Porting & Polishing Gen III Blower

Quote :

the decreased boost is proof of increased efficiency. You make more power with less boost.

Really? What if all the coating peeled off the lobes of my supercharger rotors? Boost would decrease. Is that proof of increased efficiency? What if my air filter were clogged with dirt? Boost would decrease. Is that proof of increased efficiency?

I understand how you can have more HP when you open up the engine (increase flow), which lowers boost. The part that concerns me is where the MAP sensor measures vac/boost. To my knowledge, the MAP sensor measures vacuum inside the manifold, the area between the blower and the LIM. So in theory, dropping pressure after the manifold is good, while dropping it before the manifold is not so good.

So, when you do a breathing mod, like exhaust, cam, or ported heads, all of these things work to increase air flow, evacuating pressure after the manifold. This makes sense because you are moving more air overall, but with less boost. The boost was there, but flow mods after the manifold allow it to escape. You can add more fuel because mass air flow is increased.

But if you decrease boost before the MAP is measured inside the manifold, how is this more efficient? How is that moving more air? How does that result in more power? Imo, lowering boost before the manifold is another way to define "restriction".

Does anyone else agree that a blower that makes more boost is not less efficient than one that makes less? Also, how can a blower that makes less boost flow more air?!!

I'm with AA on this one. If changes are made to the supercharger and nothing else, and boost goes down, you have lost efficiency. Maybe gained a bit cooler running, but efficiency is down period. Since these are positive displacement superchargers, boost is built up in the LIM ONLY. So it you made a change upstream(the SC itself) so the SC could flow more air, and boost goes down, you have lost efficiency. The idea of a good P&P is to improve how the air flows through the SC so there is less heat, but without sacrificing efficiency; otherwise you have wasted your time and might as well just put a bigger pulley on the SC as it would accomplish the same thing: less boost, less heat.

I could have two blowers: perfectly the same. making say 13psi.
lets say on one engine one gives the 13 psi, but on the other it gives 10psi. This is because the second engine flows better from the LIM on, and hence makes better power. A decreased boost number is only proof of increased efficiency of the ENGINE and how it flows from the LIM on(because these are positive displacement SCs)

I agree with AA on this. The goal is to make less heat, increase potential flow of the unit, and increase the target efficiency range of the blower. At WOT with the motor in its power band, there should be equal or more boost. If its equal, we assume its pushing a cooler charge in and using a little less torque to do so resulting in more power for at least two different reasons.

As I see it, if done right, there is no drawback to porting blowers like this. Most of what is done is correcting factory limitations. The second part is, in a sense, re engineering the unit to work to a higher power demand.

The only way I can think of that you might see less boost and I can't imagine it would even be enough of a difference to see is by opening up the intake manifold and blower housing for an I/C without putting the I/C in, effectively increasing the volume of the intake manifold. Theory: The same amount of matter (boost or not) occupying more available space means less pressure.

I basically did that but since the cam happened at the same time, there is no way to make a judgment on its effect on boost.

My head is going to explode!!!
Can anyone just recommend who does the best porting job?
which company should get our business? ZZP? WBS?

Erik, that would be nice to know, but I want to understand the science behind this so I can do it myself - the right way.

WBS VS3


I got it when wbodystore was running a discount

Aside from the unfilled silencing vents, the porting work seems very similar to Kemps'. For the $199 I paid for it on special, I wouldn't even have tried doing it myself.

Thanks Jason. That helps a lot!

AA wrote:

Thanks Jason. That helps a lot!

Kemp does use a CNC machine to bore out the outlet of the blower to get rid of that wall

but he wont tell me what his mystery filler is

Quiksteel....


Pics of my work in progress.





And the inlet from the old SC I ported on the riv.

AA wrote:

Quote :

the decreased boost is proof of increased efficiency. You make more power with less boost.

Really? What if all the coating peeled off the lobes of my supercharger rotors? Boost would decrease. Is that proof of increased efficiency? What if my air filter were clogged with dirt? Boost would decrease. Is that proof of increased efficiency?

I understand how you can have more HP when you open up the engine (increase flow), which lowers boost. The part that concerns me is where the MAP sensor measures vac/boost. To my knowledge, the MAP sensor measures vacuum inside the manifold, the area between the blower and the LIM. So in theory, dropping pressure after the manifold is good, while dropping it before the manifold is not so good.

So, when you do a breathing mod, like exhaust, cam, or ported heads, all of these things work to increase air flow, evacuating pressure after the manifold. This makes sense because you are moving more air overall, but with less boost. The boost was there, but flow mods after the manifold allow it to escape. You can add more fuel because mass air flow is increased.

But if you decrease boost before the MAP is measured inside the manifold, how is this more efficient? How is that moving more air? How does that result in more power? Imo, lowering boost before the manifold is another way to define "restriction".

Does anyone else agree that a blower that makes more boost is not less efficient than one that makes less? Also, how can a blower that makes less boost flow more air?!!

I think you're reading too much into my statement. Or perhaps my statement was too vague. Yes, decreased boost can mean alot of things. I wasn't saying that decreased boost ONLY means increased efficiency. Its just a sign of it. Its also a sign of many other things. Perhaps I should have said decreased boost with increased HP is a sign of efficiency.

Also, when I did my porting, I already have the engine opened up after the MAP.Headers, rockers, etc were already installed.

Also, a "blower that makes less boost but flows more air" is possible, because of the removal of restrictions. Which is what porting is really all about. The smoothing of the porting process reduces turbulence allowing air to flow more easily. Perhaps the reduction of turbulence is what causes the reduced boost. It surely causes reduced knocked. And were not talking about losing half your boost in a porting job. Maybe 2psi.

I still disagree that the ported supercharger's drop in boost means that the engine is processing more air better. Yes you can end up with more power because of less turbulence and less heat buildup and it might seem that the drop in boost is a symptom of better flow.

BUT, I don't believe that the engine is flowing any more air better that would make a difference to drop the boost by a couple of psi for this sole reason: The boost is built up IN THE LIM. Any changes to air flow from the LIM forward CAN drop boost because of better air flow efficiency.

however, if a change is made to the SC ITSELF, IE BEFORE where boost is made, and the boost drops, then you have lost some of the efficiency of how much air the supercharger can move. In a few cases this is good and can be seen as a HP increase from the smoothing of the air-stream and the resulting lower heat. But what is happening is still a trade-off of a bit of boost for lower temps.

Another example would be to take two SC's. One stock, and one ported. Lets say you made a testing manifold where you could bolt each up and measure its PSI and air charge temp with no engine in the equation at all. I will bet any money that the stock one will build a higher PSI, but also higher heat. The ported one will blow a cooler charge with the sacrifice of a few PSI. The ported one will make more horsepower because of a cooler charge and less turbulence, but has lost a bit of "air movement" efficiency.

My point is that this drop in PSI should not be confused with the drop that can be seen when changes are made in areas of the LIM on through to the exhaust manifolds. From the LIM on, changes are made so the engine can process more air and use it faster, hence the resulting HP and slight drop in boost.

From an article Karma posted in another thread,

" In essence, adiabatic losses within the supercharger appear as raised delivery air temperature, thus causing a higher boost pressure, without increasing charge density, and also predisposing the engine to the evils of detonation."

So , in theory lower temps of the ported blower just create a denser charge , so because there is less boost , it doesn't mean there is less air , or power.

TonySmooth89 wrote:

From an article Karma posted in another thread,

" In essence, adiabatic losses within the supercharger appear as raised delivery air temperature, thus causing a higher boost pressure, without increasing charge density, and also predisposing the engine to the evils of detonation."

So , in theory lower temps of the ported blower just create a denser charge , so because there is less boost , it doesn't mean there is less air , or power.

exactly, what I was trying to say in this thread, as far as what is really changing with a supercharger port job. Although all aside, the end result is still more HP.

I think the quote Anthony posted actually seems to defend dreww's point. I still don't understand the "how" & "why" behind it, but it might explain how a port & polish could lower boost and still move the same (or more) amount of air.

you should fill in those silencer ports, then it will be louder

Other than making the blower whine louder, is there a clear advantage to filling the silencer ports?

according to Eaton you will see a slight increase in efficiency by plugging them. They were put there to lower noise to a level that GM could sell with the cars.

If you compare the Gen 5 to the Gen 3, You will notice the Gen 5 silencer ports are much smaller. FYI.

So QuickSteel is the best adhesive for this use? Anyone else agree, or have other suggestions? I've had mediocre luck with JB Weld in the past

There is lots of speculation in the best way to plug them properly. :
from what i posted on the previous page that has a section devoted to the silencer ports:
http://www.eatoninside.com/showthread.php?t=156

If theres an intercooler under, Quicksteel, magnumsteel, cold-weld, jb-weld all are not really a problem cause if they blow loose it will just collect onto the IC core and not enter the engine. According to the Colbalt SS crowd anyway.

That being said, there are those who use various methods(JB, TIG welding) with no trouble at all.

Personally if I were to do it with an M90, I'd make a plate that will raise the SC up slightly(like 1/8" or below) and a machine contoured top that nestles up inside the M90 outlet that will block off the ports. Then use QuickSteel behind it as the sealer. The only thing stopping me doing something similer with the M62 is not being able to raise it up without "changing" other things. However that solution is time consuming to make.

Thanks. Lots of good info there. What is this "dual-pass endplate" they suggest for heat reduction?

AA wrote:

What is this "dual-pass endplate" they suggest for heat reduction?

Looks like its an endplate for the end of the LIM, that fires the coolant through another rad(or the main one) and then back into the LIM/intercooler. So for instance, an adaption on the series one LIM, this guy:
https://2img.net/h/i21.photobucket.com/albums/b251/bcphotos/DSC03862.jpg

could be replaced with one that re-directs it through another core(or the main core to re-cool) and then back into the LIM. (keeping in mind that this would only further cool your coolant and not really help you much more than adding a cooler thermostat)

From the cobalt SS world:
http://www.cobaltss.net/forums/showthread.php?p=2193740

really for them its basically a IC, but in stock form their "built in" intercooler is quite heatsoaked from the engine, the "duel pass end plate" for them is a way of getting the coolant back as cool as possible for the boost charge...

I don't think this really applies for us as our IC's are mostly custom anyway, so we can already set it up to have the coolent for the IC as cold as possible...

Karma wrote:

looks like old fashoned JB, or maybe perma-steel, or magnum steel, or cold-weld or all that good stuff... as long as the sides of the ports are scuffed up to be nice and rough it should hold no problems.

-still best porting of m90 IMO that i've seen ever...

Why thank you.

AA wrote:

So QuickSteel is the best adhesive for this use? Anyone else agree, or have other suggestions? I've had mediocre luck with JB Weld in the past

QuickSteel would be the best thing to use. It's just how you prep the metal/surface/structure before applying it that counts .

And to the original poster, If you don't have access to a manual mill (x/y) or some sort of cnc mill, you're gonna be hard pressed to get your desired results.

Everyone here is bickering over outlet ports and such, but your real significant gains are coming from opening up the inlet side of the blower. Remove the intake restriction, and you're making the blower work less to pull that air in. Simple as that.

If anyone has any Questions feel free to post them up!

-Chris

i have a question, is it true that ur gonna be putting my cam,in to Travis's car