Roller rocker debate
01-05-2017, 06:27 PM
#51
Registered
I mentioned how "stroke" plays a big part in cam selection, or should I say , duration levels. Here are the cams my software spec's for the following combinations. This is based on a Dart 308 Head flow file, but you'll get the point .
For 5500 RPM MAX
454 230/236 (4.00x4.25)
502 233/239 (4.00x4.47)
489 239/245 (4.25x4.28)
540 243/249 (4.25x4.50)
For 6000 RPM
454 243/248
502 246/252
489 253/258
540 256/262
Even though the 489 "stroker" , is smaller than a 502ci, it will require longer duration cam. Its not just cubic inch when playing the cam game. Full Force Tim's cam , was a 241/246. His cam was done right about 5400-5500rpm on the dyno. He gained about 7hp, from 5300 to 5900rpm. There is absolutely no reason, to spin his engines faster than about 5300rpm. Spinning an engine faster is ok, but only if there's power to be gained by doing so. Technically his HP "peaked" at 5800-5900, but that means nothing to me personally.
For 5500 RPM MAX
454 230/236 (4.00x4.25)
502 233/239 (4.00x4.47)
489 239/245 (4.25x4.28)
540 243/249 (4.25x4.50)
For 6000 RPM
454 243/248
502 246/252
489 253/258
540 256/262
Even though the 489 "stroker" , is smaller than a 502ci, it will require longer duration cam. Its not just cubic inch when playing the cam game. Full Force Tim's cam , was a 241/246. His cam was done right about 5400-5500rpm on the dyno. He gained about 7hp, from 5300 to 5900rpm. There is absolutely no reason, to spin his engines faster than about 5300rpm. Spinning an engine faster is ok, but only if there's power to be gained by doing so. Technically his HP "peaked" at 5800-5900, but that means nothing to me personally.
01-05-2017, 07:51 PM
#53
Registered
01-05-2017, 08:26 PM
#55
Registered
iTrader: (3)
The flow data, or ratio, remained unchanged. That's why you pick heads, then a cam. Not the other way around. If i simply reduced the exhaust port flow, but left intake port alone, you would see a larger split. Increase exhaust flow, and then gets closer to single pattern cam .
Its a pretty cool program. If you have measured cross section , fps of port velocity, throat diameter %, and so on, it factors that in as well.
Its why I kinda giggle now, when i see people say a head will or wont work based solely on port volume alone. Theres so much more to it. These modern programs, really teach you alot. Of course nothing is better than real world experience, but heck, how many engine builders are sitting there swapping cams back and forth, swaping heads back and forth, etc , to learn what works best. Not many. Cant blame them, alot of work, and hard to make a living playing experiments.
Plus making power is one thing. The program does not ask you, what kind of idle you like, will water reversion be an issue, and so on. It simply calculating a bunch of math. I do think its a hell of alot better for a do it yourselfer like alot of us, to pick out a camshaft using a program like this, rather than what you heard about in a bar, or read on the internet.
01-05-2017, 08:35 PM
#56
Registered
Thread Starter
The flow data, or ratio, remained unchanged. That's why you pick heads, then a cam. Not the other way around. If i simply reduced the exhaust port flow, but left intake port alone, you would see a larger split. Increase exhaust flow, and then gets closer to single pattern cam .
Its a pretty cool program. If you have measured cross section , fps of port velocity, throat diameter %, and so on, it factors that in as well.
Its why I kinda giggle now, when i see people say a head will or wont work based solely on port volume alone. Theres so much more to it. These modern programs, really teach you alot. Of course nothing is better than real world experience, but heck, how many engine builders are sitting there swapping cams back and forth, swaping heads back and forth, etc , to learn what works best. Not many. Cant blame them, alot of work, and hard to make a living playing experiments.
Plus making power is one thing. The program does not ask you, what kind of idle you like, will water reversion be an issue, and so on. It simply calculating a bunch of math. I do think its a hell of alot better for a do it yourselfer like alot of us, to pick out a camshaft using a program like this, rather than what you heard about in a bar, or read on the internet.
Its a pretty cool program. If you have measured cross section , fps of port velocity, throat diameter %, and so on, it factors that in as well.
Its why I kinda giggle now, when i see people say a head will or wont work based solely on port volume alone. Theres so much more to it. These modern programs, really teach you alot. Of course nothing is better than real world experience, but heck, how many engine builders are sitting there swapping cams back and forth, swaping heads back and forth, etc , to learn what works best. Not many. Cant blame them, alot of work, and hard to make a living playing experiments.
Plus making power is one thing. The program does not ask you, what kind of idle you like, will water reversion be an issue, and so on. It simply calculating a bunch of math. I do think its a hell of alot better for a do it yourselfer like alot of us, to pick out a camshaft using a program like this, rather than what you heard about in a bar, or read on the internet.
01-05-2017, 08:42 PM
#57
Registered
Sure wish I had my Dyno Sim 5 program years ago! It would have saved me a lot of cash, time and heartache!
01-05-2017, 08:52 PM
#60
Registered
Joe I will download the controlled induction program, thanks for the info! So wish I was born into this information age!!!
I can remember doing homework with the encyclopedia. true story LOL
I can remember doing homework with the encyclopedia. true story LOL
