MP for P-Mags

[Tiger28760]

This is for an IO390 EXP119 installation with dual p-mags.
How are you providing Manifold Pressure to the p-mags?
This may seem like an elementary question, but there appears to be multiple paths and I’m unsure what’s best.
Thanks,
Jeff

 

[lipper03]

At this point I've put in the fitting on rear right port per plans. I need a tee to get over to the pmags. Aircraft Specialty makes both a Garmin and Dynon kit, I'm leaning towards the Dynon kit, as I have already mounted the sensor in the rear right location. I have Garmin, but looks to be the same fittings, so I don't think it matters which kit. But this is something that can change, I might just move the sensor to the left side rail and do the Garmin kit. So not much help besides I'm planning on using one of these two options.

https://www.aircraftspecialty.com/rv-14.html
https://www.aircraftspecialty.com/PDF Documents/RV-14 FF1.pdf

 

[RViator60]

What I did was replace the F-4 DTX-S on the Garmin firewall-mounted transducer with a 4-MTX-3 tee and 4-G6X-S adapter to 1/4" NPT where I connected a 90 deg 1/4" pneumatic swivel fitting. I ran 1/4" tubing to an insert tee then ran the rubber tubing supplied by E-Mag to each p-mag with the supplied pulse dampener in each line. On the RV-14A, the manifold pressure is taken off the #3 cylinder with a braided hose supplied by Vans which connects to the other side of the 4-MTX-3 tee.

 

[Tankerpilot75]

This is for an IO390 EXP119 installation with dual p-mags.
How are you providing Manifold Pressure to the p-mags?
This may seem like an elementary question, but there appears to be multiple paths and I’m unsure what’s best.
Thanks,
Jeff

On my old RV7A, I struggled with fluctuations in my MP readings until someone suggested I put a “restrictor” inline to the MP sensor. My RV was getting its MP pressure from cylinder #3 with the dual PMags (that I had installed professionally by a very competent shop) getting vacuum from cylinder #4. Each PMag had its own inline restrictor installed to stabilize its internal pressure.

Here’s the restrictor I used on my MP sensor.

Restrictor Fitting

Brass restrictor fitting for use in oil, fuel and manifold pressure instrument lines to prevent excessive leakage due to ruptured lines. Installation at the fuel pressure connection will also dampen needle fluctuation due to fuel pump action. Orifice size .040. 1/8" male to 1/8" female NPT.

www.wicksaircraft.com

 

[Larry KMYA]

I’m just dealing with this now. I have a Dynon system with the pressure gauge on the upper R firewall. When I look at the Aircraft Specialty set up it looks WAY too over-engineered (and I’m sure expensive). I ran rubber hose fron the cylinder #4 to the sensor on my Bearhawk for 10 years without any issues. I just need to obtain a T that will split the black rubber hose from the cylinder to the sensor and come off with a 1/8” barb to connect the E-mag hose and use a 1/8” T to each mag. If anyone has sourced the two T-fittings I’d appreciate a link.

 

[Ironflight]

On our dual P-Mag airplanes (four of them), I simply run the supplied black tubing (which is 1/4” OD I think) to a quick-connect “Y” fitting, then a single line to a quick-connect fitting with a 1/8” NPT screwed into Van’s manifold. The MP sensor goes into the manifold, and a braided SS line goes to the left aft cylinder’s port on the head - simple, straightforward, inexpensive, and reliable for many years.

 

[georgemohr]

These guys make a hose and fitting kit that makes the setup very easy.

KitPlane Mods

 

[F18Sailor]

On my bird with dual P-Mags and a Dynon MAP transducer, the builder used a 2-2-6 or 2-2-8 aluminum manifold from spruce: https://www.aircraftspruce.com/catalog/hapages/alummanifoldfit.php?clickkey=6557

Source is the #3 cylinder on the right hand side, with high temp braided hose run to the manifold through a 90deg fitting and what appears to be an inlet restrictor. One of the 4 outlets is capped; the others have NPT brass barbed fittings in them to allow for the supplied hose to connect the P-Mags to the manifold. I recently replaced these hoses (age), and used 1/8" ID silicone tubing.



It's been reliable and makes mag timing easy!

 

[TS Flightlines]

this is typically how we do the PMag tee for Garmin senders, mounted in the sender manifold. Restricted AN823-4R in cylinder 3, hose to the dual tee ( not fancy but workd very well) then 2 of our -3 hose end stems and nuts connect with the black silicone hose PMag provides. Last port is for the hose to the sender manifold. LOTS of ways to do this, we found that this was pretty universal, but also adaptable. Second pic is from the original RV14 Garmin install by the plans, sender mounted newr the brake reservoir. Dynon similar, for the older block style MAP sensor. We understand that Dynon may be shipping threaded senders, similar to Garmin, so using the sender manifold works too. For those that use the Show Planes mount, this can work too---with some modification.

 

[Carl Froehlich]

Here is a simple way to do this. A piece of hex stock, some holes tapped to 1/8 pipe thread and fittings. The AN fitting is to connect the standard Van’s MP hose to the cylinder. The two small diameter fittings are for the pMags, the larger diameter fitting is for the MP sender hose.

I typically mount this on the firewall behind the pMags.

Carl.

 

[climberrn]

There is absolutely nothing wrong with steel fittings and braided hose for MP but we are talking about minimal pressure on the tubing, minimal exposure to oil, not much heat, and if in the unlikely event you get a leak, it is not a safety issue.

I have a restrictor fitting on cylinder #3 per plans, a quality rubber, cloth braided hose with an adel to the motor mount to limit movement after that. Then have NAPA nylon barb T’s to the PMags, and a nylon 1/8 Y just above the oil filter to split to both mags, using the supplied silicone tubing. Have had 10 trouble free years out of this on the 7. I removed a pound of steel fittings and braided lines off our -6 and did it the same way. The MP sensor is on the firewall near the right top motor mount to firewall. As for heat, I have a thermocouple on the battery, 6” from where the lines are and rarely see temps over 110F in flight.

 

[TS Flightlines]

Here is a simple way to do this. A piece of hex stock, some holes tapped to 1/8 pipe thread and fittings. The AN fitting is to connect the standard Van’s MP hose to the cylinder. The two small diameter fittings are for the pMags, the larger diameter fitting is for the MP sender hose.

I typically mount this on the firewall behind the pMags.

Carl.

Carl----we looked at this. But we needed to do something that everyone could do, taking into consideration that some builders arent machinists, or fabricaters. Using 2 tee and a union serves the purpose.

 

[bobrath]

Plugged an AN fitting holding a short piece of 1/8 tube into a tapped port just ahead of #4. Then used the supplied plastic tubing secured with a high-temp (blue) wire tie. Ran the tubing to a barbed Y fitting and then to the nipples on each P-Mag and secured those with the supplied fasteners. Tied down the tubing runs along the way.