blow thru carbs arent cheap if they are set up correctly,figure 700 for the carb, engine needs to be set up for boost if its gonna be worth your while to add a blower, forged internals,lower compression,etc. Youll need a good fuel system as well.
Whipple is a screw type blower
Holley,Weind,B&M,6-71s,8-71s etc are all rooots blower
Procharger is a centrifugal.

They all work differently, for a boat where torque isking
you cant beat the whipple, makes the low end power and
is way more efficient than the old school roots blowers .
Except for cost they are way better in every way than
the outdated roots blowers.

Roots blowers make great power but take more power
to turn and have poor adiabatic(sp?) effieciency which
basically means they heat up the air way too much.
They are also the cheapest way to go..

Prochargers make linear boost,means they start off at
almost no boost and build dependant on rpm so they
dont give you the instant kick in the *** the otehrs do
but can make insane amoubt of power on top,they are
also more forgiving on drivetrain parts such as your drive.

 

Yea, I'm aware of the different types of blowers. I considered them for my car - Roots (Eaton) vs. centri (Paxton, Procharger or Vortech) vs. Twin-screw (Kenne-Bell). I also considered a turbo or even nitrous. Now I'm considering all of those for the boat's future. I may never do it, but am thinking/dreaming about it. I'm just hoping to hear from people who own or have owned one or more of the various blowers/forced induction options.

 

I had a pair of B&M 144's in my boat for a while. In my opinion they are way to small. I have 355's and I had to use the smallest pulley they made. An inter-cooler would have helped though. Anyway if you do something roots, I would use a B&M 671. It is allot bigger but they can be had for not much more money and require the same amount of work and fuel system mods.

Another option is to machine an adapter for the 144 manifold to hold the 177 blower. I made some a long time ago and never used them. I ended up using the aluminum for another project.

I bought my 144's on ebay at separate times for around $900ea. complete. Then another $300-$400 for fuel system upgrades. (pump, larger lines, and larger vent) The merc ignition will work fine but requires a V6 module ($75) or do like I did and buy a billet HEI distributor and adjustable rev limiter for $175.

The last thing needed will be a modified carb, like a 750 mech. secondary. ($200 used $450 new) I had my carbs done by nickerson for around $300 ea.

So expect around $2200 to have a safe reliable set up using used and new parts.

 

That sounds like a good price. How much of a power increase do you think the blower gave you per engine?

355 - if it was at 400 hp and went up to 550 that would be a very good increase. 100 hp increase would be good. 200 hp would be GREAT.

 

I would say it was a hundred or so based on the prop and speed increase. You just had to spin it hard to make 6 pounds of boost. An inter cooler would be perfect. I know someone makes one ($1000), just can't remember there name.

 

How much did it raise the height of the flame arrestor? I have to make sure it will fit under my hatch or I will have to factor in a modified or new hatch into the equation. Are you running a spacer between the blower and the carb for heat reduction?

 

If I recall, it adds about 5.75 inches. I can get the exact dimension since I still have the manual. I will look it up tomorrow and post the findings.

Yes, I ran a 1/2" phenolic spacer. The above dimension did not include the spacer.

 

I will have to measure, but I don't think I have 6" available. If I go the blower route, it may have to be a centrifugal or I will have to add a scoop on the hatch. I then lose the sleeper look as people assume you have some serious power if you have a scoop. Right now everyone assumes that my boat will run 50-60 so I surprise people.

 

Twin, Do you have the height increase with the addition of an intercooler? Curious minds would like to know. :winker:

 

Dennis, go with a 174 or 177 blower on that Libby. Yeah you might need a scoop but people are still gonna think it all show since Libby's aren't known for high speeds. We could have everything installed and running in a weekend.

 

Here are the dimensions:


For a PMF intercooler (super chiller) add 4" for all blowers

Add another 1/2" if you make an adapter for the 174 or 177 to fit the small block intake.

B&M 144:
Front dimenesion (front of block to end of pulley) = 7.35"
Height dimenesion (top of block/bottom intake to carb mount) = 7.79"

B&M 174:
Front dimenesion (front of block to end of pulley) = 7.35"
Height dimenesion (top of block/bottom intake to carb mount) = 7.87"

B&M 250:
Front dimenesion (front of block to end of pulley) = 7.35"
Height dimenesion (top of block/bottom intake to carb mount) = 10.68"

B&M 420:
Front dimenesion (front of block to end of pulley) = 7.90-8.83"
Height dimenesion (top of block/bottom intake to carb mount) = 12.18-12.53"

 

To keep that sleeper look, remember you can also put a slight hump in your hatch that would require some mods and or a new sun pad. You can also use colored stripes in the stitching to make your eyes focus on the stripe not the hump. That way you really have to look to notice.

Also remember the fuel water separator. I forgot to mention it. You can modify your stock one by re-drilling and tapping for a 3/8npt. Or do the right thing and buy one with 1/2" npt which also uses a higher gph filter.

 

Another thing for sbc users with newer small blocks...

My original setup was the 98' gen+ small block which has vortech heads. For the 144 intake to fit (different bolt pattern) you can set the intake on the block and transfer the holes. Then tape off the lifter valley and drill/tap the new 3/8-16 holes.

You also need to use the felpro 1/8" thick intake gaskets with the intake.

 

Dennis, go with a 174 or 177 blower on that Libby. Yeah you might need a scoop but people are still gonna think it all show since Libby's aren't known for high speeds. We could have everything installed and running in a weekend.

I am just dreaming at the moment. I'm not sure how fast I want the boat to run or how fast the hull is capable of running. It runs very well at 70 now. 72 - hairy. If I threw another 100 hp at her, I'm not sure it would do too much. 5 mph? I am going to get the prop lab finished over the winter and see what that does. I'm toying with the RPM Air Gap intake swap too.

 

I had a pair of B&M 144's in my boat for a while. In my opinion they are way to small. I have 355's and I had to use the smallest pulley they made. An inter-cooler would have helped though.

Twin - what happened with your blower motors? Did you upgrade to bigger blowers or just go N/A again? If you went back to N/A, can you tell me why?

For $2,000+, I might consider a 177 blower. I wouldn't have to buy the new Air Gap intake then so I would save that money. I already have a good 750 Holley that I could send to Nickerson.

Besides the height issues, has anyone had any real problems running a roots blower at low boost say 3-5#? If I went with a Superchiller, how much can you safely up the boost?

 

Anyone else out there besides Twin that has experience with a carbureted SBC with a blower? Any kind of supercharger since I'm being open minded.

 

201,

I removed them because I had purchased some 671's to install. I ended up selling them and wen't back to NA. I changes cam, did a bunch of head work, cut the heads down and wen't with thin head gaskets to get the compression back.

The main reason I sold the big blowers was to fund my extension box project. One of these days I will start selling them and all of the other parts I make.

With the boxes, I gained the speed back and improved the overall handling.

Keep in mind the 177 will require selling the intake and finding/buying a 144 small block intake.

 

Still looking for some additional info:

Besides the height issues, has anyone had any real problems running a roots blower at low boost say 3-5#? If I went with a Superchiller, how much can you safely up the boost?

Is the 144 too small for my 383 if it was intercooled? I like the low profile look, but don't want to waste my money on something that isn't going to give me much of an increase in HP. I would also consider a centrifugal supercharger such as a Procharger or Vortech as I wouldn't have to worry about the height issue.

 

Shouldn't help the competition :laugher: My friend has a procharger on his stock 350 mag mpi in the same boat I have and it does 75gps.Never had a problem with it and swears it has been a blast.I assume the same setup on your 383 means lots of fun.Also I drop down the list.

 

Shouldn't help the competition :laugher: My friend has a procharger on his stock 350 mag mpi in the same boat I have and it does 75gps.Never had a problem with it and swears it has been a blast.I assume the same setup on your 383 means lots of fun.Also I drop down the list.

I'm assuming it is their intercooled setup. I was comparing the dyno chart from a 383 with a 177 Weiand (non-intercooled) with one from a 383 with a non-intercooled Procharger D1-SC. The 177 put out 67 ft-lb more torque at 3,000 rpm, but by 3,500 it only had 46 ft-lb more. The lead was down to 14 at 4,000 rpm. From there on the Procharger had more torque +9 by 4,500; +30 at 5,000; +67 at 5,500; and +78 at 6,000 rpm. The Procharged engine would have a higher top speed with the same drive and prop. The Weiand might get out of the hole quicker, but with the torque these engines put out I don't think either would have a problem. In fact, I think the driver would have to be careful with both blower motors for fear of blowing the drive because even the Procharged motor had 490 ft-lb of torque at 3,000 rpm.

Some day I might have one or the other. I think I would have a lot of fun and a boat that would top 85 with either setup.

 

Yep,intercooler.With the weight of your boat the bravo should hold up.I think the real problem is moving the greater mass of the big boats and the drag of their hulls that tear up drives behind big hp and tq.My boat gets on plane now with about 1/4 throttle not much load.I guess you just don't jump all over it and it will last.

 

I agree with the load being pushed makes a difference. My boat might be heavy for a 21' boat but it is nothing compared to the 26-28' boats being pushed by a Bravo with big HP motors.

I don't need to hammer it since my boat will get on plane easily unless I have it loaded with people. I don't hammer it then either as I know I'm putting more load on the drive.

 

Take a look at this motor running on YouTube. I think this roots blower 383 would make my boat run at least 90!

http://www.youtube.com/watch?v=xW1Ee0s7WVE&mode=related&search=

 

My concerns with a blower:
1. Hatch clearance - might have to get a scoop and lose the sleeper look, but then again I might enjoy the "raceboat" look.
2. My crank is not forged. It is an Eagle cast steel 383 crank. I think Eagle rates them at 500 HP, but I have read about many people having them in 600-700 hp motors (or is that engines - joke about another thread). Will it last?
3. My pistons are SRP/JE inverted dome forged pistons with a static CR of approx 9.5:1. I know the CR is a little high for a blower.
4. Cam - thinking about changing it no matter what, but I can probably get more aggressive if I'm going to use a roots blower. DomScott's boat showed me how a blower somewhat tames a big cam.
5. Can the hull handle the extra power and actually use it. If I'm going to go 75 N/A (next summer) and only go 78 or 80 with a blower it is NOT worth it. If the hull will go 85+, then it would be worth it. That is why I would like to talk to anyone with a Libby that runs over 80, especially a 201 Libby.

In the meantime, the prop will get lab finished and I might get the RPM Air Gap and change the cam. I think I would then have about the maximum N/A pump gas HP available with my engine and should hit 75+.