Twin Port Rb20 Head?

[heyhey!]

hi guys

while working on a rb20 silver top tonight we took the inlet manifold off to reveal this!

twin port head with a separate flange with butterflies all through

i had no idea rb20 came out with this style different head?

Edited January 23, 2008 by heyhey!

[spilmer]

looks like a toyota motor with tvis

[FATGTS-R]

LOL, what you were working on was not a silvertop then.

The original Rb engine was the REDTOP RB20 that came out in the HR31 skylines. It featured a 12 port cylinder head with the sandwich plate with the butterflies.

It kept 6 ports closed at low throttle openings for improved low down torque and then opened it all up for max power.

Obviously it must not have worked very well as they ditched the idea in the silvertops.

A common mod with a redtop like I have done is to remove all the butterflies altogether as its only a restriction at the top end.

Some redtop owners migrate to the silvertop ecu and injectors. Did it have hosetail type injectors or O ring? Redtops had hosetail injectors identical to VLT.

Redtops also had a more aggressive inlet cam.

Edited January 23, 2008 by FATGTS-R

[FATGTS-R]

double post.

Edited January 23, 2008 by FATGTS-R

[heyhey!]

ive searched around for pics of red top plenums...and the top half plenem looks nothing like those in the pics

yes it has hose tail injectors but im positive the rest of the plenum is the normal silver top eccs plenum...it seems as though the lower half and the head are red top

unless this was one of the very very very early silver tops

PS: how the hell did you attack the butter flies? just take the flaps out or everything?

[blind_elk]

Almost 100% that is a REDTOP head. They used butterflies to create variable length inlet runners. Problem was the butterflies often jammed, causing crap performance.

[FATGTS-R]

There were two versions of the redtop. A NICS and an ECCS version.

The nics has the different style plenum you are refering to but the redtop eccs plenum looks like a silvertop unit. It would not be a silvertop plenum (although they can be used) as you mention it still has the sandwich plate.

I still have the sandwich plate but the flaps and actuating rod are gone.

You def have a redtop eccs as the eccs has the injectors plumbed into the lower runners where the nics had them plumbed directly to the head. You can see in your first pic where the provision for injectors directly to head are plugged up.

red eccs pics: http://forum.r31skylineclub.com/index.php/topic,27815.0.html

Edited January 24, 2008 by FATGTS-R

[heyhey!]

link doesnt work??? need to be a member

ok well it makes sense that its a red top eccs plenum

i dont think a silver top plenum can be used...the injector squirts directly right into the separator of the 2 ports???