i was bro....but we're coming to the races in GH soon....this weekend is the poker run...next is the texas race...then GH....then back to texas....and THEN.....**** i was HOOOOOPING to get this job in cali....time will tell.

hummmmm...i know V...., KAMMA's engine man....well i have never met him but i sure did see a lot of his engines in our shop with his mark on the heads.

Change the cam! Add a dual plane manifold! You're probably giving up at least 30-50 ft-lbs of TQ at the 4000-5200 rpm range. With that additional TQ you will be able to pull a bigger prop and also have a higher cruise speed. You want to maximize your TQ in operating range.

Get a desktop dyno for the computer and play with it. Look what a smaller vs. larger cam does to the TQ curves. They are cheap at Jeg's or summit.

Think about this. My motor dynoed @ 640 hp @ 5700 rpm with 5.5 lbs of boost.

Once in the boat the boost was @ 6.5 lbs @ 5300 rpm. Why the difference in boost at lower rpm? I have been told that dyno load and boat load are 2 different things.

Ken-- That's exactally why we need an ON-BOARD-DYNO on the boat. Different exhaust, ignition, fuel supply, temperature, load. So how much HP does your engine make at 6.5lbs and 5300 rpm? Don't know!

Exactly!:D

You could also try to advance the cam 4 or 5 degrees. This will increase cyl pressures slightly in the low end and will pick up some low end torque. You will then need to prop for the desired RPM. The best bet is to talk to a good engine builder and get the right cam for your application. Oh ya, running at peak HP may not be the best place to run depending on where your peak torque is occuring. I would try a bunch of props and see what RPM is providing the best performance before making to many adjustments. Just because peak HP is at 5600 doesn't necessarily mean it will be faster or better performing than
running at a lower RPM. Your peak torgue RPM may have more
influence especially in a boat.

A dyno is a Great TOOL is used properly for dyno comparitive testing at a specific facility. Each machine will read a little different, and work different so the numbers are only truly accurate vs. themselves. Next bottom line doesn't matter what the dyno says, it what the boat, or race track says that counts. I know of engines that during a race run in a very short RPM band within say 500 up and down, but change the numbers above or below that (in an area they never see going around the track) and you'll change the acceloration rate changing the performance. An on board dyno is great as a tuning ad for that specific combination, but I don't know that it is the end all be all answer either.

Bottom line a dyno is a great place to break in your combination, and do your baseline adjustments, you can also (if you take the time) try different things so that once you try them in your boat you'll now how close to the line your are going, but you've still got to see what your boat wants. The on board dyno, or some other data aquisition would make this a quicker process.

Interesting, I just had a motor built that peak horse power is @5,600 rpm and I am going to prop it to be able to turn 5,600, I typicaly won't run it that high, but thats where it making the big numbers, engine builder said with a different intake 6,000 would have been the magic number.
Am I making a mistake? This is a fully machined, Balanced & Blueprinted 468 roller motor, 500 hp

What WETTE VETTE said. Advancing the cam timing drops the torque peak. Every cam and application is different but I like to set my #1 intake lobe center at 105 degrees for a 5000 rpm engine. Run Bravos over 5000 rpm for a few hrs and watch them explode.;)

Probably the biggest reason I changed cams was because I felt that on the dyno I saw a lot of rich black sooty stuff in my exhaust which I believe was caused by over scavenging via large tube headers, fully ported heads and too much over lap on the cam specs. I didn't think I needed too big of a cam because the heads were fully ported and thus flow so well that it is causing everything to slip out the exhaust! Now, I know my theory could be TOTALLY WRONG and I could have left the cam in there, BUT I'm the kind of guy who likes a WELL TUNED, EFFICIENT running engine. I don't want to throw any UNBURNED gases out the tail pipes that aren't doing me any good. I want to try and effectively burn all the gas in the cylinder before kicking it out the exhaust. The cam that I had in there on the dyno was 244*/244* duration and .601"/.601" lift on 112*lobes. This cam had about 74* of overlap and made 699hp @5750rpm and 682hp @5500rpm which made very good power with my engine combination. But I have replaced that cam with a 236*/244* .601"/.601" on 114* lobes which brings the overlap down by maybe a few degrees--- 4*? However, I have not dyno'd my engine with this new cam change and one thing that I can NOT stand is throwing unburned gas out the tailpipes...some guys it doesn't bother, but I do NOT like that idea and if it means losing some power then so be it. I'll be testing these new cams in the boat vs the dyno and I also prefer to run the engines at 5500rpm at the most...not 5750, so I will prop it as close to 5500 as possible.