[Kthen]

Hey guys,

K24 with Drag cartel 3.2 cams, currently testing the vehicle with only 10deg VTC in high cam, and conservative ignition timing before going to dyno, however, in the midst of testing, we're finding that the VTEC engagement is intermittent and it engages and disengages VTEC.

Is this due to not having enough VTC on the crossover? Or would this suggest other issues?

Here is a photo of the log where the issue is happening;

• Low cam and high cam maps are both at 10deg VTC at crossover
• Crossover is at 5500 lower / 5750 upper
• Low cam is fully dyno tuned at 12.5 AFR, have copied low cam fuel and added 15% for high cam fuelling
• Low cam IGN is 25 deg and high cam is 25 deg

Trying to sort out the disengagement issue bringing to dyno, any ideas would be appreciated.

As soon as it revs past the hesitation, it revs out nicely to the limiter 😂😂😂😂

Thanks in advanced!

 

[LotusElise]

Crossover is at 5500 lower / 5750 upper

There exactly starts the problem, but only the symptom, the low quality tune is the root cause. You can't expect high speed cam having any power at 10° VTC, especially not of an DC 3.2 cam. Your tuner may not having any idea of what that engine need.

Did you guys clay the engine or only limit VTC to 45°?

 

[Lotus]

Makes sense. Essentially power drops so much on the high cam that revs drop below the lower cross-over threshold.

 

[Kthen]

You can't expect high speed cam having any power at 10° VTC, especially not of an DC 3.2 cam.

As mentioned:

currently testing the vehicle with only 10deg VTC in high cam, and conservative ignition timing before going to dyno, however, in the midst of testing

If it's crossing over in a weird manner on the road, it'd surely cross over in the same manner on the dyno no?

 

[Lotus]

no, not necessarily. The dyno will regulate acceleration varying resistance depending on dyno type. it won’t allow rpm to drop unless the operator stops the run.
Crossover will show as a big drop in power.

 

[LotusElise]

If it's crossing over in a weird manner on the road, it'd surely cross over in the same manner on the dyno no?

Depends, dynamic measurements on inertia dyno yes.

What you still need to understand is, if you run the very left engine speed of the high speed cam in 10° VTC you will have way less power as on 10° VTC of the low speed cam. The VTEC controlling hysteresis setup leads to that back and forward bogging as well as the VTC setup. You need FULL ADVANCE (valve-to-piston clearance in mind) at high speed cam at the left corner if your header setup is not more worth then a cheap China copy of a worse original US header. If you run stock you need at least 25° of VTC at high speed cam from VTEC switch point till around 6500 rpm...start with that.

Again, what you have done to the calibration is out of any thermodnamical sense and dangerous to the engine. It runs actually out of any rational lambda and VTC window. Before you tune it, please check compression if not already washed down the hone structure...I don't know how long you drive around with that mess of calibration.

 

[Gilbert]

Hey guys,

K24 with Drag cartel 3.2 cams, currently testing the vehicle with only 10deg VTC in high cam, and conservative ignition timing before going to dyno, however, in the midst of testing, we're finding that the VTEC engagement is intermittent and it engages and disengages VTEC.

Is this due to not having enough VTC on the crossover? Or would this suggest other issues?

Here is a photo of the log where the issue is happening;

• Low cam and high cam maps are both at 10deg VTC at crossover
• Crossover is at 5500 lower / 5750 upper
• Low cam is fully dyno tuned at 12.5 AFR, have copied low cam fuel and added 15% for high cam fuelling
• Low cam IGN is 25 deg and high cam is 25 deg

Trying to sort out the disengagement issue bringing to dyno, any ideas would be appreciated.

As soon as it revs past the hesitation, it revs out nicely to the limiter

Thanks in advanced!

My Cams like those normally with stock bottom k24a3 my lift hits at 4000rpm and max
vtc as DC mentioned as I spoke to them is 40max but also as if havnt gone all out to lock vtc and check p2v clearance with those CAMS

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