Off the shelf Cam- Dyno results
06-16-2016, 06:43 AM
#21
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06-16-2016, 07:01 AM
#23
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235/243 .610/.627 114 LSA cam.
http://news.compperformance.com/wp-c...I-Camshaft.pdf
Nice combo. Should work well in that big 45 Wellcraft. Excellent torque. Should live a long time , as the lift is reasonable. No .680 lift needed to make the power,and I'm sure the valve spring pressures are reasonable as well.
http://news.compperformance.com/wp-c...I-Camshaft.pdf
Nice combo. Should work well in that big 45 Wellcraft. Excellent torque. Should live a long time , as the lift is reasonable. No .680 lift needed to make the power,and I'm sure the valve spring pressures are reasonable as well.
Could it be something off in the combos, yes but I surmised it might be low airspeed caused by opening intake valve too fast, too early or too high, reducing air speed and not filling the cylinders completely until air speed picked back up at higher rpm.
I don't post much but read A LOT and your posts about cams made me think very carefully about cam selection
06-16-2016, 07:06 AM
#24
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But we did find out that they are not std BIII, they are one of the Xs. We ordered new upper seals based on drive SN on engine plate and they were too small. So they've been replaced at some point and internally they look great....fingers crossed need to get thru this season
06-16-2016, 07:13 AM
#25
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Sometimes that torque dip is just a result of the dyno catching up with the motor.
Other times it is caused by exhaust tuning resonances.
Some times it is caused by the cam.....but wider LSA like yours tends to keep this away. Results in flatter torque curve...well, almost a flat line. Good ? Well, that depends on what you call good and always up for a debate. I wish I knew how to make graphs as I could much easier show what 'bad is bad, good is good, bad is actually good, and so on and so forth." LOL. BTW: the terms bad and good is when torque curves are critiqued heavily. Not something we worry about in a massive beast going thru / on the water.
Other times it is caused by exhaust tuning resonances.
Some times it is caused by the cam.....but wider LSA like yours tends to keep this away. Results in flatter torque curve...well, almost a flat line. Good ? Well, that depends on what you call good and always up for a debate. I wish I knew how to make graphs as I could much easier show what 'bad is bad, good is good, bad is actually good, and so on and so forth." LOL. BTW: the terms bad and good is when torque curves are critiqued heavily. Not something we worry about in a massive beast going thru / on the water.
06-16-2016, 07:22 AM
#26
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What are you going to do on the exhuast side? Still out the side, or try to go out the transom. What kind of speed are you getting now? I have 2 spare bravos 3s now. So time to up the power also
06-16-2016, 08:02 AM
#29
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You have nothing to worry about, great job! I wish I had some of this info when I built by engines... I am the first person ever probably looking forward to refresh time to change it all. Go Bob! Thx for nothing
Agreed I wanted to keep lift at a "reasonable" level. I spent many many hours agonizing over cam selection. I reviewed as many dyno charts as I could get my hands on, asked for recommendations from a bunch of suppliers. One thing stood out on every one of the dyno pulls was a torque dip sometimes as much as 500 rpm wide right where I didn't want it in the 3000-3700 range. Granted they aren't huge losses but, with what I'm trying to accomplish with this heavy boat, I could not afford to loose anything in that range.
Could it be something off in the combos, yes but I surmised it might be low airspeed caused by opening intake valve too fast, too early or too high, reducing air speed and not filling the cylinders completely until air speed picked back up at higher rpm.
I don't post much but read A LOT and your posts about cams made me think very carefully about cam selection
Could it be something off in the combos, yes but I surmised it might be low airspeed caused by opening intake valve too fast, too early or too high, reducing air speed and not filling the cylinders completely until air speed picked back up at higher rpm.
I don't post much but read A LOT and your posts about cams made me think very carefully about cam selection
06-16-2016, 08:34 AM
#30
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SB- It was explained to me that on a computer controlled dyno; programmed to pull a certain rpm/sec, the computer sees the torque dip and releases the water brake to allow engine to continue on the preprogrammed pull rate. So in essence when you see the dip not only are you getting a reduction in the torque output of the engine, but also the dyno is "helping" the engine by reducing the load to stay on track.
