Air Flow - Technical question of ts/tb versus Spider

Daniel,
It has definitely been discussed before, particulary in some threads related to the radiator/fan operation on the 355, and possible reason this may cause a rough idle. Obviously, there is more than just possible restriction from plumbing, but also at lower speeds, the intake could also be sucking in some warm air from the radiators. This was postulated to be a cause for rough idle when stopped at a light (upsets the air intake temperature probe just after the mass air flow sensor).

I am not aware of any studies on what the net effect is...doing dyno tests on 10 355B/GTS's and compare to 10 spiders would be pretty definitive.

 

If iI remember correctly, a big point on the Spiders unveiling, was it has the exact same top speed as the coupe. That pretty much says it all as far as hp is concerned. Yes the Spider may make less HP at idle . But once on the run........




Darrell.

 

Not postulated, proven. Anyone that owns a 95 that is experiancing the symtoms need only tape a 2" extension of cardboard on the bottom of the end of the air intake to proove it for themselves. Look at the shape of the 96 and later air duct in the front of the fender and then look at the 95. It will be seen the 95's have a "V" cut in the bottom and this is the problem area. Corrected on the 96 and on cars, Ferrari obviously knew about it but wasnt talking! That said I never bothered to figure out if it upset the airflow readings or the air density readings. Dont really care as long as the engine doesnt die when the left fan comes on.

I havent tested the airflow charactoristices on a Spider but played with shapes and fences on the B's a fair amount in a search for the correct wing heights and sizes. Based on how the flow spills off the roof on a B at speed I suspect there would be a measurable differance of clean airflow at the intake on a spider.

 

+1 ........... the sheilds worked to stop the rough idle on my car ......... aeroengineman tried the sheilds and said he got a noticeable improvement ..... then also claimed similar results by just replacing the fans, with the suspicion that older fan motors draw more current, pull more load on the alternator and thereby more load on the engine. Which would affect it most at idle. So coupled with the reasons Dave mentioned, there may be more than a few factors that cause the rough idle.

 

You will notice that the Spider had its air intake in the strakes, versus the coupes which pull air behind the quarter window. At speed there just has to be greater air velocity. I do know that the TS sounds way cooler than the Spider partly because of the reverb through this upper air intake. I always thought that the coupes benefit from a small amount of air ramming due to the air intake location over the Spiders.