MILD THUNDER

Tim doesnt have GEN 3 . The Gen 3 manifolds, are giant compared to the standard ones...

tad117

So after all the info what are your thoughts? You have seen tims torque and horsepower numbers vs the computer genterated numbers and tim stated that the engines feel sluggish. Do you think he is going to be able to make some changes and be happy or the smaller cube motors just not going to push the boat the way the original motors did?

Full Force

The cams I had peaked and fell fast, that was the biggest issue for carrying the boat... and powerband was too short

endeavor1

That's it? I thought they also butchered your valve train, caused Undo personal stress that you shared with the OSO membership, cost you thousands of untold wealth, wasted personal time that could have been devoted to personal causes and on top of it all, the boat went slower or same speed.

MILD THUNDER

It be interesting to see the results of those cams from the cam doctor

MILD THUNDER

I think theres alot of guys, not understands what I am saying, when there is more to a cam, than .050 numbers. Let me show an example here. Short seat timing, relative to .050 timing, is what determines lifter acceleration, which also can determine how quickly the valve opens. Short seat duration, compared to long seat duration, with a given .050 duration, can accelerate the valve quicker. What does this do? Make more torque at low speeds. Longer seat duration, will give up some low speed output, but carry a little longer in the powerband. Now, everyone wants maximum power throughout the powerband. SO, what cam companies can do, is grind you a cam, with shorten seat duration to get quick valve movement, and boost power output, and adjust the .050 duration , to meet the max rpm one wants to turn.

Heres the problem. These aren't drag cars. Slamming the valves open, and slamming them closed, can lead to bad stuff. Parts wear out faster, parts break, and so on. I'm sure everyone heard the sales pitch, about how "antiquated" the crane hydraulic roller profiles are. It has nothing to do with the date the cams were designed. What crane was supplying, was a camshaft, that isn't goign to kick the chit out of your valvetrain. There's a reason Mercury Marine used crane cams in their engines. They worked. A 500EFI, HP500, etc, didn't slam the valvetrain around. It didn't need crazy spring pressures to keep things under control. It was a simple setup, that would last many hours. Do they leave some power on the table, of course.

Tim's cams, having a 241* lobe with 680 valve lift, surely sounds like it was an aggressive lobe, just going off that info. However, without anymore info on the cam, its speculation. The thing could have a wider seat duration, to maybe help calm things down. Does it? I highly doubt it. What makes a cam sale, is a dyno number. After that, any failure, could easily be blamed on something, anything, besides the design of the camshaft.

Anyhow, First picture, will be 741 cam as shown earlier. Next picture, will be 741 cam, with 10* longer advertised duration, and third picture, is with 10* shorter advertised duration. By spreading the seat duration, the ramp rate goes down quite a bit, by shortening it, it increases quite a bit.

endeavor1

Interesting data sims that you posted. Wish I understood the variations of the inputs better.

SB

SB

SB