Map
Posted: Wed Aug 26, 2015 1:52 am
by wlarson861
I upgraded to the turbo AeroVee and have never seen more than 36 inches of manifold pressure. my cruise is spot on with others and climb is good, so why the low max power number? I take off at about 35.9 inches and climb at 7 to 9 hundred feet per min solo. I cant get anywhere near 40 inches of manifold pressure. Any ideas? I am using auto gas and compression is set at 7:1
Re: Map
Posted: Wed Aug 26, 2015 9:01 am
by Rynoth
wlarson861 wrote:I am using auto gas and compression is set at 7:1
Could this be part of the problem? I thought the Turbo was required to be run with 100LL.
Re: Map
Posted: Wed Aug 26, 2015 10:22 am
by marsolgp
My guess(es) would be either indication problem (what does MAP read when engine is not running?) or waste gate partially open. Did you preload the waste gate controller to hold waste gate closed?
By the way Bill, I went ahead and installed a ‘vent grate’ in my cowling above the turbo, to let heat out after landing…… works good and no ill effects during flight.
Re: Map
Posted: Wed Aug 26, 2015 11:03 am
by wlarson861
When the turbo was being developed it was always stated that auto gas was ok in the lower compression engine builds. Talked with Joe who said they were testing auto gas in the test cell but something took priority and they had to delay the auto gas.
As to the waste gate, I don’t think I did anything to pre-load it. I’ll have to check that. It makes sense that the gate is opening too soon since it has all the right performance at the lower settings.
Re: Map
Posted: Mon Aug 31, 2015 12:19 am
by wlarson861
[quote=“marsolgp”]My guess(es) would be either indication problem (what does MAP read when engine is not running?) or waste gate partially open. Did you preload the waste gate controller to hold waste gate closed?
Good call. Removed actuator rod end from waste gate and turned 1/2 turn tighter. Didn’t see more that 36 inches on take off. Level at 2500 I added throttle and watched it go to 44 inches before full throttle was reached. Pulled back to 40 inches for a few seconds and then back to 30 .8 inches. after landing I took off again and the MAP went above 40 inches as I climbed out at 80 mph. It appears I didn’t have enough tension on the waste gate to hold it closed at high power settings. Further flights should tell if this the case. I am encouraged.
Thanks Geary
Re: Map
Posted: Mon Aug 31, 2015 9:47 am
by Sonerai13
You don’t want to put too much tension on that wastegate controller. You want to set it so that you get 40 inches MAP for takeoff, but you want it to do it’s job and limit MAP to about 42 inches max. Too much tension on that controller arm will allow MAP to go well above 42 inches, which is not what you’re looking for. A half turn one way or the other when you’re close makes a significant difference. Err on the low side rather than the high side.
Re: Map
Posted: Mon Aug 31, 2015 10:46 am
by marsolgp
Waste gate springs are calibrated with proper preload figured in… You do not adjust manifold pressure with the preload, that is done with the correct spring installed in the waste gate controller. The spring installed in the supplied waste gate controller is a white one, this is the ‘lightest’ spring made for this waste gate and is set to STARTopening at approx 40" MAP… It doesn’t fully open til about 44" MAP. This why you have to pay attention with throttle setting, because this turbo will produce more boost than you need or are allowed.
Oh, and you’re welcome Bill…
Re: Map
Posted: Mon Aug 31, 2015 1:46 pm
by Sonerai13
Geary,
The amount of pre-load does indeed make some difference. We played with this in the test cell and found out that the MAP at which the wastegate would open would vary somewhat with the amount of pre-load we placed on the rod.
Re: Map
Posted: Mon Aug 31, 2015 3:49 pm
by marsolgp
I don’t disagree…… this is an old trick from street racers to easily increase boost by keeping waste gate closed past the springs boost setting, because you are essentially changing the spring tension…. My point is, with the proper spring and proper preload, ‘adjusting’ preload should not be needed, nor used. This turbo installation will easily produce 44-45" at sea level when adjusted properly. The pilot needs to use throttle to control this.
Now, to get a little deeper into the subject, I didn’t like the idea of pulling my throttle back during T/O but it was necessary because as you roll down the runway, the RPM and Boost do increase. So what I did was install a ‘helper’ spring on the outside of the waste gate controller (with an adjustable collar) that effectively cancels out some of the tension applied by the white waste gate controller spring. I now have everything adjusted so that when I apply full throttle, my turbo only goes to 40-41" and I can concentrate on my T/O and climb out.
Re: Map
Posted: Mon Aug 31, 2015 5:39 pm
by wlarson861
I don’t think I have any “pre-load” on the actuator. I think before it was not fully closed and was opening too far. The maximum MAP I was seeing was 35.80 in.
Re: Map
Posted: Mon Aug 31, 2015 5:48 pm
by Rynoth
On page 46 of the turbo manual (http://www.aeroconversions.com/support/ … Manual.pdf), step #8, it describes setting up the wastegate actuator as follows:
“Adjust the actuator’s pushrod so it JUST holds the wastegate in the closed position, but also has no end play.”
I take this to mean just enough pre-load to fully press the wastegate closed and take up all slack between the wastegate and the spring, without actually compressing the spring.
Re: Map
Posted: Thu Sep 03, 2015 1:07 am
by wlarson861
Ok so for my bad. I didn’t get a stop nut for the waste gate actuator in my kit. I thought that since the end was captured at the waste gate end the stop nut was unneeded. I was wrong. I put the stop nut on the actuator and the engine performed as advertised. I feel stupid at this point but will continue to test the turbo further. I don’t understand how the actuator really works but this seems to have worked for now. I had to go back to the manual to see the jamb nut and then go buy one from the local hardware store. By the way its a 6mm by .75 metric nut. I didn’t realize that the shaft of the actuator could turn when the engine was in flight. I’ll try to fly more to confirm my fix is complete. Today’s flight was a blast going out at 40’in of MAPin climb and cruising at 30.9 and seeing around 140 mph true
Re: Map
Posted: Thu Sep 03, 2015 9:01 am
by Rynoth
wlarson861 wrote:I don’t understand how the actuator really works but this seems to have worked for now.
Basically, there’s a plunger with spring pressure on one side, and manifold air pressure on the other side (via the line connected directly to the compressor side of the turbo.) When manifold pressure reaches a certain point (~44psi), it overcomes the pressure of the spring and the plunger gets depressed, opening the wastegate via the actuator arm. This also happens to be why excessively pre-loading the spring will actually raise the manifold pressure required for the actuator to engage (more spring pressure = more manifold pressure required to move the plunger,) therefore more maximum boost pressure and less safety margin.
I imagine that the plunger itself can rotate within the housing, which is how the actuator arm rotated during flight without a lock nut. Seems like a smoking gun, I bet you’ve solved it!
Re: Map
Posted: Thu Sep 03, 2015 2:28 pm
by wlarson861
Another test flight today and it performed as advertised.
Re: Map
Posted: Thu Sep 03, 2015 9:44 pm
by MichaelFarley56
marsolgp wrote:By the way Bill, I went ahead and installed a ‘vent grate’ in my cowling above the turbo, to let heat out after landing…… works good and no ill effects during flight.
Do you by chance have a picture of this Geary? I’m interested in what you’ve done. I haven’t had any ill effects on mine but the cowling does get pretty warm on shut down on my engine.
Also, how do you like the VG’s on your airplane? Any noticeable effects?
Re: Map
Posted: Fri Sep 04, 2015 2:36 am
by wlarson861
I really love this conversion now that I figured out the details. I was getting the low power benefits but now I get the high power stuff too. Now all we need is for Sonex to come out with a retro fit auxiliary fuel tank so we can go 3.5 hours with 45 min. reserve. I want to go places now that I can go fast!!! Hope to get to Crossville this year since I have not made it since 2012.
Re: Map
Posted: Fri Sep 04, 2015 10:27 am
by marsolgp
Mike, I’ve sent you a PM to answer your question and attached a couple photos of the vents. I still haven’t had any luck posting photos here, so feel free to repost photos if anyone else is interested.
Re: Map
Posted: Fri Sep 04, 2015 9:58 pm
by Brett
wlarson861 wrote:Now all we need is for Sonex to come out with a retro fit auxiliary fuel tank so we can go 3.5 hours with 45 min. reserve. I want to go places now that I can go fast!!!
That would be great to have a factory approved additional sub tank. Even if limited to one passenger for those long treks.
Re: Map
Posted: Sat Sep 05, 2015 2:43 pm
by MichaelFarley56
If anyone wants to see Geary’s new cowling vents, here are a few pics. This is a great idea and I will probably be doing the same thing here soon!
Re: Map
Posted: Sat Sep 05, 2015 4:08 pm
by marsolgp
Thanks Mike for posting pictures…… for anyone curious, the vent on the LH cowl is over my MGL RDAC. This was actually my main reason for the vents, the RDAC would give me some crazy CHT reading (700 + degrees F), on the ground only, after the compartment got heat soaked. This has solved that issue and has got to be beneficial for other electrical components that are ‘trapped’ in this oven after shutdown (ignition coils and triggers especially).
Re: Map
Posted: Sat Oct 17, 2015 1:11 am
by wlarson861
today I re-clocked the output side of the turbo to better align with the intake elbow and get a better seal for the intake. I was well over 42 in. of MAP on climb out. Not ready to declare victory but am very encouraged that the system is fixed. I am very glad I did the turbo even though I had problems. Even with less than optimum boost I still got better performance than normally aspirated. The lesson here is make sure the intake is free from leaks. I will test fly again when the weather permits and have a better assessment of the changes.
Re: Map
Posted: Sat Oct 17, 2015 2:43 am
by MichaelFarley56
Glad to hear you got it all dialed in Bill! Now that you do, how about some new climb and cruise performance numbers with that big prop of yours?
Fly safe!
Re: Map
Posted: Fri Nov 06, 2015 2:33 pm
by mike20sm
MichaelFarley56 wrote:If anyone wants to see Geary’s new cowling vents, here are a few pics. This is a great idea and I will probably be doing the same thing here soon!
I’m a Formula One fan and I see the pit crews put cooling fans into the air inlets as soon as the cars arrive back from the track. Obviously we don’t run the engines on the razors edge the way they do, but it seems to me that a similar ducted fan blower and battery could easily be made to fit inside the inlets, in order to be nicer to the engine, turbo, and all the components inside. Basically keep it from becoming an oven in there after shutdown. I like the vent in the cowel above the RDAC, I’m just wondering what you Turbo guys thoughts are on this possibility.
This is the best example I could find, but it’s much more complicated than it needs to be for a Sonex’s purposes.
Re: Map
Posted: Fri Nov 06, 2015 2:53 pm
by Rynoth
What, if any impact might these vents have on the cooling airflow through the cowling during flight? This idea is interesting, but I wouldn’t want to negatively impact the low pressure area downstream of the baffles (I’m not saying it would.)
Re: Map
Posted: Fri Nov 06, 2015 3:00 pm
by mike20sm
The idea is not to have them a permanent fixture of the plane and have it used in flight, but to have them in the cockpit or hangar and pop them in shortly after stopping the engine and getting out.
Re: Map
Posted: Fri Nov 06, 2015 3:40 pm
by Rynoth
mike20sm wrote:The idea is not to have them a permanent fixture of the plane and have it used in flight, but to have them in the cockpit or hangar and pop them in shortly after stopping the engine and getting out.
Interesting, what seals the openings during flight?
Re: Map
Posted: Fri Nov 06, 2015 4:03 pm
by mike20sm
no other opening created, just use the existing inlets that are in the cowel already. the way I imagine it, It’s totally temporary and non invavsive. I’ll try to find a video which would more clearly demonstrate.
Re: Map
Posted: Fri Nov 06, 2015 4:25 pm
by Rynoth
Sorry, I think we were talking about different things… I was referring to the vents in the cowling tops.
Your fan idea on the ground seems like it would work also, provided the fans themselves can stand being that close to the heat of the engine. A couple of 12v (or 5v usb) computer fans (installed inside a plug that fits the fwd cowling openings) could be powered from a 12v socket (or usb socket) in the cockpit with minimal current draw off the battery. I think those fans draw like .25 amps.
Re: Map
Posted: Fri Nov 06, 2015 5:54 pm
by mike20sm
https://www.youtube.com/watch?v=DPTq4KpgB_0
This video at 51:18 you can see one of the inlets on the drivers left has the blower and, the other doesn’t
and 51:50 you can see the dry ice and garden blower cooling the brakes and right after that is a good shot of the blower insert.
These would be the two main components involved in the external cooling device I’m imagining. The blower is from a boat engine blower which is used to evacuate the engine compartment before starting. It’s too big but just visualize a similar fan embedded in some closed cell foam similar to those “Pool Noodles” that are used for swimming pool flotation devices. and the battery is just a compact 4 cell lithium that would power it for more than enough time to get things to a reasonable temp.
Re: Map
Posted: Fri Nov 06, 2015 7:10 pm
by Bryan Cotton
Been a long time since I read the Bingeles books. I seem to remember an idea he wrote about. Put a little door on the top of the cowl, hinge to the front, opening down. When you are parked they are open due to gravity. When you have flow into the cowl it blows them closed and the delta-p holds them shut.
Re: Map
Posted: Sat Nov 07, 2015 3:59 pm
by Bryan Cotton
I perused my copies of the Bingeles books but did not find what I tried to describe above. I don’t think it is an original idea, but you never know. They say memory is the second thing to go.
A couple buddies built a nice RV7. It has a generously sized oil fill door. They open it after shutdown to let more hot air out. This is a good and simple idea.
Re: Map
Posted: Sun Nov 08, 2015 4:47 pm
by marsolgp
Ryan,
I read through this thread again and it looked as if you were directing a question to me about any effects the louvers/grates have on the low pressure area behind the engine… I have not seen any negative effects, CHT’s and oil temps are the same, other temps that I monitor back there are identical to the temps before the louvers, only difference is that temperature inside cowling drops quicker once engine is shutdown. And like I’ve said before, that’s got to be good for the electrics that hang out behind the engine…