OEM D-Series Intake Manifolds

[saxophonias]

B intake manifolds won't fit for sure

[SquirtAndSpark]

B intake manifolds won't fit for sure

of course, but the theoretic concepts it's the same

[Dodo Bizar]

Really good articles, especially this one:
http://www.chrysler300club.com/uniq/all ... theory.htm

I always knew half of this story, only I missed the part that I should take the origin when the valves close as the point were the sound waves start... makes things a lot easier btw. And the plenum reflection was also not that clear to me hehe.

I once did some measurements to both my D16Z6 and Skunk2 runner lengths, but I kinda forgot the numbers which came out. Think it was around 30-35 cm for runner length. Plenum length included I never measured... damn.

Really want to come back to this one... see how my setups turn out theoretically vs practically. Remind me.

[Law_]

it would be very nice if you could measure that Joris.
i'm interested too

[Dodo Bizar]

Can anybody help me find the lift specs on various D-series cams? I know there once was a site that had these for OEM, Crower, Skunk2 and several other cams.

Right now I measured my manifolds. Not very accurate measurements, but they give probably an idea:

D16Z6 and D15B7 manifold, both run about 30 cm from the centre of plenum (measured from aside) to the inlet flange. Both plenums are about 6cm in diameter, maybe just 5.6... but gives a start. So runner length is approximatly 30 minus half the plenum diameter, is around 27 cm, while full reflection length (so the wave reflecting to the aft of the plenum) is 30 plus half plenum makes around 33cm.

Since the Skunk2 manifold is less bend it is also shorter, around 28 cm centre of plenum towards flange. Plenum is 7cm on the inside, I know this since I drilled the TB out to 7cm and it seemd the plenum was just straight 7cm all the way. So this gives runner length 24.5 cm and full refelction length 31.5 cm.

To make some usefull calculation als the distance inlet flange to valves is needed to know. I just poked into a D14 head which is similar to D16's and it seemed the average distance travelled there will be between 8-9 cm.

And don't forget my heatshield, it is around 4mm thick. Doesn't make sense to take all measurement literal, but it might be fun to look at the relative shift a heatshield of 4mm makes with regard to an ~1 mm OEM gasket.

So I can start making some nice calculations with these numbers. But I need lift opening times... so that is were I am stuck now. Anybody?

[SquirtAndSpark]

Can anybody help me find the lift specs on various D-series cams? I know there once was a site that had these for OEM, Crower, Skunk2 and several other cams.

...

http://rapidshare.com/files/269197902/dseries.xls.html
please download this file, have some measurements of various cams (and some more things ).

do you have the specs of a d14a4 cam? i read once that d16a6 cam gives more power to d14, but in another site they told me that the cams are the same... so a need the d14a4 cam specs to compare !

cumps

[Dodo Bizar]

Thnx for the list, unfortunatly it has only the Skunk2 1mm specs, I'd rather have the 0.010 inch specs... now I have 225 deg while I know it is on the 240 deg site what I need to know.

As for the D16A6 cam, forget about it, it is a completely different type of head. Order of lobes, positions of bearings completley different. But I accidently measured a few cams once. It is lobe lift, so multiply with the rocker assembly ratio... I should be able to guess it from the Skunk2 specs.

Hmmm tried the guess but I have two numbers quite off... multiply by 1.5 to get inlet valve lift and multiply by 1.6 to get exhaust valve lift. Maybe it is correct, valvetrain is not neccessary symetrical.

Measurements are lobe# = 0.1 mm camlobe - 0.1 mm lobe base = 0.1 mm lobe lift

D16A6
Camgear – rest] – in1 – ex1 – rest – ex2 – in2 – [repeat from in1 x 4
In1 = 368 – 313 = 55
Ex1 = 368 – 323 = 45
Ex2 = 368 – 323 = 45
In2 = 368 – 312 = 56
Timing in1 and in2 seems equal.
Timing ex1 and ex2 seems equal.

D14A3
Camgear – rest] – ex1 – in1 – in2 – ex2 – rest – [repeat from ex1 x 4
Ex1 = 372 – 331 = 41
In1 = 350 – 302 = 48
In2 = 350 – 302 = 48
Ex2 = 372 – 331 = 41
Timing in1 and in2 seems equal.
Timing ex1 and ex2 seems equal.

Skunk2 D16Z6 Stage 1
Camgear – rest] – ex1 – in1 – in2 – in3 – ex2 – [repeat from ex1 x 4
Ex1 = 391.5 – 328.5 = 63.0
In1 = 371.0 – 318.5 = 52.5
In2 = 395.0 – 318.5 = 76.5
In3 = 373.0 – 318.5 = 54.5
Ex2 = 391.5 – 328.5 = 63.0

[Law_]

some nice calculations going on... sorry not to help.
first i hate maths and second i dont have the parts.
but keep going

[Dodo Bizar]

Got some nice pictures worked out in Excel, will show them soon but have to fiddle around a little bit still.

Anyway it seems 6 total reflections in the runner is what is happening around the 7000 rpm area. Six is good, 5 or 7 is bad since the reflected wave will be negative. The OEM setup is around 7000-8000, so on stock ECU not working. With the stock D16Z6 cam and manifold I saw power being quite flat in the 7000-7500 rpm area.

The 6th reflection in the Skunk2 setup, especially for the manifold. Is lowered to the 6500-7000 rpm area according my (flimsy!) calculations.

It would mean that I might get some more power at lower revs but since the 7 reflection area is kicking in earlier I will loose power faster.

Hmmm.... the above is exaclty what happened with me, the OEM setup was not so strong, topped at 137 bhp around 7500 rpm... but hardly diminished towards 7800, the rev limiter at that time.

Now with the Skunk2 setup I got a lot more torque, 10Nm in the 6000-7000 rpm area and also a few hp more (145 total). But indeed the power is killed all of a sudden after 7500 rpm, it diminishes much faster compared to the OEM setup towards the current limiter of 8100.

Now one thing is contradicting this story... I had once an intermediate setup, OEM cam with Skunk2 manifold. The measurement showed no diff between both setups at all, while the calculations I made show the manifold makes a bigger change than the cams which I swapped later. Though this measurement was on a different dyno, different in location and type.

So there might be some nifty stuff going but it might also not be... it actually might mean that getting the OEM manifold in again might produce MORE power since the refelction band is upped around 500 rpm .

Wow... not funny to change it and I still have the OEM manifold, but got a seller for it right now. Hmmmm... please somebody prove me wrong hehe. This weekend I will dig deeper in my past dyno's and setups to see if it does or does not correlate.

Weird thing in this story is that I assume 240 deg of inlet valve opening on the Skunk2 cam which is actually less than OEM or any other aftermarket cam, which usually are bigger. But the smaller openeing time indicates higher rpm aspiration and Skunk2 says they match manifold and cam... can be true since I got good results still... but worries me, should OEM manifold be even better?

[saxophonias]

wow...
Did you keep the same inlet tube between these different sessions? Calculating is a big issue. Up to now i was convinced that if you are after a 1st stage or even a mild set up then d16z6/y8 manifolds and even e-bay headers do the job. Still if your job is done even with big cams and high revving, then i pitty my 250usd for my edelbrock manifold

However the differences in capacity and plenums i think is visible when you hit the gas pedal suddenly. The pull is extraodinary comparing to my oem manifold. Am i able to say that as i had the filter, the header and exhaust installed with the stock manifold for some time.