Author Topic: Prochargers for twin big block Chris Craft  (Read 3969 times)

willy11699

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Prochargers for twin big block Chris Craft
« on: January 08, 2013, 06:57:20 pm »
Anyone who is currently thinking about upgrading their engines to boost units, I have two M3SC procharger units for sale. These have never been used. They have the fuel pumps, regulators, fuel lines and 7 inch balancers. Long story as to why I didn't use them. All receipts. Paid over 12,500. Will take 7,000 or best offer.
« Last Edit: March 02, 2013, 07:26:48 pm by willy11699 »

stinger390x

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Re: Prochargers for twin big block Chris Craft
« Reply #1 on: March 10, 2013, 11:31:09 pm »
Do you have the intakes for the 454's?
What else would I need to convert my stock 420's to use the blowers on my boat?

willy11699

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Re: Prochargers for twin big block Chris Craft
« Reply #2 on: March 15, 2013, 11:39:32 am »
The intakes that you have are all you need. All the mechanical parts bolt straight on to a big block Chevy motor. The carb has to have some modifications but that kit is included. The carb sits in an air box that the supercharger pushes air into and downdrafts the carb. If you wanted to change out your intake, you can but unless you want a bigger chamber or straighter passages, I wouldn't. Let me know.

stinger390x

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Re: Prochargers for twin big block Chris Craft
« Reply #3 on: March 15, 2013, 11:12:48 pm »
I don't follow you?
I presently have as carbs a pair of 550's on the engines. It is centre mount (as factory) Are you saying the blowers mount on this centre mount intake to the original bolt patterns? Does the carb sit on top? I thought it was an injection system for upgraded blowers?

So I take it this setup comes with harmonic, idler, and tensioner pullies etc all ready to convert the engines installed in the boat?

Here is a before and after pics of my boat. The blower motors are what came in the boat originally  which had a pair of dual carbs per engine, but they were replaced with naturally exaspirated single four barrel 420's in 2005. Fuel consumption went from 65gph to 35gph at WOT. I lost about 400hp and about 40mph but the fuel savings alone are good...especially at the price of fuel today.
When my boat was bought new in 1985, the original owner claims he could fill the tank for 180 bucks. It costs over 1200-1300 bucks to fill the tank today.

I'm wondering if I can get some more speed out of the boat with the blowers again and how much hp do you estimate I could get with your setup?

Original setup in my 390X


As it is today...
« Last Edit: March 15, 2013, 11:16:35 pm by stinger390x »

willy11699

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Re: Prochargers for twin big block Chris Craft
« Reply #4 on: March 16, 2013, 03:44:01 pm »
The bottom picture looks exactly like my engine compartment. You will get about 1/3 more power with these. You have to rejet your carb because it does take more fuel but not as much as 65gph. A guy over in Discovery Bay has one of these on his single engine Tahiti and he said it wasn't really that much worse on gas. The kit has everything including the parts to refloat the carb but not rejet as that is based on how you use the boat. If you look at ATI Prochargers website, they have a good write up on how the system works. It really is bolt on. They include the hoses you will have to change for the intercooler and the instruction book is really good. I wanted these on my boat badly but the guy took my build money about half my parts money, went out of business and declared bankruptcy. All I could do then was have them rebuilt to stock but I owe the guy who built them. Thats why 12000 dollars of parts are 7000. I really don't want to lose it in a mechanics lean. I just read you have 550s for carbs. They recommend 800 holley marine units so you don't lean out the motors. As long as you have 8 to 1 compression and the right jets, you could get about 78 to 80 mph with a clean hull and smooth water.