As seen in Speedboat Magazine’s Jan/Feb 2019 Issue.
Add a Pickup
If I have a Bravo XR Sportmaster lower and I want to add a supercharger with an intercooler, do I need to add a water pickup or will the drive supply enough pressure for the cooler and motor?
Justin Farmakakis San Marcos, TX
The only way that I would recommend that you use your drive as a pickup for both the engine and the intercooler is if you are using a two-stage water pump. I am assuming that this is not the case. If you add a supercharger to your engine, it will need all the cooling water to keep the temperature low and the increased flow will help prevent steam pockets from occurring in your motor. If your engine is going to have carburetors on top of the blower, it is usually better to force feed the intercooler with a separate pickup. Having water flowing through the intercooler at idle causes the fuel to puddle and may result in poor idle quality. Fuel injected applications can be programmed to compensate for water being pumped to the intercooler during idle conditions.
The best way to do it with a single stage water pump is to add a Pickup plumbed through a sea strainer that forces water through the intercooler when the boat is on plane. I would not add a supercharger without including an intercooler. Using a SuperChiller, you should add a pickup that feeds a separate dedicated sea strainer that is routed to the intercooler on the low side with the outlet on the high side which keeps the intercooler core full while under way. When you come off plane, the intercooler will drain and improve your idle quality around the docks.
Pickups are available that mount on the transom as well as through the bottom. On a single engine application with a right-hand rotation propeller, it is best to mount the pickup on the port side of the keel or in the port sponson, because with all things being equal, the port side of the boat runs slightly deeper in the water because of the propeller torque. Throughhull dumps will need to be added for the intercooler water going overboard.
I do not recommend stealing water from the engine cooling water. I have seen installations where a sea strainer has an outlet to feed the intercooler. This is not a good idea because the sea pump can draw air backwards through the intercooler and cause water starvation and an overheat condition at idle. Even if a check valve is in the system, this is risky because a small piece of debris can compromise the check valve, causing it not to seal, which will result in air being drawn back to the sea pump-causing possible overheating and damage to the pump and impeller.
Whipple Carb to EFI
I have a custom carbureted engine with a 3.3 liter Whipple Charger that had been dynoed at over 800 hp. I’m considering converting it to an EFI with a kit because I’ve been told that I can expect more reliability and performance. Is this true? What are the pros and cons with converting my motor over?
Eugene Travis Hammond, LA
If your motor is running good and is reliable in its current configuration, converting it to an EFI set up might not be the best answer. That being said, more than 90 percent of the Whipple Charged engines that I build are EFI. That is because we have programs that are validated and emissions compliant. Not knowing what your engine actually is, it may be difficult to create a one-off program that will replicate what your carbureted set up is providing.
Carburetors have a way of compensating for various conditions, if properly set up. An EFI program has to be more exact because it is somewhat isolated (but not completely) from various conditions.
The carbureted version of the Whipple SuperCharger is referred to as a 3.3R which is different than the EFI version known as an AX. The AX version utilizes a throttle body feeding the supercharger from the rear instead of on the top. The normal 3.3AX uses eight injectors in the throttle body. Port injected versions are also available but really not necessary depending on how complicated you want the program to be. Normally, for your application, batch fired injectors in the throttle body are sufficient. Also having the injectors in the throttle body helps cool and lubricate the supercharger.
The only way you can convert your Whipple Charger to an EFI is by utilizing some sort of throttle body instead of the carburetor. Using a throttle body on your current blower might put you into uncertain territory. I am sure it has been done by somebody, but I have not attempted it.
If your carbureted version is running well and has decent idle quality and so on, I cannot guarantee converting it to EFI will create more reliability or power.
The one factor that you should consider is the expense of the conversion compared to the benefit. By the time you purchase all of the components you will need including harnessing, computers, sensors, programming, and so on, you could spend in the neighborhood of $5,000 to $10,000. If you decide to convert to a 3.3AX, the cost will be more. If your set up is a one-off it will likely require dyno testing and the program validation in the boat, as well. My gut feeling is to be happy with what you have. On the other hand, if you are intending to keep the boat for a long time, you might feel it is worth making the conversion.
For your chance to be featured in Teague On Tech, email your questions for Bob Teague to Ray@speedboat.com.