If someone could measure the width, height and length of the Drag pak intake plenum...external measurements would be fine - I'd greatly appreciate it.

I want to compare plenum volume with my "modified" Modman.

Thx in appreciation

Bumpity..

It would really help me as I need to compare plenum volumes btwn my modified intake and what we know works for a carb inducted Gen 3

Maybe now people know the reason for my asking.....

Its just 3 lil measurements.

Sixpackgut? Steff??? Maybe someone can step up? :

Wouldn't runner length be important too?

Thanks Steff...cheers mate!

72 Swinger - You are correct - but the issue is more complex than just the intake.....

What I want to do first is make sure the plenum volume is not crazy....

Ive already put a temp gun on the exhaust headers and the fuel distribution has improved big time with the divider.

Once I get the Carb to Plenum ratio sorted - I can worry about the bear in the room...which is camshaft related and not an easy fix with factory slugs..

Needless to say....Im not running a cam that's 8 degrees retarded out of choice....but that's where we're at with most "off the shelf" cams and factory slugs.

Thx for your interest.

Paging Steff - Did u have a chance to take a measurement?

I would like to know what your coming up with. And what % of PV to CI you think you need.

A multi carbed mod man does well with the theory of equal plenum volume in relationship to the cubic inches of the motor.

Im at 414 cubic inches and 390 cubic inches of plenum volume using the std. way many measure, which is like 96% shooting for 100%.

I know many are going to say wtf, but its a reality. Using a multi carb setup. And if done right can be as responsive as fuel injection.

With a .660 lift solid cam with with aggressive lobes that would run with a roller with near the same specs 1.9HP per cubic inch was the end result.

But this being the mopar world few will think out of the box, the best thing anyone could do is toss every single "How to build a xxx mopar" book in the crapper and look at other areas and brands of motorsports.

The mod man is a awesome manifold but very few really understand it.

But from ootb to a good end result is a long haul time wise.

I have more or less made mine into a one piece unit.

The detractors who do not understand or have even seen one will say the bottom flat floor will puddle fuel and not flow hitting a flat bottom.

Well they need to look at a oem dual plane as its dead end flat where the mod man is 1/4 inch higher on the plenum and gently slopes to the runners.

Also many complain the runners are two short, refer back to a oem manifold and 4 of the 8 are shorter in length and the others are equal.

I wish you the best of luck, there are many other ways to increase PV on the mod man if needed and you don't have to go up.

The best thing about a LA unit as I built is its within 1/4 inch of the height of a oem dual plane.

Its a proven setup, just freshened for another project.

The mod man concept is not new, a large plenum short runner unit was used and raced by fords long long ago.

Mal,
What sort of divider did you use ? I used a a trianguler insert running the length as a semi divider. Took out about 15-20% of the volume. Have not tried since doing motor mods a year ago

Tex

Porter67 - Im sorry but I cant agree - any intake that shows:

- a 4mph improvement going from a single to dual carbs, and

- a 2mph improvement just thru the addition of a 1/2" wide block of aluminium,

,,,,,,,,isnt a 'great intake' - especially when you consider this comparison was also verified on the Dyno. The only other change being an extea 2 degrees INITIAL timing.....

I appreciate your thoughts on plenum volume but Id like to do the comparison anyhow,

FWIW I saw no evidence of fuel "pooling" when I had the top plate off,

TEX - As stated - a full height 1/2" wide full length block of aluminium

At the time I did the testing the divider was shadowing the venturi holes in the top plate - so less than ideal.

Since then Ive profiled the top edge to allow a straight shot from the carbs into the plenum with no interference

Steff - No rush man.....whenever you can get to it...

Here you go.

Thx Steff....thats better than I expected - Ill do the math and post the results...

Mal,
I remember Indy saying i would need more rpm,maybe towards 6700. Seems most agree short runner equals higher rpm,plus volume too big equals low rpm performance loss. Thats why mine is off,be fine on 500ci
I filled my intake with water,just over 5 litres

Tex

Cheers Tex...Did that 5 litres include the runners?

As far as the intake - I can tell you my G3 is still making power at 7000 - but part of that is about the retarded off the shelf cams they sell for these G3s....

It makes me wonder if the sluggishness off the mark is all intake related....or the 114 ICL has kicked me in the nuts while I was worrying about the right jab from the intake signal.....

Mal,
that included runners - I bolted a plate across each intake face .
On the street the intake seemed fine - at the track a different story . Killed the 60' but ran same mph. On the dyno made similar power to the M1 single plane I was running at the time . Could not get it to richen up enough . I have since put better flowing heads that woke up the motor but have not retried the modman .Maybe next season

Tex

Single or dual carbs? - my 60 improved with duals...but the divider was the real improvement .

Still not great at 1.83... But part of that is cam related also...

dual quad setup. even added 4 hole spacers helped a bit but added volume back in
may simply be too much volume for my cubes and rpm range

Tex

I reckon you're right...thats why I want to do a plenum volume comparison.....but remember...its also those huge head ports as well!

You put a new hemi in your charger? Care to trade it to me now?