[deibral]

Promised to measure the runners so here they are. Measuring is a bit tricky as they are much curved and within one runner one side of the runner is longer than the other .

Longer side (inside the manifold):

Shorter side (inside the manifold):

Measured outside:

So I would sum up that longer side has 180mm, shorter side has 165mm. Runners measured outside have 145-150mm but as you can see first and fourth runner are longer than the second and the third. Also outside measurment do not include curving factor.

 

[LotusElise]

Yes. We need to spin these engines to 10k.

LOL ...seems to be like that. Using the 84 mm stroke crank of the F20C engine would help for both, piston acceleration-wise and journal bearing load-wise. 10 krpm is really hard for a K20 endurance application...more like one or two races and finished . The other approach would be to design the intake manifold for the capable engine speed range...but this seems to be the hardest path...LOL .

I need to test street mani on k20. Maybe it will work better on k20.

If the runners of the S2 US IM are wider and shorter? I have my doubt's on that...the air velocity which is needed to produce proper VE would be reached more right...more high end torque maybe, but overall I have my doubt's. How will test it ?

Promised to measure the runners so here they are...longer side has 180mm, shorter side has 165mm. Runners measured outside have 145-150mm but as you can see first and fourth runner are longer than the second and the third. Also outside measurment do not include curving factor.

Thanks deibral, I really appreciate your effort and measurement :up:!

Did you occasionally measure the inlet ID at the bell mouth too?

Markus

 

[flesh199]

thx you for these pictures deibral.

 

[deibral]

Anyone tested new Skunk2 Ultra Centerfeed plenum?

http://skunk2.com/catalogsearch/result/?q=centerfeed

It is S2 Ultra Race dedicated but wonder what would happen if I put it on S2 Street manifold. I am trying to get Skunk2 feedback if that is possible and how that would affect powerband.

Any ideas, dynos or users?

 

[fo0]

Anyone tested new Skunk2 Ultra Centerfeed plenum?

http://skunk2.com/catalogsearch/result/?q=centerfeed

It is S2 Ultra Race dedicated but wonder what would happen if I put it on S2 Street manifold. I am trying to get Skunk2 feedback if that is possible and how that would affect powerband.

Any ideas, dynos or users?

how would you fit it on? isnt the race and street different sizes

 

[deibral]

Yes they are, but skunk2 said in his first e-mails that there is some kind of adapter that makes it fit to S2 Street version runners. But I am in the process of getting more info as there is nothing about that on the web page and I did not receive part number.

 

[flesh199]

Anyone tested new Skunk2 Ultra Centerfeed plenum?

http://skunk2.com/catalogsearch/result/?q=centerfeed

It is S2 Ultra Race dedicated but wonder what would happen if I put it on S2 Street manifold. I am trying to get Skunk2 feedback if that is possible and how that would affect powerband.

Any ideas, dynos or users?

My tuner tested a skunk2 ultra race center feed vs a ultra race side feed on my friend's 88x99 13.5 cr k24

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[LotusElise]

My tuner tested a skunk2 ultra race center feed vs a ultra race side feed on my friend's 88x99 13.5 cr k24

Thanks for sharing flesh199. The better cylinder balance shows us it efficiency .

Markus

 

[flesh199]

Thanks for sharing flesh199. The better cylinder balance shows us it efficiency .

Markus

look again markus,the center feed is worst than the side feed

 

[slofu]

Not bad, considering the center-feed plenum is 5L and the side-feed is 3.5L. Too bad they don't make a 3.5L center-feed option, though I'm guessing that the larger volume will work better on boosted applications.

 

[LotusElise]

look again markus,the center feed is worst than the side feed

Didn't I wrote that ?

Anyway I am curious about the intake, TB and CAI setups of both. Is there more info avialable flesh199? I would appreciate it!

I wish you a peaceful and contemplative Christmas Eve .

Markus

 

[deibral]

The results are very strange as bigger plenum should boost high end rpm and according to pics it does not. But not when it is too big.

So everything above 3,5l plenum seems to be too big for a K24-K26 N/A motor... that revs up to 8500-9000 rpm in my opinion.

How about k-tuned etc. big plenum manifolds?

 

[Nyborg Garage]

Flesh has a great tuner, but I wonder if he spent enough on time on that test. Very strange how it has a nice peak at 7500, and then very abruptly falls on it's face. Looks a bit like it swiched over to a vtc map with to little timing, or something else. The sudden change in hp/tq just seems unrealistic.

 

[deibral]

Flesh has a great tuner, but I wonder if he spent enough on time on that test. Very strange how it has a nice peak at 7500, and then very abruptly falls on it's face. Looks a bit like it swiched over to a vtc map with to little timing, or something else. The sudden change in hp/tq just seems unrealistic.

Even so, there should be a 10-20HP range improvement straight away puting a centerfeed plenum. That is what Joe McCarthy I think experienced few years back on his manifolds by equaling the runners flow by centerfeed plenum.

And on the picture we can not see that. So either plenum is too big or this manifold (S2 Race no matter what plenum) does not fit to the engine specs correctly to see the difference.

Flesh199 - do you have a torque graph for this comparison?

 

[flesh199]

Even so, there should be a 10-20HP range improvement straight away puting a centerfeed plenum. That is what Joe McCarthy I think experienced few years back on his manifolds by equaling the runners flow by centerfeed plenum.

And on the picture we can not see that. So either plenum is too big or this manifold (S2 Race no matter what plenum) does not fit to the engine specs correctly to see the difference.

Flesh199 - do you have a torque graph for this comparison?

I will talk about info and torque graph to my friend(tuner)

 

[slofu]

I'm guessing that the superior air distribution of the center-feed accounts for the fact that the larger plenum doesn't kill the low-end, but the smaller side-feed plenum affords a tuning benefit at the high-end.

 

[UdwanaGaMama]

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.

Thanks for sharing man. I would love to see this running live.