2 liter 16V Turbo Italian engine tuning guide. Part I. 

In this engine tuning guide/article I’ll explain how to make very powerful and rugged Italian 2 liter 4 cylinder 16 valve turbocharged engine found on very famous cars like Lancia Delta integrale, Alfa Romeo 155 Q4, Fiat Coupe 16VT and some more.

All information used in this article is collected from the leading rally, drag race, engine-tuning specialists and my personal experience. It took countless hours, sleepless nights and tons of beer to examine and proof all the collected knowledge, and finally the bulletproof engine is here!

As written earlier, this article concerns about one engine that was used in many Italian cars. Where are some differences on these models like engine management, ignition, but

the main theory about tuning hardware remains the same.

I. Engine

First of all lets look at technical specifications of this engine:

Engine displacement: 1995 cm3,

Bore: 84 mm,

Stroke: 90 mm.

Cylinders: 4 inline

Valves: 4 valves per cylinder

Compression ratio: 8:1

I have made many experiments on this engine trying to squeeze additional horse power and after all I can say – this is one of the best engines ever made (of course it has some bugs, but which engine is bugless ?). Being turbocharged this engine has quite low compression ratio that gives more space for increasing turbo boost. Long stroke guarantees high torque (on over boosted engines extremely high torque in low rpm usually kills transmission components) and big punch.

The most common engine failures during horsepower increase:

1. Blown gasket,

2. Melted pistons,

Before doing anything to your engine decide what do you expect from it? High mileage? High power? Low fuel consumption? Or what?

Many owners say that they want maximum power with highest possible mileage (and low fuel consumption). If all your answers were “yes” I’ll suggest buying a bus ticket and stopping reading this article. I consider about engine power and wise mileage.

1. Camshafts, cam gears, valves and valve train.

Lets start from the top of this particular engine. After removing head cover we see 2 camshafts. One cam is pushing intake valves and another one is pushing exhaust valves. Common problem with camshafts is cam lobe wear. Cam lobe wear usually occurs because of low engine oil level and low oil pressure. Weared cam lobes don’t open valves enough and decreases engine power. Bad inlet cam causes lower power because less air enters combustion chamber and less fuel cam be burned. Bad exhaust cam causes lower power; engine and oil heat (especially on higher rpm) because hot burned gases don’t exit the engine. For longer operation oil pump and oil level must be regularly checked.

Selection of camshafts:

Road car: if car is for a road use – stock camshafts are ok. As said before cam lobes must be checked and if lobes are ok, you shouldn’t worry much about it. Stock cams give good low rpm torque but lack high rpm power. With stock cams I suggest smaller turbochargers boosting 30% more air at middle rpm then at high. It makes less sense boosting turbo at high rpm, because of short valve openings don’t give much more air. Racing cams give more valve overlap (inlet and exhaust valves are both open) and with small turbocharger due to backpressure in exhaust manifold hot gases flow back to cylinder and decrease “fresh” fuel mixture amount (decreases engine power), also hot gases can cause detonation. If using nitrous oxide stock cams are also good because of special nitrous characteristics. Stock cams are good for 250 – 300 Hp.

Race car: it’s preferred to use specially designed racing cams, but I have found that stock cams from 2 liter atmospheric engine are also good (very cheep way, but needs very special timing adjusting). Wild racing cams are track use only; because of terrible low rpm (below 4000rpm) throttle response and huge fuel consumption. At same turbo boost racing cams let more air flow same time increasing engine power. With racing cams engine power moves to the very top. It’s suggested to increase rpm limit to even 7500 rpm, because engine pulls to the very last rpm.

This engine has two cams – one for intake valves and second for exhaust valves, it’s possible to adjust cam timing by tuning cam gears. Of course you need special adjusting cam gears. Adjusting cam gears can be made from a stock ones, and then they can be adjusted by using simple bolts. It’s preferred to use chassis dyno for a cam timing tuning. For a road use I don’t suggest to tune camshaft timing, because it can cause some not wanted problems, but for a racing use tuning cam timing is a must. If stock atmospheric cams are used and you don’t have adjustable cam gears, don’t forget to replace turbo cam gears with atmospheric cam gears (this will help, but it’s only temporary way – adjustable cam gears are needed).

In conclusion I should say that custom cam selection should be maid keeping in your mind what type of racing/driving car will be used because cams will vary depending on road driving, rally, circuit or drag racing. Later I’ll discuss about special techniques fighting with exhaust backpressure and providing better mixture inlet. These techniques can free your hands making more power.

Valve train

Stock valves and valve train is good enough even for 500 Hp. Of course check valve train condition (especially valves) and if no defects found they cam be used. I can confirm that stock valve train can handle over 8000 rpm for a short bursts.

If you have lots of money you can buy bigger titanium valves, but this engine has more components and they can fail even at lower rpm, so for a road/mild racing stock valves are good enough and won’t cause problems.