B18C5 crazy dip in air flow/ fuel from 6000-7000rpm . Cam timing off?? Or head porting?? Or wrong cams??

Engine specs for B18c5 / 98ITR. 91octane 208whp 135tq

Skunk 2 Tuner 2 cams

Stock bore CTR pistons with milled Type R Head compression is 12:6:1

Type R rod’s and crank.

ported and polished head Supertek springs and retainers and valves

skunk 2 Ultra St. manifold with 74 mm throttle body

550 cc alpha injectors fuel regulator 60 psi

skunk 2 cam gears both In&EX@+2 advanced

DTR TRI-Y race header 72mm-76mm TestPipe

76mm skunk 2 megaRR exhaust

3inch I.D. Custom cold air intake with velocity stack

so there’s a big dip in power from 6000-7000 rpm. I’m not sure what is causing it. There’s also a big dip in air flow and fuel. The cams were installed using the stock Honda timing mark’s they were not degreed. My intake and exhaust system is free flowing. I will attach the hondata air/ fuel table and the dyno graph and my cam specs .

my question is what is causing the air flow to drop off and Hp/ TQ so much from 6000-7000 rpms then it picks back up from 7000 till redline??? Is it the cam timing out of sync?

It's not that unusual for an engine to have a dip as intakes, exhausts, camshafts, etc interact - with the B18 it's more extreme because of the variable camshaft timings.

You may be able to fill it in a little by confirming the base camshaft timing is correct and/or moving them a couple of degrees either way (you need to know your V2P clearances under the VTEC, though), but it would be easier to move the VTEC cross-over point to earlier in the rpm range to see if that improves things.

Hi, so my vtec is set at 5500 and the cams start come alive at 6000. What would you recommend trying to drop the vtec down to?

It won't help the higher rpm dip*, it's already well onto the secondary cam lobes by then, but it looks like lowering the transition is going to lift the torque/power below the current point.

*that'll be down to other factors that may need some experimentation to identify and correct, as Shota and David said in your other post on the subject. While the exhaust side is usually blamed, the intake side is subject to exactly the same cruiteria for tuning diameter and lengths. That said, the exhaust is much easier to work with and there are many formulae on-line that should get you in the ball park if you average them out - remember, there's no such thing as a "one size fits all" with exhausts.

About the cheapest and, potentially easiest, thing is to make up some slip-on extensions for the exhaust pipe, to see if lengthening, or shortening, the outlet length helps anything. On that, a rough, old school, guide is if there's a colour band part way along the collector, cut it of in the middle of the band.