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  #1  
Old 12-25-2010, 07:55 PM
charlief1 charlief1 is offline
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Default Better turbo design

Granted that I have posted most of the info on another board but I though I'd add some of the info here just in case.

The stock turbo for the draw through system is inadequate to say the least. It's completely backwards to the way most designs that work well. The stock turbo flows roughly 350 CFM where the updated design flows 675 CFM.

I started looking at the stock turbo and if there were any upgrades out there. There are none that will not increase lag but they will work better at higher RPM's. To decrease the spool time on the turbo you need to completely redesign it. It's not near as hard as some would believe.

What I did is look at the 301 TTA turbo and the 86-87 design. I was lucky enough to get the turbo maps from Garrett so I could compare them. With the large exducer (exhaust side) and small inducer (intake side) the engine just doesn't flow enough to spool the turbo properly. What I ended up with is using the exducer off the 86-87 turbo and the inducer off the 301 TTA.

Here are the maps for comparison so you can get a better idea of what I'm talking about. The are posted using the 83 turbo, 86-87 turbo, and then the TTA turbo.
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  #2  
Old 12-25-2010, 08:12 PM
charlief1 charlief1 is offline
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Default Re: Better turbo design

Here is where you get to see the different sizes of the inducer wheels and housings. The inducer on the CHRA is the 86-87, the one on the floor is the 83, and the one in my hand is the 301 inducer. You can see how much bigger the one on the CHRA and the one in my hand are. this is one of the keys to making this work. the second pic is the wheels off. The dirty one is the 86-87, next is the 301, and finally the 83.

Now on to the the inducer housings. As you can see the 86-87 and the TTA housing are about the same size but the 83 is much smaller.
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Last edited by charlief1; 12-26-2010 at 12:21 AM.
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  #3  
Old 12-25-2010, 08:41 PM
charlief1 charlief1 is offline
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Default Re: Better turbo design

Now onto the exducers. The first pic is of all three exducers from the top. As you can see the one on the left is much lighter than the rest. It's the 86-87 exducer. The other two are the TTA and the 83 exducers. As you can see the 86-87 is the lightest of the three.

Now look at the housings. The smallest one is the 86-87 and the largest is the TTA. The one in between sized is the 83. You can see how much lighter the 86-87 is compared to the other two. This also changes the AR rating on both sides. This by itself is a great upgrade to the stock turbo if you just want a faster spooling turbo. Even using the 84-85 exducer is an upgrade for the stock turbo. The only drawback to this is you will have to make a down pipe and up pipe for the tubo.
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Old 12-25-2010, 09:13 PM
charlief1 charlief1 is offline
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Default Re: Better turbo design

Now onto how you adapt the inducer housing to the plenum. First thing is there's a difference in height and mounting flange to the intake. The height really isn't that big a difference but to make it fit on the plenum mount that goes on the drivers side head. Height difference is .48" measured with Mititoyu digital calipers. You can have a machine shop cut it down or you can do like I did. I took the measurements and locked the calipers so I could mark the housing.

What I used was the calipers set to slightly less than the .48" to account for the thickness of the blade. I set it at .45" and used a knife to leave a fine line on each of the bolt bosses. Then using a hand saw I started cutting on one boss. After I got in some I used that cut and moved to the second mark and used the saw in the first cut so I could make sure all were at the same height. This takes some time and it took me 2 saw blades to do it.

You have to move the saw around from one boss to the next in a circle and keep it between two of the bosses. This will keep the saw straight and give you a good cut. It does take some time and if I had a mill I would've used it instead of doing this myself.
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Old 12-25-2010, 10:06 PM
charlief1 charlief1 is offline
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Default Re: Better turbo design

As you can see this isn't rocket science here. It really is easy if you're careful and take your time. The first pic is of the cuts fully started and the second is after I got the piece off and put the two housings down to measure the heights to verify that I'd gotten it cut right. The third pic is the amount of metal left over. Don't throw this away because you'll need it later to modify the plenum to fit.
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Old 12-25-2010, 10:36 PM
charlief1 charlief1 is offline
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Default Re: Better turbo design

Now on to the mounting flange for the turbo to the intake. A good friend of mine, Jerry Berger SR offered to do the work for me and he did a beautiful job. The first pic is of the differences between the stock turbo foot and the larger inducer foot. This has to be corrected by either moving the holes in the intake or on the turbo's foot. It is much easier to move them on the turbo so that's what I had Jerry do. You can see the steps that must be taken to do the work. It does take a machinist to do this as well as a very good welder.

One other thing I asked Jerry to do is open up the throat of the inducer to match the outlet of the plenum. He did this on a lathe and beveled it so that it would be a smoother transition for the air fuel mixture.
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  #7  
Old 12-25-2010, 10:41 PM
charlief1 charlief1 is offline
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Default Re: Better turbo design

Just to give you a better idea of what sizes the inducer wheel differences are here you go.

oad= overall diameter

301 inducer is 2.7130 oad. 2.0605 for inlet side.
83 T Type inducer is 2.3665 oad. 1.8355 for inlet side.

I don't know what that would do as far a p trim but that's a heck of diff on the intake side. Someone else can calculate what the diffs are.
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Old 12-25-2010, 11:06 PM
charlief1 charlief1 is offline
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Default Re: Better turbo design

Now that the feet are in the right place and the plenum side is opened up I did a little truing of the area that the plenum attaches to. I used a file on the flat side and did what's called draw filing. This uses the flat section of the file but you don't use it in the normal way. You grab the ends and slide it sideways, not back and forth like you normally do. What this does is keep the file on an even plain so that it will take just enough off to true the surface up. You must keep moving the file so that you don't scallop the surface up while doing this. Think about the turbo as the face of a clock. The foot is the big hand and you start with it in the 12 position and the file moves from the 6 to the 12 position, then move the foot to the 3 or 6 position and keep filing. Do this after a few minutes and you will get a level and true surface to mount the plenum to.

Now on to the plenum mods you will need to do. The piece that was cut off is now needed. The second pic is of the differences between the holes on the inducer housing and the stock plenum. Just enough to allow for an issue mounting the plenum. To fix this I elongated the top and bottom holes just enough to center it on the piece I had removed from the inducer housing. Bolted the two together and used a tap to cut away the material needed to fit the plenum to the turbo. Go slowly so you don't screw up the plenum or bind the tap and break it. Once you tap the parts this will give you an area to file out so the bolts will mount up. Do it one at a time and this way you can make sure you keep everything centered
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Last edited by charlief1; 12-26-2010 at 12:24 AM.
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  #9  
Old 12-25-2010, 11:10 PM
charlief1 charlief1 is offline
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Default Re: Better turbo design

A few more pics I forgot to include.
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  #10  
Old 12-25-2010, 11:14 PM
charlief1 charlief1 is offline
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Default Re: Better turbo design

This is a far as I have gotten so far and this is the condensed version. Here's the mocked up pics after my friend Ronnie Martin offered to do the powder coating for me. He did a fantastic job to say the least.
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Last edited by charlief1; 12-26-2010 at 12:26 AM.
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