Our regional club had a Dyno Day yesterday, so I ran my Boxer. Info/photos at: http://ferrarichat.com/forum/showthread.php?t=10496 The numbers seem a bit strange to me. The torque rating was very high, but horsepower seemed a bit low. My Ferrari owners manual specs list: 340 horse/323 torque at the flywheel. Testing results: 260 / 283 The car is running great and the dyno guy said the air/fuel ratio curve looked perfect. Does anyone else have any dyno test results from their Boxers to compare?? If so, please post them.
That seems to say you have about 317 hp at the wheel, I assume SAE. If DIN, as many Ferrari specs are, that's about 330. The flywheel torque is about 345. You sure they didn't reverse your numbers? Any number of things can cause 'goofy numbers': tire slippage, high rolling resistance due to underinflation, etc. One thing that came to mind was that it looks like you probably have good low-end power, but fall off up high - this could be due to flow obstruction such as a dirty air cleaner, etc. Also a clogged exhaust on whatever system your car was federalized on (All US Boxers are converted grey market cars). Time for a new catalytic converter? Would love to see the graph if possible with the AF data. Beautiful car, obtw! best Russ
Russ, My Boxer has been converted back to the original Ferrari factory exhaust system (no cats) and the air filters only have about 3K miles on them. Here's the charts:
Gary Thanks for the graph. Well, interestingly, something is awry as I cannot believe your engine is tuned for a hp peak at 5200, although you have monster torque. There are other guys here who know more than me, but I'll take a shot: The dyno tech was right, your AF is great. You did mention that your engine is running smoothly, so I assume your plugs are ok. The top of the hp curve did not jiggle around like you get with detonation or slippage, so that combined with the AF data (and assuming your ignition is good - should check that it advances correctly) leads me to believe you have an airflow problem. If as you say you can rule out exhaust or airfilter obstruction, that leaves me to postulate that your cam timing is off. These numbers may be generated by a cam timing problem, either done at the last belt change or as a part of conversion to meet emissions testing. This is consistant with the hp falling off if you have everything else Euro-spec. Those cams should peak out well over 6000 rpm. Things I think you should check: exhaust cam timing intake cam timing ignition curve plugs/wires I'm sure there are many with more experience who can chime in here. May should cross post to tech. Hope this helps get you started best Russ
Russ, Thanks for the tips. I just got off the phone with the service manager at Continental Auto Sports in Chicago (they did the last major service/timing belts). He said they are very fussy about getting the cam timing perfect on the older 12 cylinder engines and that they use a degree wheel to get them exactly right. He felt that maybe the advance weights on the distributor are sticking and that this is a very common problem with Boxers that have sat around without being driven very much. I'm going to talk to my mechanic about it today.
Gary, IMO your A/F is too rich in the upper RPM ranges. On my DynoJet the A/F ratios that produce the best numbers are right around 13.5:1 to 14.0:1 for naturally aspirated. This applies to both carbureted as well as fuel injected. Steve
