I've posted on here several times over the past (7) years with questions and feedback on various things relating to pushing the limits of alpha drives with built small blocks. I've reached a point where a re-cap might be beneficial to several others who are trying similar things. First off thanks to all the help along the way, especially from (3) members that have always taken the time to lend advice, ACrooks69, SB, and Ryan00Tj. For those not familiar, I started with an old 1994 sylvan Barritz 209 that I bought used in 2015. It had a 305 merc with 4 barrel quadrajet and made a whopping 220 hp that pushed the boat to a blistering pace of 43mph with 1/4 tank of fuel and my family onboard. In 2016 I started the season fixing a soft spot in the floor which led to rotten stringers and a complete rebuild and a modern updated interior layout upon completion. I had a new 383 from another project in the shop and decided to throw it in while the renovation was underway. That first engine was probably 330-340 hp but was a nice increase from the stock 305. From there I am currently on engine build (6) for this hull. The current engine is a 394 (4.060 bore x 3.800 stroke) O.E. roller block. 10.04:1 compression with Speier Profiler 195cc custom ported heads with 8mm stem 2.08 / 1.6 valves. Ported Super Vic intake with 4 hole HVH 1" spacer and a custom Pro-Systems 850 Holley DP with annular boosters. Cam is a 231/235 @.050 on a 112 lsa hyd roller with Rhoads Vmax lifters to reduce exhaust duration at idle for reversion purposes. Exhaust is GLM aluminum manifolds with Imco Long risers and 6" of riser spacers to adjust for my captains call and side exit exhaust. Idles at 750 without reversion. This Spring with the new carb I decided to pull the engine out of the boat and dyno it before hitting the water. Best pull of the day was 536 hp @ 5600 and 519 torque at 5200. I've been asked several times along the build why i went with such a high rpm intake. It was to create a power curve that allows the alpha gears to survive by softening the torque down low when the boat is lugging to come on plane, yet optimize it up top where the peak power meets peak resistance. The carb has annular boosters to improve atomization at low flow off idle with the big single plane intake to make low speed boating possible.

Last year I bought a sternjack (thanks SB) and installed. The prop shaft is deep on this boat (7.5" below pad). The stern jack really helps leverage this heavy boat out of the water, but the reduced drag of an SS would definitely help top speed (feel free to send me one for "testing purposes"). The other drive related item I've tested is a nosecone. I can testify that an alpha drive rigged this deep does indeed cavitate at 68-69 mph without a nose cone. With a 21p mirage it will hit a wall at 69.4 without and will hit 73.7 with a cone and at 7% less slip.

So far this season I've been testing props. Last week I compared at 21p mirage with the barrel flare removed, a 21p solas titan hr3 (very close to a mirage plus), and a 23p Laser 2. The laser 2 gave the best speed at 75.7 with 8% slip, but takes forever to get on plane with the small diameter. The Solas did 74.1 @ 7% slip and had manageable chine walk. The Mirage netted 73.7 @ 9% and also caused a hop with the entire hull like it would lift the entire hull too far and couldn't sustain the lift. The Laser had some serious chine walk from 68-71 that you had to throttle and trim through but at 73 cleaned up and took off.

My original goal was to break 60 mph with this hull. I've definitely surpassed that. At this point its just trying different combinations to see what they accomplish. I do have an 80 mph mark from years back with Ryan00Tj to try to eclipse yet though...

Hopefully this information helps someone down the road.

Thanks for sharing your experiences. I’d say you’ve done better than most that take on a project like this. Slip numbers are really good too. Gotta be a fun sleeper boat for the whole family. You’ve probably heard it before but be careful tho because that hull probably was never designed to go that fast and could throw you a curve ball at any moment. Have fun!

#smallblocknation
#alphasgetnorespect

I’d let you try my AlphaSS, but….,only here in person. If your ever out this way (NH) let me know. :thumbs

I ran into prop blowout with OE alpha right at 65. Hydromotive nose cone alleviated that.

New SEI outdrive outdrive almost 3mph slower than regular alpha missing 1/2 the skeg.

Congrats! I like that 394ci build!! Keep looking for sn SS. They show up occasionally. I picked up 5mph & 500rpms no other changes.

Congrats on your very nice build. I thought about doing a similar intake a few times but haven't made a move. I might do something similar if and when I opt for more power. My setup is for torque and does well, but with 170cc intake runners and small valves it stops increasing HP at around 4700 rpm. This being my first scratch build I went with heads that were too small. If I were to switch them out for a good flowing bigger head I bet the power would spring right up. And the lifters with the high ram intake, good logic.
I'm really happy to see the slip numbers you calculated because I have a 19" and a 21" Mirage plus. Just completed my engine rebuild in July and had to wait to heal up a little after taking a fall.
But it's in and I am hoping to get a run in on Sunday or Monday. I boat on the same lake SB is on but I haven't met him in person. I did some port work over the winter and had my block decked .010 which allows me a MLS gasket set. I had been fighting the steel shim gaskets in the past. Blew 2 sets.
My engine went to the dynamometer to run in the rings and check it over. I feel as if that was a good play cause it's set up now by a pro. Surprisingly he kept it conservative. 30 degrees timing at all in and 12:1 afr.
I have always just eased into the throttle to avoid breaking something, but the lifter and intake combination makes some sense at your bigger power levels to keep your alpha together. I also use a drive shower and fill it with Amsoil Severe Gear. No problems yet.
I have to gps my boat one of these days, but I never seem to get a spot for a run to top speed. Or, when I do, I don't have it recording. Thanks for the details.
Hmm, heads, lifters, intake. Maybe next time. Or maybe sometime.

Congrats

NHGuy,
I had a set of ProMaxx 183cc heads before this set of Profilers. They were very good, but really choked flow too compared to where the Profilers are. With the smaller heads, an rpm air gap intake and a 780 holley and multiple different cam profiles from 218/224 to 227/231 I couldn't get any power past 52-5300 rpm. Best crutch is an open spacer on top of the dual plane intake to help top end breathing. I struggled with driveability with the open plenum intake with a downleg booster carb no matter what I through at it. The annular booster carb solved that. I've found side by side carb tests where the annular style booster picks up 80-90 hp down low where port velocity is terrible by improving atomization.

We did our dyno work with dry headers and tuned to 12.4-12.6 AFR. I've since opened up secondary high speed air bleeds 2 sizes to lean out top end just a touch more with the poorer breathing wet exhaust. I found best power at 33-34 degrees. Good chambers with flat top pistons or reverse dome don't need a lot of timing since the flame travel is very efficient.

Shim head gaskets are very picky on surface finish, I've never had long term luck with them.

If your having issues with holding shim gaskets you'll have no better luck with MLS. Find a different machinist to surface you block and heads. In this day and age there is no reason for a rough surface on the deck. Shops that do diesel machine work are the best places to go. They have better equipment and you get a much better job on every stage of your machine work from line bore/hone, cylinder finish, and deck surface. And they cost no more than anyone else.
You might try coating your shim or MLS with Copper Coat. Coat one side and let it tack up, then do the other side. The copper will fill in the rough surface.

Way back in the day there was a guy up there in New Hampshire that had a sea ray ,think it was 19 or 20 foot small block alpha combo ,ended up real close to triple digits. Actually made his own version of a ss drive ,and I believe at one point had a modded outboard lower on his alpha. One thing to consider on those old hulls is to put a nice edge at the hull transom joint ,where they are (old ones anyway) radiused to help get out of the molds fairly easy and cheap to do you may pick up 2 or 3 mph

Many of us remember. Very tough personality. He was not from NH.
Was a stingray. Ended up with a 600+hp 434cid. He was the fastest person on earth. :wink Lol