Here's my Dyno sheet stock, i'd like to know about that dip around 7000 RPM, what do you guys think...? Image Unavailable, Please Login
Every 550/575 we have dynoed tends to start dropping at 5,800 rpm, its normal. Your numbers are low, what brand dyno did you go to?
remember we are in Florida, hot, humid air = less power. At least, I hope that's what it was.. Dyno used was a "Dynomite" by Land and Sea, eddy current dyno... I expected a dip in power at 6000, but what about the spike from 7000 - 7600?
The drop in torque after 5800 does seem to be typical of this engine, but it also seems like the drop demonstrated here is more extreme than "normal". Below is a chart comp[aring the dyno runs of a '95 456GT and '97 550 done 5.5 and 4.5 years ago respectively. This graph is typical of all 550/456/575s we seen tested in club events, and shows a similar, but far less pronounced drop in HP at 7600 rpm than waht your plot shows. Don't have AFR numbers for comparison, sorry. This was done on a Dynojet Research dyno, and numbers are SAE corrected. Image Unavailable, Please Login
Sorry, thought that was obvious. The 456 is the lower powered of the two cars. I found it interesting that both models exhibit that same drop right before the rev limiter cutoff. I'd imagine its something to do with the electronic cutoff system. Maybe the computer cuts or retards the ignition or in some other way reduces the power just before it then cuts the juice at its final top rpm. It'd be interesting to see the curve of one of these engines with an aftermarket chip that removes the rev limiter to see how it behaves. But of course, then other things would have been changed, too.
Please don't try to compare results on different cars and or dyno's. Even different days will produce different results. The only thing a dyno is useful for is comparison... with minimal time between runs... The numbers are mostly meaningless...
thanks Phil...but do you have any explanation for the drop at 6000 and then the spike at 7000-7600? is that normal?
Yeah, I get that and wasn't tryng to show anything more than a couple more plots that demonstrate this little dip before the end of the run. I think the three different results are interesting in their similarities wrt the drop right before peak rpm. And it appears that the drop in the first chart is more exagerated than that seen in the others. I suppose it could be all down to different scales each graph is plotted at, so the graphical comparison is flawed.
Exactly... The dip is normal... the variable inlet is mostly responsible... messing with it can be interesting... but time consuming... you can lock it in the "engine off" position for full power if you like... but you'll lose some low end torque... not much either way, but you'll notice it. Pic of manifold removed (to fix water leak and inlet gasket failure) see other thresd coming soon.. Image Unavailable, Please Login Image Unavailable, Please Login
