Mailing List Message #58422
From: William Mason <>
Subject: Re:buying a turbo
Date: Mon, 18 Jun 2012 19:53:58 -0700
To: <>
Great shot David.

I could recall from our discussion at GoldenWest that you were running a stock-housing BNR unit but couldn't recall what you said about the stage and compressor specs.

I think I will probably go with a T3 to T4 adapter with an external waste gate fitting and a different turbo.  I'll shoot for something with a larger turbine housing.  

I'm thinking a T04b v trim compressor with a 1.15 a/r exhaust housing. If I'm reading correctly it's right in the wheelhouse.

I'll check with a pro before buying though.


From: David Leonard <>

Subject: Re: [FlyRotary] Re: buying a turbo
Date: Sun, 17 Jun 2012 12:26:06 -0700
To: Rotary motors in aircraft <>

Hi Bill,
I am not particularly an expert on turbos, so take everything I say with a grain of salt. First, mine is not a T-3/T4 hybrid, and I would not recommend one. Mine is a BNR stage 4, and that is all TO4 but uses a modified stock turbine housing. My compressor is T04E-50trim.

The general answer to your question is: yes that should work nicely - it is pretty much what I use. A large external waste gate would be optimal, but not necessary by any means. I do not have one - I use the internal waste gate that is probably inside the turbo you are looking at. The A/R in the stock housing is also less than optimal, but it sure makes for an nice compact and off-the-shelf package and you won't notice any difference unless you plan on hard core racing.

You will limit overboost by using the throttle judiciously. I never have used full throttle, even at Reno. Turbo overspeed should not be a problem for flying an RV-7, but you will have to keep the EGT down to prolong turbine life. Do that by staying well rich or lean of peak EGT.

If you take that turbo, and cut off the waste-gate flapper door (making a fixed exhaust bypass) then you have a very nice solution. I have another turbo set up that way. Though it is not enough boost to use at Reno or impress my friends, it does leave me with just enough boost at WOT to keep up with any C/S 180h.p. powered RV6/7 (and be faster than most). You still have to keep EGT's away from peak, but then you never have to worry about overboost or overspeed and it is a little more efficient as well. Now that I am done with Reno, I will be re-installing that turbo next time I have the engine apart (which will hopefully be a long time from now...). The only difference between that turbo and my current turbo is the installation of the stock waste-gate flapper/cover and the actuator. Careful, once you take a dremel to that flapper door you can never put it back without a new one and help from a welder.

Hope that helps.

BTW check out this pick from Golden West airshow last weekend!

David Leonard

Turbo Rotary RV-6 N4VY

On Sun, Jun 17, 2012 at 6:54 AM, Kelly Troyer <> wrote:

This needs to be answered by Dave Leonard (Our resident Reno Air Racer)..............He is flying a TO-3/TO-4 hybrid
with much success and I bet can clue you in on what you have and what he has that obviously works well..............

Kelly Troyer
Dyke Delta_"Eventually"

On Sat, Jun 16, 2012 at 11:50 PM, William Mason <> wrote:

Hello there gentlemen (ladies too),

I have the opportunity to purchase a BNR stage 3 turbo mounted on a stock S5 FC manifold.
I'm not sure what the A/R is on the turbine housing, so I'm not sure if I'll be able to use it as-is.
If it's too low of an A/R I'll have to install another housing in order to use it.

*Important question*

If it's got a 35mm wastegate with an adjustable actuator, will I be able to dump
enough exhaust energy to keep from overspeeding the turbo at cruise speeds using
an RD-1B?

I don't want to run too much boost and I won't need to. I've got a mild streetport and will be
mounting it on my RV7. Anything over 180 hp will be fine with me.

It's a modified stock turbocharger (hybrid) so really it's a t04b 60-1 (some people are calling it a t04e)
with an aggressively clipped h3 compressor. Is this too much turbo in a too-tight housing?

I wish this stuff made more sense to me but it doesn't.

Bill Mason
RV7 13b EC2 RD1
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