First Flight Since Rebuild

[Chucker]

Thanks for the description.

When I initially installed the fuel tank, I didn't realize that the vent line went down in front of the landing gear (I reworked it after everything was completed).
I had installed a PCV valve to act as a vent.... that way it would allow suction but prevent fuel from splashing out.

Thinking of reincorporating it into the current system:
View attachment 15047

Normal venting can occur using the drain line - green line but if it ever gets plugged and a suction starts, the PCV would take over and allow air to enter through the top - orange arrows (under the cowling).

I think it would be a simple fix with parts I already have.
Thoughts?

It looks like a simple fix. Worst case, fuel is trapped in vent line due to ram air pressure. In that scenario you would still have atmospheric pressure through your PCV.

 

[Chucker]

Has anyone here attempted a "static thrust" test with a direct reading scale, like one of the large spring type fish scales?

In theory, he should be developing around 200lbs of static thrust with that prop @3,100rpm.

A static pull thrust would remove all doubt. However, if the prop is truly turning 3100rpm, the only thing that could limit the thrust would be a poorly shaped/pitched prop.

 

[Veedubber]

Playing by ear, that engine ain´t reving more than 2,400-2,600 RPM.

VeeDubb

 

[nzgrip]

Same engine running same prop, but you changed carb. You said that color reading the plugs seemed normal but you were running full power at full rich, should the plugs not read rich? Possibly running lean?

 

[myles-dean]

I was able to photo tach the engine rpm it while tied up on the ground and I confirmed that it will produce 3000rpm.
I'm really thinking that the overfull fuel tank caused an issue on initial full power application, which caused the engine to not produce full rpm's.

The next plan is to go to a wider/longer runway and do some testing.

Playing by ear, that engine ain´t reving more than 2,400-2,600 RPM.

VeeDubb

 

[myles-dean]

The plugs should be looking normal after the full power run.
I had ran full throttle for awhile and shutdown with no idle time.
I would expect some discolouring if the engine was allowed to idle, as it would be running rich at that time.
If I pulled the plugs and they were white after the full power run, I would then suspect it was running lean.

Same engine running same prop, but you changed carb. You said that color reading the plugs seemed normal but you were running full power at full rich, should the plugs not read rich? Possibly running lean?

 

[Chucker]

According to my Revmaster manual you can check your full power mixture by slowly leaning the mixture until the engine begins to falter. If you can get a 50 degree rise in EGT before the stumble than your mixture is good. Less means you are too lean and more means you are too rich.

 

[103]

According to my Revmaster manual you can check your full power mixture by slowly leaning the mixture until the engine begins to falter. If you can get a 50 degree rise in EGT before the stumble than your mixture is good. Less means you are too lean and more means you are too rich.

Consider switching revflow to ram air. I had a restricted small K&N would not allow my needle to be lean enough at WOT and rich enough at idle. I have a new airplane now snappy smooth throttle repose. Turn 3250-3300 on take off with a 58x34 STERBA Prop. On shut down you should see a minimum 100rpm spike just before quitting when pulling the mixture to idle cut off. I suggest you do not fly until the carb tune is correct. A Sonerai should turn much faster at take off. A longer runway is only a mask on a symptom of a problem that still needs to be addressed. Gaining altitude rapidly creates margin for when things go wrong no compromise! Soap box retired! Yes I am a Sonerai Lurker wearing a Cygnet SF2A

 

[myles-dean]

I have a brand new AeroInjector installed and did the EGT test to check for mixture; it was about 100F which is correct (Spec is 90-100F hotter when leaned) .
Thinking I will check again... but it shouldn't have changed.

As for the longer runway, the intention is to have the opportunity to land safely straight ahead..... if there was an issue again.

I appreciate all the feedback and suggestions!

 

[mhflyit]

Apply the power steadily. The Aerocarb doesn't like quick power increases from idle. Good luck!

 

[103]

Apply the power steadily. The Aerocarb doesn't like quick power increases from idle. Good luck!

The Revflow can be jammed in over less than a second real snappy response.

 

[Chucker]

My Revflow never stumbles.

 

[103]

My Revflow never stumbles.

Yes there are subtle difference that give Revflow an edge over Aerocarb. Our long intakes are another issue. I have room to move to the top I am considering an Ellison style intake. Yes I know I complicate things with pumps and regulators but they are manageable. My interest is even fuel distribution. I may even oil heat the manifold box


An alternate I am considering to the Revflow apart from the unobtainable Ellison EF2 on top is the Mikuni BN38 carb (34mm venturi) the small Brother of what Jeff Lang is using on his Turbo Sonerai. I would miss the Idle cut off, Mixture and easy priming the Revflow offers...

 

[Chucker]

According to Joe Horvath, having a longer manifold tube (from the Revflow to the split) will help atomize the mixture and balance the flow. That may be counterintuitive. We think of the mixture being best atomized when it leaves the carb and then re-condensing along the way to the cylinders. He described it as little onions. The droplets are still large when they leave the Revflow. As they flow through the tubes they peel off layers like an onion. The longer primary tube allows more peeling before the split and results in a more balanced mixture.

I took Joe's word for it and tucked the split right up under my magneto. My primary tube is about 10" long before the split. The balance between banks seems pretty good. The pipes on the right side run a bit darker than the left. The plugs look identical. Temperatures are slightly cooler on the left even though the pipes are telling the opposite story.

 

[czr7s1]

This is interesting...for what it’s worth, I had a customer of mine (who is heavy in the surface drive boat motor world down here in LA) come to the shop I was partnered in back in 2016 with the idea of a custom intake for carbureted models of the Briggs 35-37hp. All he brought was a carburetor and intake manifold and said see what you can come up with. Only difference between our VW motors and these is a couple cylinders short and that he had a full dyno setup at his shop monitoring temps, exhaust gasses, and other sensors. Being experienced in Solidworks and having access to a couple CNC mills with 4axis capabilities, I designed and machined a prototype where the plenum size (chamber after carb but before split) and small straight section could be shortened and lengthened according to what the dyno said. We also tried a few surface finishes which made less than single hp differences but every positive outcome was integrated into the production run. Long story short, we picked the setup with the best hp/torque numbers and machined a run of over (220) for his customers. Curious to know what the numbers where? On his higher level 3 kits (larger bore, custom grind cam, ported heads) and our intake, he consistently sold 70-72hp kits to customers with only (2) cylinders. Pull our intake off and the setup would not make over 65hp. Keep in mind these are stock Briggs motors that are running 500hrs + getting beat to hell in the marshes around here. I have tons of pictures but searching back through over 10,000 on this phone is cumbersome. Picked a few to attach. Since then (mid 2016), the fuel injected market took over and he phased these intakes out but I still have one in my office to look at everyday. You guys think our engines could benefit from something like this? I have all the files ...

 

[103]

This is interesting...for what it’s worth, I had a customer of mine (who is heavy in the surface drive boat motor world down here in LA) come to the shop I was partnered in back in 2016 with the idea of a custom intake for carbureted models of the Briggs 35-37hp. All he brought was a carburetor and intake manifold and said see what you can come up with. Only difference between our VW motors and these is a couple cylinders short and that he had a full dyno setup at his shop monitoring temps, exhaust gasses, and other sensors. Being experienced in Solidworks and having access to a couple CNC mills with 4axis capabilities, I designed and machined a prototype where the plenum size (chamber after carb but before split) and small straight section could be shortened and lengthened according to what the dyno said. We also tried a few surface finishes which made less than single hp differences but every positive outcome was integrated into the production run. Long story short, we picked the setup with the best hp/torque numbers and machined a run of over (220) for his customers. Curious to know what the numbers where? On his higher level 3 kits (larger bore, custom grind cam, ported heads) and our intake, he consistently sold 70-72hp kits to customers with only (2) cylinders. Pull our intake off and the setup would not make over 65hp. Keep in mind these are stock Briggs motors that are running 500hrs + getting beat to hell in the marshes around here. I have tons of pictures but searching back through over 10,000 on this phone is cumbersome. Picked a few to attach. Since then (mid 2016), the fuel injected market took over and he phased these intakes out but I still have one in my office to look at everyday. You guys think our engines could benefit from something like this? I have all the files ...View attachment 15087View attachment 15088View attachment 15089View attachment 15090View attachment 15091View attachment 15092View attachment 15093View attachment 15094

Very cool but look to heavy for flying. Please work on a tuned variation for VW, After POC a lighter variant will be needed. I hope Briggs exists from Chapter 11 they are in my backyard. 30+ Engineers and Technicians have recently applied for work at my company. Does not look good for Briggs.

 

[DeadRinger]

What we really need is direct cylinder injection on a Vw. I tell everyone I can that it needs to be prototyped. The benefits are two many to mention but primarily torque it quadrupled at low RPM and heat absorption in the combustion chamber from fuel vaporizing.