V6 255 (Phase 2) Plenum Design

[Lankan]

Some questions for the experts:

How do you rate the design of the Phase 2 Intake Manifold and Plenum?

Even if the manifold is ported/polished & matched, are there shortcomings in the design itself that will prevent the engine breathing or performing at its best?

Does anybody know what the actual plenum volume is of a standard Phase 2?

I have read that for a NA engine a value of around 80% of engine capacity is ideal, which would make the plenum volume of a Phase 2 around 2,356/7 cc.

Comments/thoughts?

 

[Jamesv6]

Non expert comment............

My standard plenum capacity was measured prior to fitting the upgraded "thing". They told me the standard plenum was lacking in capacity. Of course keep in mind they were not likely to tell me it was fantastic as standard.

The "thing" created a heck of a lot more capacity (and NOISE). I don't doubt more in equalled more power, it certainly did, my Vee was shockingly faster!

The "thing"

 

[Lankan]

Non expert comment............

My standard plenum capacity was measured prior to fitting the upgraded "thing". They told me the standard plenum was lacking in capacity. Of course keep in mind they were not likely to tell me it was fantastic as standard.

The "thing" created a heck of a lot more capacity (and NOISE). I don't doubt more in equalled more power, it certainly did, my Vee was shockingly faster!

The "thing"

Goodness me, that "thing" does look like a UFO [smilie=icon_eek.gif]

Did you run without the engine covers then? The noise would have been horrendous.

You don't happen to have the results of those measurements do you?

Was that the only mod you did or was that part of a very extensive, and perhaps expensive, list of mods?

Do you know how much of an increase the "thing" made in terms of power (BHP) and torque?

 

[Kett]

The "Thing": soon it will be free and become one of us.

 

[Jamesv6]

Figures indeed.

I had a decatted exhaust and some different cams, think they called them Schrick. The gains I was given on an Excel* document said 297bhp. After a few trips to various rollers, I was getting between 280 and as much as 322 from one place. Taking notice of some of the more technically minded on the forum, I plumped for a fiqure called "It's faster"

* A document specially produced from graphs which were magically lost

 

[Lankan]

James, seems like you embarked on a very expensive journey....

I trust you don't run this set up anymore. Therefore, apart from being intrusively noisy, what made you revert back to the standard set up, if that is what you ended up doing? Was it reliability or simply because it was too noisy?

 

[RUSSO]

I've been asked to make a set of spacers up but never got them fitted so no idea of increased performance etc.
Spike may be along shortly to advise :approve:

 

[Lankan]

I've been asked to make a set of spacers up but never got them fitted so no idea of increased performance etc.
Spike may be along shortly to advise :approve:

I suspect the design of the Phase 1 Plenum will result in less than ideal volume, which is why I suspect you were advised to install spacers, but what I don't know is by how much. Hence the question about the volume.

Can I ask where you got those spacers made, and what their thickness is?

Are you planning on any other mods?

 

[RUSSO]

The spacers are for the Ph2 inlets and cover ( not sure how much different they are from Ph1's )
I made the spacers up in my spare time have access to CAD/CAM software and CNC machine. The spacers were never going to get fitted on my car, I was only asked if I could possibly make a set.
The ones in the photo are 15mm thick and internal sizes ( excluding rads ) are roughly 280mm X 97mm.

 

[Jamesv6]

An interesting topic Dulan. LINK

Forum user "xllifts" in that topic now has my "thing" installed.

 

[Lankan]

The spacers are for the Ph2 inlets and cover ( not sure how much different they are from Ph1's )
I made the spacers up in my spare time have access to CAD/CAM software and CNC machine. The spacers were never going to get fitted on my car, I was only asked if I could possibly make a set.
The ones in the photo are 15mm thick and internal sizes ( excluding rads ) are roughly 280mm X 97mm.

Oops, my mistake. I meant to say "Phase 2 Plenum Design". As I understand it, the Phase 1 & 2 plenums are completely different, and your photograph clearly shows that the spacers were for a Ph2.

 

[Lankan]

An interesting topic Dulan. LINK

Forum user "xllifts" in that topic now has my "thing" installed.

Thanks James. Fascinating read.

Some food for thought there......but I did come to the same conclusion once I had at look at what was possible.

Interesting that "xllifts" has your "thing" installed - according to the forum he has a Phase 1.

 

[Mulgari]

I've been asked to make a set of spacers up but never got them fitted so no idea of increased performance etc.
Spike may be along shortly to advise :approve:

Nice work russo!!

 

[Spike]

I've been asked to make a set of spacers up but never got them fitted so no idea of increased performance etc.
Spike may be along shortly to advise :approve:

Nice work russo!!

i must have dozed off!
spacers still available from myself. 16mm is my std size but a can do attitude gets any size you want.
i have no idea on power figures, i have done that much dyno testing its sent me bozeyed, i am not going down that road, james has the best answer, "its faster", i will agree with that, these seem to improve the midrange and top end a little, the only figures available were from ray and tim who also had a load of dyno work done, i am assured they made about 4-5 bhp extra but dont quote me. they used a 10 mm spacer, mine are 16mm.
imho the car just feels more powerful and considering its a bolt on/off part i am up for that.

 

[Ali]

Interesting stuff!