Series 2 Stagea Plenum

[wolverine]

i think i have found a potential restriction to airflow in a series 2 stagea (manual). here are some pics of the gaskets from a series 2 Stagea and an R34 GT-t. this seems to indicate that the runners for the Stagea are smaller and i am guessing but possibly the cams are different (not verified yet) contrary to most information i had found previously. the plenum visually appears smaller. i am guessing this has been done to improve down low performance on the heavier car sacrificing some top-end!?!?

thoughts anyone?

[beastien]

That would be my guess too

[Spammeoff]

I thought that the general idea was that the Skyline/Stagea motors were the same in all these major aspects, whereas what you've seen here indicates what I'd call a pretty big difference. Shows you shouldn't make assumptions on these things, Nissan seem to be willing to customise their engines for various cars in quite major ways looking at that manifold difference! And obviously consider the Skyline somewhat more performance orientated, not that its a surprise I guess..

[AlexCim]

Thats really interesting.

Good to see that people are actually finding differences between the Stagea and Skyline.

So far

- Stagea detuned

- Neo has smaller inlet

[pixel8r]

On power figures alone, the stagea s2 doesn't appear to be detuned compared to the r34GT-T.

But the findings above show that there are clearly differences between them and I'd agree with the point about more low-down power in the stagea, sacrificing some top-end. My S2 stagea (completely stock) is good off the line but runs out of puff at about 3000-3500rpm after which its a slow climb up through the revs.

Great discovery wolverine!

[darrinspencer]

So if the runners are smaller diameter, does that mean the inlet port size on the head is smaller aswell?

Possibly check runners to head gasket part numbers between Stagea and R34?

[wolverine]

i think the part numbers are different. some one with FAST will be handy here (hint anyone).

i just got the car back and it has been a huge head scratcher why we were running out of puff. everything was checked or changed unfortunately that left the factory parts like cams and plenum (which we thought would be the same as an R34). we struggled to get much over 210-215 rwkw without screwing in a whole lot of boost so there was clearly a restriction.

the car finally made 237rwkw with a GT-RS turbo (with all the appropriate fruit attached to the car).

anyway i hope the next person to modify can add/confirm some of the details above.

[Sydneykid]

Ah, I wondered whose car it was that John was calling me about, now I know it was yours. Big head scratch that one, my guess was cams, which I hope to confirm shortly. I didn't think of inlet differences.

The top gasket in that picture looks like an RB25DET NON NEO one.

If so, it still wouldn't explain the low power, R33GTST's easily exceed that. So my guess is still with the cams.

cheers

Edited August 7, 2006 by Sydneykid

[darrinspencer]

Stagea neo Rb25DET cam spec's

Inlet 236 deg 8.4 mm lift

Exhaust 232 deg 7.0mm lift

These sound fairly tame?

What are R34 neo spec's?

[wolverine]

SK the top one is the neo stagea gasket as it was explained to me. the other one was from an R34 GT-t (unless i have my wires crossed).

we compared prank's plenum (S1) and it is substantially larger (visually).

UAS spoke to nissan and confirmed the cams are the same but i still have my doubts.

Edited August 7, 2006 by wolverine

[darrinspencer]

Any updates?

Anyone know what the R34 GTT cams are compared to the Neo Stagea?

Whether the cams are the issue or not, which Tomie Poncams would suit the best

Type A 252 duration 9.15mm lift

Type B 252 duration 9.15mm lift

Turbo rated at 450hp

Street use

SK?

[Abo Bob]

What you have there is; top, a neo gasket, bottom a non neo, r33, series one stagea, whatever gasket.

It's the neos that have the smaller runners. Previous models had bigger ones. Doesn't seem to restrict at all. I think it would help having smaller ones to keep air velocity. Ie; I think the air would expand a little in the plenum and inlet manifold then compress again going into the ports with the bigger one but with the smaller one (neo) it would keep the air more compressed all the to the ports thus requiring less effort to recompress and being ultimately less restrictive.

[wolverine]

abo bob, my understanding is that the plenum and runners are smaller on the neo stagea vs neo skyline. the top gasket is for a neo stagea and the bottom one came off a neo skyline.

[Abo Bob]

I know that's your understanding. I'm telling you what is actually there. I have both those gasket at home in my garage and I know what engines they came off. The bigger one doesn't come off a neo from any car.

[wolverine]

cheers bob

can you measure the ID of both?

[Abo Bob]

53mm for the r33 one but I can't seem to find the R34 one. I suspect I may have tossed it cos it was broken.

[ian]

I've been travelling, or I would have already commented..

Given I have both a R34 GTX turbo and a Stagea RS4S I can say that -

a) they appear to be absolutely identical (NEO) engines - at least from the outside.

b) I don't run out of puff in the stagea at 3000-3500 revs! (as someone suggested above)

c) taking into account the 200kg difference, the engines seem to have the same power. Though the stagea is of course more grippy because of the weight, and the four wheel drive, so I think it makes up for the weight difference quite a bit by getting more power to the ground some times... They both move well when you want them to..

d) the only slight difference I had been finding was that the R34 was going on boost faster. But that has recently been tracked down to a leaky hose, so I'll see what it is like in the next few weeks…

If the engines are different in any major way I'll be a bit surprised..

Hope that helps someone..

Ian

[darrinspencer]

Stagea neo Rb25DET cam spec's

Inlet 236 deg 8.4 mm lift

Exhaust 232 deg 7.0mm lift

What are R34 neo spec's?

Just found the R34 spec's

Inlet 236 deg 8.4 mm lift

Exhaust 232 deg 8.7mm lift

So would the difference in the R34 exhaust cam lift be reason for the different power levels?