how much ?
 

how much hp would it take to push a 1991 311 sr1 to 80 mph ?

I'm lookin to find out.

I'm procharging, hydraulic roller camming, gapless ringing, Holley carbing, CMI E-topping, extension boxing my way that direction this fall...

I'm actually in the middle of sleepless nights trying to figure out if I need a neutral extension box or a +3" box. I guess I expect the answer to crash in and slap me in the face one night at 3am...

I'm figuring my X-dim stock is pretty dang right for all-around boating. I get good leverage on the bow and can trim up and hop the boat out of the water so the kids can levitate on the front berth (like NASAs vomit comet). I need all the leverage I have for WOT to get the nose up and air out the boat (max speed is lots of positive trim with Mirages).

If I use an extension box, then I am afraid that the x-dim will be too deep at std mounting location (since the farther rearward you place the drive, the higher the water runs across it). Yet I am afraid that if I go to the significant hassle of jacking everything up 3 inches, that I might end up way too high and the boat will only be good for speed runs ( I don't wanna have to really baby her out of the hole, I don't wanna give up the vomit comet rides for the kids). The boat handles so marvelously that I am afraid to f*ck it up with a too-high X...

Any thoughts?????

my guess would be around 600 hp a side. I had a 311 with 450 a side and Kaama drives that saw 68-70 mph

Bob

A friend had a little over 600 a side with Kaama drives and he was just touching 80.

Jon

A friend had a 336 (which is a '93 version of an updated 311 - within 300 lbs of same weight and same overall length within a couple of inches and same nonstepped 24 degree hull).

He had 525sc's and ran 83.