Engine Choice

Our kits allow the installation of any small block Chevy engine: 265, 283, 302, 305, 307, 327, 350 or any of the 400 derivatives. The important thing to consider is compatability of your engine of choice with the transaxle. The stock 901 transaxle works fine for most any of these engines except the 400 derivatives, which include any of the engines which utilize the 400 crankshaft. These include 377, 383, 400, 406, etc. The 915 transaxle from the 911 is very well suited for these "stroker" engines. It is capable of handling the 400+ ft-lbs of torque these engines produce. The stock 901 transaxle allows use of the stock 914 shift linkage with a slight modification to the shift rod between the firewall and the transaxle. The 915 and 930 transaxles require new shift linkage, trans. mount, clutch cable mounting bracket, as well as larger axles, CV joints, and CV spacers. In addition, both the 915 and 930 will require modification to flip the ring gear for mid-engine operation.


Exhaust System

We normally use either Corvette headers or Corvette ram's horn exhaust manifolds. There are a variety of headers available that will work. One of our customers recently used a set of Blazer headers (Hedman PN 69230 for Chevy Blazer/truck) that worked quite well. These headers allowed the exhaust pipes to be routed above the axles for better clearance, as opposed to the Corvette headers that require the exhaust pipes to go under the axles. The Corvette exhaust manifolds allow the exhaust pipes to be routed over the axles, and allow for larger mufflers than the headers normally do. Any of the "Turbo" type mufflers will fit, and the Anza resonator tips can be mounted to the mufflers to decrease the exhaust noise on high compression engines.


Cooling System

There are a few options to choose from when installing the radiator into your V8 914. The least expensive method is to obtain a used radiator from a late 60's Chevy Nova or equivalent. This should be the heavy duty core which is thicker that the standard radiator. You will then design and fabricate radiator mounts, sheetmetal pieces for the sides, top, and lower rear, and possibly a custom fan shroud as well. It is also possible to find an electric fan/shroud combination from an older mid-sized car that should be adequate in cooler climates for non-AC cars. Another possibility is to have your local radiator shop build you a custom copper/brass radiator to your specs. You will want to have them install the water inlet, outlet, and air-bleed at the appropriate locations to mate up to your water lines. Then build the mounts and shrouding to fit. We have had a few customers who have successfully installed Corvette radiators in their V8 914's with good results.

For the cars we build, we normally use a custom built 4-core, high efficiency, cross-flow copper/brass radiator with 1" diameter fittings and an air-bleed installed at the top of the left-hand tank. This radiator mounts into the 914 using our custom built radiator mounting frame assembly and clamps. We use one of our custom built fan shrouds with dual electric fans. This radiator system works quite well here in Tucson, where the summer time ambient air temperature runs 100 to 115 degrees F. This radiator also allows the installation of a full size AC condenser mounted directly in front of the radiator. We offer these same parts to my customers along with templates for the sheetmetal pieces.

We prefer to run steel water lines under the car from the front radiator compartment back to the engine compartment. These are connected to the radiator, water pump suction fitting, and coolant filler using 1" I.D. Gates heavy duty hose. An alternative is to run water lines inside the rocker panels from front to rear, but we prefer to leave these areas available to run AC hoses when required. Some builders run the rubber water hose right under the car clamped to the underside of the floor pan. This works fine, but leaves the hoses vulnerable to road damage - a torn or punctured hose could really "ruin your day".

The water pump we prefer is our one-piece, TIG welded housing utilizing a Chrysler impeller assembly. This housing has no threaded water fittings, as they are an integral part of the housing. This design precludes the possibility of water leaks at the threads or getting threaded 90 degree fittings oriented incorrectly. It is sometimes a problem that to have the threaded 90 degree fittings in the proper orientation, they are either over tightened or too loose. It is not uncommon to have to resort to epoxy to seal the threads - which works fine as long as you do not need to remove the fittings. Some 914 V8 builders are now installing electric water pumps, which seem to work fine. The only downside to the electric pump is the potential for motor failure, which can happen instantaneously. The belt driven water pump will normally wear out over many years of use - gradually. And a broken drive belt is easy and inexpensive to replace.


Chassis/Brake Upgrades

Some chassis upgrades are essential to the 914 V8 conversion. The installation of heavy duty coil springs to replace the stock rear coil springs is a must. The least expensive method is to purchase a pair of heavy duty springs intended for the 914 V8 and install them onto your stock or existing shocks. Some of the Koni and Bilstein rear shocks allow the installation of an adjustable coil-over kit - which allows adjustment of the rear ride height and also facilitates independent spring load adjustment when corner balancing your car using chassis scales.

The installation of the 914 chassis stiffening kit and the 914 trailing arm boxing kit both help to increase the torsional stiffness of the chassis as well as reinforcing the areas that are prone to fatigue cracking due to the increased forces exerted on the 914 chassis under hard cornering. The addition of a front anti-sway bar will make a significant improvement in flat cornering. Some 914's came with a factory front anti-sway bar. Weltmeister adjustable front anti-sway bar kits are also available in a few different diameters for the 914. When lowering the front of the 914, it is advisable to install steering rack spacers so as to maintain the tie rods in a horizontal position. This will help to prevent "bump steer" under loading.

The Porsche 911 front struts are a direct bolt-on to the 914. Koni, Boge, or Bilstein struts with ventilated rotors and large S or A calipers are recommended. The larger calipers increase stopping power, the ventilated rotors help to reduce "brake fade", and the 5-lug pattern allows the installation of any of the 911 wheels. Porsche 911 rear hubs, stub axles, ventilated rotors and brake calipers will also bolt right on to the 914 trailing arms with the addition of caliper adapters and hub bearing spacers. Porsche 911 axles and CV joints will bolt on as well, provided that 915 drive flanges are substituted for the stock 901 drive flanges in the 901 transaxle. The shorter 911 axles will require CV spacers with longer bolts.

BMW 320i front brake calipers can be installed onto the stock 914 front struts for a noticeable improvement over the stock 914 front brakes. It is also common to upgrade the stock 914 17mm master cylinder to a 911 19mm unit, accompanied with the installation of stainless steel brake hoses front and rear. This will greatly improve pedal feel. Porsche 930 turbo tie rods are a direct replacement for the stock 914 tie rods. These turbo units incorporate a steel ball-in-socket in lieu of the 914 rubber couplings at the inner ends of the tie rods. The turbo units give a much more precise steering feel with none of the slop associated with the stock tie rods.

An adjustable brake proportioning valve is often installed in place of the stock 914 valve. This allows some of the rear brake bias to be removed, lessening the chance of rear wheel lock up under hard braking. These adjustable valves are available from Wilwood, Kelsey Hayes, and others.

Some notes on using the 915

When using the 915 transaxle in the 914, the ring gear must be flipped over to the other side of the differential. This involves disassembly, machining out the case for clearance, and reassembly. Once you disassemble the transaxle, it will be evident where to remove the material so that there is adequate clearance between the case and the ring gear. If you are using one of the later aluminum case 915's with electric speedometer drive, then you will need to plug the existing pickup hole and machine a new hole in the opposite side for the pickup.

Also, be sure to shift the transaxle into all the gears after the ring gear is flipped - you will notice that one of the internal shifter rails will need to be shortened - just enough to clear the ring gear. Unless you have the correct Porsche factory transmission tools, we recommend that you find someone who does and have them reassemble the transaxle. There are some critical settings: pinion depth, backlash, side bearing preload and turning torque to name a few - that need to be set correctly for optimum performance and longevity. If you do not know the condition of the bearings and synchros, this will be a good time to have these inspected and replaced as necessary. The same ring and pinion can be used. If you don't flip the ring gear, you will have 5-reverse gears and 1-forward gear - because the 911 is rear engined and the 914 is mid engined. Some people just turn the whole 915 trans upside down, which effectively flips the ring gear. But then you need special pressure feed for oil to the gears - this is usually only done in race cars.

Unless you are installing an engine with a 400 SBC crankshaft or equivalent - which will normally produce well over 400 ft-lbs of torque, our recommendation is that you stick with the 901 transaxle. It is quite expensive to do the 915, especially if you will be paying someone to do the machine work, assembly, and such. You will also need an electric speedometer if you happen to use the later aluminum case 915. The adapter kit is more expensive, and you will need 915 shift linkage, cv/axle spacers, clutch cable mount, etc. The only reason to use a 915 is if you are using a stroker motor, ie. 377, 383, 406 where the 901 simply will not handle the torque. Even for a 400HP 350, the 901 is fine. In fact, we personally much prefer the 901 to the 915 due to the better stock gear ratios, better shifting, easier clutch pedal, and ease of installation.

914/901 shift linkage modifications

click on picture

allows clearance for V8 motor mount bar and trans. relocation