The V8 Owners Forum -

I got the 4.6 with all the goodies,300 dur cam, and the 45mm trumpets, ported base etc

But I just hate the plenum/trumpets/uneven runner idea its big, messy and no doubt not as good as it could be,

Looking at the MEZ intake archive you can see there's alot better out there,

My gut feeling is the wildcat single plane with 4 barrel throttle body would be the best for max power in my application and would probably gain me 20 odd bhp

Any one want to throw there 2 pence in?

He's a few of my favourites



As above with injector bungs machined out

Alexchim wrote: But I just hate the plenum/trumpets/uneven runner idea its big, messy and no doubt not as good as it could be,

Not sure I follow. The idea of the uneven trumpets is that they even out the inlet tract length between valve and trumpet mouth. So the AFM gets a uniform airflow through it. Surely that's the optimum!

The exhausts on the other hand are a nightmare for tuning, so is that not where some easier gains might be?

Chris.

How about a weber Ida or idf manifold with some throttle bodies on the top. Allthe same length

But I hope your cheque book os big!

Ian

I am a bit biassed, but this seems to work for me.

Hi Eliot,
Looks good,
Has it been tested yet?
Do the blue hoses tend to collapse under high vacuum?

Regards Denis

How well designed is the quad SU 'boxer' setup? Would that work well converted to throttle bodies and port injection?

dnb wrote:I am a bit biassed, but this seems to work for me.

DNB I have pics of this saved on my home computer impressive stuff Clive F input? that looks like a Scooby-Doo expansion bottle too

Hi
The boxer set up has it's faults, namely carb 4 feeds two cylinders firing 90 degrees apart this tends to have the second firing cylinder robbing charge from the first. Secondly it effectivly creates 1 pulse at the carb 40% stronger than the others then nothing for about 450 degrees of crank duration, this makes this carb/ inlet trace behave very differently to the others. On carbs you can set up 3 the same, but you need a totally different set up for carb number 4. On throttle body injection you would need to to probably be able to inject during this event and time the injection purly to coinside with the single pulse, that is if you wanted to get a precise set up.
Port injecting would be better but again I suspect you would need different size injectors on the two ports to get over the charge robbing. . .
Best regards
Mike

SimpleSimon wrote:DNB I have pics of this saved on my home computer impressive stuff Clive F input? that looks like a Scooby-Doo expansion bottle too

My (insane) design, but made by Clive. It's the version 2 of the pictures Eliot posted.

It is indeed an Impreza expansion bottle. Why re-invent the wheel when Subaru are pretty good at it?

DEVONMAN wrote:Hi Eliot,
Looks good,
Has it been tested yet?
Do the blue hoses tend to collapse under high vacuum?

Regards Denis

That's DNB's mk1 - i think they did collapse, hence i the mk2 with hard pipes.

Oddly enough, it wasn't the blue hoses that collapsed - we made the plenum chambers themselves out of thin aluminium and didn't put enough compound curve in the top and bottom.

The blue hoses have a double helix of wire to stiffen them. The problem with them was the absolute pain of a job assembling the whole thing on the car. The mk 2 can be removed and refitted as a single piece, and doesn't need to be removed to change the spark plugs.

Just to add to this - all manifolds are a compromise and "Best" is also a bit vague.... However in terms of maximum power then I would think that the one on the Tim Garlick RV8 must be considered as it got the car into the mid 8's and on the Big Rover (Wildcat based??) into the 7's using what looks like a tunnel ram with Split Holleys.

has anyone seen this 4 barrel manifold before

https://youtu.be/Zrjw1L9W73Y