Rb26 Greddy Plenum Vs Stock Plenum

[Roy]

RB30s are only for people who cant use a clutch and use the 5 gears Nissan gave them

[juggernaut1]

  femno said:

I cant see how you could possibly have better throttle repsonse with a single TB compared to six smaller ones basically bolted straight to the ports in the head?

As for lean on one cylinder, most a/m plenums have the same problem anyway with distribution.

Has anyone driven a SR20 Silvia then driven a GTI-R straight after? Tell me you cant notice the difference...not power wise but response.

And you cant really compare a built 26 with std TBs which probably runs lower CR too. My car is slightly 'doughy' compared to a factory 26.

Something to ponder......I wonder whether the extra response of the multi t/b setups might be from having a greater overall blade surface area compared to the single t/b setups.

My stock s15 had a smallish 50mm t/b then I bolted on the n/a t/b which was 60mm - it felt more responsive especially off boost. Then I did a built motor and Hypertune intake with theri 76 mm t/b setup and it also feels surprisingly responsive.

Is it the larger throttle blade area creating a larger opening for a given throttle movement be creating the phenomenum of response......which is why multi t/b plenums feel more responsive as they probably have a greater overall combined throttle blade area than a smallish single t/b.

[den001]

  shanef said:

i bet both were 2.6's though, silly kents shoulda went 3.0, problem solvered

bit ot but i hate how 26's are down low, throttle responce mite be 'snappy' but theyve got n o t h i n g until about 4

im gona have to agree with you, firstly single tb is actually more responsive....

whoever posted about the suilvia and gtir, cannot compare as there are completly different sr20's, yes there is a difference, im pretty sure there are 131 differences between the gtir and silvia sr20

ive actually driven a gtr with firstly a standard setup, then a straight swap for a hypertune setup, untuned, the car responded exactly the same under 3500rpm, in the mid range and top end it was a shitload better than the 6 t/b's

[N1GTR]

  shanef said:

i bet both were 2.6's though, silly kents shoulda went 3.0, problem solvered

bit ot but i hate how 26's are down low, throttle responce mite be 'snappy' but theyve got n o t h i n g until about 4

They're both going RB30 now actually, funny how that works!

  Roy said:

RB30s are only for people who cant use a clutch and use the 5 gears Nissan gave them

All 5 gears are only needed by RB20 owners trying to keep up with RB30 owners

[Roy]

  juggernaut1 said:

Something to ponder......I wonder whether the extra response of the multi t/b setups might be from having a greater overall blade surface area compared to the single t/b setups.

My stock s15 had a smallish 50mm t/b then I bolted on the n/a t/b which was 60mm - it felt more responsive especially off boost. Then I did a built motor and Hypertune intake with theri 76 mm t/b setup and it also feels surprisingly responsive.

Is it the larger throttle blade area creating a larger opening for a given throttle movement be creating the phenomenum of response......which is why multi t/b plenums feel more responsive as they probably have a greater overall combined throttle blade area than a smallish single t/b.

What you are after for crisp throttle response is good velocity and the ability to regulate it with the enough control that you can accurately fuel the engine and wind the ignition in. If you have a large throttle body then a small crack in the blade equates to a fair bit of air flow. Good for outright power, but for part throttel, crisp acceleration a small throttle body woudl be better. Thats why the smaller individual throttles woul dbe better for crisp acceleration as they being smaller diameter the gradient of airflow from the slightly open to fully open is more linear and therefore easier to control fuelling and tuning.

LOL, well thats at least what i learned / recall from designing an inlet system for a ZX6R engine. There is a reason why bikes run barrel/slide etc inlets and majority of race cars etc all run multi setups/

[shanef]

  Roy said:

RB30s are only for people who cant use a clutch and use the 5 gears Nissan gave them

oh but roy what about putting sedately around on the streets?

[Roy]

  shanef said:

oh but roy what about putting sedately around on the streets?

Hey, i drove a 800cc 3 cyl Handivan whilst building my old 427 Impala. Normal people seem to make do with 1.8L Corollas so there is no issue putting around the streets in a 1280kg RB20 powered GTSt.

I am curious to know more about the people that have gone single and picked up throttle response. Unless you are putting in a fill piece replacing the throttle bodies and install a throttle body onto the std plenum, then any change could be a result of aerodynamics in the plenum

[juggernaut1]

  Roy said:

What you are after for crisp throttle response is good velocity and the ability to regulate it with the enough control that you can accurately fuel the engine and wind the ignition in. If you have a large throttle body then a small crack in the blade equates to a fair bit of air flow. Good for outright power, but for part throttel, crisp acceleration a small throttle body woudl be better. Thats why the smaller individual throttles woul dbe better for crisp acceleration as they being smaller diameter the gradient of airflow from the slightly open to fully open is more linear and therefore easier to control fuelling and tuning.

LOL, well thats at least what i learned / recall from designing an inlet system for a ZX6R engine. There is a reason why bikes run barrel/slide etc inlets and majority of race cars etc all run multi setups/

Actually the big single is a very crisp and bordering on twitchy at light load/low rpm throttle apps....and yes it did take a bit of time to tune for drivability in this area of the map. However, a larger pulley wheel could be made to slow the opening rate of the larger throttle butterfly down if it couldn't be tuned out.

[R31Nismoid]

  shanef said:

not street driven but throttle response and low end power delivery is almost everything. same as why most cars run low mount twins instead of big singles.

so ud rather have a poorly designed manifold and tune out the flaw? I'd rather have a proper manifold that flows evenly as possibly.

Proof please

  shanef said:

i bet both were 2.6's though, silly kents shoulda went 3.0, problem solvered

bit ot but i hate how 26's are down low, throttle responce mite be 'snappy' but theyve got n o t h i n g until about 4

My turn... Armchair expert?

Mine is all in before 4000rpm. In fact it's hauling ass by 4000rpm... but then that's on a well developed set of bits and a tip top tune (that's only running 15psi, 20+psi would see it purely savage)

[Cjmartz2k]

Yeah, I drag primarly, but I can go through the twisties with the best of them, and I don't know how awful much of that I ever spend below 4k rpm. My big arse slow spooling diesel bus turbo is full boogy by right at 4k and I think the way it hits when I put the hammer down is more than enough to compete with your 3.0L, but I'm not familiar with your setup, so I'd reserve judgement until I saw it. I love down low torque--I'm a V8 guy at heart and have a jeep with a stroker I6 in it in the states, but I don't know how aweful useful power below 4k is unless your talking about tight parking lot courses or crawling over rocks in the jeep.

[RedDrifter]

http://www.nengun.com/nismo/intake-collector-plenum

Not cheap though.

[shanef]

  Roy said:

Hey, i drove a 800cc 3 cyl Handivan whilst building my old 427 Impala. Normal people seem to make do with 1.8L Corollas so there is no issue putting around the streets in a 1280kg RB20 powered GTSt.

I am curious to know more about the people that have gone single and picked up throttle response. Unless you are putting in a fill piece replacing the throttle bodies and install a throttle body onto the std plenum, then any change could be a result of aerodynamics in the plenum

i was taking the piss from ashlette sorry roy

  R31Nismoid said:

Proof please

My turn... Armchair expert?

Mine is all in before 4000rpm. In fact it's hauling ass by 4000rpm... but then that's on a well developed set of bits and a tip top tune (that's only running 15psi, 20+psi would see it purely savage)

proof of f**ken what? you urself said they run leaner at the back and to get around that u tune them out. put a proper plenum on it and itd flow near even and make more power, everywhere

u really should read ur posts, then ud see how flamen stupid you sound most/sometimes

whats 'all in'? 250kw and 130ft/lb? sounds right for a hipo rb20

[Buraz]

Dude, he has an Rb26 in his R31.

[R31Nismoid]

lol RB20... typical ignorant comment when you know full well I'm running a RB26/GT-SS

They run slightly leaner, is it a big deal? No. Makes next to zero difference for someone that has half an idea. Clearly most tuners must being its not an issue for ANYONE otherwise there would be dead motors all over the place from the "apparently so bad flowing factory RB26 intake"

I think you should stop with the smoke and mirror posts to try and detract from the fact your wrong by using race cars as examples of what is a good street setup. The two are nothing alike.

So go and get the proof that a single large T/B & plenum are going to be as good around town as a 6 T/B RB26 setup. You don't have anything to back it up at all which doesn't surprise me

[a31lunacy]

i have to agree what works on the street wont work on the track and visa versa. you have a lot of variables on the street that you would not take into account on a race track its more point and shoot. has anyone actually measured the cross sectional area of the six individual butterflys compared to say a single 100mm item i'm thinking it would be larger in overall diameter

[Adriano]

Unfortunately its not that simple, as only one cylinder breathes through each throttle(obviously), so its not all the time, only on intake stroke.

As for issues with uneven distribution with intake plenums, uras recently posted some interesting info, and there is plenty of evidence of it being an issue with rb26's, as almost every one that cracks a piston does it on #6, although this could be a combination of plenum distribution and uneven cooling system distribution.

or my setup im running multi throttles, with ram tubes and the biggest custom plenum i can fit in the bay to try and minimise the distribution problem by unshrouding the ram tubes and slowing the airflow velocity through the plenum over the ramtubes.

[Adriano]

Another supposed benefit of the multi throttles is improved part throttle volumetric efficiency/torque/fuel efficiency, due to the throttles being a barrier to the reversion when using bigger cams.

[eXquiSit]

any further info on this discussion?