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Welcome to my Z-car project web site! This site contains information about Carlo's Chevy powered 240-Z project car.
It is generally accepted that the 240-Z is extremely fun to drive. It is a light weight, nice handling sports car, with decent power. Even though it is faster than other cars of its time, it is not as fast as a basic Porsche 911. Since I lived in Southern California, I was surrounded by many sports cars. Unfortunately, a large percentage of them were 911s. I felt the need to build a car that was a fun to drive as a 240-Z, but fast enough to take on these other cars on the curvy roads of Southern California. I studied the options for heavily modifying the engine of a 240-Z, double the horsepower was the goal. Although many of my friends were experimenting with turbochargers, I decided that a small block Chevy would more reliably yield the power needed. I looked at the Scarab conversion kit but did not like the fact that it put the engine so far forward not to mention that it used an automatic transmission. I decided to go it alone..... This project began in 1982 when I bought a 1973 240-Z with a good interior for $1500... Needless to say the mission has been accomplished. This car has destroyed most every challenger to come along. Driving this car is wild. At full throttle, it is downright scary. Today, after more than 20 years of refinement, it runs better than ever. In fact, I drive it to work almost every day. To put the extra power to the road, big wheels and tires are needed. 15x9" aluminum Epsilon 3 piece wheels are used in front and 15x10" wheels in back. Tires are Dunlop SP Sport 8000s, 225/50-15s in front and 245/50-15s in the rear. To fit these, 4" fiberglass flares are bonded on and blended into the body on all four corners. A Kaminari rear wing is added to the rear deck lid. Being careful not to create a go cart like ride, the suspension is mildly beefed up with Datsun Stage I racing springs and Bilstein nitrogen gas shocks. MSA graphite impregnated polyurethane control arm bushings are installed on the rear. The interior is completely original except for the addition of 2 electric fan indicator lights, an alarm, and seatbelts from a 1975 Z-car that have inertia reels on both the lap and shoulder belts. The engine is a 327 Chevy 2 bolt main small block from a 1967 Camaro. It has been upgraded over the years to behave more like a sports car engine, and less like a truck engine. Initially the engine was stock. It had tons of torque and revved up to about 5500 RPM max. It used to easily burn rubber right off idle. Now it has less torque down low but revs quickly and has a much broader power band. Power really kicks in from 4000 to 7000 RPM. I call this the "hyperspace region" of the tach. It can be difficult to keep the nose pointed in the direction of travel when operating in this region. Engine Mods include a Holley Dominator II dual plane manifold, with a Holley 750 CFM 4150 Dual Pumper carburetor, Holley high flow mechanical fuel pump, Isky .465 inch lift 280 degree duration cam, Manley stainless steel Pro Flo valves, strengthened valvetrain, screw in studs and guide-plates inside the stock FI heads, and balanced and blueprinted lower end. I even took 10 lbs off the flywheel to help it rev faster. Ignition is a Pertronix Ignitor II ignition. It now feels just like a sports car engine, only with 350 HP on tap. This is over double the power the car originally came from the factory with. Engine cooling is provided by a Griffin 1.25 inch HP aluminum radiator with dual 14 inch electric fans and a 14 inch engine oil cooler. The 19 x 22 inch Chevy radiator fits nicely in the engine compartment. This has proven to be a great combination, even in traffic in Phoenix Az. on a typical 115 degree hot summer day. The clutch is a Dual Friction clutch by Centerforce. The transmission is a Borg Warner T-5 World Class 5 speed from a 1989 Chevy Camaro. The shifter is a Hurst Billet shifter. The drive shaft is half Chevy and half Datsun, spliced together in the middle. The rear end is an R-200 Limited Slip Differential from a Nissan Skyline with a 3.90 final drive ratio. First gear is good for 40 MPH at 6500 RPM. Fifth gear is a 1.37 overdrive. The engine turns at approx 2500 RPM at 65 MPH. For years I hated the Z-car brakes. I enjoyed blasting around, but dreaded having to stop the car in any rapid fashion. Sometimes I found it necessary to push on the brake pedal as hard as I could. Steel braided lines helped a little. I then heard about the trick Toyota 4 x 4 Truck 4-Piston Caliper mod. I tried out a pair of front calipers for a whole $75 at NAPA. They made all the difference in the world. With no other changes, brake feel was greatly improved. Its hard to describe. I went from not being able to lock up the tires at all, to being able to lock up all four tires fairly easily. There is at least one photo of me with all four wheels locked up in one of those little red light cameras.... The exhaust system consists of Hooker Corvette headers with dual stainless 2.50 inch pipes running all the way out the back. There is a crossover tube just ahead of the twin Cherry Bomb type glass packs. Originally, the car sounded a lot like a stock Camaro making it somewhat of a sleeper. However, all of the glass has long since been blown out. It now has quite a throaty sound at idle, and screams a full throttle. People around me know right away it is not a normal 240-Z. I love the sound even though it sometimes seems a little loud, like when trying to order a hamburger at the Jack in the Box drive up window. The engine mounts and transmission mounts are custom fabricated from .125 steel plate. They are designed to place the engine as far aft and low as possible. This also puts the shifter in the stock position, allowing the interior to remain totally stock. The stock clutch slave cylinder is mounted to the Chevy bell housing and stock Chevy clutch via a custom bracket. Clutch feel is excellent. Relays are added to the starter solenoid to improve hot weather starting, and to the Cibie Z-Beam halogen headlights. The concept of relays works great in this application. I struggled for years trying to get the car to start when real hot. A $5.00 relay finally did the trick. The driving impressions of this car can be best described during a trip from Los Angeles up to Monterey Ca. up coastal Highway 1 on a weekend where Superbikes were racing at Laguna Seca Raceway. In the City... We plan to depart from a friend's house near LA. Getting in the car and the interior looks like a stock 240-Z. There is nothing to indicate anything different. Turn the key and the car starts right up into a low rumble and settles at 900 RPM. The throaty popping of the big V-8 at idle is definitely different from any normal Z-car. Blipping the throttle and the engine crisply revs, almost faster than the tach can respond. All of the interior gauges come to life and read normal. After a minute or so the water temp starts to rise and we pull out into the road to begin our journey. The clutch feels light, and the throw of the stick shift is short and sweet, very much the same as a stock 240-Z. Driving down city streets the car feels docile. Starting in either first or second gear, the engine pulls smoothly off idle. Keeping up with the flow of traffic is easy in almost any gear. Once up to cruising speed, you can put the car in 5th even down as low as 1200-1500 RPM. The exhaust has a throaty sound. When accelerating it has a definite "braaaap" sound characteristic of Chevys with glass packs. When cruising it quiets down enough to hear the stereo. The ride over mildly bumpy city streets is firm but not too stiff. The Bilstein gas shocks are impressive. They excel at absorbing the little bumps while stiffening up over larger dips. There is some feedback into the car from the big tires, but it is less that a Corvette. The big tires also make the steering feel heavy at very low speeds. The brakes also work well. There is much more braking power and pedal feel than a stock 240-Z. Couldn't help but open it up a few times when there was an opening ahead. Flooring the throttle in either first or second gear yields face peeling acceleration. The engine roars and the tach needle flies up towards the 7000 RPM redline so fast you have to start thinking about shifting right away to avoid over-revving the engine. It is hard to find words to describe this cars expression of raw power and acceleration when blasting thru the lower gears. On the Highway... As we get out onto Highway 1 the road opens up. It is an asphalt two-lane undivided highway that winds along the Pacific Ocean. Being a mountainous two lane road, there are many instances where passing is required. We frequently come across lines of cars piling up behind a motor home or bus. There are also motorcycles all over the place. They have little trouble passing not only because they are fast, but because they are 2-dimensional. The Z's width is a disadvantage but it has plenty of power to pass at will, even when going up some pretty steep hills. Third gear is great for passing at speeds around 50 MPH. Floor it and you can feel the engines horsepower increasing steadily with RPM. Power doesn't start to level off until well over 6000 RPM. At the 7000 RPM redline in third we are doing 100MPH. Having this much acceleration on tap sure makes passing on two lane roads easy. Once we got further away from LA, we ran into less traffic and were able to fly a little bit up the road. On one long straightaway, we let it run up thru the gears. The car pulls strongly thru third and fourth gears. High speed stability is excellent. We briefly see over 150 MPH in fifth gear at about 5800 RPM. At those speeds, wind buffeting gets really noticeable. I remember having thoughts of the hood and the mirrors getting ripped off by the wind. Jamming up the road thru some fast sweepers, we came up behind a 900 Kawasaki Ninja and a CBR1100 Honda that wanted to play. In the turns there was simply no competition. I could see sparks coming off their pegs so I know they were pushing it. We were cruising at about 85%. I knew that when we hit the straights, they would think they would be able to get rid of me. Sure enough, all tucked in they blasted down the next straightaway. They were very surprised to see me glued to their tails the whole time. They then decided to pull aside and let me lead for a while. We soon got into a series of tight second gear corners connected by short straights. I decided to see what the Z would do with clear road ahead. I braked late, downshift into second, powered out of the turns with the engine pulling hard above 4500 RPM, lighting up the rear tires on the exit, drifting to the edge of the road, then shifting into third down the straight, then braking hard, back down to second, then third, back to second....over and over again. I got into this rhythm for about 10 minutes. Then, when I looked back there was no one behind me anymore. Weighing in at just over 2400 lbs, the car feels really light on its feet. It seems to enjoy being tossed around. There is very little body lean or dive under braking. The big sticky BFG Comp T/A tires have tremendous grip. When they reach their limit they don't just "let go" like most other tires. The grip remains about the same even when they are sliding. This gives the driver a lot of confidence letting the rear end hang out in the turns. When the car is at the limit there is a tendency to under-steer slightly at neutral acceleration. This changes to slight over-steer when accelerating. This along with tons of power on tap makes it easy and fun to "steer with the throttle". One needs to be careful when braking deep into turns however. The under-steer can bite you. One time, when braking real late into a right hand second gear turn, the front end took off and the car just went straight. I let off the brakes and straightened out the steering for a split second, just enough to get it hooked up and then continued around the turn. Fortunately there was no one coming the other way, as we ended up using both lanes of the road. After that, better sense prevailed and we decided to back off a bit and enjoy the scenery the rest of the way up to Monterey. We managed to resist the temptation to play with the motorcycles the rest of the day. Carlo
This page was last updated on 08/25/07.
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