Loss in Power after swapping IM

[CS!]

A buddy of mine has a freshly built B18c.

Motor set-up is as follows
JDM B18c (GSR) block
.25 over bore with PR3 pistons
B16a head with Supertech valvetraim
OEM 3 layer HG
S2 Pro 1 cams, set to +3/+3 ( this is what the motor liked best, based on the dyno graph)
Skunk 2 Pro series intake with oem ITR TB
Custom 3' CAI
PLM SMSP rep header mated to a 2.5' exhaust.

A week ago he decided to swop to a Performer X IM and Skunk 2 68mm TB
Nothing else changed on the set-up except for the PX and S2 TB.
To our amazement the car lost 9kw and 5nm, and peaked at 8 000 rpm, instead of the previous 8 300 rpm
Also, the motor preferred for the exhaust cam to be retarded. cam settings are now +4/+0.5

Please feel free to add your thoughts on the reasons behind the loss in power?

 

[freewilly]

did not retune?

 

[CS!]

did not retune?

Yes, the loss of 9kw/5nm was after the retune

 

[fez]

Are the runners shorter on the new mani?

 

[Tsuchinoko]

Try the Performer X with the oem ITR TB.

 

[CS!]

Are the runners shorter on the new mani?

The runners on the PX are longer

 

[CS!]

Try the Performer X with the oem ITR TB.

The ITR TB has been sold.

 

[Vtec6000]

Did it pick up power between 2-5k rpm?

 

[Rich777]

Runners/plenum volume. You need to retune it properly on the same dyno, it may just be it prefered the old setup...

 

[CS!]

Runners/plenum volume. You need to retune it properly on the same dyno, it may just be it prefered the old setup...

So you think it's loss is air velocity?

 

[Rich777]

So you think it's loss is air velocity?

Maybe, i think you need to experiment with those cams a bit though.

 

[blinx9900]

the skunk2 pro series IM is better than the performer X, another user proved this on the forum on his race car some years ago. Put the S2 Pro Im back on or if your compression is high enough and you want just top end for the victor X.

Intake manifold design is often hit or miss, even for professional companies, this was told to me buy a guy who owned a shop doing custom 1800whp twin turbo V8's, Nelson Motors here in USA and he made custom intake manifolds for most of his builds which cost about $90,000USD.

 

[CS!]

the skunk2 pro series IM is better than the performer X, another user proved this on the forum on his race car some years ago. Put the S2 Pro Im back on or if your compression is high enough and you want just top end for the victor X.

Intake manifold design is often hit or miss, even for professional companies, this was told to me buy a guy who owned a shop doing custom 1800whp twin turbo V8's, Nelson Motors here in USA and he made custom intake manifolds for most of his builds which cost about $90,000USD.

Thanks Blinx.

He is looking for good midrange with a smooth linear torque curve. I must be honest, I expected the PX to outperform the SKUNK 2