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The restrictive KKK-style turbine may require a post peak torque RPM switch point that will prevent the 16V+short intake combo to flow to its peak HP potential.
The results are already better than I expected, but that may be because the turbine is not quite completely choked yet with only 15.5 psi of boost.
It's very interesting and reassuring that the numbers and curve correlates so well to my old Green Hunter engine combo. Some notes:
* Surprisingly good numbers and curve with that turbo!
* Power continues to rise. I wouldn't be afraid of at least letting it spin to 7k.
* The Green Hunter had a better turbo but was tuned and dynoed on pump fuel. Considering this I think the numbers would pretty much line up on the same fuel! There was also a lesser flowing short runner intake on that car compared to the one you have now.
* I was in fact running Variocam. I saw on the dyno that having Variocam activated gave more power up to around 6800 rpm than without if I remember correctly. So I programmed it so that it was always activated istead of having it switch off so close to redline. So here you have some midrange gains waiting.
The results are already better than I expected, but that may be because the turbine is not quite completely choked yet with only 15.5 psi of boost.
It was better than I expected also
Originally Posted by ealoken
Nice numbers, what Turbo is in your car?
LR Super 65, with some mild mods by Charlie at Evergreen. I was not involved with the turbo rebuild but I am going to try to get some more details.
Originally Posted by Duke
Great results!
It's very interesting and reassuring that the numbers and curve correlates so well to my old Green Hunter engine combo. Some notes:
* Surprisingly good numbers and curve with that turbo!
* Power continues to rise. I wouldn't be afraid of at least letting it spin to 7k.
* The Green Hunter had a better turbo but was tuned and dynoed on pump fuel. Considering this I think the numbers would pretty much line up on the same fuel! There was also a lesser flowing short runner intake on that car compared to the one you have now.
* I was in fact running Variocam. I saw on the dyno that having Variocam activated gave more power up to around 6800 rpm than without if I remember correctly. So I programmed it so that it was always activated istead of having it switch off so close to redline. So here you have some midrange gains waiting.
Good job!
Thanks Gustaf. Your intake is form and function at its best.
* I was in fact running Variocam. I saw on the dyno that having Variocam activated gave more power up to around 6800 rpm than without if I remember correctly. So I programmed it so that it was always activated istead of having it switch off so close to redline. So here you have some midrange gains waiting.
If we remember that your engine back then had a CR of 9.5:1, while "Shawn's" here has 8:1, both results and observations make sense.
As the Variocam activated, the advanced IVC seemed to work well enough with your higher CR and better flowing turbine that most likely allowed a "higher" effective compression ratio up top, while on "Shawn's" engine here, retarding IVC may help maintain an effective compression ratio that may be dropping up top because of the lower CR and the restrictive turbine/slightly mismatched turbo.
I could be wrong but I believe the higher the turbine inlet pressure, the lower the variations in peak power the Variocam will make.
If you have the data, I'd love to see the intake manifold and exhaust manifold pressure over the rpm range. In the spirit of "I'll show you mine if you show me yours", here's mine from about 10 psi boost run (1.6 bar absolute on that graph):
I think (but don't know) that the "torque" setting that produces high valve overlap will work great as long as the (cycle average) exhaust back pressure is lower or at least not much higher than the intake manifold pressure. If the exhaust back pressure starts getting much higher than the intake at high rpms, then switching to later IVO and IVC points probably makes sense. If the turbo is really freely flowing and the wastegate bypasses only relatively small fraction of the exhaust flow, conceivably it might only want the less overlap setting at below 1500 rpm for smooth idle.
Interesting comparison, my 8V Hybrid Stroker vs Jon951's 3L 16V motor.
Notes:
- 8V power is corrected based on volume, 3.12L vs 3L
- 8V power is at 24.2 PSI and the 16V power is at 18.2 PSI
- 8V turbo is a GT3582R with 0.82 A/R
- 16V turbo is LR Super 65 with P Trim turbine, extrude honed, lightened
- 8V Cam is high lift CEP Cam and 16V Cams are stock 968.
- Both motors were running E85
- Both motors had large plenum, short runner intakes.
- Both motors are running 3" exhaust with stock exhaust headers.
- Both motors have approximately 8:1 static CR
Observations:
- Peak cylinder pressure is similar for both motors assuming no knock, so running a 16V motor at 18 psi is like running a 8V motor at 24 psi, extreme caution is required to manage knock on a 16V motor (especially running pump fuel)!
- Although peak cylinder pressure is similar, the turbo on a 16V has to work much less, therefore ALOT less heat is produced.
- LR Super65 performs much better than I would have expected, note that the 16V head puts much less demand on the turbo.
- 16V has a much flatter torque curve resulting in more power up top, I wonder how much of this is due to the VariCam vs Z factor losses (supersonic flow). Further dyno testing should shed some light on this.
- The exhaust note produced by a 16V motor is far superior to an 8V motor
6 psi less for the same, and in some cases more power is excellent. Would have thought the 8v would be nosing off right about there and the 16v to keep climbing. Rev them both to 7000-7500rpm and see a massive difference. Lets see the 16v @ 24psi next.
03-03-2017, 05:35 AM
