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Some dyno numbers. We still have some electrical issue we are chasing but overall pretty encouraging. The motor put down 492 rwhp at 15.5 psi! We were making a higher boost run at 18.2 psi (E85) when we started getting some misfire issues and called it a night. I think we were on our way to a 550 rwhp run on the 18.2 psi run. Seeing over 20 hp/psi, this with a LR Super 65. Car is going to put down some pretty serious power Interesting what happens to the torque curve after the Variocam retards the intake cam at at 5000 rpm. No sign at all of falling off up top.
that's awesome..
but if you are running the variocam like stock (ish), isn't it turning *off* after 5000rpm, returning the cam to the retarded position?
that's awesome..
but if you are running the variocam like stock (ish), isn't it turning *off* after 5000rpm, returning the cam to the retarded position?
it is an interesting bump up on an otherwise table-flat curve.
can you adjust the "off" rpm? say 4000 or 4500?
you might find some more power in that range (due to further torque bump) as the retarded cam timing maybe lets a little more air in with the delayed IVC?
Great job, Shawn. Some things you may want to consider if you go back on the dyno:
- You may find the strong top end is simply a result of the superior 4V breathing rather than the shift in cam timing
- You may find that this engine prefers VarioCam activation at different points than the NA 968 with its dual resonance intake manifold
- You may find that the engine prefers to run in the advanced position all of the time - or in the retarded position all of the time.
If you have the time and the inclination, all of this could easily be incorporated into your dyno test plan.
//// Just saw Spencer's post. We're thinking along the same line.////
Great job, Shawn. Some things you may want to consider if you go back on the dyno:
- You may find the strong top end is simply a result of the superior 4V breathing rather than the shift in cam timing
- You may find that this engine prefers VarioCam activation at different points than the NA 968 with its dual resonance intake manifold
- You may find that the engine prefers to run in the advanced position all of the time - or in the retarded position all of the time.
If you have the time and the inclination, all of this could easily be incorporated into your dyno test plan.
//// Just saw Spencer's post. We're thinking along the same line.////
Thanks Micheal for all your help on this build, the custom pistons, the bearing mod, the head work and of course your knowledge and insight. Thank You!
We had a complete Dyno plan but as often happens it did not go as planned. Only got a few runs. Definitely think the Variocam makes a big difference. Below is Duke's awesome 16V Green Hunter Dyno (17 psi). I do not believe he used the Variocam. He noted how sensitive his motor was to cam timing. He also was running a much better turbo IMO, a GT3582R. We will definitely be moving the retard point lower in the RPM range. I think the 16V head along with short runner intake (Duke's - Revline Racing) and Variocam all combine to make for a VERY flat torque curve. Pretty rare and pretty cool and it makes for great top end power at relatively low boost.
02-26-2017, 10:58 PM
Interesting what happens to the torque curve after the Variocam retards the intake cam at at 5000 rpm. No sign at all of falling off up top.
