Hemco Upper

[ttipe]

WTB

[Steve Wood]

send me your address and I will mail one to you

[earlbrown]

What is it about the Hemco that makes them so noteworthy?  Is it marketing or do they do something better that I don't know about?

I've never put my hands on one but it seem like it's basically an elbow more so than a plenum.

[ttipe]

Steve if you serious about sending me one my address is

WAYNE SHERMAN
27436 POND DR.
NEW HUDSON MICH.
48165

[ttipe]

Earl the power plate creates a significant and unecessary back pressure (2 to 3 psi) across the compressor. The Hemco (properly prepared will distribute air evenly without the back pressure. Several well known names in the community use them and are running 9's with their street cars. Are you still re working GM front covers?? 

[Steve Wood]

if I can find it, I will send it out next week...finding may be harder than shipping smh

[ttipe]

Hey Steve thanks for looking whether you find it or not.

Wayne

[Steve Wood]

No problem...I should have a couple of uppers-one being a hemco...just have to figure out where they are...I need an organizer

[earlbrown]

Earl the power plate creates a significant and unecessary back pressure (2 to 3 psi) across the compressor. The Hemco (properly prepared will distribute air evenly without the back pressure. Several well known names in the community use them and are running 9's with their street cars. Are you still re working GM front covers??

I understand that it's supposed to even out the flow to all cylinders, but from what I understand it really doesn't.  Seems like it's one of those things that look like it will flow "X" ways, but in actuality, doesn't.  From what I recall from seeing a picture of one years ago, it had a square discharge right in the middle of the plenum opening.  A side effect was losing plenum volume, which I am against.

The reason I asked if it was more of a marketing thing is because I'm working with a foundry/CNC shop to start making upper plenums.  My main goal is more plenum volume with the stock architecture with the side effect of not needing the powerplate.


Yeah, I still play with oil pumps from time to time. 

[Steve Wood]

The Power Plate works quite well when comes to evening distribution.  This has been shown by six egt sensors in before and after tests.  It also helps one run closer to the edge tuning wise. 

But, there comes a point somewhere in the high nines where it can become a hindrance because it redistributes air flow by restricting flow to the back cylinders and forcing it to go elsewhere.

I had not thought of Wayne's point about back pressure on the compressor but it is obvious when I think about it.  Typically, we measure boost in the plenum and the major restriction between the turbo and the plenum is the IC so that we may have 28 psi at the turbo outlet and 26 in the plenum...but what really matters is the amount of air going into the cylinders and thus the PP restriction might further limit the flow so that our 26 is higher than what is going down the lower intake...not saying that boost is important but the flow is and the turbo efficiency of a non alky car becomes more critical

Normal cars probably  don't see this as significant but a really strong one easily could.

Earl, plenum height gets dicey fast as the hood gets in the way right at the height of the PTE

[Steve Wood]

oh, yeah, I found the Hemco just as I was about to give up

[earlbrown]

Yeah, I can't go up too much. Not any higher than the vacuum block that is.  Plenty of room to the PS but the DS has to contend with throttle bracket and I don't want to reinvent the wheel there.  Oh, and can't go too far forward because of IAC/MAF pipe clearance...     So I've been getting creative trying to increase volume, keep from having to replace the nearby componets, and increase flow distribution. 
   I wish there was room to move the TB forward. Then it would be easy easy to do some cool stuff.


If you get bored snap a few pics of that hemco before you mail it off.

[Steve Wood]

this used to be on my site  http://www.vortexbuicks-etc.com/plenum_comparison.htm

I guess I decided it was obsolete and it is not linked anymore to the index

Does that help, or do you want more?

[ttipe]

Steve any data/imfo that you have usually has value.

[Steve Wood]

with me, data/info and opinion are often pretty close to one another LOL

I guess these things have become rare.  I am glad I did not throw it away.  Hopefully it will serve you well.  I think it is probably the 58 mm version but I am sure you can enlarge it when you polish it up inside