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[jimsfatboy2]

Has anyone heard anything about the mr103 cams from s&s. the dyno sheet says 94 hp and 109 torque in 103. Looks like a great cam. any input would be appreciated. Additionally dos anyon have an idea of what the labor costs for cam replacment and pushrods

[TorqueInc]

  Was a crane grind a few years ago....didn't catch on I guess S&S tried it again

   Much better cams out there for a 103

[jimsfatboy2]

really? I thought the dyno results looked phenonenal. looking for more torque. what would be  a better cam only installation for the 103 without any head work

[HILLSIDECYCLE.COM]

Let's put some of those in service under a good head/intake/pipe and let's see how they play out.
Scott

[TorqueInc]

  Designed as a bolt in,dyno results do not ALWAYS reflect how the cam works in the real world.

  If you install an AC good pipe the need for a cam with 26 degrees more exhaust duration and equal lift ?

  And again this is not a new cam,S&S taking it from the crane book from a year or so ago someone would have ran this cam and nobody has heard anything about it.

  New does not mean better

[INDEPENDENT_1]

Looks promising but the exhaust duration is reminiscent of the earlier S&S grinds designed to overcome the poor exhaust ports sported by the early Twin Cam heads. Id like to see a sheet with a 2-1-2 pipe also.

[HILLSIDECYCLE.COM]

That exhaust timing is absolutely fine, as there is more than just 1 way to get around the barn.
Scott

[TorqueInc]

    Another way to get around the barn if you use the .....well this pipe sounds good or looks good mentality and slap on a lousy performing pipe that kills a combo...we all know what they are and yet people continue to use them.

   The cam does not meet the snuff test as a bolt on......100 ft lbs @ 2500.....given the parameters of the engine with a freeflowing air cleaner and a good pipe the right cam should be able to extract this from a factory 103....not the higher compression waterhead that is a different can of spam.

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   Exhaust events are compromised by the need to extract all the torque possible before opening the exhaust valve, and the need to extract all the burned exhaust gases possible before the intake valve opens. After TDC the exhaust valve closing, if longer than needed for low-speed dynamic control, allows excess exhaust reversion to enter the intake from exhaust gas pulsations. This is why I claim the exhaust valve closing is the least important of the four events; It only affects low-speed power. at higher speeds the other events are much more important.
The exhaust cam gets in a race all its' own, a race between how much torque can be made by delaying exhaust valve opening, and how much exhaust can get out before the intake valve opens. How much exhaust gas is out of the cylinder affects how much intake charge can get in.
Peak Horsepower occurs when the exhaust can no longer effectively clean out the cylinder, and leaves residual gases in the cylinder, hindering intake filling.
Intake opening before TDC is to minimize exhaust gas reversion into the intake port, which aids in cleaning out the port entrance after the piston starts down ATDC. The sooner the intake can start flow into the cylinder, the higher the intake port velocity can be, the more inertia ram you can develop in the intake port, and the longer you can fill the cylinder ABDC.
As long as intake charge is still entering the cylinder, it doesn't matter too much when you shut the intake valve. I have had this proved to me for 30 years, with unsymmetrical cams still providing good bottom-end torque, even with delayed intake closings.


UDHarold

   Read carefully and explain why you would want to do what you are suggesting.......its like trying to turn right in a nascar race

[HD Street Performance]

Yep UD designed cams for my buddies 56 Chev when he was at General Kinetics, NHRA Jr Stock. Broke kids running a tenth or two off the national record. We changed heads every 9 rounds with hammered valves and rockers and didn't care it ran so good.

[INDEPENDENT_1]

@ Hillside, I wasn't discrediting SnS. Simply making an observation. Matter of fact I run SnS cams in my own bike. I have never really been a big proponent of some of the smaller cam grinds SnS has like the 583 for example. I've tuned that cam and was a little disappointed. It made decent numbers but area under the curve was less than stellar. That said, I read something on the 3 new cams they just released. Someone mentioned the exhaust duration and the possibility that some area under the torque curve may be smaller because of the exhaust lobe hanging open longer than one might think would be optimal. SnS stated that based on the testing they did they actually worked better with the longer duration hence the cam design you see from them. Who knows what exhaust this was based off of and how well it scavenged the burnt charge? Not to mention SnS has the money and the equipment and resources to test product to make it work to its best potential. I am a fan of SnS and Im currently building a 106 for a customer and Im using their Super Stock heads with the 79cc chambers. The heads are very impressive to look at but this is the first time they will be on my dyno. The cork in the build is the terrible exhaust (Samson Cholo's with fish tails). Id like to get their 2-1 pipe on the drum although Im not a fan of the looks I suspect it works well. That being said, obviously there are other things to consider such as cross section area of throttle body, cylinder head ports and exhaust used when designing a cam but designers are forced to spec cams without knowing what the end user will be using regarding all the variables. That being said, we all know that its give and take. There are no free rides so to speak.

[HILLSIDECYCLE.COM]

When I hear the word Samson, it usually has me in wonderment in regards to exactly what really lies within the engine, as it sure isn't coming out via use of that exhaust.............
Scott