i'm thinkin of riggin up some kind of external wastegate and i think i figured out the cdr i found some fittings and stuff so i think i'm out of questions guys i really do appreciate it

 

What you need if the turbo is not waste gated is a blow off valve.

That is what the import tuners are running on the gas motors, and many diesels also go that route.
I was looking at an Isuzu delivery truck a while back, they used blow off valves on their engine instead of wastegated turbo's.

 

A blow off valve like what the ricers run will not work for this application. I have one on my turbocharged gas engine and the only time they open is when there is a difference in pressure between the intake and the turbocharger, this difference is a result of the throttle body closing when you let off the accelerator, and these diesels do not have a throttle body of course.

Some type of pop off valve would bleed excess boost but it would also allow over speed of the turbo chargerSo it is not a good idea.

If you want to use a turbocharger that is not internally wastegated but will make too much boost for your application, then you need to run an external wastegate. All you have to do is put it somewhere in the piping before the exhaust enters the turbocharger and then run a boost reference line to it from you manifold , just as you would for a boost gauge. One you get it plumbed in you put the appropriate spring in for your desired boost setting and voila. The external wastegates are preffered over the internal wastegates (such as those in the stock garretti used for the 7.3l IDI) in high performance applications anyway and they also allow you to use a boost controller if you so choose.

By the way the purpose of a blow off valve is not to limit boost, it is to prevent the turbo stall or fart that occurs when the turbo is forced to come to a very fast stop or slow down due to you letting off this throttle and boost backing up in the piping. The is also handy because it lets the turbo keep spinning, allowing a faster spool up after shifts.

 

where can i get a wastegate that i know will work with that turbo and be compatible for my engine though because when you start piecing an engine together with different parts the parts people tend to not like your recomendations

 

With the kit you are using about the only decent place to mount an external Wastegate is in the Crossover pipe that runs from the Passenger side manifold to your drive side manifold. You could also build a plate to go between your manifold and turbo to plumb a wastegate into but I think the previous set up would be much easier and work just as well.

For a wastegate I would find something at least 38mm or bigger because you are going to be shooting for a fairly low boost number (>15 psi). I would look at something like this:

eBay Motors: UNIVERSAL jdm'S 38MM 16psi TURBO MANIFOLD WASTEGATE (item 350123913847 end time Nov-17-08 18:07:03 PST)


Or any other 38mm or bigger extrenal wastegates ,If you use too small of a wastegate it will not be effective at maintaing your level of boost for this engine.If you were trying to make really high boost numbers and didn't want to bleed off much exhaust pressure then you could use a smaller gate. look carefully on ebay and find a decent one, you don't want a junk one but you don't want to pay a butt load for one either, some of them can get really expensive. I would suggest getting a spring for whatever wastegate you decide to go with a couple pounds below your target boost level, for example if you are going for 15 you may have to get a 12 or 13 psi spring if you can find one.

I would also strongly suggest that you securely attach the boost line to the turbo with a clamp, back when I first turbocharged my old truck 5.8l gas, the boost line gradually slipped off the wastegate due to a poor clamp and then next thing I know I cram into it and it pegs a 30psi boost gauge and IT detonated very badly destroying my engine. In a diesel you would probably just blow the head gaskets, but still, you really don't want to do that either.

 

does anyone have a diagram of how a wastegate would work or how to plumb it up sorry for bein retarted but as i have said turbos and are foreign to me. would something like this work even better?

http://cgi.ebay.com/ebaymotors/Parts...ayphotohosting

 

I am pretty sure the auction that you linked to is only for the dump tube ( the pipe that goes from the wastegate to the atmosphere or back to your exhaust) and not the wastegate itself.

A wastegate is really simple to Plumb. For instance you would cut a hole with a bit or hole saw in your cross over pipe (pipe from passenger side manifold to drive side manifold) somewhere convenient. Then weld a short piece of pipe with the flange attached (the flange is normally supplied with wastegate), onto the crossover pipe at this hole. You will then bolt the large inlet of the wastegate to this flange. Then you will run a boost reference line from the intake manifold (just like you would for a boost gauge) down the the small 5/16" or 1/4" barb on top of the wastegate. After this you can either make up a piece of pipe and plumb the large outlet of the Wastegate back into your exhaust post-turbo, or dump it off somewhere else, Most "ricers" just dump this under the engine or somewhere else under the vehicle but I wouldn't recomemnd that for a diesel due to the smoke.

I can draw up a diagram but it is really pretty simple.

 

That looks like a blow off valve to me.

A wastegate is built into the turbo and allows exhaust gasses to bypass the turbine.

I don't have a picture of the business side of a wastegate.
You can see the wastegate arm sticking out of the turbo outlet on the right in this one though.



The wastegate needs a passage in the turbo that can allow the gasses to bypass the turbo when boost reaches a predetermined level.
So you would have to modify the turbo housing to add one.

 

Those type are called internal wastegates, the kind you need if you do not have one of those is an external wastegate. An External Wastegate serves the same function but is not located in the turbo.

A blow off valve has to do with intake pressure, it's sole purpose is to prevent the hard backup of pressure that occurs from a throttle valve shutting and stopping the flow into the engine, another benefit is that turbo also spools faster after the shift (manual trans) because it wasn't forced to slow down so much.

There are also Bypass valves used in an intake to prevent the same thing, except a bypass valve doesn't dump the excess air into the atmosphere, it dumps it back into the intake tractor pre turbo but post MAF sensor, this is normally a stock OEM configuration designed to keep metered air in flow to the engine because it is already figured into the fueling algorythm by the Mass Air Flow Meter.

I have also heard wastegates called bypass valves because they allow Exhaust to by-pass the vanes of the turbine of the turbocharger, but I have never heard an external wastegate called a blow-off valve. You understand the function just fine, it is just a mix up of terminology. To my knowledge a normally Blow-valve has no application in diesel due to no-throttle valve ( I know that the early 6.0l had a throttle valve, but its purpose was vaccum for EGR and would not work for this application).

You could probacly make a blow off valve work on a diesel but you would either have to make it electronically actuated ie. by a micro swith on the throttle, or mecahnically, similar to an old auto kick down cable/lever, but really I woulnd't see the point in either, it would just complicate a fairly simple system.

but in summary:

Wastegate (Internal or External)= Exhaust
Blow-Off valve= Intake (AFAIK only gasoline applications)


Pics
This is a Blow-Off Valve

OR



Where this is an external Wastegate:

 

I just went back and looked at the picture again and see the pressure line connection to the actuator.

Don't know why all I saw last night was shiny polished blow off valve.

Isuzu uses blow off valves on their medium diesel truck engines, spring only control and mounted on the intake manifold.
They look a lot like that picture you posted a link to, but far from polished by the time I see them.
When the intake pressure reaches a set level, the valve vents excess boost to the outside air.

 

I really want to see this setup now, I wonder if they are still controlling the exhaust flow with a wastegate. If you were to control boost pressure soley by venting the excess boost and not by also by-passing excess exhaust, it would make it very easy to overspeed a turbo.

It would be like running a turbocharger without the compressor side hooked up, it would let the turbo run crazy with RPMs and possibly tear it apart.

 

Ok so the what would the dump tube do if i plumbed it into the downpipe i know it wont do anything performance wise but what would it change my exhaust sound to and is there some kind of formula to calculate the wastegate psi from the size of it because i have been looking at multiple wastegates and some say the psi and some just say size in mm

 

also i think it would be easier to hook the wastegate up on the rectangular section right before the turbo in this pic. the only prob that i could se there would be that my pyro would be on the other side of the rectangular section would that hurt anything?

 

I have a stock turbo outlet that I could measure the size of the wastegate on.
From memory it is only about 3/4" in diameter.

Back when it was a stock setup, the wastegate only opened about 1/4" at full stroke.

I will go see if I can find it as soon as I get through all of the posts.

 

If you try to put a wastgete in the manifold it is going to be in a pain in the a$$, you want to avoid welding on the cast iron if at all possible. You have to weld a flange to attach the wastegate to and I really would not recommend welding this to your manifold, the crossover pipe is a much better option.

If you see a MM in reference to a wastegate it is the size of the opening that exhaust can leave through (ex 38mm is the size of the opening in the gate). Springs are all rated in PSI or Bar, normally there is a color code to identify them by, you can find this online.

EXAMPLE:
SPRING RATE GUIDE

38mm/41mm Wastegate
0.25 Bar - 3.63 psi - Small Yellow
0.4 Bar - 5.80 psi - Small Red
0.5 Bar - 7.25 psi - Small Green
0.6 Bar - 8.70 psi - Small Blue
0.7 Bar - 10.15 psi - Large Yellow
0.8 Bar - 11.60 psi - Large Red
0.9 Bar - 13.05 psi - Large Green
1.0 Bar - 14.50 psi - Large Blue

Or for bigger gates:
44mm/46mm Wastegate
0.2 Bar - 2.90 psi - Small Yellow
0.3 Bar - 4.35 psi - Small Red
0.4 Bar - 5.80 psi - Small Green
0.5 Bar - 7.25 psi - Small Blue
0.6 Bar - 8.70 psi - Large Yellow
0.7 Bar - 10.15 psi - Large Red
0.8 Bar - 11.60 psi - Large Green
0.9 Bar - 13.05 psi - Large Blue



The dump tube is just for getting the exhaust away from you wastegate and for your application really I don't see the need to buy one, it would be easier to take a piece a pipe yourself and plumb the outlet from the wastegate back into your exhaust post-turbo, to keep from having smoke under your truck whenever you cram on it.