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Author Topic: A Treatise on Turbo Upgrades  (Read 12307 times)

Rocketman

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A Treatise on Turbo Upgrades
« on: September 24, 2013, 12:20:33 PM »

Okay. Let's talk turbo upgrades here. Some of us XR2 owners would like more power, and have heard terms like "hybrid" turbos thrown around. This post will assume you know the basic parts that make up the turbocharger itself.

Our stock turbo is an IHI "VJ14". IHI is the manufacturer. RHB5 is the series of the turbo. VJ14 is the model designation. THE NUMBER HAS NOTHING TO DO WITH THE TURBO SIZE.

IHI was pretty kind to us, and made their turbo units somewhat modular. This means that we can interchange components from other RHB5 series turbos.

So once you've pushed your VJ14 to its limits and you want more, here's what we have available:
VJ14/VJ11 hybrid
VJ11/TBird hybrid
There are VF hybrids (VJ is Mazda, VF is Subaru designations) that are out there, but I am not too familiar with these.

With any upgrade, (beneficial for the stock turbo as well) it is necessary to port the wastegate! Failing to do so will result is major boost creep & overboost issues.



The VJ14/VJ11 Hybrid
This upgrade will flow enough air to break the 200whp mark. This turbo should not be pushed past 16psi!
The VJ11 turbocharger is found on the F2T engine in the states here, which was put in the first gen Ford Probe GT, Mazda MX6 GT & 626 GT. There are several differences with this turbo the main thing being the Compressor flows more air (cfm) which will equate to more power. For this upgrade, at the minimum you will need the compressor wheel and compressor housing. It's not a bad idea to obtain the whole turbo unit though.

The basic premise of the 14/11 is that you swap the compressor wheel & housing with the VJ14's units, retaining the stock mounting & fluid lines making for an easy to install low-impact upgrade. The mechanics of the swap itself are a little more complicated should you attempt this yourself. (the nut retaining the compressor wheel is reverse threaded!!!) It's highly recommended that a professional turbo shop swap the components & balance the rotating assembly. You may want to have the turbo rebuilt at the same time. The major thing to note with this method is the wastegate actuator bracket will need to be re-drilled, as the VJ11's compressor housing has slightly different bolt locations.

There's another method that does not require dis-assembly (& thus needing re-balancing) of the CHRA (center housing) but it is more overall work to install. You will need a whole VJ11 turbo in good shape! For those on a budget this may be the option for you, as rebuild/balancing can be quite pricey. For this method we will take the entire VJ11 assembly, and take off the iron turbine housing. The turbine wheels are the same. Fit the VJ14's turbine housing to the center section - you've now made essentially the same upgrade as above. The VJ11 has different coolant routing, and you'll need to test fit the turbo and adjust the placement/clocking of these fittings as needed. Again you will need to re-drill the VJ14's wastegate actuator to fit. Use transmission cooler or similarly rated line to route new coolant lines, being sure not to kink them as the fitment is not like the stock soft lines.

The VJ11/Tbird
This upgrade uses turbocharger parts from a 1987/88 Ford Thunderbird TurboCoupe. It *HAS* to be these years, it is an IHI unit. The earlier years used a much larger Garrett turbo which is not at all compatible with the IHI units. This hybrid is more of an "extreme" upgrade it's a little laggy but the power comes on real hard and stays.

The VJ11/Tbird uses the VJ11 turbine housing, with the Tbird compressor wheel. You can use either CHRA, it is easier to use a good Tbird and stick it into the VJ11 so you don't have to have it balanced. The compressor housing will need an adapter to connect your intake piping, and the coolant lines will need re-fitting.

The VJ11 turbine housing has a larger A/R and is capable of providing much more flow at higher power levels. The VJ14 turbine housing would choke flow and could potentially cause crazy overboost issues with this combo. This comes at the cost of some spool time, but the top-end benefits are worth the tradeoff.

The 11/Tbird hybrid should be capable of 250-275+whp @18-20psi.


Upgrade the 11/Tbird
There is an upgrade for the Tbird turbo called the "16T" upgrade. These were available from a seller on eBay - it is a Mitsubishi 16T compressor wheel reamed out to fit the Tbird, along with a re-profiled compressor housing. The CHRA also needs some modifications to fit the compressor wheel. Performing this upgrade brings the flow from 384cfm to 425cfm.


« Last Edit: October 03, 2013, 03:07:54 AM by Rocketman »
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Jim Simms

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Re: A Treatise on Turbo Upgrades
« Reply #1 on: January 03, 2014, 03:05:31 AM »

The more I read your educational material, it is appreciated even more. The temptation to pump up my 91 XR2 is becoming more than an afterthought. Thank you for your educational and instructional posts.
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Rocketman

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Re: A Treatise on Turbo Upgrades
« Reply #2 on: January 09, 2014, 08:42:57 AM »

I am glad this material is helpfu to you. Thank you!

Modifying the Capri is quite a lot of fun and very rewarding.
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Jim Simms

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Re: A Treatise on Turbo Upgrades
« Reply #3 on: April 28, 2014, 01:52:41 AM »

I am so close to doing the hybrid, and hear different prices for rebuilts. You have been great with your recommendations.

If I send my VJ14 unit for a rebuild, and want the shop to do a VJ11/VJ14 hybrid, will I only have to supply the VJ11 compressor housing and the VJ11 compressor wheel ?

Will the compressor wheel fit onto the center unit, directly onto the same shaft?

I learned about porting out the wastegate, which you had suggested, on a you tube video.

Is it of much advantage to port the wastegate on a regular VJ14 rebuild?
What about installing the boost control on a regular VJ14 rebuild?

I know I dropped a couple questions on you.  Thank you for all the help.
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Rocketman

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Re: A Treatise on Turbo Upgrades
« Reply #4 on: April 28, 2014, 05:04:38 PM »

You supply JUST the VJ11 compressor wheel, and compressor housing, along with your stock turbo.

Anytime you have access to the wastegate, it should be ported, stock or not. It will be of benefit in the long run if you do an exhaust upgrade or other work.

Boost controller on a stock VJ14 is fine, but not for the scope of this thread.
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Jim Simms

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Re: A Treatise on Turbo Upgrades
« Reply #5 on: April 28, 2014, 05:27:54 PM »

Thanks for the info.
This site sure helps when talking to locals.
I found a turbo mechanic in Costa Mesa. CA, and the Team Capri info helps a lot.
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xan175

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Re: A Treatise on Turbo Upgrades
« Reply #6 on: February 17, 2016, 09:52:24 PM »

So i'm just kind of curious why you wouldn't just bolt on the T-bird turbo? or the VJ11 without making a hybrid?
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Rocketman

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Re: A Treatise on Turbo Upgrades
« Reply #7 on: March 06, 2016, 11:40:39 PM »

So i'm just kind of curious why you wouldn't just bolt on the T-bird turbo? or the VJ11 without making a hybrid?

The Tbird turbo uses a T3 flange, and will not bolt to the Capri manifold. The VJ11 and VJ14 are the only bolt-on turbos.
You can use the full VJ11. The turbine housing is optimized for a larger engine and will thus spool slower.
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Ed Hunter

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Re: A Treatise on Turbo Upgrades
« Reply #8 on: July 15, 2016, 03:35:15 PM »

Hello rocket, i found on the MX6 forum that compared the VJ11 vs a VJ5 which showed they are basically the same turbo (I guess the coolant inlet out let bosses are in a different spot which is not a big deal for this hybrid style). I was curious because i had access to a good used VJ5, So i grabbed it. Well i created the hybrid with my VJ14 and VJ5, drilled out the waste gate hole, bolted it on for testing purposes and it worked great. I have (and had) a small oil leak from my VJ14 so i'm going to get it professionally rebuilt and balanced like you suggest. Just thought i'd let you know it's another option. Thanks for this super helpful post.
-Charles
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Gaz

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Re: A Treatise on Turbo Upgrades
« Reply #9 on: September 18, 2016, 10:54:24 AM »

Delete this, I got my answer.
« Last Edit: September 18, 2016, 12:27:15 PM by Gaz »
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Gaz

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Re: A Treatise on Turbo Upgrades
« Reply #10 on: September 23, 2016, 11:14:20 AM »

Okay, looks like I found a Vj11 with Upgraded comp housing using ht12 wheel and tbird housing for $200 plus shipping. Should I do it? I've got no info on the HT12 wheel benefits.
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Gaz

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Re: A Treatise on Turbo Upgrades
« Reply #11 on: October 23, 2016, 03:13:46 PM »

Well, I went ahead and did it. What fittings will I need to adapt to that chra, if any?
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Gaz

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Re: A Treatise on Turbo Upgrades
« Reply #12 on: November 01, 2016, 04:49:44 PM »

So, I got it in the mail, and it has cracks all over the wastegate port, one of which runs fairly deep along the inside tract of the turbine housing. I don't want to run it like this, but in the unlikely event I can't hot weld it, would it become a safety concern if I ran it as is?
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Rocketman

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Re: A Treatise on Turbo Upgrades
« Reply #13 on: November 02, 2016, 10:36:21 PM »

Similar to the chronically cracked XR2 manifold, most VJ11 seem to have a crack on the WG.

Mine did, ran fine for me. It's not a safety issue - it may leak but it'd cost you spool time, rather than overboosting.
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Gaz

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Re: A Treatise on Turbo Upgrades
« Reply #14 on: December 13, 2016, 06:50:28 PM »

Is this ht12 wheel comparable to a 16t wheel, you think?
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