scientific question on 355 motronic type

On US 355s 2.7(OBD1) was '95 and all factory challenge cars('97-'98). 5.2(OBD2) was on all 355s from '96-'99. I'm not sure when the Euro cars changed to 5.2 maybe the same year as US cars. The 5.2 cars have a single ECU and single air flow sensor, the 2.7 cars have 2 ECUs and 2 airflow sensors. The reason I tell you this is that you could look at '96 and newer euro cars and determine the difference. Regards, Vern

 

5.2 has better emissions than 2.7.

2.7 has more low down torque and revs more freely (slightly more performance but only a couple %).

I imagine Ferrari left the Challenge cars with 2.7 as they had old stocks (or they are cheaper) and emissions are not an issue on race cars.

In my opinion 2 ECU's = more electrical stuff to go wrong and I think the single throttle / air intake is prettier in the engine bay

 

Yes, there is such a thing as a 2.7 Spider. TonyH has one (Euro spec).

Ric.

 

They weren't used because of old stock and they are actually less comlpicated(other than using two ECUs) in their electronics than a 5.2.
The 2.7 was used on the challenge cars because of more breathing capability,2 flow meters, and less complicated in the sense that there are fewer monitoring sensors(no sensor on the gas cap or knock sensors for example) than the 5.2 has. It was easier to modify the exhaust on the challenge cars, no rear 02 sensor (the 5.2 has frt. and rear). The upper exhaust on the challenge cars have no cats or by-pass valve. The 5.2 was used to meet more stringent US emmissions in '96. Regards, Vern

 

A few thoughts...
1) 5.2 is like two ecu's in one box, simplistically speaking
2) US Challenge F355 from '96-'99 were 2.7 due to, just like about everything in business and engineering, cost. Cost to manufacture. Yes it was less headaches too, but that wasn't the main motivator.
3) Engine mechanical specifications are different between 2.7 and 5.2. I converted a 5.2 from a wreck to 2.7 back in '97. Fuel injectors were quite different and did not flow as much as the earlier engines, though had an improved pattern. Basically, Ferrari put a lot of effort into maintaining power AND cleaner emissions. (BMW accomplished it with more displacement 3.0 to 3.2 for the M3...)

Best,
Rob

BTW, "5.2 revs more freely"... I don't agree with that. The engines accelerate the same for the same load.