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NISMO Plenum for GTR

Roy

By Roy,
in Engines & Forced Induction

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RH9
RH9

Guys sorry to reply so late, I see there have been a few comments re this plenum. As far as my boost goes, the issue only occurred after going from the previous turbo's to the 2530 Kai's and installi

OYEAHA
OYEAHA

Ah unlucky was worth a try ! Only thing I can hide from the mrs is credit/PayPal account lol

bigmikespec Veteran

bigmikespec

Posted
Posted

I don't think there will be much in the way of results... the only way to do it properly would be to have O2 sensors in each exhaust runner and test back to back to the stock RB26 plenum. The aim of the plenum is to achieve equal flow distribution, there will be a small power gain because of the increased volume.

  • 9 months later...
RH9 Rookie

RH9

Posted
Posted

Hi guys,

Just digging up this thread for the benefit of anyone who is considering using one of these.

I aquired one from a mate who is parting out his race motor - never intended to buy one due to the price but I got a sweet deal.

I was expecting more low end torque and a significant power increase.

Very hard to compare todays dyno result to last time as the air temp between winter and summer is so different along with air density.

Anyway; basic motor spec:

RB26 bored 0.5mm

Ported cylinder head

Tomei 270/260 Pro cams (I think)

HKS GT2530 Kai's

Factory cast iron manifolds.

1.7 bar boost.

No other changes other than the Nismo plenum and the weather conditions.

Previously made 620nms at 5,100rpm and 467kws @ wheels at 7,200rpm (DIN).

Today made 610nms @ 5,100rpm and 473kws @ wheels at 7,800rpm (DIN).

Power used to drop off sharply after 7,200rpm but now its flat all the way to 8,000rpm.

Boost curve is around 100rpm slower to build but still peaks at approx 5,000rpm. It has less "spool" from 3,000 to 4,000rpm but climbs much more steeply from there. Boost curve is more stable than before as it used to dip down slightly between 5,500rpm and 6,000rpm. Now it sits flat to redline.

We tried more boost but the EBC couldnt control the boost steadily over 1.7 bar so we stayed at this level.

My conclusion is that its a worthwhile mod but perhaps not so useful on this particular spec engine.

Pro's: wider power band, more stable boost, more even cylinder temps at #6.

Con's: price unless you get a good deal.

Just bare in mind the plenum may work better or worse depending on your engine spec. Happy with the stronger top end but somewhat dissapointed I didnt get the torque increase - maybe just the weather??

Cheers

Andy

R31Nismoid Grand Master

R31Nismoid

Posted
Posted

Thanks for the results Andy - fits perfectly with the 2% quoted by Nismo, given its pretty much what the results show there :thumbsup:

Boost stability should'nt change with a properly sealed plenum.working EBC be it Nismo/Greddy or stock - so it sounds like the EBC (or whatever method), something has changed there. Perhaps a slight leak with the old plenum.

Piggaz Grand Master

Piggaz

Posted
Posted

It's funny that in RH9's case the peak torque was slightly less at the same RPM when the runners are longer and 2 mm smaller.

I know years ago, Yavuz spun mine to 9000 RPM and power held flat. It didn't really "nose over" as such. Hmm..

Lithium Grand Master

Lithium

Posted
Posted

Very very solid power for the old RB26 on low mounts, gotta be happy with that.

Thanks for the results Andy - fits perfectly with the 2% quoted by Nismo, given its pretty much what the results show there :thumbsup:

Boost stability should'nt change with a properly sealed plenum.working EBC be it Nismo/Greddy or stock - so it sounds like the EBC (or whatever method), something has changed there. Perhaps a slight leak with the old plenum.

It's funny that in RH9's case the peak torque was slightly less at the same RPM when the runners are longer and 2 mm smaller.
I know years ago, Yavuz spun mine to 9000 RPM and power held flat. It didn't really "nose over" as such. Hmm..

Yep - and with this whole 2% difference thing the results are so close that there any range of minor variables could result in those changes, as said... a tiny boost leak, some other random thing that may have changed, even the way the tuner set up the boost control or conditions on the day. You can see that difference between a cold and hot run even, so it is a bit hard to jump to any major conclusions on - as Andy indicated.

Was it previously running a factory plenum?

bigmikespec Veteran

bigmikespec

Posted
Posted

It is easy to write off the results as insignificant... the increase in power and extended power band until later in rev range is more than likely due to increase plenum volume compared to anything else. You would see this with any larger plenum.

There is no mention of actual cylinder temps, if someone was serious they would have an O2 sensor in each runner, that would tell a story. Until then people can continue to scoff at the results so far which dont really say anything.

Lithium Grand Master

Lithium

Posted
Posted

Can't really scoff at the dyno results - or otherwise, its so close.

If there is definitely a noticeable improvement in temperature across the 6 cylinders then it HAS to be a good thing. I'm a firm believer in making the engine happy first, and power gains being a result of that is a nice bonus - but the same power with a less stressed motor is brilliant.

R31Nismoid Grand Master

R31Nismoid

Posted
Posted
2530s @ 24psi falling over @ 7200rpm on a 2.6ltr...
Boost control wasn't consistent from 5-6k...
Obvious something, albeit minor, was up beforehand.


(and again, not discounting the #6 reaffirmed etc, its all good and useful information).

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