Original Stratos engine configurations

[GaryFitz]

To start with, please excuse my ignorance as I am new to these cars. I am looking for advise/information on engine configurations for Grp4 Stratos rally cars.

My understanding is that the original rally cars ran the standard iron block/aluminium 2 valve heads but used bigger valves and usually ran Webber 48mm IDF'd to produce around 240hp.

I think somewhere along the line mechanical injection was homologated on these 2valve heads to give approx 280hp.

A seperate homologation was made for the 24 valve heads, which I think are refered to at the Formula 2 motors? and with the mechanical injection these produced over 300hp. I also understand these engines are quite rare and very valuable - over 80,000 euro. I am not sure if these engine ever run with just Webbers?

So what I really want to know, is if the various combinations I have listed are correct, and what the general power and torque characteristics of the engines are, specifically if anybody knows the power bands and RPM for max tourque curves.

The reason I ask is that I am trying to determine what engine configuration is going to give me the widest power band and the lowest RPM for max tourque to be used in a Grp 4 rally car.

Is there a book or information source I can go to that may have this information? Over to you guys.

[tryphon]

Hello Gary,

The combinations you have quoted are all factual. Keep in mind that only Lancia Works cars used 4 valve heads (effectively of F2 provenance) up until they were banned by the FIA. These heads produce more power at the expense of torque and of an overall slide of the torque curve towards a higher rev band.
They are also known to be more fragile than 2 valve heads.
Although the exclusivity enjoyed by 4 valve heads is a nice thing to have, only 2x50 heads were casted hence 50 engines made, there are not any real advantages of running them except for originality of course if your car was fitted with them. Also keep in mind that if something goes wrong there are no spares available anywhere.
You can expect up to 315bhp from a perfectly tuned 4 valved Dino.

The 2 valved cars used oversized valves and larger carbs to produce up to 270-280bhp from the best examples. These figures can easily be reached today for any Dino engine appropriately tuned.

Exact power and torque figures are pretty secret and kept by each tuner but in general the 2 valved cars will produce more torque and their power band is wider.

[GaryFitz]

Very informative, thankyou. Does the fitting of mechnical injection system assist engine drivability or improve torque? or is this another complication for little advantage over a regular 48mm IDF setup?

[tryphon]

Mechanical injection would render things quite complicated. The vast majority of works cars never used it. It was mainly destined to track cars if I'm not mistaken and it was Fachetti that experimented with it the most.
A well tuned weber setup, either 44 or 48, will be perfectly driveable.
As Maglioli used to say: "Whatever you don't have can't break..."