Installing the hybrid T3/T4 turbo

A lot of people are considering running a hybrid T3/T4 turbo and that always brings up a number of questions- 

How do you attach a wastegate or control boost?
What do you do for coolant and oil lines?
How do you attach intercooler hoses?
What about clearance to the head and firewall?
Should I run a BOV?

Lets start at the top.

Wastegate control

Yes the housing comes polished like this.

As you can see in the first picture the factory wastegate canister is attached to the front of the compressor housing.

No such provision here!

There are four ways around the problem, the first three solutions assume you are using stock style "flapper door" wastegate. The fourth assumes your using a turbine housing from another application that doesn't have an internal wastegate or you just desire to have an external unit. 

1) Weld bosses on the front of the new housing. Two problems with that, one is that the hybrid housings are larger and the angle will be wrong and difficult but not impossible to make work. Two, if you need to rotate the housing in the future you will have to relocate the bosses again!

2) Find something from another manufacture that will fit. (Thanks to Paul Velliky for sending this tip and pictures in)

Front view


3) Take a 84-87 Turbo I wastegate can, remove the "can" by drilling out the spot welds, attach the bracket (modify if need be to get correct angle) to the back of the compressor housing using the existing compressor fasteners. Drill two holes in the bracket to mount a Turbonetics "large can" wastegate can (PN 30314) or something similar and your all set. Minor alterations of the bracket may be needed. I set the arm tension so that 9 psi is needed to just get the wastegate to start opening, stock 89 TII or S-60 is 6 psi. This affects Minimum Obtainable Boost of course, in my case that's 22 psi! 

Here you can see the modified bracket and the single bolt holding it onto the back of the compressor cover.

For my Reliant I wanted to use the internal wastegate for issues of installation compactness BUT since it was a race application I wanted something that flowed a little better on the outlet! What I did was take a 84-88 2.25 outlet and cut off the end where the exhaust headpipe attaches. Then I welded a piece of 3 inch pipe to the outlet and then cut the pipe flush, then welded a regular 3 bolt header flange to the pipe.

After that it was a simple matter to make a matching pipe to direct the exhaust flow where I wished.

Installed in the car- remember I'm using a header so the turbo sits rather low.

4) External wastage (I.E. Deltagate) expensive and your manifold, header or turbo has to be configured for this provision of course. 

Here you see a Deltagate installed on a SOHC engine. A plate (which can be purchased from Turbonetics or make one yourself) with holes for the wastegate & turbine exhaust paths has been attached to the turbo. The arrows show the path of exhaust gas flow when the wastegate is open/opening regulating the amount of gases through turbine housing- hence regulating the amount of boost the engine is producing.

Here is a beautiful assembly & downpipe fabricated by Dave St.Louis

Shown installed on his 16V DOHC Shadow

Another SOHC assembly- In this case from Steve Calder's Shadow. The plate is clearly visible with the (W)astegate and (T)urbine openings labeled.  The red arrows show the exhaust path when the wastegate is open so gases bypass the turbine, lowering the boost. Only downside with Steve's setup was that the Deltagate intruded into the p/s pump area so he converted his car to manual steering. 

Coolant and oil lines

Most hybrid users are using stainless braided lines with AN fittings- These items (hose, end fittings and adapters) are readily available from local speed shops or mail order speed parts companies. Durable with extreme resistance to heat and pressure they will outlast factory units several times over. For a race applications I would not even bother running the lines for the liquid cooled center section, it isn't needed as long as synthetic oil is used and proper idle-down after racing is observed.

If running the TBI/Carb header you will have to install an oil drainback into the oil pan, I welded mine in.

How do you attach intercooler hose?

Two ways actually- One is to use 2 rubber 90 degree elbows clamped together so the compressor is discharging towards the intercooler OR you could have aluminum elbows welded to the compressor cover to direct the airflow, or even a combination of both. In the above picture you can see that I have welded a single 90 degree elbow on the compressor and then attached a rubber elbow. In the picture below you can see I have done away with the rubber elbows altogether in the interest of simplicity and durability. The first 90 degree out of the compressor gets very close to number four exhaust runner which could over time damage a rubber connection. I did use reflective fire sleeving in this area when I was running a rubber elbow but still.. better safe then sorry!

In case you were wondering that's a three inch outlet I have welded to my compressor.

Brian Slowe is using rubber elbows on his hybrid.

What about clearance to the cylinder head? 

 If your planning on running a hybrid with the stock exhaust manifold you will have to clearance the head for the 90 degree bend that's going to be attached to the compressor outlet. Areas pointed out with red arrows will have to be removed.

Brian Slowe sent in this picture of a hybrid installed on his Shadow. Clearly you can see the area that was ground off so the compressor discharge hose clears the cylinder head.

What about firewall clearance?

If running the TBI/Carb style header you wont have to do any grinding to the cylinder head but firewall clearance gets real tight. Don't be suprised if you have to remove the heatshield and persuade the firewall to move back a little. If using a "can" wastegate try to tuck it in as close as you can towards the head for maximum firewall clearance. 

In the above picture I'm doing an initial test fitting using a regular non-hybrid turbo.

If using the factory exhaust manifold you wont have any firewall issues with a hybrid.

Should I run a BOV?

You're running a larger then stock compressor under high boost conditions and your wondering if you should run a Blow Off Valve? 

I would.

Thank you for visiting Donovan's Dodge Garage