by Tom McGaffigan

In 1983 Lancia became the first modern day automobile manufactured to offer a production car with a mechanically driven supercharger. Since then supercharged production cars have been offered by Toyota (1986), Ford (1988), VW (1989) and now Buick (1990). Lancia also had another first in 1985 in offering a limited production car, the Delta S4, with both supercharging and turbocharging. Other manufacturers have yet to accomplish this although the 1989 Toyota MR2 was rumored to have this combination. but did not.

Ever since seeing my first supercharged Lancia 037 in 1984, I wanted one. I did have one of its blood brothers at the time, a 1977 Lancia Scorpion, but its performance was well below that of a 037. This performance difference was reaffirmed when Ray Pike of I.M.M. in Arizona gave me a ride in his 037. That car is quick! And what response! Now I knew I needed a supercharger for one of my two scorpions.

In true Lancia fashion, I completed assembly of the engine on Wednesday and drove it Thursday and Friday to the reunion in Oregon, 800 miles away. Aside from the carb not being jetted correctly, the car ran perfectly. And torque, boy does this baby have torque! Five pounds of boost are available at idle and with peak boost, 8.5 PSI, being obtained by 3500 RPM. Boost is flat from 3500 RPM to redline indicating excellent breathing and efficiency. More boost can be obtained by use of a milder cam but I chose to use 40-80's with 300° duration. These cams are a little too wild for a supercharged motor, but the stock Volumex cams are too mild. If the Volumex cams (timing 13-39-37-3) are used with the standard 1.32 drive ratio this setup will deliver approximately 9.5 lbs. of boost on a 1800 cc. This is up from the stock 6.5 lbs. on the 2000 cc due to the supercharger forcing the same amount of mixture into a 13% smaller engine.

Today I have about 7000 miles on the engine with no problems to report. I estimate about 175 HP is on tap and gobs of torque. Detonation is not a problem so long as 92 octane premium is used. Gas mileage is about 20 mpg for city/highway. This could be increased if taller gears were installed because with all the torque available, 5th could be much taller.

Below are the specifics of the engine:

• 1756 cc twin cam, block and head. Head must be

• redrilled for Vx manifold

• 8 to 1 compression ratio, stock pistons and rings

• 1130 cc Volumex supercharger 70% adiabatic efficiency

• 1.32 overdrive on supercharger

• 40 DCOE Weber with 32mm chokes K & N air filter

• 40-80-80-40 steel billet cams, 10mm lift, retimed

• 4-2-1 and a header and quad tip exhaust

• Abarth stainless steel valves, lmm oversize

• ported and polished head and manifolds

• bronze exhaust guides

• 3 angle performance valve job

• High performance valve springs

• Volumex head gasket and bolts

• grade 8 studs and nvlock hardware used throughout

• additional motor mount installed midships

• recurved distributor with capacitive discharge ignition

• fuel pressure regulator, pressure varies with manifold pressure.

Editor's Note: This is the first of a two part feature on the Volumex csion. In the second, to appear in the next Lanciana, Tom discusses the technical characteristics of the supercharged engine.

by Tom McGaffigan

Lastly in this segment are horsepower and torque curves for various engines in different states of tune.

I hope this article is enjoyable. my Volumex sure is!

1800 cc is superior for sustained high rpm use. 2000 cc has more torque due to larger displacement and mechanical advantage of longer stroke. 1800 has more compact combustion chamber at same compression ratio and is more forgiving under high boost. 1800cc was already in the car. Note late 1800's have a large crank snout which fits the Volumex drive pulley. Early ones do not. Volumex drive pulley will not fit early 1800's. 1800 has .5 inch shorter deck height

Volumex has vastly superior throttle response. Boost is available at any load and rpm instantly. Volumex is as efficient as a turbo, 70%, if boost is kept below 10 lbs. Turbo is altitude compensating, i.e. constant boost despite increase in elevation. Turbo lag however is greatly increased with altitude while Volumex response is not affected. Volumex allows much more freedom in cam selection. Cams in a turbo must be kept mild or lag will increase. No extra plumbing or red hot exhaust pipes.

8 to 1 compression allows responsible combination of off boost operation plus an effective compression ratio under boost. Effective compression ratio is approximately 10 to 1 with 8.5 lbs. of boost.

Over driving of Volumex permits optimum volumetric efficiency at low engine speeds. This results in maximum boost at low engine rpm. This more than compensates for hot cams.

Larger chokes than standard Volumex carb; 32 mm vs. 26 mm in stock Volumex. Mounts directly to Volumex essentially without a manifold. This promotes good throttle response and prevents fuel puddling in manifold. It fits!

Compromise for Volumex application. There is slightly too much overlap. but still permit responsible low end boost. Cams have enough material on base circle to allow for a regrind for best profile for supercharged use.

Long primary and secondary pipes enhance low end torque. This helps overcome loss of low end due to cams. Good scavenging when off boost.

Increases coolant flow rate due to increased size. 145mm vs. 135 mm, an 8% increase. Works well with Scorpion huge coolant capacity of 16 quarts.

Better heat resistance than stock. 1mm larger provides better breathing with stock seats.

Retains factory manifold, all runners go downhill, preventing fuel puddling in manifold. For those of you who may he considering a project such as this here are some useful charts and formulas to help determine boost level expected, horse power, etc.

For example: at sea level my formula is:

P.R. = 14.7 + 8.5 = 1.6

14.7

Effective compression: by looking at Figure 1 the effective compression ratio can be determined. For example, my VX with a static compression ratio of 8:1 has an effective compression ratio of 10:1 with 8.5 lbs. of boost.

obtained by measuring the temperature of pressure in the intake manifold. This density ratio is a measure of how much more mixture the engine will be breathing. This increased mixture will increase power by a proportional amount so for a density ratio of 1.35 power will be increased by 35% over the base engine.

A base engine is one with the same cams, valve sizes and exhaust system. For example: A well tuned 1800 with 40-80 cams. Ansa header and 9.0 to 1 compression and dual 40 DCNF Webers puts out 130 hp at 6200 rpm. Using this as our base engine we get 130 hp + 35 % = 175.5 hp. Now this figure may sound too high, but it is exactly the horse power figure for a two liter Beta Volumex with the standard 7.5 to one compression, hotter cams and a rejetted carb, running the same supercharger and drive ratio.

Torque = (HP)(5252)

RPM

Torque = (175) (5252) = 148 ft. Ibs.

@ 6200 rpm 6200

By using the above formulas and charts I was able to generate the following horsepower and torque curves. The data for the stock Scorpion 1800 cc and Montecarlo 2000 cc was taken from the factory manuals. The "hot" 1800 and 2000 data was obtained on a dyno.

Pertormance is great! (See table 1.) Boost is available instantly at any rpm and any load. Low end torque increase is huge. As an example of how tractable the engine is; it can be put in first gear and allowed to crawl along at idle (1000 rpm). It can then be given full throttle instantly and it will not bog down or stall but instead build boost instantly and scream to redline.

Blower whine is present and it's a great noise. When not under boost it sounds like a 300 hp electric motor humming behind the passenger seat. Under full throttle at high rpm it sounds like a blender on puree. Cruising is much quieter than my dual DCNF Scorpion.

I'm afraid to add it all up! New Volumex Superchargers are $2500 alone. Machine shop time for the two custom adapters and the idler pulley set up was approximately 80 hours.

For those of you who are interested in obtaining a Volumex for your car, Tom Mulhall at Route in Pista (415) 871-6023 may still be importing a few. Also Chris Obert at (408) 423-0218 can import stock factory parts. For fitting a Volumex into a Scorpion, the factory system must be modified or adapters built such as the ones I designed and built from aluminum billet. Since only about 300 Beta Volumex cars were sold in the U.K. finding a used one like I did will be difficult. It took me approximately a year to design, build and obtain all the parts necessary for this installation, but boy it is worth it! So much so that I'm in the process of converting my other Scorpion also.