Welcome to Just Commodores, a site specifically designed for all people who share the same passion as yourself.

New Posts Contact us

Just Commodores Forum Community

It takes just a moment to join our fantastic community

Register

25mm top and bottom spacers

daniel199260

Member
Joined
May 12, 2011
Messages
36
Reaction score
0
Points
6
Age
31
Location
Geelong
Members Ride
VT 2000 SII
I know a lot of people run 12mm plenum spacer and 25mm manifold insulator, but have not seen or read of anyone running 25mm top and bottom? Wondering what the go is there. Is it do able or?
 

commodore665

expat Saffa
Joined
Dec 30, 2011
Messages
2,845
Reaction score
2,265
Points
113
Age
54
Location
New Zealand via Cape Town
Members Ride
2005 SV6 & Alfa Romeo 156 V6
that combination would work best only in forced induction , IE supercharged or turbocharged , you'd lose to much bottom end torque otherwise .
 

MACE

Well-Known Member
Joined
Mar 30, 2008
Messages
3,185
Reaction score
93
Points
48
Hi daniel199260,

Thank you for your enquiry.

"I know a lot of people run 12mm plenum spacer and 25mm manifold insulator, but have not seen or read of anyone running 25mm top and bottom? Wondering what the go is there. Is it do able or?"
The reason is that for NA (naturally aspirated) applications, ideally you would want to run a 25mm manifold insulator and 12mm plenum spacer. Otherwise, if you're running some form of boost, we would recommend a 25mm plenum spacer and 12mm manifold Insulator as the thicker plenum spacer offers even greater air distribution between cylinders when dealing with greater air flow. On this note, if you attempt to run a 25mm plenum on a NA ecotec, it will impair driveability and performance.

If you have any other questions, please do not hesitate to ask.

Kind Regards,
Michael
 
Joined
Oct 31, 2017
Messages
34
Reaction score
2
Points
8
Age
48
Location
Sydney
Members Ride
2009 WM STATESMAN
I know a lot of people run 12mm plenum spacer and 25mm manifold insulator, but have not seen or read of anyone running 25mm top and bottom? Wondering what the go is there. Is it do able or?

Just not a good cobination, it also implies that you need to add or make other changes to your sytem? Like a larger throttle body or twin throttle body, I did read somehwere that adding a larger throttle body fixes the issue with the 25mm top and bottom, but why I don't know?
I think the standard throttle body opening is not large enough and it is choking the airflow, but that is just a guess. Common sense tell me that if you add a larger throttle body more air will be allowed to flow and thus fixes the issue.
 
Top