GPM

You could just run a boost controller on the Pro Charger, have all the bottom end you want along with the top end.

dereknkathy

Boost controller modifies waste gate to increase the point it opens to limit boost. It can't make a centrifugal supercharger make more boost at low rpm's. The whole problem here is the 1 speed trans using the ocean (or lake michigan) as a torque converter is geared for the power engine makes at high rpm and boost.

GPM

Or you could spin the Pro Charger a little faster to increase the bottom end and use the controller for over boost at high RPM, nah, that couldn't work.

abones

Just hit the "Like" button on this!

Turbojack

I had a 26' cat with procharger. Coming on plane was wot and sitting back. Once rpm got to around 2500 the boost would come on and it would rip the prop loose. As stated before I think the low torque at low rpm saved my Bravo.

I now have a 30' cat with whipple motors. When I take off now I have to baby the throttles to keep from tearing the bravos up. I like the whipple motors better.

indysupra

iTrader: (3)

I missed this thread so I will give my input since one of the three boats is mine.
Boat is a 98 42 fountain, 19.5 inch on center stagger , prop shafts are 1.5 above the bottom with ssm 4/5's. Motors are 540", brodix heads, pretty big cans, gill exhaist with m3sc blowers only running 8.5 lbs of boost. Didn't dyno the motors but they are making in the 950 range judging by duty cycle and speed.

When I first got the boat done the first set of 5 blades I tried were 2" smaller pitch and the boat planed like a
ski boat with no tabs. Second set were the same size as current but boat planed no problem with tabs. Props did not slip during planing but the slip was high as could be while running. Also know that my boat was originally a triple boat that I converted and has tiny tabs on it that I am planning on swapping out for some 380's. Last set that I tried are new style mercury 5 blades with a ton of cup in them. Boat is tough to get on plane because it lugs the motors right at 2400 rpm. Last trip out I hurt a sea strainer lid and have not been able to get back out but when I got the boat home there was a ton of soot on the transom. I download the logs and because of how differently the new props loaded the motor it was running 1.5 pts richer while trying to plane. So with some tuning I think it will be ok but if not im going to get creative and build some #6 style vent tubes for the props. Low sub 3k rpm with pro chargers sucks for sure and is a deficiency but with my big intercoolers and me even feeding them off the crossovers(read not lake temp water) my iat's are pretty impressive. Long 2 min pull of wot and over 100 mph i dont even see 100 deg on a 90 degree day with fairly high lake temps. When you pop the hatches my cold side pipes fog up. I think plumbing the coolers off my strainers I will see a decent drop in iat's. I Will report back with how much better it is after I lean out the planing rpm
but I expect it to be much better. As long as I can get on plane I don't care, I care about how it
performs once running and so far it is a beast!!!! The pull when I hit the sticks at 50mph is nothing short of impressive and because of the cool iat's it's a super safe setup and works awesome with the efi. I have more
to add but need to get to work right now.

MILD THUNDER

iTrader: (3)

I was shocked to see my roots blowers with 9lbs boost with IAT temps in the 110* range . Intercooled of course. Id like to try some more water to the intercooler and see if it changes temps

Eric, are you port injected , or throttle body injected , I forget

I remember a while back , looking into boost relief valves for procharged setups. Do you guys ever see boost spikes when on and off the throttles in big water with prochargers ?

indysupra

iTrader: (3)

It's port injected. No I don't see any spikes. New pulleys just arrived so I will see after that but doubtful. In a car I know it can be an issue when the boost gets higher. I know 100 deg is obtainable with other setups i was just posting it because of where I'm getting my water from ( almost engine temp water). With some testing I did with doing one motor directly from the sea strainer and the other thru the crossover it was 18 degrees cooler but was in different operating conditions. I have the fitting to change it over but don't want to change too many things at once. Also another note on iat's i know of many setups that are in excess of 130. And that in a boat is to the point of needing timing pulled.

articfriends

iTrader: (1)

The flow curve starts out slower the bigger a procharger is, my m3sc made 900 or 950 ft lbs tq at 3500 and 890 or something like that at 3000 but it was pulleyed waaay up, i DRAG raced roots blown flat bottom vdrives from a 40mph roll from 3500 up and surprised quite a few of them with my 272 baja, fwiw, smitty

articfriends

iTrader: (1)

I also sheared off billet Max Works prop and vertical shafts doing stupid s*** like that