Today my 456 was on the dyno. Mid muffler replaced by straight pipes, inlet valve throates flowed with 3 angles, BMC air filters. The correction made in the power curves for the drive train losses was 18%. Two things where obvious, 1) until 4000 rpm, the ait fuel ratio was 14.7 or even leaner. This is good for pollution, but not for power, As from 5500 rpm the air fuel ration was around 12, which is right for max. power. I measured this on the left and on the right, so both ecus are doing the same. Because of that, probably some 25 Bhp is missing at 3500 rpm. 2) The difference between Ferrari air filters and with BMC filters is 19 Bhp, 420 and 439 Bhp resp. Image Unavailable, Please Login
I forgot to mention that max torque of 540 Nm as specified by Ferrari, went up to 606 Nm with the mod's I have made.
That is a nice increase in torque. Did you put 2 straight pipes or did you put an X pipe in place of the center muffler?
First a correction because I got the figures wrong. I mentioned that losses in the drivetrain where assumed to be 18%, but this was a misunderstanding from my side. All measurements were taken in 4th gear. Losses where 14 Hp@100 Km/hr (3193RPM) and 44 Hp@200Km/hr (6387RPM). The Dyno operator took the average of both figures and landed at 0.18 Hp/Km/hr. This equals to 31Hp@5500Rpm or 7% losses at maximimum power (439Hp@5500RPM or 172 Km/Hr) AND NOT 18%. I used 2 straight pipes, since Steven found out in the past that this gives more power than X pipes. The straight pipes costed less than $ 100,-, BMC filters $200,- and porting of the head was done for free while replacing the valveguides. I will publish the torque curve later today, where you can see the impressive increase in torque. Since the effect of the airfilter is already shown in a separate power curve, and the effect of the portshaping is similar to the airfilter, the reason for the bump in the torque can only be the removal of the mid muffler, being replaced by two straight pipes.
Here is the Torque curve, belonging to the power curve with the Ferrari air filter. Quite obvious is the bump in torque starting at 3500rpm. One could ask, why is the torque below 3500rpm so much lower ? Torque has a direct relation with the amount of mixture in the combustion area. Since a mixture of 15:1 has 23 % less fuel than a 12:1 mixture, it does not come as a big surprise that the engine has 20% less torque below 3500rpm. This is enough of a reason why torque drops from 600 Nm to 500 Nm below 3500rpm. What we really need is a set of remapped PROM´s for the ECU´s for below 3500rpm. With this change, we would have 600Nm all the way from 1500 rpm until 5000 rpm. Image Unavailable, Please Login
To get a different mixture, you will need another set of PROM's for your existing ECU's, or as you indicate a set of aftermarket ECU's. Changing PROM's is relatively easy, the hard part is finding someone with enough crediblity to produce the PROM's for you. The Bosch ECU's are very hard to understand.
Very good Hans: congratulations on your work. What kind of dyno did you use? How is the air intake while the car is on the dyno? What was the air temperature through the test? Is any air being forced into the air intakes? I believe that when the car is in motion there is a mild ram effect in the intakes that actually boost the power output: have you taken that in consideration? Regards, Alfredo
The Dyno was a Dynojet 2wd. Air temp was not measured during the test. No air was forced into the air intakes. I agree that, while driving, a ram effect is taking place, as well as a much better cooling under the hood, both helping to produce more hp. This was not taken into any consideration. Hans
Hans, thanks for your reply. Then I think the power reading you got from your car is very good: congratulations. Alfredo
I bought them from their subsidiary in Germany. They are direct replacements for the standard filters. Hans
This is a very interesting write up, thanks and congrats Hans! Fantastic to see the graphs. So you are running with the std end cans if I understood right? Why did you replace the resonator and not the end cans? I mean that I have been playing with the same idea but then... somehow I have thought that the resonator is there for a reason.. not that I really know. For the filters I was thinking about K&N, any comment regarding them? but then... if you found BMC good, why go different.
I replaced the resonator, because the 575 did the same, and because the existing resonator acts like an Xpipe, meaning that the left and right bank gasses are coming together in this muffler. Originally I had the idea to build two separate expanders on this spot, giving the engine the feeling that the exhaust ends here, since the pipelength to the rear muffler is a bit long. But I did not come to this yet, and I was not unhappy with the power gain. Hans
Hello Hans, very interesting information, do you live in Germany? I need a good Ferrari shop to do a full service on my 456 in south Germany. The one near me in Switzerland seems not willing to have any more business. What happened to the sound level when you took away mid muffler? Where in Germany can I buy the BMC filters? Thanks very much for your reply HRS
For anyone interested in the BMC filters in the US or Canada, here is their on-line store. The main difference between the BMC and OEM Ferrari paper filters are they are made of cotton. There had been some worry the oil used on them would react with the mass flow meters. http://www.bmcairfilter.com/index.asp Taz Terry Phillips
I live in the Netherlands. BMC filters can be ordered here: http://www.bmc-sportluftfilter.de The sound level increased, but in the car only noticeable at idling and when accelerating. Cruising on a highway is the same soundlevel as before. Hans