articfriends

Im infatuated with these intakes, having made good hp now with two of them on motors I built and dynoed I plan on doing some testing soon with the rectangle port version. The last one I built and dynoed IS going in a 280 powerquest like the OP's hull. A few things on THAT hull is there is very little room in front of intake on a front mounted throttle body, we determined there is only enough room in front of TB for about a 7, 7.5" ' long cone filter. Tested multiple cone filters and adapters on flow bench AND dyno on this last one. A 90 degree bend feeding the TB on the proflow IS the end of the world as far as hp so its very important what goes on front. Id be interested in whats done to that TB on the Pat mussi engine as the box stock edelbrock needs work to make real power from its stock form.
I DO know the 280 hull is VERY touchy, I bought one this summer as a short term investment and I have quite a few customers with THIS hull.
Jason scott's 280 ran 85 radar at shootout this year, on my dyno his motor made about 630 hp and foot lbs of tq in dyno trim during a glory pull, as installed in boat was probably more like 580, 590 ish. It had a extremely modified 502 mpi intake and a great tq band. While tuning on the water, we saw high 70s in his boat. I will tell you though, with ANY weights in that hull, especially in cabin or a full tank of gas, its GLUED to the water and feels like a slow , ass, turd. I drove his boat loaded down weeks after the shootout at hotboat and it felt like it really needed a supercharger, it went from being sort of zippy to struggling to get on plan from adding extra fuel and passengers with a 28 labbed on it
Jeff H had the same hull, 280 PQ, ran 82 If I remember right at shootout with another 502 I modified the intake on and dynoed here then tuned on the water, his made about 610 hp in dyno trim on my dyno, made about 580 with water EMI jacketed manifolds . His boat ran mid 70s in normal operation but again, very sensitive to load.\
The stock 280 I bought has a 340 hr 502 mpi in it, boat wouldn't break 60 mph with a std 24 pitch although its been claimed and accepted that different versions have ran mid to upper 60s bone stock under perfect conditions. I did a injector change on this one after I flowed and cleaned the stock ones, determined there were several over achievers (running rich), I then reflashed ecm and added a 02 bung to one stock manifold to actually dial in the tune properly. That got the boat into the 62/63 range, having hull bottom cleaned and a labbed 26 over trimmed on fumes, by myself got boat into the 66 or so range BUT throw 2 passengers in and boat wouldnt barely go past 60. IF you really wanted one of those to go fast, Id gut the cabin out, alot of weight in front of the step which is very far forward.

SB

Arcticfriends - how about something like this and run two fa’s/air cleaners ? I’ve never tested one. But…..

articfriends

Id like to see what it did on the flow bench and on the dyno. The condensed version ive experienced was THIS :
"1150" cfm edelbrock 90 mm tb flowed sub 1000 out of the box,the 92 mm holley was very similar.
With my dyno partner norms grinding, massaging, etc, we got from sub 1000 to 1200, 1220
bolting a fairly long radius 90 on took us back below 1000, a short radius 90 was worse
clamping on most 4.5"id cone filters that will fit in a boat and not hit back seat in a single took us back to that 1000ish mark or less
putting a 18$ siectre 4.5 x 6" volute on tb took us from that 1200 mark to around 1400, it took a 102 mm tb that barely flowed 1200 to over 1700). With most 6" id clamp on cones, on volute, we went back to 1150 to 1280 depending on size, length, media density
so on the dyno,this 9.4-1, oval port 502 was in the 650/660 hp range. With.most the 4 5" id clamp ons we went to the 620 to 630 range (i spent over 500$in cone filters, pieces out of my own pocket to try)
i stretched the 4.5 x 6 volute over the tb by slicing the area it clamped on, stretching it with heat gun grinding lip off od of tb , etc
very next pull we made over 680 hp. With tuning was mid 680s. Then we tried every 6" id clamp on i bought. Turns out a USED 6" id KN chevy truck filter i borrowed worked the very best and there was virtually no hp penalty.
the first boat i put one of these proflow intake motors in was slow AF but, boat was water logged, ( this was 3 years ago,boatshowed up for motor install with bilge plug in, green slime growing in boat, 2 feet of water in it) single vee , scaled 9200 lbs on a aluminum trailer (29 ft envision single).with a 90 degree elbow on in that boat (this was before this last dyno ,flow bench experiment), boat lpst 300-400 rpms and 3,4 mph.
So im learning these moniblade tb's can make ppwer but smallest thing can KILL power, Smitty

Brad Christy

Arctic,

Just my Frankenstein mind wandering here....

I know this sort of thing happens all the time in the model boating world, because I've made "long" rods for many engines within our realm. It's pretty easy to do, with only a shim under the cylinder sleeve equal in thickness to the difference is rod length from stock. While I'm sure there are a number of "lack of" success stories that didn't bother reporting back, I got many calls from very satisfied customers. Being two strokes, with piston/sleeve transfer ports for valves, there are other factors coming into play when doing these sorts of things in our model boating world that are not in play with cam valved four strokes in our monster motor world, but reducing rod angle was one of the benefits being chased after.

Since rod angle seems to be the primary concern for the 632, If one were to go with, say, a 565 build, would it serve to start with a 10.2 deck block and use longer rods? Just doing the basic math, using 6.7" rods instead of 6.385 rods takes up all but the last .085" of the difference between the 10.2" and the 9.8" decks, assuming the difference would be exactly .400" between the two deck heights. An automotive machine shop could easily take that off and one would be back to nominal deck height and an even milder yet rod angle. Would there be any benefit in this? Any harm? I know other alternative parts would come into necessity, like pushrods, but that shouldn't be an hill for a climber, I wouldn't think.

After some rudimentary AutoCad work, some numbers, if applicable, based on 4.25" stroke:

6.385" rods reaches max rod angle of approx.18.4 degrees of rod angle, at 71.6 degrees ATDC and 1.7805" below TDC.
6.700" rods reaches max rod angle of approx.17.6 degrees of rod angle, at 72.4 degrees ATDC and 1.7960" below TDC.

Don't ever let a self employed toolmaker get bored...... Crap like this happens: (I did that, BTW.)

Thanks. Brad.
(937)545-8991

Brad Christy

Dan,

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I would use the 540-555-565 Super kit, and substitute the rods for 6.7" rods, assuming no condemnation from the previous post.

Thanks. Brad.
(937)545-8991

KWright

After reading through your post, I see you talk about being able to pull a water skier. If that is your goal you need to have an engine that will pull right off idle. Torque in the 800 to 400 rpm range. That's going to take a whole different set up. The cu in is not going to carry you down that low with performance style heads. I think you are at a fork in the road, stump pulling low end power for sking or high end power for speed. Jmo

F-2 Speedy

Gen 6 502 to a 540 would be a nice combo and pretty easy on the wallet...........4.25 x 6.385 x 4.50

SB

imho - building more torque just for water skiing is crazy thinking to me. It’s so damn easy to change a prop, unless you are surrounded by great white sharks or alligators, oh well no skiing then snyway…..lololol

More torque for using thr bigger prop to water ski. Nuts.

I don’t think the op has broken enough outdrives yet and thus this line of thinking…..,,,,,;

Brad Christy

KWright,

I hear ya. And I know there is very often a choice and a tradeoff that needs to be made. I've been boatin well long enough to know that everything is a sacrifice of some sort or another in a boat. But, here's my crux....

Back in the day, my dad had a SeaRay 260cc (built on the Pachanga hull, as I understand it), with the bone stock 315HP 454. It weighed 5500lbs. We all skied behind it. We all called it "Great White". It was, by no means, a performance boat. Granted, having grown up skiing behind a 21' semi-flat bottom with a blown 482 V-drive, it was a bit underwhelming for me, as a ski boat, but my wife and several friends learned to ski behind it, and it would pull several of my dad's fat azz friends out on slaloms. This boat would also ran 55MPH or so.

The PQ we've got now weighs almost a 1000lbs less. I'm looking for neither Wakesetter ski boat performance nor race boat performance. I'm looking for something right down the middle, but performing better at both than I'm currently getting. That tells me more everything: HP, torque, ci, etc.... I have to think this is not unattainable, and I'm not looking for the ultimate in anything, other than as much the best of both worlds as I can find.

Thanks. Brad.
(937)545-8991

Brad Christy

SB,

I haven't broken a single outdrive yet, eleven years into owning my own boat (after four decades of boating with by dad prior), and I intend to keep it that way. Obviously, the outdrive would be addressed and upgraded as part of this project.

Truthfully, my days of skiing much are likely behind me, but my son likes to ski. Although the kids don't spend much time with us on the boat anymore, we do still boat as a family enough to want to be able to jerk a skier from time to time. I think we dropped the ski rope out maybe twice this last year.

As I stated just prior, I have to think a middle ground is feasible. Besides.... More HP is never going to go to waste, right? Always a good thing, right?

Thanks. Brad.
(937)545-8991