylinder pressure would be (7.5)^1.3 × atmospheric pressure, or 13.7 bar. (× 14.7 psi at sea level = 201.8 psi. The pressure shown on a gauge would be the absolute pressure less atmospheric pressure, or 187.1 psi.)
The two corrections for dynamic compression ratio affect cylinder pressure in opposite directions, but not in equal strength. An engine with high static compression ratio and late intake valve closure will have a DCR similar to an engine with lower compression but earlier intake valve closure.
:roll: :roll: :roll:
11-22-2007, 09:30 AM
#15
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Here is one of those situations again, when its a street car, where, a guy is worried about loosing "low end tq". Not bashing anyone here, just trying to put a different perspective on that whole magazine phrase. I would agree, its a lot easier making power with more cubic inches for sure, but this is a case where its going to be rediculously over kill, which, some guys like, lol.
That cam is way to small for a 582. It will make all the tq low in the rpm band, where, that car will NEVER hook it. In fact, it will be down right dangerous. I have customers with more 100 less cubic inches, that have put similiar cars, in the ditch, and almost wrecked the car, or died, because the car got completelty out of control. One guy, called me and told me he switched tires, because he was killing his Hoosier quick time pros, before he even made it to the track, so he put his old BFG Radial T/A's on it, to save his good tires. I said, be very careful. Huh he said. I said, don't do what you used to, going 50-60mph on the highway, drop it into second, from drive, and hammer it. Why? You will end up in the ditch. He didn;t listen. Called me a few days later, and told me you were right. Going 50, dropped it into second, hammered it, and ended up in the ditch on the other side of the road, faster than he could react. Car lit the tires, got out of shape, he paniced, lost control, and put it in the ditch. Did about $2000 worth of body work damage, and lucky he didn;t get killed.
That was only 461 cubes, that made 600hp, and 575 tq. Thats 1 story, there are others. With 582 inches, and monster tq, my guess, would be somewhere over 750+ ft/lbs at fairly low rpm, 4500, somewhere in there, with the above combo, in that chassis, it will be hairy. If that sounds fun, than do it, but, just be careful is all I am saying.
If you think about it, trying to kill low end power in a true street car, with limited tires, and chassis, is a good idea. Purposely do things to reduce tq, and shift peak power up top. This thing will make a ton of power regardless, and still be a tire frier supreme. Thats just my advice from expierience.
Frank
Advanced Performance
www.get-ap.com
That cam is way to small for a 582. It will make all the tq low in the rpm band, where, that car will NEVER hook it. In fact, it will be down right dangerous. I have customers with more 100 less cubic inches, that have put similiar cars, in the ditch, and almost wrecked the car, or died, because the car got completelty out of control. One guy, called me and told me he switched tires, because he was killing his Hoosier quick time pros, before he even made it to the track, so he put his old BFG Radial T/A's on it, to save his good tires. I said, be very careful. Huh he said. I said, don't do what you used to, going 50-60mph on the highway, drop it into second, from drive, and hammer it. Why? You will end up in the ditch. He didn;t listen. Called me a few days later, and told me you were right. Going 50, dropped it into second, hammered it, and ended up in the ditch on the other side of the road, faster than he could react. Car lit the tires, got out of shape, he paniced, lost control, and put it in the ditch. Did about $2000 worth of body work damage, and lucky he didn;t get killed.
That was only 461 cubes, that made 600hp, and 575 tq. Thats 1 story, there are others. With 582 inches, and monster tq, my guess, would be somewhere over 750+ ft/lbs at fairly low rpm, 4500, somewhere in there, with the above combo, in that chassis, it will be hairy. If that sounds fun, than do it, but, just be careful is all I am saying.
If you think about it, trying to kill low end power in a true street car, with limited tires, and chassis, is a good idea. Purposely do things to reduce tq, and shift peak power up top. This thing will make a ton of power regardless, and still be a tire frier supreme. Thats just my advice from expierience.
Frank
Advanced Performance
www.get-ap.com
11-24-2007, 10:24 AM
#16
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Join Date: Jun 2004
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Originally Posted by Pwmax
Here is one of those situations again, when its a street car, where, a guy is worried about loosing "low end tq". Not bashing anyone here, just trying to put a different perspective on that whole magazine phrase. I would agree, its a lot easier making power with more cubic inches for sure, but this is a case where its going to be rediculously over kill, which, some guys like, lol.
That cam is way to small for a 582. It will make all the tq low in the rpm band, where, that car will NEVER hook it. In fact, it will be down right dangerous. I have customers with more 100 less cubic inches, that have put similiar cars, in the ditch, and almost wrecked the car, or died, because the car got completelty out of control. One guy, called me and told me he switched tires, because he was killing his Hoosier quick time pros, before he even made it to the track, so he put his old BFG Radial T/A's on it, to save his good tires. I said, be very careful. Huh he said. I said, don't do what you used to, going 50-60mph on the highway, drop it into second, from drive, and hammer it. Why? You will end up in the ditch. He didn;t listen. Called me a few days later, and told me you were right. Going 50, dropped it into second, hammered it, and ended up in the ditch on the other side of the road, faster than he could react. Car lit the tires, got out of shape, he paniced, lost control, and put it in the ditch. Did about $2000 worth of body work damage, and lucky he didn;t get killed.
That was only 461 cubes, that made 600hp, and 575 tq. Thats 1 story, there are others. With 582 inches, and monster tq, my guess, would be somewhere over 750+ ft/lbs at fairly low rpm, 4500, somewhere in there, with the above combo, in that chassis, it will be hairy. If that sounds fun, than do it, but, just be careful is all I am saying.
If you think about it, trying to kill low end power in a true street car, with limited tires, and chassis, is a good idea. Purposely do things to reduce tq, and shift peak power up top. This thing will make a ton of power regardless, and still be a tire frier supreme. Thats just my advice from expierience.
Frank
Advanced Performance
www.get-ap.com
That cam is way to small for a 582. It will make all the tq low in the rpm band, where, that car will NEVER hook it. In fact, it will be down right dangerous. I have customers with more 100 less cubic inches, that have put similiar cars, in the ditch, and almost wrecked the car, or died, because the car got completelty out of control. One guy, called me and told me he switched tires, because he was killing his Hoosier quick time pros, before he even made it to the track, so he put his old BFG Radial T/A's on it, to save his good tires. I said, be very careful. Huh he said. I said, don't do what you used to, going 50-60mph on the highway, drop it into second, from drive, and hammer it. Why? You will end up in the ditch. He didn;t listen. Called me a few days later, and told me you were right. Going 50, dropped it into second, hammered it, and ended up in the ditch on the other side of the road, faster than he could react. Car lit the tires, got out of shape, he paniced, lost control, and put it in the ditch. Did about $2000 worth of body work damage, and lucky he didn;t get killed.
That was only 461 cubes, that made 600hp, and 575 tq. Thats 1 story, there are others. With 582 inches, and monster tq, my guess, would be somewhere over 750+ ft/lbs at fairly low rpm, 4500, somewhere in there, with the above combo, in that chassis, it will be hairy. If that sounds fun, than do it, but, just be careful is all I am saying.
If you think about it, trying to kill low end power in a true street car, with limited tires, and chassis, is a good idea. Purposely do things to reduce tq, and shift peak power up top. This thing will make a ton of power regardless, and still be a tire frier supreme. Thats just my advice from expierience.
Frank
Advanced Performance
www.get-ap.com
ops: ops: ops:
11-25-2007, 07:54 AM
#17
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You won;t have to rev it 7500. If all you had were mushy small blocks in the past, this combo will be a huge eye opener. As far as cams go, is this going to be a weekend type fun car, or do you plan to run it cross country? If it were mine, I would be building it on the more radical side, as I don't really cruise my car all that far in a givin trip. That many cubes will need a fairly large cam. Not necessarily lift, but, duration. The more lift the better obviously, but then you get into more longevity issues with lifters and springs.
If it were mine, I would put a cam in it that had a lot more duration than most guys would even consider for a " street" car, but, like I said, I live no more than 15 miles from numerous cruise spots where I live, and, I am big into drag racing, so, if I built a big engine like that, I would want to take advantage of it. With that said, I would have 2 sets of intake rockers, like a 1.6 and a set of 1.8 or 1.85:1. Use the low ratio rackers on the street to keep the loads down, and max it out with the high ratio rockers for the track. Knowing me though, I would just run the 1.8's all the time, and just keep tabs on overthing. But, I would be in the 280 range at .050, with .800+ lift, with wide lobe sep. If thats too radical, then something in the 270's, with mid .700's would be good, and I would use a lobe that wasn;t quite as aggressive, like a Comps Hi-Tech roller lobes.
To know for sure on the cam, what your plans are with the car, and what you want to do with it need to be known.
Frank
Advanced Performance
www.get-ap.com
If it were mine, I would put a cam in it that had a lot more duration than most guys would even consider for a " street" car, but, like I said, I live no more than 15 miles from numerous cruise spots where I live, and, I am big into drag racing, so, if I built a big engine like that, I would want to take advantage of it. With that said, I would have 2 sets of intake rockers, like a 1.6 and a set of 1.8 or 1.85:1. Use the low ratio rackers on the street to keep the loads down, and max it out with the high ratio rockers for the track. Knowing me though, I would just run the 1.8's all the time, and just keep tabs on overthing. But, I would be in the 280 range at .050, with .800+ lift, with wide lobe sep. If thats too radical, then something in the 270's, with mid .700's would be good, and I would use a lobe that wasn;t quite as aggressive, like a Comps Hi-Tech roller lobes.
To know for sure on the cam, what your plans are with the car, and what you want to do with it need to be known.
Frank
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www.get-ap.com
11-26-2007, 05:32 AM
#19
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Didn;t see the 90% street part, sorry. :roll: There is an eye roll back to you. Then, if thats the case, i wouldn;t build a 582. I would build a 509, or a 532 with a 4.6 inch bore, if you want more cubes, which you won;t need. In which case, I would use a big custom high lift hydraulic roller cam, with good lifters, and the right springs. Crane lifters, will rev 7000. I know how most guys think, have been around this stuff a long time. I know he says 90% street, but, he wouldn;t be thinking 582 and solid roller, if he didn;t want big power. I know a mild 582, would give a huge kick in the shorts, but, I think he might be disapointed with the top end. It wouldn;t really matter anyhow, because in that car, it will never hook. Even a 509 makes crazy power for a street car.
Case in point, I know of numerous guys who have bought 502 and 572 Gm core engines, and, were totaly disapointed. Decently snappy on the bottom, but then are dead before 6000. So, it blows the tires off, then falls on its face because there is nothing left. I have revamped at least 5 502's, and one 572 after 1 summer for that very reason. One guy with a 572 in a chevelle got smoked by one of my customers, in his super budget 496, and was mad. They got to talkin, and I fixed it up. 770hp from 620, and it was no less streetable. The 502's get turned into 509's, and make 730 and 660 on the tq. Thats basicaly 225hp, from a cam, and porting the heads.
Frank
Advanced Performance
www.get-ap.com
Case in point, I know of numerous guys who have bought 502 and 572 Gm core engines, and, were totaly disapointed. Decently snappy on the bottom, but then are dead before 6000. So, it blows the tires off, then falls on its face because there is nothing left. I have revamped at least 5 502's, and one 572 after 1 summer for that very reason. One guy with a 572 in a chevelle got smoked by one of my customers, in his super budget 496, and was mad. They got to talkin, and I fixed it up. 770hp from 620, and it was no less streetable. The 502's get turned into 509's, and make 730 and 660 on the tq. Thats basicaly 225hp, from a cam, and porting the heads.
Frank
Advanced Performance
www.get-ap.com
11-26-2007, 11:47 AM
#20
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That was only 461 cubes, that made 600hp, and 575 tq. Thats 1 story, there are others. With 582 inches, and monster tq, my guess, would be somewhere over 750+ ft/lbs at fairly low rpm, 4500, somewhere in there, with the above combo, in that chassis, it will be hairy. If that sounds fun, than do it, but, just be careful is all I am saying.
Here is another one.
I built a customer a 505 and used his junk pro comp heads. After putting in seats, some weld in the chambers, and port work, they ended up about 370cc and went 380-390cfm with a 2.300 valve. 10.5:1 compression. custom 262 274 @ .050 on a 110 with .720" with jesel 1.75 rockers. Edelbrock port matched super victor with a 1050 holley.
Made 742 hp @ 6900. The man just KNEW he needed 700hp. Now he rides around and wastes about 200 on the street. Has good response and drives good, just too much for a street car without good suspension. Wheel hops at 80mph.
But if your after big power, im with curtis. Go big with it.
I have done a few others with bigger cams, but this one drives the best. More dangerous also though!
Steve