Help Analyzing S52 Dyno Graph

[pazi88]

Is that whp or calculated crank hp? Or from hubs?

But can't tell anything without proper logs from the ecu during that dyno pull. And don't even know if you can get those from obd1 ecu. Original obd2 ecu of s52 would be much easier to get logs.

[sebe20]

I have no expierence with s52's on dynos but as i recall it's somewhat based on a M52. The M52 engine family has peak HP at 5500rpm and peak torque at 3500 to 4000rpm. But considering the S52 is labelled at 240HP on Wikipedia something seems to be way off.

These Modification you've already done sound really promising for power and torque gains.

was the ecu tuned on the dyno? what fuel are you running? is the pump sufficent?

also i've never heard of a 20HP loss (compared to the 240HP claims on wikipedia) because of exhaust resonance issues either. Maybe you loose some on the way to the rear wheels.

[ian e30 318is]

To start, this is the 2nd iteration of tuning for my s52. I'm curious why there is a dip in the graph at 5,500 RPM and never returns to full power. Is this is tune issue, a system issue (Vanos, exhaust), or possibly a resonance issue?? Most of the other graphs I have seen for s52's with similar modifications seem to be linear to redline. We also played around with the intake filter and inlet conditions with minimal changes.

Mods during dyno session are as follows:
-s52 converted to OBDI
-413 red ECU with custom chip by a knowledgable tuner
-Stock s52 cams
-24lb injectors
-3.5" euro MAF
-M50 intake manifold
-Raceland headers to OBD II midpipe and supersprint exhaust
-Rogue engineering pulleys
-Rebuilt Vanos with Beisan's seal kit

Graph is below and noted that AFR's are not shown, but my wideband read high 11's to low 12's until redline.

Performed on a DYNOmite dyno