flyrotary@lancaironline.net Mailing List Archive

Message

Rusty,

Don’t even think about removing that turbo. You keep thinking in terms of boost, but you should be thinking in terms of h.p. (and RPM) What I mean is that I have never heard of a 13b blowing itself up that was producing less than 250 hp. Let alone less than 200. If you are not making the h.p., then you are not stressing the engine. Same argument goes for normalizing. So what if it takes 11 psi of boost at altitude? You are just producing sea level MAPs (or slightly more) so it wont hurt the engine. While I really recommend an intercooler, I know you could produce 180 hp safely with your set up all the way to altitude.

Do it! Get in that thing, climb to 8-10K feet right over your airport. Push that throttle forward until you have 6000 rpm in level flight (or fuel flow for 180 h.p). Don’t worry about what the boost gauge says. If the engine is not producing the power (by turning the RPM and burning the fuel) then it is not really seeing the boost either.

What do you have to loose. Worst case, its really not that hard to re build an engine (compared to re-doing the intake and exhaust systems).

David Leonard

The Rotary Roster:

http://members.aol.com/_ht_a/rotaryroster/index.html

-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Russell Duffy
Sent: Tuesday, September 16, 2003 7:13 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Not sure how many horses really came back

Greetings,

Here's my log from today. I'm not too optimistic that the next climb will be all that great.

Rusty (turbo depression)

9-16-03

I tuned the engine today, after setting the timing to the correct point. It’s now running well on both controllers. Idle is 16-17 inches of vacuum (13-14 MAP). I had to cut the fuel injector flow down by 4-5 steps to get in range, which seems odd, but maybe it makes sense to someone. I set the staging point to about 19-20 inches MAP (12 inches vacuum on the gauge, which I know to actually be 10-11 because the gauge is crap). The staging transition is still ugly, and will continue to be that way until I get matching injectors. I had to make the staging point a bit on the rich side to keep it from surging. Once I got done with the A controller, I copied A to B, and then had to touch up the mixture just a bit across the board. It’s obvious that the copy function is working, because the ugly transition is certainly where it should be. I ran as high as 7 psi of boost briefly, and it really seemed strong, which is more than I can say for 0 psi. I’m going to be surprised if I picked up any significant performance with the timing change.

FWIW, the rpm at 30 inches MAP was 5000 static. I’m pretty sure that’s partially stalled though, so it’s worthless if it is. If it happens to be correct, then it will be an increase in power. Only a climb will tell.

As a side note, the oil and water were both great during all the ground running. Water stayed rock solid on 180, and oil made it to maybe 190. This is running the absolute snot out of the engine under boost.

Unfortunately, I’m still thinking that it will take about 5 psi to get the engine back to what a healthy NA engine would run. That means I’d have to run that on climb from sea level, and run as much as 11 psi to get the amount of normalization that I want. This is more boost than I will be comfortable running, so if the next climb doesn’t change my mind, I’ll probably start working on removing the turbo. 190 HP is plenty for an RV-3, and if I really feel the need to optimize climb and cruise, I’ll have to come up with a variable pitch prop.