32 Skater with supercharged Rtech 800EFIs
 

Here is a photo journal of the supercharger installation, dyno testing and engine installation. This is a late model 32 Skater that ran ~110 mph with stock HP500EFIs and Bravo drives. Victory Marine in Texas is handling the installation. Engines were freshened using Cometic head gaskets, ARP rod bolts and better bearings; stock heads, cam and exhaust.

Re: 32 Skater with supercharged Rtech 800EFIs
 

Supercharger installation is straightforward. Vortech blower, mounting brackets and drive assembly are used. Fuel system is different from stock; we uses bigger rails plumbed in parallel and an Aeromotive regulator with 50 lb injectors. The injectors are good to 800 HP, the rails and plumbing are good for more. Large intake mounted intercooler and upper plenum reduce restrictions to air flow and increase cooling effectiveness versus typical remote mounted intercoolers.

Re: 32 Skater with supercharged Rtech 800EFIs
 

One of the engines was taken to Precision Marine for dyno testing and three days of ECU calibration. Although readings of 830-840 HP were measured, the 50 lb injectors were really done at 800 HP. Since this was our target anyway, fuel and spark maps were set up accordingly. Manifold air temperature was 73F using 60F city water. Engine was held at 5200 RPM for six minutes on one run to allow observation of temperatures under steady load.

Re: 32 Skater with supercharged Rtech 800EFIs
 

This is Victory's closed cooling system, nice addition to a salt water boat. The extra size and capacity of this system will be mandatory when we start supercharging 525EFIs. First engine going in the boat. Two engines installed waiting for exhaust system. Using the air filter assembly shown requires that the water inlet on one of the elbow tops be modified. These particular headers were also modified to take a wide band O2 sensor for further testing. Boat should be in the water on Saturday for prop testing. Results to come...

Re: 32 Skater with supercharged Rtech 800EFIs
 

Nice looking project. Did you ever flow that intake?

Re: 32 Skater with supercharged Rtech 800EFIs
 

Hi Gary:

We didn't flow the intake and I don't know at what RPM/CID it becomes a bottleneck. I did talk to Jim at AS&M and others about it, and decided that the long runners were good for this application with the stock cam. We want to maintain as much low RPM grunt as possible on the engine alone and let blower's linear boost curve do the work on the top end.

This is a conservative approach that works well in big boats. With a big engine in a smaller boat you can build the engine for higher RPM and make much more horsepower, but I don't have to tell you that. :cool:

Re: 32 Skater with supercharged Rtech 800EFIs
 

Nice job Tom. You've been busy. What were the boost numbers at each rpm? Does that skater have Stelling boxes?

Re: 32 Skater with supercharged Rtech 800EFIs
 

TC, I was just wondering how your manifold compared to a reworked 502 EFI manifold.

Re: 32 Skater with supercharged Rtech 800EFIs
 

Hi Marty: The boost numbers are typical centrifugal. As far as I know it's a Bravo transom assembly with Imco drives.

RPM - Boost
3000 - 2.25
3500 - 3.00
4000 - 3.93
4500 - 4.46
5000 - 5.57
5500 - 7.01

Hi Bill: The heads and cam are stock. Victory Marine has a bunch of these 500EFI engines that are takeouts and/or Mercury service returns. When they asked what to do with them to prepare for the the Rtech kit I just said use Cometic gaskets. But I think they do make a little more power because air enters the upper intake manifold through a big hole in the top, after passing through a perfect diffuser (the intercooler). This has to improve air flow into the ports compared to having high velocity air entering that plenum through a relatively small throttle body at one end. I don't really have a "back to back" way of testing this theory, but the overall improvements of the intercooler plumbing and air flow into the intake manifold contribute to the high HP numbers for relatively low boost.

Hi Gary: If you tell me exactly how you flowed your intake I will try to duplicate the test procedure with the next intake we do. It would be good to know. I have heard of people extrude honing the lower intake.

Thanks,

Tom Robinson
www.rtechperformance.com
(416) 709 - 8714

Re: 32 Skater with supercharged Rtech 800EFIs
 

The boost curve just about looks almost just like the HP curve. Can you plot those boost numbers on the graph above?