Skyline Owners Forum banner

1 - 19 of 19 Posts

·
get your grinders out!!!
Joined
·
87 Posts
Discussion Starter #1 (Edited)
rb20de R34 GT Neo engine

I have searched a lot about the question i`ll be asking in a sec. Searched here, on NissanSilvia.com and on the internet ( obvious ).

There are loads of butterfly-valves in the RB Neo engine, i know how these work as the Japspec s13`s came with the same valves, to make the emissions and mpg better ;)

Now is my question this, can i remove them valves without any issues to run the rb20 properly? So not giving in on the rev-ing what they are capable to, and stuff like that.
I am not really interested in good mpg and saving the world :) But they seem restrictive as god knows what.

Hope that you guys can help me ;)

JJ
 

·
Everybody knows that the bird is the word
Joined
·
9,198 Posts
The only 'butteryfly' in the car is your throttle body, which obviously you can not remove... what valves are you talking about?!

There is a carbon canister and PCV valve fitted for emissions
The carbon canister is easy to remove. Don't touch the PCV valve.
 

·
get your grinders out!!!
Joined
·
87 Posts
Discussion Starter #3
Ill make it a bit easier with pics :)





Only got the engine mate, not the Skyline where it used to sit ;)
 

·
Everybody knows that the bird is the word
Joined
·
9,198 Posts
Woah :eek: shows what I know about the NEO lol
Ya learn something new every day eh
 

·
get your grinders out!!!
Joined
·
87 Posts
Discussion Starter #5
It is basicly to make the Neo part work.

As they are quite the same as i said as the Japspec CA18DET heads.

Frag me...perhaps ill reconsider removing them...

Anyone can prove the Neo part works btw? By mpg sheets and low-end torque differences?
 

·
get your grinders out!!!
Joined
·
87 Posts
Discussion Starter #6
Other question...perhaps more important then those funky valves i got :D

Will there be any differences in the engine looms? Neo vs non-Neo?
Same goes for DET vs N/A....
 

·
Registered
Joined
·
6,068 Posts
As they are quite the same as i said as the Japspec CA18DET heads.
Nice pictures-

These butterflies don't work quite the same as Jap Spec CA18DET ones...

On the Jap Spec CA18DET there are 8 inlet ports, 2 for each cylinder. There are 4 butterflies on runners 2, 3, 6, & 7.

Below about 3800 rpm these ports are left shut. This increases the speed of the gas flow which makes for a better combustion mixture (better 'swirl')- more homogenous.

That is why the 8 port head makes a lot more torque below 3800 than the 4 port head. This also makes the turbo spool better as well so low speed driveability is much improved....

Runners 1, 4, 5, & 8 remain open at all times- although the butterfly spindle is always present.

The obstruction caused by both the butterflies and the butterfly spindle means that the 4 port head flows better at high revs. So 4 port heads make better power at high revs.

The neo heads operate differently- all ports have single individual runners controlled by single butterflies, and a second butterfly to separate cylinders 1,2,3 from 4,5,6....

Chris
 

·
Registered
Joined
·
6,068 Posts
We did put some thought into removing the CA18DET 8 port butterflies, but blocking the holes left by the long butterfly spindle and making an accurate gas seal made the job unrealistic- too much work for a small gain...

Any small air leaks would have played havoc with the tuning and there were too many small holes in hard to reach locations to block!!

Chris
 

·
get your grinders out!!!
Joined
·
87 Posts
Discussion Starter #9
Was hoping you would respond Chris :)

Thanks for the input on this!!

There are quite a few people with the Japspec ca18det heads that just left them valves in place, but disconnected the vacuum to it.

I guess my best option is just get everything connected as it should :)
Have to look into this when im actually connecting the engine to make it run.

Hmmm....frag...hard to make this decision :)

-edit-
Any ideas on differences in the looms of Neo vs non-Neo and RB20DET engines Chris?
 

·
Registered
Joined
·
6,068 Posts
JJ-san

In fact I wanted to ask about this picture-

Can you describe the two lower holes beneath the actual runner itself? What is the relationship to the runner? Are they connected? Or are they a bypass? What happens on the cylinder head side?

Chris
 

·
get your grinders out!!!
Joined
·
87 Posts
Discussion Starter #12
Ill jump into the shed after my tea mate. And make some pics to clear it up :)
 

·
Administrator
Joined
·
25,962 Posts
JJ-san

In fact I wanted to ask about this picture-

Can you describe the two lower holes beneath the actual runner itself? What is the relationship to the runner? Are they connected? Or are they a bypass? What happens on the cylinder head side?

Chris
if its the holes i think your talking about its the holes you use to bolt the runners to the head and then the manifold to the runners b
 

·
get your grinders out!!!
Joined
·
87 Posts
Discussion Starter #15
They are not actually....









Aligns with the 2nd half of the inlet manifold. The part where the injectors come in.
Hope the pics make it clear :)

Chris, do you have got any rb20de loom around for sale?
 

·
get your grinders out!!!
Joined
·
87 Posts
Discussion Starter #17
Yes. Otherwise the engine would stall i think.

As you can see the butterflies only close the biggest part.



Only closes the red-squared part ( ignore my paint skills :) )
 

·
Wanting more skyline parts
Joined
·
31 Posts
Its a clever variable length intake manifold system

That valve is for the air swirl controlling, basically it will give you better low end torque by remaining shut etc, the other six valve aid fuel to air mixing by reducing or creating turbulence and it flow pattern (swirl pattern) .

There for more efficient power delivery, a/f mixing and reliability.

Variable length intake manifold systems are found on a fair few other engines from most of the common manufactuers.

I dont think there is much if any advantage of getting rid of the system; to better understand search for the R34 workshop manual pdf, It has perfect exploded diagrams of the manifold system for the rb20/25de (&25det).

hope this helps
 
1 - 19 of 19 Posts
Top