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Discussion Starter · #1 ·
Would a tuned length inlet plenum with individual runners the same size (similar to an exhaust manifold in design) be a way to totally overcome the problem with number 6 cylinder running lean on an RB motor?
Here is a picture of a very serious quad GT47 blown V8 featuring such a plenum.

 

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Yes it would. The runner length is very important for shock wave tuning. I'm not too sure the setup in that pic is very good. Some VTEC engines and motorcycle engines have variable length trumpets/hornh to get the optimum lenght as the engine revs up.
 

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Discussion Starter · #3 ·
R32 Combat said:
Yes it would. The runner length is very important for shock wave tuning. I'm not too sure the setup in that pic is very good. Some VTEC engines and motorcycle engines have variable length trumpets/hornh to get the optimum lenght as the engine revs up.
I know how important tuned (and variable length) runners are on high revving N/A motors but a isn't a forced induction plenum more about equal and adequate flow charateristics to each cylinder? Would the "exhaust manifold in reverse" design not reduce each intake pulse interfering as much as on a regular "common tank" plenum design or would the shock waves have just as much or even more effect when they are further from the intake valve ?

The motor pictured dynoed at 3900bhp on 91 octane btw :bowdown1:
 

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COSSY, u got a link to an article on that engine?? Sounds MEGA. I assume its a marine engine??

TT
 

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NO WAY !!!!!. How are you ever going to get that kind of power down on the tarmac. Mr Leno would be as well buying a few hundred new tyres, pouring petrol over them and setting light to them as they're all gonna go that way in the end.

Tut-tut........4K HP in a car.......eedjit:chairshot :chairshot :chairshot

TT
 

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Talking of plenums guys..........is the greddy plenum a good upgrade on the gtr???

Seen quite a few cars running them............
 

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Discussion Starter · #8 · (Edited)
Lamb said:
Talking of plenums guys..........is the greddy plenum a good upgrade on the gtr???

Seen quite a few cars running them............
Hugh Keir runs one and posted pictures before and after gasflowing
Std Greddy plenum


After gasflowing


The Nismo plenum appears to be about the best for equal distribution but when I asked what power they are good for nobody could give me an answer.
 

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Discussion Starter · #10 ·
ChristianR said:
sorry for off topic, but more info on that Camaro please!!
Its Jay Lenos toy, he has over 200 amazing cars in his collection. He drives the Camaro on the street but its a full on drag car.
There is a video torrent of his car and bike collection kicking about on the net inc his gas turbine powered 280mph bike and the above Camaro.

Now back to the pros and cons of tubular inlet manifolds/plenums......
 

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As far as I'm aware, the inlet design doesn't change massively for forced induction. You still get shock waves, you just don't get inertial ramming issues with N/A.

The problem with the GTR is the physical room around no6, hence no6 suffering from inertial ramming. Fitting a GTS inlet does seem a good way around this but its tuned for a different engine rpm.
 

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R32 Combat said:
As far as I'm aware, the inlet design doesn't change massively for forced induction. You still get shock waves, you just don't get inertial ramming issues with N/A.

The problem with the GTR is the physical room around no6, hence no6 suffering from inertial ramming. Fitting a GTS inlet does seem a good way around this but its tuned for a different engine rpm.

What inlet do you run on your beast Andy?
 

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I've got a STD GTR inlet with a single throttle at the mo.

I've started to make my own plenum, something along the JUN/Veilside design.

I ordered a book about inlet designs, but it's gone out of publication so I've ground to a halt. I might just bite the bullet and carry on anyway with my ideas.
 

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COSSYCam said:
The Nismo plenum appears to be about the best for equal distribution but when I asked what power they are good for nobody could give me an answer.
How do you ever know "what power they are good for"? There are plenty of big-power cars using the standard plenum with no problems, and the Nismo one is supposedly an improvement in terms of flow and equal distribution over standard, so ...

I suppose it depends how much of your own time and money you want to spend trying something different, and quantifying the results. There are so many variables (plenum volume, runner lengths and diameters etc.).

Also, how much space is there to do something different?

Phil
 

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Discussion Starter · #18 ·
Philip said:
How do you ever know "what power they are good for"? There are plenty of big-power cars using the standard plenum with no problems, and the Nismo one is supposedly an improvement in terms of flow and equal distribution over standard, so ...

I suppose it depends how much of your own time and money you want to spend trying something different, and quantifying the results. There are so many variables (plenum volume, runner lengths and diameters etc.).

Also, how much space is there to do something different?

Phil
I've not seen any cars running over 650bhp or so with a Nismo plenum.
Space isn't an issue (within reason) as the RB in question is not going in a Skyline.
 

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COSSYCam said:
I've not seen any cars running over 650bhp or so with a Nismo plenum.
Space isn't an issue (within reason) as the RB in question is not going in a Skyline.

Im considering the Greddy inlet manifold and just wondering if its much omprovement over the standard one......
 

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Discussion Starter · #20 ·
Lamb said:
Im considering the Greddy inlet manifold and just wondering if its much omprovement over the standard one......
I was told that over 750bhp it shows a slight improvement but was not worth it for less than that as you could get more from spending on other areas.
 
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