Cam intensity question
05-31-2015, 10:01 AM
#31
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iTrader: (3)
i am thinking about building a 15-1 compression ratio,huge cam,big chief headed n/a engine for a 24 foot baja that is for sale on ebay,it should make 1000 hp and need valve train maintenance every 25 hrs but who cares about little things like that.i am going to use neo oil in the alfa drive so it should hold up well.i am going to run it on e85 so fuel won,t be to expensive.the ebay add said the transom is soft but i think some super glue will bring it back to snuff.my question is will the 23 pitch aluminum prop that comes with the boat work or will i need one of those high priced stainless steel 4 blade props.one more question,will my s10 pickup pull my new boat ok?i only live about 40 miles from the canal i plan on running it in.
05-31-2015, 10:09 AM
#32
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Very true. From my experience with my engines, and a few friends engines, that have had lobe lifts of .370 range or less, with duration numbers of 235ish to 245ish, have seen good life from the valvetrains. Not talking 1000 hours, but 200-300 hours isnt out of the question, with moderate spring pressures. What concerns me, is a few buddies who've got custom cams for their marine engines, that have similar duration numbers, std bbc journal, std .842 lifters, but are sporting .400-.410 lobes. The cam guy they use doesnt provide them with duration numbers at .200 on their cam spec sheets.
I guess time will tell how their valvetrain holds up, and if the extra little bit of power, was worth it or not for them.
From the little I am learning on this stuff, is there is no getting around increasing lobe intensity increase, if duration doesnt grow with the lobe size. So, while most think they are simply adding valve lift, they are also increasing lobe aggressiveness..?...
Would it be wise to assume, keep gentle ramps, keep lobe lift down, run enough, but not excessive spring pressure, and make your power in other areas of the build, if long valvetrain life is what you want. Especially on forced induction marine stuff.
I guess time will tell how their valvetrain holds up, and if the extra little bit of power, was worth it or not for them.
From the little I am learning on this stuff, is there is no getting around increasing lobe intensity increase, if duration doesnt grow with the lobe size. So, while most think they are simply adding valve lift, they are also increasing lobe aggressiveness..?...
Would it be wise to assume, keep gentle ramps, keep lobe lift down, run enough, but not excessive spring pressure, and make your power in other areas of the build, if long valvetrain life is what you want. Especially on forced induction marine stuff.
05-31-2015, 10:40 AM
#33
Tony, you got me playing with the sim software.
Just for chits, I built a 540ci, 10:1, Dart 335 headed engine with a dominator carb and single plane. With a Crane "651" cam, 244/256 114lsa, .632/.632 lift cam, 1.7 rockers, the sim came back with 685HP peak. Changing nothing but making the lobe larger, going from .371 to .410, which netted .697 lift, the horsepower 702HP. 17HP gain. What did change, was the auto calculation feature, that displays lifter acceleration. It doesnt give specifics, but basically categories. It moved the stock setup which was between "oem and aftermarket street", to the larger lobe moving it between "aftermarket street" and "limited street".
I then changed to the famous "741" 236/244 .610/.632 112lsa crane cam everyone loved lol. This combo netted 647hp. Again, by going to a .410 lobe, and increasing lift at the valve to .697, the HP jumped to 662. 15hp gain. Again the lifter speed increased, to a higher point than it did with the longer duration 651 cam.
According to the sim software, those lobe changes certainly didnt put it into their category of "all out racing" or "pro stock", but it did increase it further from "oem performance " and "aftermarket street performance" closer to "drag and limited street". Although this information is just from a simulator, it seems to coincide with what companies like crane, comp, have in their lobe catalogs for "marine endurance" as far as lobe lifts go. Of course their is probably many many variables, like when getting into 55mm cores, larger lifter diameters, etc etc. Its more standard bbc stuff.
Being that in a boat like mine, 15-17hp gains, will barely net me 1mph in top speed gain, I'd much rather go with the lobe thats easier on parts.
Just for chits, I built a 540ci, 10:1, Dart 335 headed engine with a dominator carb and single plane. With a Crane "651" cam, 244/256 114lsa, .632/.632 lift cam, 1.7 rockers, the sim came back with 685HP peak. Changing nothing but making the lobe larger, going from .371 to .410, which netted .697 lift, the horsepower 702HP. 17HP gain. What did change, was the auto calculation feature, that displays lifter acceleration. It doesnt give specifics, but basically categories. It moved the stock setup which was between "oem and aftermarket street", to the larger lobe moving it between "aftermarket street" and "limited street".
I then changed to the famous "741" 236/244 .610/.632 112lsa crane cam everyone loved lol. This combo netted 647hp. Again, by going to a .410 lobe, and increasing lift at the valve to .697, the HP jumped to 662. 15hp gain. Again the lifter speed increased, to a higher point than it did with the longer duration 651 cam.
According to the sim software, those lobe changes certainly didnt put it into their category of "all out racing" or "pro stock", but it did increase it further from "oem performance " and "aftermarket street performance" closer to "drag and limited street". Although this information is just from a simulator, it seems to coincide with what companies like crane, comp, have in their lobe catalogs for "marine endurance" as far as lobe lifts go. Of course their is probably many many variables, like when getting into 55mm cores, larger lifter diameters, etc etc. Its more standard bbc stuff.
Being that in a boat like mine, 15-17hp gains, will barely net me 1mph in top speed gain, I'd much rather go with the lobe thats easier on parts.
05-31-2015, 10:43 AM
#34
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iTrader: (2)
Very true. From my experience with my engines, and a few friends engines, that have had lobe lifts of .370 range or less, with duration numbers of 235ish to 245ish, have seen good life from the valvetrains. Not talking 1000 hours, but 200-300 hours isnt out of the question, with moderate spring pressures. What concerns me, is a few buddies who've got custom cams for their marine engines, that have similar duration numbers, std bbc journal, std .842 lifters, but are sporting .400-.410 lobes. The cam guy they use doesnt provide them with duration numbers at .200 on their cam spec sheets.
I guess time will tell how their valvetrain holds up, and if the extra little bit of power, was worth it or not for them.
From the little I am learning on this stuff, is there is no getting around increasing lobe intensity increase, if duration doesnt grow with the lobe size. So, while most think they are simply adding valve lift, they are also increasing lobe aggressiveness..?...
Would it be wise to assume, keep gentle ramps, keep lobe lift down, run enough, but not excessive spring pressure, and make your power in other areas of the build, if long valvetrain life is what you want. Especially on forced induction marine stuff.
I guess time will tell how their valvetrain holds up, and if the extra little bit of power, was worth it or not for them.
From the little I am learning on this stuff, is there is no getting around increasing lobe intensity increase, if duration doesnt grow with the lobe size. So, while most think they are simply adding valve lift, they are also increasing lobe aggressiveness..?...
Would it be wise to assume, keep gentle ramps, keep lobe lift down, run enough, but not excessive spring pressure, and make your power in other areas of the build, if long valvetrain life is what you want. Especially on forced induction marine stuff.
05-31-2015, 10:54 AM
#35
I know Eddie young has 1000hp deals like that running around that have exceeded the 300 hour mark plenty of times before coming in for a refresh. I also know his valve lifts are not in the .700+ range, and his spring pressures are not nearly 600psi open on a hydraulic. I kinda want to take a page from his book .
The LS stuff is really cool, and no doubt a better design, but not into spending all the money to ditch my twin stelling exhausts, engine mounting , accessories ,and all that other stuff. The BBC is capable of my goals all day long, as long as the valvetrain isn't designed for a drag race engine .
Last edited by MILD THUNDER; 05-31-2015 at 10:57 AM.
05-31-2015, 11:48 AM
#36
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iTrader: (1)
What about going solid roller to lower valvetrain mass for lower spring pressures with the benefit of more accurate lift? I know solid roller lifters are lighter. Has anyone did any research on mass of valvetrain components from brand to brand, and different materials? I am sure the nascar guys scrutinize this stuff. I would think a lot of performance and longevity could be gained from mass reduction.
05-31-2015, 12:01 PM
#37
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What about going solid roller to lower valvetrain mass for lower spring pressures with the benefit of more accurate lift? I know solid roller lifters are lighter. Has anyone did any research on mass of valvetrain components from brand to brand, and different materials? I am sure the nascar guys scrutinize this stuff. I would think a lot of performance and longevity could be gained from mass reduction.
Last edited by Precision; 05-31-2015 at 12:07 PM.
05-31-2015, 05:41 PM
#38
Registered
Tony, you got me playing with the sim software.
Just for chits, I built a 540ci, 10:1, Dart 335 headed engine with a dominator carb and single plane. With a Crane "651" cam, 244/256 114lsa, .632/.632 lift cam, 1.7 rockers, the sim came back with 685HP peak. Changing nothing but making the lobe larger, going from .371 to .410, which netted .697 lift, the horsepower 702HP. 17HP gain. What did change, was the auto calculation feature, that displays lifter acceleration. It doesnt give specifics, but basically categories. It moved the stock setup which was between "oem and aftermarket street", to the larger lobe moving it between "aftermarket street" and "limited street".
I then changed to the famous "741" 236/244 .610/.632 112lsa crane cam everyone loved lol. This combo netted 647hp. Again, by going to a .410 lobe, and increasing lift at the valve to .697, the HP jumped to 662. 15hp gain. Again the lifter speed increased, to a higher point than it did with the longer duration 651 cam.
According to the sim software, those lobe changes certainly didnt put it into their category of "all out racing" or "pro stock", but it did increase it further from "oem performance " and "aftermarket street performance" closer to "drag and limited street". Although this information is just from a simulator, it seems to coincide with what companies like crane, comp, have in their lobe catalogs for "marine endurance" as far as lobe lifts go. Of course their is probably many many variables, like when getting into 55mm cores, larger lifter diameters, etc etc. Its more standard bbc stuff.
Being that in a boat like mine, 15-17hp gains, will barely net me 1mph in top speed gain, I'd much rather go with the lobe thats easier on parts.
Just for chits, I built a 540ci, 10:1, Dart 335 headed engine with a dominator carb and single plane. With a Crane "651" cam, 244/256 114lsa, .632/.632 lift cam, 1.7 rockers, the sim came back with 685HP peak. Changing nothing but making the lobe larger, going from .371 to .410, which netted .697 lift, the horsepower 702HP. 17HP gain. What did change, was the auto calculation feature, that displays lifter acceleration. It doesnt give specifics, but basically categories. It moved the stock setup which was between "oem and aftermarket street", to the larger lobe moving it between "aftermarket street" and "limited street".
I then changed to the famous "741" 236/244 .610/.632 112lsa crane cam everyone loved lol. This combo netted 647hp. Again, by going to a .410 lobe, and increasing lift at the valve to .697, the HP jumped to 662. 15hp gain. Again the lifter speed increased, to a higher point than it did with the longer duration 651 cam.
According to the sim software, those lobe changes certainly didnt put it into their category of "all out racing" or "pro stock", but it did increase it further from "oem performance " and "aftermarket street performance" closer to "drag and limited street". Although this information is just from a simulator, it seems to coincide with what companies like crane, comp, have in their lobe catalogs for "marine endurance" as far as lobe lifts go. Of course their is probably many many variables, like when getting into 55mm cores, larger lifter diameters, etc etc. Its more standard bbc stuff.
Being that in a boat like mine, 15-17hp gains, will barely net me 1mph in top speed gain, I'd much rather go with the lobe thats easier on parts.
05-31-2015, 06:46 PM
#39
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I'm building a coates cammed engine so I don't have to worry about all that valve train junk.
05-31-2015, 06:58 PM
#40
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iTrader: (1)
Cool,so you can port the 'valves' right ?
