Velocity Stacks Intake Manifold Photos

[speedybenz]

Here is the last mod to the engine prior to the crash of 2006. The velocity stacks seem to really boost low and mid range power, with noticable gains at the top of the RPM range. These pics were taken before I blended all the rough spots and matched the epoxy to the manifold runners

Jeff

[jnenad16]

jeff, how did you connect the throttle body to it?

nenad

[coolcarlskic43]

Kool!Any b4 pic(stck) to compare this with? I know the E39 M5 has these stacks on the top of the block covered with the Air filter box cover. This should make a tremendous difference on our V8's. Is this a task you would undertake for those interested in doing this mod Jeff? Just asking!I need to do this mod!

M5





Click on pics for bigger view!

[Ashkan's C280]

how much power did this mod add? How long did it take? and what were the costs?

[c55m8o]

Originally posted by jnenad16
jeff, how did you connect the throttle body to it?
nenad

Kewl Jeff. So this is inside the manifold, and the standard filterbox, MAF and MAF housing is still used? Is the two stage aspect of the intake runners gone then, or are they there further inside?

Thanx much for the pix.

[Ashkan's C280]

stupid question, but why do some of the look melted

[c55m8o]

Originally posted by Ashkan's C280
stupid question, but why do some of the look melted

lines up along the inside edge of the other 1/2 of the manifold. ...jeff is what's pictured the top 1/2 actually?

[SLAMMED_C]

Originally posted by speedybenz
[B]Here is the last mod to the engine prior to the crash of 2006. The velocity stacks seem to really boost low and mid range power, with noticable gains at the top of the RPM range. These pics were taken before I blended all the rough spots and matched the epoxy to the manifold runners

Jeff

those velocity stacks are freaking awesome man..

[speedybenz]

Yes the pics are showing the top of the intake manifold. The bottom of the manifold is open except for where the velocity stacks protrude. I have not had the two stage runner length operating for about a year.

I found through trial and error and back to back testing that disabling the two stage runners and removing the bottom, long section of the manifold runners opened up the plenum area greatly and seemed to almost eliminate most of the lost low end torque, when the mod was combined with the ram air system. It also allowed the torque to stay up much higher after the torque peak, which allowed the HP to increase all the way to red-line. It was a big reason I was looking to increase the rpm limit to around 6800 to 7000 rpm.

The velocity stack length was set, based on some calculations made to capture the 3rd or 4th order intake wave. At certain rpm's and intake tract length you can capture a negative wave pulse that is returning back to the open intake valve during the minimal valve overlap and increase the cylinder filling. This can result in a increase of Hp of 5% to 8%.

The big problem was I ordered the wrong diameter velocity stack and had to not only hammer and form it into the rectangular shape of the stock manifold runner and had to cut out around 10mm of the diameter of the stack. Lots of work as it turned out.

Jeff

[c55m8o]

thanx very much for that detail. Both Carl and I have extra manifolds (mine from the 5.4L motor that we didn't use in my swap because it was in the fire). My manifold's just crying for me to open it up and have at it as you describe. I may have to bug you for some exact specs and supplier.

Do you have any recommended reading about the theory you are describing ? (which I assume carries over to an exhaust system too.) It reminds me of transmission line loudspeaker design. That is said to be as much art as science though since it has to do with harmonic tuning of sound which is audible and subjective, making it less of an exact science. Is the intake wave theory more of an exact science?

[coolcarlskic43]

Originally posted by speedybenz
Yes the pics are showing the top of the intake manifold. The bottom of the manifold is open except for where the velocity stacks protrude. I have not had the two stage runner length operating for about a year.

I found through trial and error and back to back testing that disabling the two stage runners and removing the bottom, long section of the manifold runners opened up the plenum area greatly and seemed to almost eliminate most of the lost low end torque,
Jeff

Now this is a mod I'd like to do immediately.I'll concern myself with the velocity stacks later.What do you think Steve?

[c55m8o]

Originally posted by coolcarlskic43
Now this is a mod I'd like to do immediately.I'll concern myself with the velocity stacks later.What do you think Steve?

...why go 1/2 way...?

But Ya, (in no particular order) ram intake + pheloic spacers + thermal insullation + manifold porting then as stated above only more recently the 2-stage removal modification is after all what Jeff ran with for quite a while before adding the velocity stacks.

Still, both of us have those extra manifolds sitting around and no hurry to use them...

[J Irwan]

Jeff,

I am just wondering how thick you phenolic spacer is. ?
How much volume were you able to gain from this spacer.


FYI:
For E39 M5 using the shorter velocity stack with stock ECU and no other mod will result lost of HP and torque at low rpm, and gain some at higher rpm

For the M5, some owner has been experimenting with intake plenum spacer to increase intake plenum volume and also chip re-mapping.

Basically its tricky to tune the velocity stack as loss of hp and torque will result in more "surge" feeling during acceleration , so butt dyno will definitely feel faster..

Bottom line if not tune carefully you will end lup osing more than gaining ...
After all the stock Velocity stack on M5 has very unique shape and length for a reason. And they a lot of research on those.

There has been a lot discussion on the topic at M5 board, but no one seems to have the right formula for getting the optimum gain using these shorter velocity stack yet.


Off course you can always play around with the trumpet length to get the best flow/resistance for the C43 engine.


Regardz,

[speedybenz]

J Irwin,

How right you are. That is why I was pretty happy when the engine ran very smooth and pulled hard from pretty low and all the way through to the top. And was doing so in faster times during measured pulls in thrid gear from 65mph up to 105 mph.

Doesn't the BMW M5 have variable valve or cam timing which would add another factor into the equation that would be very difficult to get right without lots of trial and error and dyno work. Plus every time you change the total intake tract length you will most likely change the fuel demands on the engine. And you can only hope that the ECU can adjust to the changes.

Also the Mercedes Manifold is nowhere as effieceint as the BMW M5 manifold and so I felt is was somewhat easier to make some fundimental changes to the Mercedes effort given I had a very functional ram air system and much more freer flowing headers/exhaust.

[Ashkan's C280]

Bringing this thread in light of seeing the head work being done on the 211 side of m113. Aside from the stacks, would the manifold be improved from port/polish/blue print e.g.Prject Chrome Dome more than just having new redesigned manifolds made? I am not sure the costs side by side of having that level work done to the manifold and the stacks created for it vs. a redesigned custom part, but would the hp difference between the be that great? Or even present for that matter? From what people have posted, it seems the c43/e55 m113 manifolds are not very efficient (compared to the 211, and in general) and could use improvement. Thoughts? Jeff? Anyone???



*While I miss my old girl 97 c280 (oh the good times), I am pleased to say I have upgraded to her younger, hotter, and blacker sister 1999 c43 amg. I am mid finals week and should be studying as we speak but I have some very cool things in store. Jeff thanks for the pm, I am working on a reply for you, and yes my interest level is on par with emailing you my bank account/paypal-number/blank-check... Cheers.

~ Ashkan

[speedybenz]

Ashkan,

The manifold is a great thing. You can get some pretty good results by taking the stock manifold apart and matching the runners up and opening up the size a little. There was some mis-matching between the manifold and the cylinder heads and some pretty badly formed stock turns in the manifold runners. When you clean these up and disconnect the longer runners you will find that the engine in the C43 or 55 motor will run much better on top and lose only the slightest Hp below 3000 rpm.

also by removing all the screens on the MAF you will also see some increase in Hp.

Also with the manifold changes, headers, and ram air I was able to get a traction limited 13.2 sec 1/4 mile and a trap speed of 109.5 mph. So I am pretty sure the combo is working pretty well.

Jeff