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skirkland1980

Changing turbine housings

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I took the stock T3 off my 1983 280ZX turbo a few years ago in favor of a Garrett TC4305 off of a 7.3L Ford diesel. The TC4305 has a .82 turbine housing. Could I open up the stock T3 housing to fit the stage 3 turbine? It wouldn't still be a .63 A/R anymore would it? I'm wanting it to spool at a lower rpm.

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Measure your wheel. You need to know the inducer and exducer sizes, for both the turbine and the compressor, in order to do this correctly.

 

Yes, you can have the housing machined. Yes, it will still be a .63 A/R.

 

What is "stage 3" about the other turbo? Is it a "stage 3" wheel, which not only varies by turbocharger vendor, but also by manufacturer...Many turbo shops sell the T-31 turbine wheel as the "stage 3" wheel, when it actually is just a turbine for a slightly larger turbocharger. As is the "stage 4" T-350 turbine, or the "stage 5" T-4 P-trim wheel, if we're going to go with AiResearch/Garret type numbers.

 

So, we'll get specific here, with the assumption that you have a Garret TC4305. This'll help you and others understand exactly what I'm saying.

 

The compressor assembly of this turbocharger is actually a T-04B H-trim unit, which is a pretty nice compressor for the L28. I'd keep this part intact.

 

The turbine assembly of this turbocharger is actually a T-31, which uses the same inlet and outlet flanges as a T-3, but has a differently shaped turbine wheel for more flow. Less curl to the blades, but same inducer diameter as a T-3 unit and same shaft length and diameter. Exducer diameter is *larger* than the stock T-3, which means that a T-3 housing isn't likely to fit correctly, if at all. You will need the exducer enlarged in the stock housing.

 

Getting back to measuring the wheel, if you are familiar with the math to determine trim of a compressor wheel, then you can figure the trim of the exhaust turbine as well. The T-31 "stage 3" wheel could be a 76 trim turbine, which is fitted in a variety of turbine housings from .48 to .82 A/R. It could also be a 69 trim wheel, which is more likely to fit into the stock housing.

 

Before you go and have the stock housing machined to fit the T31 turbine, get a compressor map for the T-04B H-trim compressor and plot your airflow map. Make sure that you're going to get the most out of the compressor...which you can, if you run a max of 16lbs of boost, and you can bring it in at around 2900-3100RPM. Bring the boost in faster and you may run into compressor surge, it's been a while since I ran the numbers for this compressor on the L-28. This compressor series is actually much better for sub-2.0 pressure ratios than it is higher than 2.0. If you want more than 16lbs of boost, you need to go with a T-04E compressor. They will yield higher efficiency in that boost range, lower compressor outlet temperatures, and a much more drivable turbocharged engine.

 

In short:

 

Yes, you can do what you are considering. I would plot the compressor map FIRST, THEN I would think about running the smaller turbine housing. THEN I would look at my power band and see if it would be more beneficial to run the smaller turbine housing (which will bring the spool time down around 2300-2500RPM) and pulling from 2300 to 5500 RPM would work better for my application than spooling at 3000RPM and pulling to 7000RPM, by using a different camshaft profile, with modestly more lift and duration, but cut on a 110-112 lobe seperation angle...Personally, I know what route I'd go with...

Edited by Xnke

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I run the T04B-H trim with a T3 exhaust turbine (stage 3).  Boost comes on slow and steady, almost feels like a big non-turbo engine.  Would work really well for an autocross car, due to the slower increase of engine torque.

 

Makes 5 psi of boost at 3000 rpm and full boost by 3500 (running about 12 psi).

 

The free flowing turbine allows 80 mph driving with 10 inhg vacuum.  The stock turbine was at 0 inhg  at this speed (starting to make boost).

 

According to the compressor maps, my engine should be in compressor surge at 3000 rpms, but it isn't in real life.  I miss the low rpm boost of the stock turbo but i'm not going to try low boost with this compressor due to the surge risk.  This compressor is better when used with a stage 1 or bigger camshaft (higher rpm cam), or at least use a NA cam.

 

Finally, the T04B-H clears the intake manifold with out the spacer that is required for the T04E-50 trim compressor.

 

 

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I run the T04B-H trim with a T3 exhaust turbine (stage 3).  Boost comes on slow and steady, almost feels like a big non-turbo engine.  Would work really well for an autocross car, due to the slower increase of engine torque.

 

Makes 5 psi of boost at 3000 rpm and full boost by 3500 (running about 12 psi).

 

The free flowing turbine allows 80 mph driving with 10 inhg vacuum.  The stock turbine was at 0 inhg  at this speed (starting to make boost).

 

According to the compressor maps, my engine should be in compressor surge at 3000 rpms, but it isn't in real life.  I miss the low rpm boost of the stock turbo but i'm not going to try low boost with this compressor due to the surge risk.  This compressor is better when used with a stage 1 or bigger camshaft (higher rpm cam), or at least use a NA cam.

 

Finally, the T04B-H clears the intake manifold with out the spacer that is required for the T04E-50 trim compressor.

 

I didn't need a spacer for my t04e 50 trim compressor housing on the stock turbine housing.

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Im currently running the T04e 50 trim with the stock turbine and housing. I start getting some positive pressure around 2500 and full boost around 3500 or so. Would there be a benefit to running a different turbine? I'm running the NA "A" cam. I'd like full boost to come in sooner since I only plan on revving to around 5500-6000

Edited by Randall

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You can pull your boost in anywhere you want it...as long as you keep the compressor out of surge. What boost pressure are you running?

 

You need to make sure you stay to the right of the surge line. Crossing it in one little point is usually OK, but try not to be to the left any more than you possibly can.

 

Bringing your boost in "faster" may make you LESS power than you have now...if you have to drop your boost pressure to keep it out of surge. Delaying "full boost" by 500RPM and allowing you to push 16lbs instead of 8lbs, for example...

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I want an end build of 350whp. I am currently getting together the parts for an intercooler. I took it to the track a couple of days ago but could not get my launch down. I ended up with a 14.8 at 98 MPH on 6psi. I think I need a tiny vent hole on my homemade boost controller because when I set it to 10psi 1st gear had full boost by 3700 rpm but subsequent gears did not make 10psi until 5000 rpm or so creeping from around 3psi at 4000. So my 10psi run actually ran a 14.7 at 97 MPH. 

 

I was thinking that a stage 3 would help bring the boost in sooner but I think that assumption is wrong correct? Probably better with the stock stage 1.

 

I don't think I would have surge with this setup according to the maps posted here

http://www.mygen.com/users/dbruce/myz31/TurboMaps/L28ET%20Engine%20Air%20Flow%20and%20Turbo%20Compressor%20Maps.htm

 

when would it be necessary to add springs to the internal wastegate actuator.

Edited by Randall

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I'm not sure about an internal gate but my evo gate will open with backpressure alone. I finally figured that out one day when I was bored with 15psi. I made some pulls with no vac line to the wg and still only 15 psi. So now I control boost with just spring pressure. With an internal gate you can connect a spring between the diaphragm and arm.

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Randall, I don't think you really understand what the bigger wheel will do...you will LOOSE a lower RPM spool, but you will GAIN high-RPM flow. In the end, HP = RPM * Torque / 5252. More RPM, equals More power. More torque, more power. More both, much more power.

 

There are numerous people running 350whp with that compressor. Shouldn't be an issue.

 

You can push the boost up, a little at a time, till about 18lbs, then you'll hit the surge line pretty hard with the stock turbine. The "Maximum Boost" method has its downfalls.

 

Fix your boost controller, then get some good rubber under it if you are concerned with the launch. Leave the line about 2800-3000RPM, and try to get launch control setup so you can leave on boost if your driveline can handle it...it's rough on the 71B transmissions but they will take a little.

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Well its going to be a street car and 350 would probably be the most I would want to push. According to the website I posted this motor looks to be pretty far from the surge line even at 20PSI (Did not know that the stage would effect this but it all makes since to me now, bigger wheel more flow less restriction in the exhaust but later spool times all affecting compressor output) I was planning on running 18psi with this setup as that seems to be where people hit the 350 mark depending on tune and intercooler effeciency. 

 

I just modified my car for flares and now have 255's on the back 235's front. Also im not running the 71b i modified and fit the 240sx 5speed into the car with custom driveshaft. I think my weakest link is the halfshafts and being an open diff.

 

2013-09-11235132_zps5c6d5aa5.jpg

Edited by Randall

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Just thought I would add an update.

 

I finally got to the dyno and I hit 15.8 PSI @ 3,100 rpm and it falls to about 14.7 PSI @ Redline (6,000 rpm)

I made 300 HP @ 5,000 (falling off to 250 HP at redline) and 350 ft-lbs @ 3800 rpm (falling off to 225 at redline)

 

I think a stage 3 or stage 5 would really be beneficial to gaining more power up top just not sure which one to choose. Either way I went I would tune to about 400 ft-lbs since that is what my clutch is rated at.

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