Guys,
I was doing Skunk2 Street manifold dyno test today. The patient is fully built K24/K20 frank 87,5x99 (CR 12,6).
THIS IS SAME DYNO, SAME CAR, SAME DAY, SAME TUNER, SAME TYRES, SAME TEMPERATURES etc.
Pics of a ported S2 manifold:
Here are dyno graphs of RRC and Skunk2 Street manifold. RRC manifold was
opened to 72mm, ported inside and welded. S2 manifold was
ported inside, opened to 74mm and had 0,5l spacer.
I couldn't use bigger spacer with S2 manifold as I was limited by FN2 chasis. Also what might be important, RRC was used with Hondata Heatshield Gasket - I couldn't use this gasket with S2, as I would not be able to fit the manifold into the engine bay, so S2 was tested using standard OEM manifold gasket.
RRC dynos were more/less tuned with AFR and VTC. VTEC was 4400rpm on both runs and I didn't change it as I wanted to check overall performance difference of those two manifolds in 5000+ rpm range
When tuning S2 manifold, I tuned AFR precisely and I checked 30-40* VTC settings within the 0-7000 rpm range and 15-40* VTC settings within 7000-8500 rpm range.
Here are the graphs. They are shifted about 400 rpm left as I had my rpm redline set 8200-8400rpm.
Skunk2 (both lines) - best 312HP at 8400 rpm and 303Nm at 6300 rpm:
Skunk2 (bold line) vs. RRC (thin line):
There are so minor dimples on S2 graph that I think could be eliminated with some more AFR tuning. But they do not blure the image of the both manifolds.
My conslusions are that these manifolds are a bit different. RRC manifold seems to be a bit better manifold for a DD than Skunk2 Street. It shows tiny few Nm more in the mid range, but the differences are very small and was not felt in the car.
Important part is however that when we tried to spin the engine higher, the power curve of S2 manifold was still climbing after 8000 rpm. In that range (after 7500rpm) RRC manifold was starting to give up.
I would say that ported S2 manifold would be a definately better option than ported RBC, which gave worse numbers than ported RRC on that car.
I think that if you have like 8500-9000 rpm red line motor (K24 or K20), then S2 manifold may give you significant amount of additional ponies than RRC will not. It will additionally provide a lot of mid range, that i.e. S2 Ultra Race will not.
Maybe with bigger spacer this manifold would give even better results, but it was not possible for me to check it.
