| Author | Message | ||
     Wayne Norris |
I made up a mold for those bullet shaped exhaust shoots. They are 4x4x13. if any body wants to borrow it they may, and lay up your own, or I might be talked into making a set for you. Has any one had problems with over heating on the ground? It looks like this cowl is made for flying,and not alot of air is going to get in there on the ground. I made a semi-plentum over the top of my engine, guess we'll see before long. | ||
| LOUIE LACY (Llacy) |
Wayne I tried to get on the correct page this time to keep Jerry off my back. I have the aluminum foil on the inside of my bottom cowl and still over heat. I noticed you had a blast tube for your alternator Do you think this provides more cooling air for the exhaust on the right side of the engine (#1 cylinder) also did you use tubing or scat duct from the engine inlet down to the alternator. Lou | ||
| jharlow |
FWIW, I also made a plenium cover for the top of my engine and am very pleased with all of my temps. In fact my oil temp is to cool and I have blocked off some of the area. #1 Exhaust pipe shows some heat marking on the inside but has not shown heat distress on the painted glass surface. I think I will try the foil idea to be safer. John | ||
| Jerry Sjostrand |
Hi Louie, I'm back. I think it a very wise idea to direct a blast tube to the magnitos and the alternator. I had a mag coil failure early on because of the heat. Inside the cowling I used a heat reflective blanket material and bonded with high heat red silicone. Then trimmed with heavy aluminum foil tape to close all the edges. It has worked great for me. The blanket material came from Aircraft Spruce over 8 years ago now. It is made up of woven glass and aluminum facing. The only experience I have had with pipe wraps was with Jim Warner when he flew to Oskosh and the pipes came apart in the air. They had been wrapped and the feeling was that too much heat was retained and the welds couldn't take it. ??? We got the EAA shop to do temporary welding to get Jim back home. My exhaust pipes are not wrapped. Bob Gisburne said he had a good experience with his so who knows the answer?? Cheers again from Oakhurst. | ||
| LOUIE LACY (Llacy) |
JERRY How did you secure the blast tube to the cowling. I have blast tubes to my mags but not to the alternator. The alternator belt broke at 160 hours and I think this was due to heat. I am concerned about securing the tube to the lower cowl was planning on using 1" aluminum tubing located right rear corner of right intake. | ||
| Jerry Sjostrand |
The blast tubes should be attached to the engine baffleing. I have seen some 1/4" to 1 1/2 " diameter tubes depending on the need. You might attach the tubes to the cowling but it sounds cumbersome. Heat certainly will take its toll and needs to be considered. I have seen an Express cowl that is badly warped near the exhaust area because of lack of protection. Don't let that happen to you. | ||
| Charles M. Robinson New member Username: F15epilot Post Number: 34 Registered: 02-2004 |
I've been working to cool things down under the hood of my Auriga, as well as cool the oil temps in by partner's Tiger. His oil temps were reading 230+, and got worse when you tried to cruise above 5K. A friend who built/owns a Thorp T-18 mentioned that he had put reflective heat shielding on his oil pan of his O-360, and that had dropped his oil temps 20 degrees or so. My partner did something similar using thermal shielding (I had it left over from my Traveler refurb) and it did lower his temps a bit. My Auriga has an IO-540-C4B5 with a straight exhaust. During my 25/40-hour fly-out, the exhaust discolored the fiberglass fairings on the inside of the engine compartment before I caught the condition and started looking for heat shielding methods. The heat also took out the battery (bulged the front). At the suggestion of some posts on the forum, I consulted the JEG'S High Performance catalog. As I found out, JEG'S sells high-perf race car stuff, to include heat shielding and insulation. I ordered the stuff Thursday; it arrived Saturday (and that was 'standard' shipping). I attached the sticky-backed reflective shielding to the sides and bottom of the oil pan (parts facing the exhaust). I also wrapped the exhaust pipes with a high-temp thermal shield to keep the heat 'in' vs. letting it radiate out. Those wraps smoked a bit on the trial ground run, but that went away after a few minutes. Finally, I wrapped the fuel lines with thermal-shielding 'Fire Sleeve' to address some issues mentioned on the forum of the fuel perhaps getting so warm as to induce cavitation of the engine-driven fuel pump (usually after landing when it was hot). I put two layers of foam-backed, foil-lined insulation on the front of the battery to reflect the heat from the engine away from the front of the battery. My Tiger-owning friend and I flew formation to JKA (about 35 minutes for me) for lunch Sunday. My oil temps were 20 degrees lower, and the EGT 20 degrees higher (expected; the probe is inside the shielding). Most significant, I was able to pull the dipstick with my bare hands after shutdown where before, it took two thick rags as ‘pot holders’ to hold the thing. JEG’s sells an FAA-approved noise/foil insulation that I’m using under the carpets and on the walls of the experimental—a bit cheaper than the stuff Spruce or Wicks sells. If you’re looking for some simple treatments to lower temps and noise, suggest giving JEG’S web site a look. Chuck PS They sell lots of fittings that either are AN or are equivalent. Good builder resource. | ||
| jpels Unregistered guest |
As regards reducing exhaust heat, a group of car nuts (Lotus owners) here in the Houston area has been using a process of header coating as supplied by PolyDyn. The headers are coated internally and externally. I have had the process done, but I have not run the car since, as it is undergoing restoration. One of the guys claims that his headers are no hotter than his valve cover. I'll keep you posted, or will happily supply any of you directly with contact info if you are interested. The cars are fiberglass and we are continually trying to get engine compartment temps down. The process is quite popular in racing circles (of all kinds), and in restos of high-end sports-cars. Looks cool as well, but I immediately thought of the Express when I was perusing some of his testimonials. John Pels |