plenum

Post by **etking** » Thu Jun 19, 2008 9:19 am

i love the "give a fuck o meter" lol

Post by **tassuperkart** » Thu Jun 19, 2008 7:35 pm

See I still stand by my point.
The theory is sound and yes, it works, but too often the whole show is ditched due to added complexity and cost versus the actual power gains achieved.
Once again, the gains are usually over a fairly narrow range and often in the low rev range to offset hotter cams and tuning to keep tractability for shopping trolleys.
Furthermore, the gains are often enhanced more on atmo engines where every ounce counts and low end torque is at a premium!

Yer, I am a cynical old prick damo!! I hate it when your so right!

My VG30det employs both VVT AND variable inlet volume but it merely alters the volume of the inlet plenum.
The plenum is divided into 2 distinct inlet areas fed at each end by a seperate throttle bodies.
There is a large rotary valve thingy in the end of the plenum which when opens, connects each side of the plenum together opposite end to the 2 throttle bodies.

C, have you tried disconnecting the servo and giving it a run to see what losses you get?
Im going to try this on mine before I get the 4" "wheel of death" out and open my plenum chamber right up into a single large plemun.

L8tr
E

Damo · Post by **Damo** » Thu Jun 19, 2008 10:18 pm

Slow down there old man.

The Vg30's hardly have a noticeable VVT! From memory, it's something like 10deg advance on the inlet cam only, and then at low revs only (and also when the auto shifts gear).
Also, I don't think that it is a 'variable volume', more of an lenghtening or shortening of inlet tract.

The NICS RB20 had individual runners for each inlet valve with a set of butterflys blocking one of each pair of runners to individual cylinders. The butterfly would be closed at low rpm to promote high port velocity for better air fuel mixing. This was turfed on later engines which went back to the traditional spliting of runners in the head.

Damo

Post by **The Renegade** » Thu Jun 19, 2008 10:29 pm

Didn't the "E" series Falcoon 6cyl have the same setup?

Post by **Ash** » Thu Jun 19, 2008 10:30 pm

The Renegade wrote:Didn't the "E" series Falcoon 6cyl have the same setup?

i'm 95% sure they did.

ETONE · Post by **ETONE** » Thu Jun 19, 2008 10:32 pm

yes yes they did, i have one

Post by **Ash** » Thu Jun 19, 2008 10:36 pm

ETONE wrote:yes yes they did, i have one

whats wrong with that? they weren't a bad car at all i reckon!

Damo · Post by **Damo** » Thu Jun 19, 2008 10:42 pm

The Aussie 6 did, but why? Like you need to have a low speed and high speed set of runners on a engine that makes power to 4500rpm

They even whacked on a type of VVT to 'stick with the times', they must have overlooked the fact that it only has one cam. Bloody genius!
It's like buying a bloke with one arm a baseball bat.

Even Holden were considdering a VVT system on their pushrod dinosaur, WTF!

Damo

Post by **The Renegade** » Thu Jun 19, 2008 10:45 pm

Ash wrote:
ETONE wrote:yes yes they did, i have one
whats wrong with that? they weren't a bad car at all i reckon!

Slap yo-self bitch!

Post by **Ash** » Thu Jun 19, 2008 11:03 pm

The Renegade wrote:
Ash wrote:
ETONE wrote:yes yes they did, i have one
whats wrong with that? they weren't a bad car at all i reckon!
Slap yo-self bitch!

oh come on, i've had some mates with em and they pulled decent skidz!

ETONE · Post by **ETONE** » Fri Jun 20, 2008 7:07 am

Ash wrote:
The Renegade wrote:
Ash wrote: whats wrong with that? they weren't a bad car at all i reckon!
Slap yo-self bitch!
oh come on, i've had some mates with em and they pulled decent skidz!

lol but mines a wagon

Callumgw · Post by **Callumgw** » Fri Jun 20, 2008 7:25 am

ETONE wrote:
Ash wrote:
The Renegade wrote: Slap yo-self bitch!
oh come on, i've had some mates with em and they pulled decent skidz!
lol but mines a wagon

Hey Campbell, there's nothing wrong with wagons. Ask your Grandpop (or E) Isure they had a cool "shaggin wagin" back in the day.....

C

BQ.05.TD · Post by **BQ.05.TD** » Fri Jun 20, 2008 11:00 am

Damo wrote:
The NICS RB20 had individual runners for each inlet valve with a set of butterflys blocking one of each pair of runners to individual cylinders. The butterfly would be closed at low rpm to promote high port velocity for better air fuel mixing. This was turfed on later engines which went back to the traditional spliting of runners in the head.

Damo

same as ca18det, it works well for stock applications but with mine ill be ripping it out so get better flow and better power, i have a big turbo already so it wont worry me either way.

the thing most people dont get is that the factory 99% of the time get it right the first time and there wont be much improvement if you re make them.
with dans et then the plenum he has on that is there for a reason etc but how many ets are that worked? leave it stock boys unless you know wat your doing or have a bullshit motor

Cherry Boy · Post by **Cherry Boy** » Fri Jun 20, 2008 6:28 pm

Personally, if I was going all out on the engine I would make a custom plenum as every BHP counts... Of course it would be last on the priority list.

Shuaib

Post by **tassuperkart** » Fri Jun 20, 2008 8:00 pm

Damo wrote: The Vg30's hardly have a noticeable VVT! From memory, it's something like 10deg advance on the inlet cam only, and then at low revs only (and also when the auto shifts gear).
Also, I don't think that it is a 'variable volume', more of an lenghtening or shortening of inlet tract.
Damo

It advances the inlet cam only @ around 1800rpm and stays advanced until above 3500 or something higher then retards back.
Its certainly not proportional, just opens a solenoid valve for retard and closes for advance.
However whatever way you consider it, its VVT whether you like it or not!!!

My post above outlines the operation of the plenum. It alters the volume that each bank of three cylinders "sees". So the theory is sound.

L8tr
E