formula 206ls engine mods
 

Alright, so my boating season has come to an end in vermont and after the first year of owning my boat, ive decided i want to upgrade. Its an 87' formula 206ls in great shape with a merc 350mag, alpha 1 outdrive turning a 21p quicksilver. Im currently running around 55mph at 4600rpm. Now i know some of u are going to say go to a big block, but its not gonna happen, so save yourself the time. And I also know my weak link, the alpha outdrive, but i can get a reman unit with 3 year warranty no questions asked if i blow it. SO....what to do??? im slightly on a budget, and would like to get the best bang for my buck. I have read a lot on the vortec head swap, and it sounds like a pretty economical upgrade, but is it gonna get me much gain without pulling the engine and swapping the cam?? The second option would be supercharger, but there are limited resources on this upgrade, dosent seem to be overly popular. Will an automotive roots style supercharger adapt to this engine without major issues??? they are reasonable priced around $2300....Any information that is available would be greatly appreciated!!!!
Thanks!

Your best bang for the buck is to switch to Vortec Heads and Intake along with the LT4 Roller Hot Cam. Depending on how your bilge is laid out you should be able to do the cam with out pulling the engine...if you can't...pulling one is no big deal. It will give you access to the bilge to tidy some things up as well as give you a chance to clean the engine and paint it.

You will be running about 400 horsepower with that combo and should be able to go to a 23" mirage that would put you in the mid to upper 60's in that light boat. You can get an Alpha to live in a light boat if you don't beat on it too much...just take care of the drive lube and put a drive shower on it and you should be ok. If you do pull the motor...consider swapping the coupler to the heavier Bravo version...it will hold that extra power. It's easier to pull a drive and change it than it is to pull the motor and change a coupler.

Personally I wouldn't mess with a blower unless you want to build a motor for it...too much drama and $$$$ for the return.

Your motor with Vortec Roller goodies will transform that little boat into a bullet,:evilb:

thanks for the info, im thinking this may be the route im going to take. Any suggestions for lift on the cam??? Also, you think an edelbrock 600cfm carb will put me where i need to be???

Do a Google search on the Cam Specs...and a 600 CFM will limit you. Think 750 Holley Mechanical Secondary Double Pumper.

soo ive been doing my research, cam selection is difficult especially since the vortec heads limit you to .460 lift. But crane makes honeycomb springs that allow up to .550 lift, and as i understand it the springs are the weak link in those heads.. the other thing i found are the rocker studs are press in and are known to damage the heads in performance aplications. Arp makes screw in studs..problem solved. so here is where im at..

screw in rocker studs
valve springs
roller cam, (undecided which one yet)
roller lifters
edelbrock intake manifold
edelbrock 750cfm carb (herd really good things about edelbrocks)
gaskets....
totals up to about $1500.00 not including heads(got for free) and install of studs. Am i missing anything????? Any other sugestions greatly appreciated!

Any performance build starts with exhaust. Running stock exhaust will always be your hold back.

You did your research. The Vortec heads and springs limit the lift so you go for the after market springs...which you have covered. Here is a link to the LT4 cam specs.

http://www.gmassie.net/13secss/lt4_hot_cam_specs.html

You will not need anything beyond the 1.6 rockers...and at that you are on the ragged edge with exhaust reversion. Unless you want to add another $1500 to your budget for good hi po aftermarket exhaust...stay with stock/near stock. If you are STRICTLY fresh water you can pick up a little power and TQ with the GLM cast pieces but some say reliability suffers.

Don't forget ignition. Check the swap shop here for used DUI or MSD pieces that you can save a ton on. You may even luck up and find a good used set of marine exhaust at half price. I have ALWAYS been dubious about used exhaust but that's because I am a salt water boater exclusively...I have seen motors destroyed with used exhaust.

Put the money you save on exhaust into a Labbed prop...once you find the right pitch. Every engine/drive/boat combination is unique.

Sounds like you have a realistic budget. Try to stay as close as you can and enjoy the project.

getting some good feeback, really appreciate it!! The boat came though the factory with through hull, silent thunder though.....so its not a true through hull. Ive seen some threads on opening up the silent thunder systems, something i should consitter??? I would just hate to have to remove the swim platform, i like having it.. And yes, i run in freshwater only. Cracked the engine cover last night, defintly going to have to pull the engine to install cam, only about 10 inches of clearance in front of it, but it dosent appear to be too difficult.. Thanks again!

you can pull the back seat and punch a cam hole on bulkhead with a hole saw. Vortecs are designed to flow well with conservative valve lifts. going over a half inch gains very little performance. but do the roller conversion...

Wouldn't pulling the balancer and timing cover still be an issue?