mopar5150 - tech info

Putting a Blower on Your Mopar

First, answers to a few questions...

Why? A blower will increase engine horsepower between 20 and 50% and nothing looks as impressive as a polished supercharger with two carbs sticking out of the hood. Not to mention the effect blower whine has on other drivers.

How much? Cost varies depending on the type of blower you use (roots, centrifugal, screw) and how much of the work you can do yourself. No matter how you slice it, a blower will cost you around $4,800. A little less if you can do your own carbs and fuel system. More if you pay someone to do the installation.

How difficult? If you can change an intake manifold and have some basic fabrication skills, you can install a blower setup on your engine. The hardest part is getting the right length drive snout and getting the accessories hooked back up.

Let's look at a few myths about supercharging before we go on...

A supercharged engine gets poor fuel mileage - Not true. Only when your foot is hard on the throttle, otherwise a blown engine will actually get BETTER mileage due to better fuel-air mixing and distribution.

A supercharged engine needs constant tuning - Not true. A blown engine requires the same attention to tuning that you would give any high performance engine. In fact, I have found my blown engine to be very forgiving for tuning errors. The first time I put a blown 440 together I used two Holley 650 double-pumpers right out of the box and was able to drive all over town with no other mods (I don't recommend doing this, but it was fun).

A supercharged engine is unreliable - Not true. Like any other high performance modification, if you do a half-baked job you will have problems with it. Most blown engines last for tens of thousands of miles with no problems. This is not just my opinion, Gene Mooneyham and BDS have given me the same info.

A supercharged engine will overheat frequently - Not true. Remember, you will be forcing up to twice the fuel-air mixture into the engine so you better have a good cooling system. This is one area where you will need to spend some money to get good results. An aftermarket radiator and a high-flow water pump, along with a good fan and shroud, will be needed.

With that said, here's what it will take to put a blower on your Mopar...

A good core engine - By this I mean a good running engine with a sound bottom end with good oiling and a fresh set of heads. A blower cam is a good idea to get the most out of your blower, but if you have a split duration (i.e., exhaust duration is larger than intake) an RV type cam that will work. A good ignition system is an absolute must. MSD distributors and ignition systems are well-suited for supercharged engines.

A NEW or really nice used blower manifold - I have found that BDS makes a great manifold. These run around $400 (raised block) and are worth every penny. If you buy a used one, make sure that it isn't warped or you will have nothing but trouble.

Supercharger - This is another place where you don't want to skimp. Try to buy a new one or a rebuild from a known rebuilder. This is not something you can rebuild in your garage unless you are a machinist. You don't need all the Teflon strips and anodizing unless you are racing, so save the money. I have owned and sold dozens of Mooneyham blowers and can't recommend them highly enough. As long as you go with a quality shop (Mooneyham, Littlefield, BDS, Blower Shop, Dyers) you will be OK.

Supercharger drive - Here is where you can save some real money. Ebay and swap meets are great places to buy used drive gear. 8mm is about the best but ½-inch will work fine on most street engines. The belts don't really wear out so a clean used one will be just fine and can be had for $60 - $90. Pulleys run used around $50 and a good idler pulley and mount is around $150. As for the drive snout, a big block will need between 5 ¼-inch and 7-inch long and will be $150 - $250. Small blocks will use a shorter snout because the distributor is in the back and that pushes the blower forward.

Crank hub - I have found that BDS makes a nice piece. This replaces your harmonic balancer on the front of the crank. Contrary to popular belief this will not hurt the crank as the blower belt and blower act as a dampener to control vibration. Most crank hubs are machined for two crank keyways and it is a good idea to have your crank machined for a second keyway (nearly impossible if the engine is built and in the car). Two keyways are required if you are going to race the engine or run a lot of overdrive on the street.

V-groove pulleys - This is a real pain in the butt area of a blower install. Most of your fabrication time will be spent here. Running an alternator and power steering isn't real hard, but it gets interesting if you want AC.

Carbs and fuel system - This can be a real expensive adventure. Remember, you are forcing up to almost twice the air into the engine so you will need twice the fuel (that is why blower setups have two carbs). Your fuel system has to be able to provide enough fuel volume to support the engine under boost. It is easy to see that if you are running under boost with the throttle wide open and you can't provide enough fuel, the engine will lean out, start to detonate (ping) and burn the pistons. Think about haw a cutting torch works, there is a fuel and air flame and then you add a bunch of air and it melts metal. You need a ½-inch fuel system with a good electric or mechanical pump with a good filter. A regulator with a pressure gauge is a must. As for carbs, if you have a good understanding of the carbs you will be using and have jetted engines before you can save a lot of money setting them up yourself. I am not good with carbs and had to pay to have my carbs done. It cost around $1,275 to rebuild my Holleys and do all the mods needed for a blower, but they worked the first time and have been trouble-free.

Fuel injection - I have seen several cars with BDS electronic fuel injection and this is the ultimate setup! Except for the fact that it costs close to $6,000.

Drivetrain - Don't forget that your engine will now be making over 490 ft-lbs of torque so you need to have a good trans and rear end or you will break something. I am running a 4-speed and an 8 ¾ with no trouble, but if you will be running slicks or making a lot of horsepower (over 650) you will need to step up to a stronger drivetrain.

Throttle linkage - You want to get this right! It would be no fun to have a 650 hp blown big block with a stuck throttle. Enderle makes a great dual carb linkage kit that will save you time and money. Lokar makes a good throttle cable setup as well.

A few words about safety...

A blown engine makes a lot of torque and horsepower and should be treated with the respect it deserves. These engines will propel a 4000 lb. car to over 120 mph in no time flat. They also put a lot of strain on the other systems on a vehicle like brakes and suspension. You can get into a real problem in a blown Mopar with a weak chassis. As for street racing, it will get you arrested and you may even lose your car. I am all for having some fun blowing the doors off another hotrod on a back road somewhere, but use some common sense. Pick a road that doesn't have any streets feeding into the side of it because someone may pull out in front of you as you approach the intersection. Remember, people can't tell how fast a car is coming at them and don't realize you will be there that quickly. Never forget children and animals can appear anywhere at any time. Don't get up to real high speeds and be sure to leave plenty of room to stop because a blown big block B-body will not stop in a block…period. You now have the power of a racecar without a parachute or a run-off road.

Stoplight action is great fun, but keep it within the speed limit and you won't go to jail. I love rocketing up to the speed limit (ok, give or take 5 mph), as fast as I can to smoke a turbo Porsche with a cocky driver who tries to prove something, but then you have to get out of it. They won't likely toss you in the slammer for getting to the speed limit as fast as you can.

What it feels like to own a blown Mopar...

Now that I have owned a blown Mopar I will never go back! The engine makes huge torque right off idle and pulls real hard to 6500. Torque is what makes a fun street car. A blower motor pulls so hard in second gear that very few cars will be able to keep up. My '55 Dodge truck will burn the tires in third gear going 70 mph on the freeway (which should make any 5.0 Mustang owner feel inadequate) and will idle in traffic like a stock Road Runner. When you go to a show and open the hood your car will draw a crowd every time, even if they have seen your car before. Believe me, if you are at a show with 30 cars just like yours the crowd will flock to yours even if it is not the nicest. I went to shows when my truck was in primer and drew a crowd. - John Hopper, March 2004

Opinions expressed above are based on my experience and should not be viewed as a definitive source for this information.

Email me if you have questions or would like additional details.