I used to have to step climb for cooling on a hot day until I added and improved my baffles. I have a question regarding intake air for the carburetors. Best I can tell the carbs ingest air preheated by both cylinder cooling air and heat transferred from the hot muffler. Doesn't this have a significant effect on engine power? Has anyone ever measured the temperature of the intake air? Given that and a hot day, max power has to be down 10 percent or so.
Upside of the existing arrangement suggest carburetor icing should never be a factor. Michael Stockhill Polson MT On Tue, Jul 21, 2020, 4:17 PM Ian Mc Phee <[email protected]> wrote: > Ian > > MGL 4 channel is a must I believe (although I have 2 gliders with KSA > CHT1DT and I add a switch arrangement with 4 channels and these instruments > are over 30 years old with transistors and still works!!!) How old is your > TV or phone.? > > Consider the MGL as a one off insurance policy on the engine for about > $A550. The bonus of always below 180deg c on climb is tappets NEVER NEED > TO BE ADJUSTED IN 700HRS! > > Yes ASI between top and bottom is great way to go to check sealing of dam. > I have just learnt a falke has added a seal below the spinner and evened up > temps even more. He uses an MGL. > > I am mostly down to 4deg C between cylinders but has taken a while. > > Ian McPhee > 0428847642 > Box 657 Byron Bay NSW 2481 > > > > On Tue, 21 Jul. 2020, 08:52 Ian Williams, <[email protected]> wrote: > >> Hi Rob >> >> >> >> Im not as technical as you, but if any help, when we were test flying the >> Grob 109 with the 2400 Stemme engine, we had to carry out a pre STC >> approval series of flight tests. One was relating to engine and oil >> cooling. >> >> So we used a standard ASI with the pressure in the engine and the static >> behind the baffles. We were comparing the indicated airspeed with the >> “baffle one” >> >> The results we got were as follows >> >> 1. Using the original baffles the ASI at slow speed was around 5Kts >> faster at higher speeds (100kts) the two came together >> 2. When we had finished the new baffles, we were getting a 15 Kt >> difference at slow speed and again they came together at high speed. >> >> In practice it didn’t have a lot of effect on the CHT’s with the Grob. >> However a similar effort to make the baffles “as tight as a fish’s bum” on >> our Dimona had a really big effect on the CHT’s. We didn’t use the ASI >> test as were very happy with the results. >> >> I have recently installed a MGL 4 ch CHT (nice colours) which confirms >> our work. >> >> >> >> I hope that is some help Rob. >> >> Best regards >> >> >> >> Ian W >> >> >> >> *From:* [email protected] *On Behalf Of *Rob Thompson >> *Sent:* Monday, 20 July 2020 12:17 p.m. >> *To:* [email protected] >> *Subject:* [DOG mailing list] Cooling airflow and Mixture relationship >> >> >> >> G'day Everyone, >> >> As many of you will know I am OCD about sealing every tiny air leak in >> the Limbach engine bay compartment with silicone, aluminium tape and rubber >> cowl seals. >> >> >> >> I have previously rigged up a water manometer in the cockpit with the >> tubes running to the top and bottom of the engine. It told me I was getting >> very good pressure difference but I didn't take much notice of the actual >> measurements. I think it was somewhere around 30cm. >> >> >> >> As well as the ram air going into the front of the engine the lower cowl >> is designed to "suck". We fitted a big scoop type bottom cowl which seems >> to suck pretty well.... particularly with the baffles tightly sealed with >> silicon. >> >> >> >> What I am wondering now is..... What is the effect of this extra suction >> at the back of the engine on the carbs and mixture? >> >> >> >> Maybe it is not much different to flying at altitude and the SU carbs >> altitude compensating ability can deal with it. >> >> >> >> Any fluid dynamics physics experts in this Dog group who can enlighten >> me? >> >> >> regards >> >> Rob >> >> >> >> Rob Thompson >> >> 0429 493 828 >> >> >> >
