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Discussion Starter #1
Hello fellow members.

After 2.5 years of building my car I finally booked it in for a tune but unfortunately ran into a vtec issue with the motor today...

Motor is:

D16Y4 block - same as a D16Y7 block
JDM D15B cylinder head & cam (not the 3 stage vtec)
ARP head studs
D16Y8 headgasket

Running a intercooled JRSC M45

Tuned with a Hondata S300 V3

As I'm located in Australia dyno numbers are a little lower than US numbers.

The tuner could only make 96.7HP on low cam, 115.1 on high cam. His dyno is also a little low reading.

There seems to be an issue with vtec engagement, It definitely works but not sure if all 4 cylinders are engaging?

Boost is also seen dropping by about 1.5 or so psi when vtec kicks in which is consistent. the engine does not run rough at all when vtec is engaged.

I'm going to be installing an oil pressure gauge on the vtec solenoid which will let me know if there's any oil pressure issues in the next few days.

We swapped out the vtec solenoid for a different one and that helped abit but still no where close.

The oil squirter was removed from the block before the head was torqued down. Also confirmed that the head gasket was installed correctly.

Anyone else experience similar issues?

Red line is low cam blue line is high cam.

 

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Discussion Starter #3
Will definitely be doing that on the next dyno run, from memory as it's a mini me the cam may be 1/2 tooth out or so.
 

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Discussion Starter #4
Should also add it has a AEM true time cam gear that is currently set to 0 degrees.
 

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X2 on cam timing. Also is it a stock cam or is it more aggressive? Cams with big overlap do not work well on supercharged cars usually.
 

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Discussion Starter #6
X2 on cam timing. Also is it a stock cam or is it more aggressive? Cams with big overlap do not work well on supercharged cars usually.
Stock cam at the moment.

Will advance it by half a tooth and see how that goes or I'll put the original cam gear back one.
 

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From what I remember, the jdm d15b doesn't really have any extra lift or duration over the y8/z6 cams, but it does supposedly have more overlap, not so much that it should dramatically hurt Forced induction performance though. My money is on the cam timing being off.
 
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