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Discussion Starter #1
I wanted to share with everybody who is looking to build a mechanical wastegate controller (aka homemade TurboMaster) that a spring with a spring rate of 50lbs/in seems to work well. I just got my gauges hooked up this weekend and noticed that my homemade controller does not seem to "peak" then drop to a sustained boost as my previous Heath unit did. Rather the boost comes up and holds steady at 11PSI, without dropping back.

I got the spring from McMaster Carr. If I can find the part number, I will post it in Part Point...

Hopefully this helps!
 
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When I was making a wastegate for my 93 with GM-3 I found that a spring that would crack/compress at 16 in/pds would get me 8psi boost. Boost lever and spring in stock location and angle . Not sure why I got different figures than you, maybe differant turbo and not talking apples to apples?
 

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Discussion Starter #3
Tracy;1737011; said:
When I was making a wastegate for my 93 with GM-3 I found that a spring that would crack/compress at 16 in/pds would get me 8psi boost. Boost lever and spring in stock location and angle . Not sure why I got different figures than you, maybe differant turbo and not talking apples to apples?
Tracy -

The spring rate will determine how the wastegate behaves once it cracks open, not the maximum level of boost. When you talk about a spring giving you X lbs of boost before the wastegate cracks, that has more to do with spring pre-load than spring rate. The pre-load is adjustable (hence the ability to adjust boost) by cranking down the wing nut on the threaded rod. I could lower the max boost on my setup as well, by backing the wing nut off, but that would not change how it reacts once the wastegate cracks open.

I have seen many people here asking how much spring or what kind of spring to use on a homemade T/M. This will give them an idea of what kind of spring to purchase. McMaster is a great place to find springs with specs so you can get one similar to mine AND some with a slightly and or slightly lower rate if you choose...

Regards,
 

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How is the spring rate you are talking about arrived at. It is not similar to how valve springs are tested. I was not able to get this type of spring rate info when I was looking for springs at the auto parts store, maybe a more specialized shop could get those figures?

I was able to test the cracking/opening pressure of the wastegate with the spring at its operateing hieght for the GM-3 by using a simple fish scale. Through trial and error I found that a larger dia. spring with more coils per inche gives gives a much more consistant wastegate operation, no spikes or droping of boost after wastegate opens. The wastegate spring I have now is consistant to within 1 psi no matter how the truck is operated.
 

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Anyone making DIY mechanical wastegates?

I would like to put in a mechanical wastegate, but rather than spending $30 in parts and fuel to go back & forth to the hardware store 6 times, would anyone be willing to make one for me? All I want is consistent boost, 8-10lbs would be fine. I drive it easy except for once in a while to get on the freeway or pass someone, less than 15-20 sec full throttle.
 

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Discussion Starter #6
bkhosken;1756289; said:
I would like to put in a mechanical wastegate, but rather than spending $30 in parts and fuel to go back & forth to the hardware store 6 times, would anyone be willing to make one for me? All I want is consistent boost, 8-10lbs would be fine. I drive it easy except for once in a while to get on the freeway or pass someone, less than 15-20 sec full throttle.
If you want to purchase one, please follow the link to Heath Diesel's Turbo Master page.

Regards,
 

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I don't want to spend $100 for one, but i woudl be willing to go $30-$40 or so.
 

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Discussion Starter #9

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Discussion Starter #11
DMDK;1758902; said:
I've read this discription for a boost controler :
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=320109944012&fromMakeTrack=true&ssPageName=VIP:watchlink:top:us

and turbo/wg operations and I am not seeing the difference. Thanks.
Here is where this thing shows its true colors: "How it works , the vacuum line going to wastegate will go trough the boost controller, by simply turning the knob you let vacuum escape"

In a 6.5TD with a vacuum controlled W/G system, the vacuum holds the W/G shut. If you are bleeding off vacuum, then you are bleeding off the ability to hold the W/G shut! That is why so many people come on here and post about "lots of black smoke and no boost"; their vacuum pump, W/G solenoid, or vacuum lines have failed thus not producing any vacuum at the wastegate pod.

I have purchased (2) 6.5TD trucks with vacuum W/G control systems. BOTH had failed the vacuum pumps and were making no vacuum at the W/G pod (and both smoked like freight trains before the turbomaster)

When it comes to making boost on one of these electronic 6.5TD's it boils down to 1) Fix the vacuum system, 2) Buy a Heath Turbomaster, or 3) Build your own homemade version of the T/M. If you already have a working vacuum system and want more boost, then you need to purchase a MAP fooler (from Kennedy Diesel), make your own MAP fooler, or install a 3bar MAP...

Regards,
 

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Exactly correct - useless as a vacuum regulator, altho that would make a nice in-cab water-drain valve, and you wouldn't have to worry about impacting the environment................

Remember - it's not vacuum that keeps the wastegate closed - it's atmospheric pressure, to the tune of 15psi on the work side of that 2" diaphragm - you gotta reduce Baro on the control side to get the working differential, not increase it.
 

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Discussion Starter #13
gmctd;1759222; said:
...Remember - it's not vacuum that keeps the wastegate closed - it's atmospheric pressure, to the tune of 15psi on the work side of that 2" diaphragm - you gotta reduce Baro on the control side to get the working differential, not increase it.
Okay, here we go again GMCTD. For someone who preaches that they like to keep things simple, you are trying awfully hard to make this complicated.

The first half of your sentence contradicts the second half:

"Remember - it's not vacuum that keeps the wastegate closed - it's atmospheric pressure, to the tune of 15psi on the work side of that 2" diaphragm". This implies that atmospheric pressure alone would keep the W/G closed WITHOUT ANY VACUUM ON THE OTHER SIDE OF THE DIAPHRAGM!!!!

"- you gotta reduce Baro on the control side to get the working differential, not increase it." Well...which is it? Or is it really both? Do you really believe that most people understand "reducing the BARO" better than "applying vacuum"? People don't have to think about barometric pressure acting on the back side of the diaphragm, because that pressure WILL ALWAYS BE THERE!!!! The part that is of concern is applying vacuum (aka "reducing the BARO") on the opposite side of the diaphragm. And who said ANYTHING about "increasing" the barometric pressure on the vacuum side of the W/G pod? That is another confusing point, as it has never been mentioned in this discussion (until you brought it up)...
 

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What is the result of adjusting the knob to "bleed off vacuum"?

For those who want to know why that 2-way valve is likely not as functional as indicated, or may have forgotten that vacuum is measured indication for any reduction in atmospheric pressure, which is also known, vicariously, as Barometric pressure, and which varies around the world according to your vertical positional relationship to sea level, and storm proximity - 15psia is good enuff fer gummint work, essentially.

2"HG = 1psi

0" vacuum = 30" Baro = 15psia

30" vacuum = 0" Baro = 0psia

15" vacuum = 15" Baro = 7.5psia

So - assume the vertical bar is your wastegate actuator diaphragm, left side is attached to the wg actuator rod, right side is the control side connected thru the wg solenoid to the vacuum pump, also known in engineer-speak as "the atmospheric pressure reducer thingy".

Baro 30" > | < 0" Baro (30" vacuum)

15psia > | < 0psia (30" vacuum)

Baro 30" > | < 15" Baro (15" vacuum)

15psia > | < 7.5psia (15" vacuum)

Baro 30" > | < 30" Baro (0" vacuum)

15psia > | < 15psia (0" vacuum)

Now - do the math to determine the area of a 2"dia diaphragm - multiply that area by the applied pressure in psi to get the amount of force on the rod which is holding the wastegate shut - compare that to the force on the control side which can be varied to allow the wastegate to open - the difference in applied pressure is the holding force keeping the wg closed (then ya gotta figger exhaust pressure on the 1.25"dia wg flapper valve area, trying to force it open, but thassa whole 'nuther can of worms, unto itself - just don't ask me to measure it!).

So, as you can see - opening that little valve allows barometric pressure to increase on the control side of the diaphragm, reducing differential pressure across the diaphragm, which is the quantity of force applied to the diaphragm, thence to the wg via the rod.

Remember - be very careful around that stuff - atmospheric pressure can get into anything that is not tightly sealed off - the cylinders in your engine, the crankcase, the compressor inlet on your turbo, the fuel tank - and especially, your lungs.

It's everywhere.......it's everywhere !
 

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Discussion Starter #15
gmctd;1759430; said:
What is the result of adjusting the knob to "bleed off vacuum"?...
The net result is a condition of (undesirably) less boost.

I think that you may have, essentially, over-complicated things a wee-bit...
 

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i dunno what my home made t/m spring rate is but it will hold 5lbs on the freeway and when i put my foot into it will max about 10-12 lbs. i can turn it up but that'd be dumb without an intercooler. i hit 17lbs when i first made it. the spring is pretty difficult to squeeze between the thumb and finger. and it is from home depot.
 

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:D It is to laff, G - even if you won't laff with me, I won't laff at you, I'll just laff without you, eh? ;)

But, yeah - I like re-covering what folks soon fergot after they got outta skool..........
 

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No one seems to mention the computer. My understanding is if you manipulate boost higher, the computer shuts off fuel. So there is a resistor that has to he added to fool computer into thinking boost is not too high. I have a early 94 that is mechanically controlled,but I believe 94 and newer is computer controlled, and just a spring on W/G doesnt improve performance.
 

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94 is supposed to be controlled by the ecm. I have a 94, its controlled via vacuum. Not too much longer and itll be mechanically controlled.

Nice resurrection! :HiHi:

It does improve performance. Over 15psi and it begins to defuel. OEM I believe is 2 or 3 psi.

The use of an f vin vs and an s vin chip or a custom chip makes a huge difference too. Or ditching the DS for a db... no ecm to regulate and control.

The more that's mechanical on these engines, the better off you are (just my opinion)

:thumb:
 
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