My tuner and I are having a head-scratch moment here I'm running the SOS w/Novi 1200 blower on an AP2 and went back for a retune after swapping for a smaller pulley. Please take a look at the plots below. The BOLD line is the new run with the smaller pulley which is putting more boost (~12psi). The thin line is my old setup with ~9.5 psi of boost. Old setup made 387 whp, new setup is 353 hp

I gained more midrange with the smaller pulley; however horsepower hit a wall around 6800 RPM and just went flat. The torque curve also crowbared. The AFR went pig rich at this RPM which may indicate there is not enough air??

I'm running ID1000 injectors with a Weldon 1100A pump. My 9 psi setup had a custom magnaflow 3" exhaust which was very high flowing. Since it was so loud I switched to a Berk 3" headerback (no cat) for my new 12 psi setup. Outside that, nothing else has changed.

We thought the restriction was coming from the intake, so we put an air horn directly on the inlet of the blower with no filter. Redynoed and got the same results. We also know the fuel system is healthy and not lacking. Compression check & spark plugs looks good. Tried advancing & retarding timing and didnt help any.

Any ideas on what the restriction or issue might be? I don't see how the Berk exhaust can be the cause, but I can't think of anything else. I'm making more boost everywhere over the baseline run, but the TQ/HP plots do not necessarily reflect that. FYI, VTEC is set at 4000 RPM.




(scaling on left plot Y-axis is obviously wrong)

 

Its because your running spring pressure on your Wastegate. if you added a boost controller then you would hit 12psi and hold to redline and not fall down to ~9psi.
If you notice from your pictures...as your boost falls off so does your power.

 

I'm bleeding excess boost past 12 PSI using a wastegate. I do realize that boost is falling off; however I am making more boost across all RPMs relative to my baseline. Regardless of belt slip (which is not the case here), I should be making more power across the board.

I'm making 1-3 psi more above 6K RPM but less HP and no torque. Should there be a leak or belt slip, that would be above and beyond what I should be making.

 

I changed from my first post because you posted this thread before the wastegate thread so it looked like belt slip from the graphs. My guess would be that you proved a few peoples thoughts that if you limited boost with a Supercharger then you would lose to much CFM's and in turn make less power.

BTW its sad to hear about the BLV as I also have a 2.8" pulley installed and just started trying to adjust it last night.

 

I hope this is not the case, but very well may be the truth.

Another thought which I think is exonerated is TQ drop due to over-spinning the blower. Based on impeller math, we overspin the blower around 7400RPM. I would think that the blower should be making enough CFM up to this point (although it would be on the edge of the compressor maps)

 

Can you explain why a boost controller will help maintain boost without dropping to 9PSI? If I used a manual boost controller, wouldn't it have the safe effect as the wastegate spring (in this case it will use the MBC spring pressure)? Please educate me I'm new to wastegates

 

You already have a AEM ems so just buy a mac solenoid and wire it up.

 

I'm using the Flashpro. The boost bleeding down to 9psi is not an issue. The issue is that I dont understand why TQ is falling off and HP is flat with more boost under the curve.

 

Power and torque are dropping at the same spot as boost. Setup boost control in your flashpro and you will be able to control boost perfectly and the power should come back.

 

OK, I just bought the MAC controller and will give it a try.