Jon Kaase Unleashes the Boss Nine 589ci Ford Mustang

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Jon Kaase Boss Nine 589ci Ford Mustang

The Boss is truly one of the most famous Fords Mustangs of all time, and every Mustang freak and his brother has sought to put one in the garage. This passion has held strong from the Classic days up through present, with many one-offs posted by the aftermarket, but none have been fully blessed by FoMoCo. The lingering lust for a high-powered pony car with the Boss lettering has Mustang fans grabbing at any possible concept they can fathom in order to reproduce the legacy of the Boss Mustang experience.  Now, Jon Kaase and his crew have taken their best shot at recreating a Boss monster–and yeah, they have a winner here, folks. With an output of 800 ft-lbs of torque and over 900 horsepower, this S197 Mustang means business…because it’s truly the Boss. Take a good look at the Kaase Boss Nine 589ci 2008 GT Mustang and witness how it became a fire-breathing thoroughbred.

Press Release from Jon Kaase

Since I was in high school, (class of 1970), I have always wanted a Boss 429 Mustang. It was Ford’s masterpiece of engineering. Their Holy Grail. Their Hemi Cuda. The problem is, I was as far away from being able to afford one in 1969 as I am today. (Considering their present value) If I could buy an original, it would be far too valuable to drive or put many miles on it.

With the release of our new Boss Hemi engine parts, the next logical step was to build our own version of the Boss 429 Mustang. I rationalized that a complete running car would showcase the new engine parts, and create a new market for our parts sales. Although this may be partially true, let’s be honest here. I wanted this car! I want to drive it home and give my family and neighbors a ride. Most of my neighbors think I have a garage that does quick oil changes. They have no idea. I have not driven anything with over 360 HP since 1974. This car with 800 ft/lbs of torque and 900 HP should be a real handful.

The late Buddy Morrison told me years ago, in his laid back Texas delivery, “ya know, in a street car, the torque is what you feel.” I absolutely believe this. I think anyone who builds one of these Boss Hemi cars for the street will definitely “feel” it.

My first idea was to buy a used 2005 mustang and start work from there. After finding that the pricing was $18,000-$19000 for a good used one, I started to investigate new cars. If you can get dealer cost, the new one was only $4500 more than a used one. What made it even better was the new one had almost no interest on the loan, and I financed the whole thing. The payment is $460/ month. It’s worth it because it’s new, and it’s pleasure to work on. (No dirt, oil, or road gunk.)

Realistically, a 466″ Boss Hemi would be about right for this car, but, as they say, anything worth doing is worth doing in excess. We took an aluminum block and Bryant crank in on trade last winter, and decided to use them on this project. The block is 4.627″ and the crank is 4.375″. This works out to 589 cu. in. With street compression, (10.5 to 1) and a 273/280 roller cam, the engine made 973 HP and 800 FT/LBS right away. The cam was a little too big for a street cruiser, so we installed a 251 degree street roller, .660″ net lift. The engine still made 800 FT/LBS, with 885 HP, only now it’s smooth at an idle all the way up to 7000 rpm.

We installed a Billet Specialties front drive for all the accessories. This includes a billet front timing cover, water pump, power steering pump, alternator, air conditioning compressor, and serpentine belt with pulleys. We bought 3″ stainless exhaust from Granatelli, which includes everything from the header collector back.

This car is a natural for the Boss Hemi swap. There is plenty of room between the shock towers, enough room for headers, and enough room between the front drives and radiator. Now that the engine is installed for good, we can see that the hood needs no modification for the air filter. It’s close but the right filter assembly will fit. A stock rear sump Moroso pan fits over the steering and crossmember perfectly.

D&D Performance engineered the trans and related parts for us. They supplied a Quick Times bellhousing, McCloud twin disc clutch, hydraulic release bearing, Viper spec T-56 six speed transmission, custom shifter, and a one piece Dynatech aluminum driveshaft.

At this time, (10/27/08) we are headed to Chuck Lawrence’s house for the final “finish up”. He has to hook up the power steering lines, A/C lines, coolant lines, and fuel system. We still have to hook up the ignition box and coil, and figure a way to get switched power to it. The worst part will be the fuel system, as the pump and lines will have to be completely re-engineered for carburetor use.

The car is still a work in progress, and we will continue to update this site with any progress. It has to be finished by Thanksgiving, as we still have to get some things done and drive it a little before the PRI show. We will have the finished car on display at the PRI show (provided I don’t crash it first). Please make plans to visit us at the show in Orlando, at booth #5336.

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