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#31
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Corvair conversion engines
On Fri, 20 Jan 2006 13:17:48 -0600, "Montblack"
wrote: wrote) I bought two 3.8L Ford V6's for $150 each, bought new pistons from Roush racing, new rings, had the best block shot peened bored and honed, had the best crank turned and nitrided, bought new bearings, new cam, new distributer with two sensors installed for dual ignition, new pistons, new timing gears and chain, planed the heads, had four new intake valves installed and new guides installed as well, new valve springs, roller rockers, new lifters, new carburetor, old style NWAero psru, ARP studs for the crank bearings and cylinderheads, fabricated my own headers, and STILL spent only about $6,000. Why not fuel injected? Also, is that two for $3K each? What does that setup weigh? Was matching a prop to your engine a problem? 3 bladed prop? Curious... Montblack I didn't go fuel injected for two reasons, simplicity and safety. Carburetors don't need an electrical system to operate and are basically pretty simple. If you are a mechanic, carburators are easy to diagnose and repair. Fuel injection requires a relatively high pressure fuel pump and of course, the injectors. Both of which are likely electrically operated. The carburetor *may* use a fuel pump, but it's of the 5 - 7 psi variety, and with a high wing airplane, isn't absolutely necessary in order to get fuel to the carburetor. So if the fuel pump fails, you likely will still be running. Plus, my entire premise was to not reinvent the wheel. Using the auto fuel injection requires the use of the car's computer. Using the computer requires all the sensors and sometimes faking the sensors out so that they give the proper information. It all seemed too arcane and difficult for me. Carburation does not produce less power than fuel injection, but it might be slightly less efficient, depending on how the engine is leaned, and how much the pilot pays attention to it. I paid $150 for each engine, and built one engine, not two. The weight of the setup is one of those "not sure's". It likely weighed in excess of 400 lbs, but probably not by much. The block is cast steel, but it's a thinwall design. The heads are aluminum, as is the timing chain cover, and intake manifold. It was the lightest V-6 being built, and may still be in it's 4.2L form. I also used the lightweight geared starter, rather than the routine Ford beast. The NWAero psru is noted for it's relative light weight compared to the Blanton version, which was it's genesis. I also used a lightweight aluminum machined flywheel, rather than the suggested Ford flexplate. Probably no gain or loss there. As to the prop, I bought an IVO Magnum and ran it using that while I tested the engine. I added largish mufflers to the header system I fabricated (header length and diameter suggested by "Headers by Ed". Ed sizes header tubes scientifically to promote maximum flow at the power settings most often used and altitude at which I would normally be flying. That required relatively small diameter header pipes (1 3/8), which is considerably smaller than the exhaust ports in the heads (1 3/4). The length of the headers tubes was also specified to maximise torque, which meant that they had to be 40" long and feed into 3" diameter collector pipes, which had to be at least two feet long each. When I first fired the engine up, all animals in the vicinity headed for the hills. It seemed like I was standing next to two machine guns blasting away. Of course, I was inside the shop at the time (with the sliding door open). I had to add two hefty mufflers to the exhaust system in order to run it outside the house without being attacked by the neighbors, even though I live in rural Vermont, with lots of trees between me and my neighbors. They were big and unwieldy and I wasn't planning to use them in the airplane. But I was unhappy with how noisy the engine was and was concerned about being a good citizen when flying in the area. I tried several inserts to try to quiet the barking down some, but nothing but actual mufflers helped. With the mufflers, you basically only heard the soft clicking of the lifters and the hiss of the carburator, over the whopping of the prop. As I advanced the throttle, the carburetor began moaning/roaring and the noise of that big prop took over with a whapping blatting roar. I literally had to chain the test stand/engine down securely or it would have tipped over for sure. I had built a test stand that was basically a fully instrumented vehical on casters. It had a battery, radiator and fuel tank. I could have strapped it into a flatbed pontoon boat and gone air boating. I had the engine up to around 3,500 or so for the last run before I shut it down and sold it and the airplane. At that rpm, lots of air was being blown back and things like rakes and shovels were flying off the walls of the car port. The test stand was tied down to the car port posts, which is why the air was blowing into the bays. It was obvious I would have needed to back off on the prop pitch a bit to get more rpm out of the engine, if I had continued. Corky Scott |
#32
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Corvair conversion engines
Is there any good reason to use the Ford instead of the Buick V6?
There are a lot more Buick V6s out there. Also, there is a lot of support from the aftermarket, hot rod and racing business for the Buick engine and apparently none at all for the Ford V6. I don't have personal experience. However, my fellow chapter members have told me that the Ford V6 engine is considerably lighter as it comes in (or from) a car. That said, the aluminum heads and blocks alleged to be available should make a lighter and stronger engine. BTW, the name "Bow Tie Racing" was mentioned, but yielded no plausible result in my quick web search. The only word of caution to which I can personally attest (from my younger and crazier days) is to be *very* careful of racing and hot rodding parts designed to give you oversized ports and manifolds. As you increase the diameter of the passages, you also decrease the velocity of the gasses; which will result in a very "cammy" high speed engine with poor pulling power and a poor ability to turn a fixed pitch propeller. |
#33
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Corvair conversion engines
wrote)
[good report snipped] I didn't go fuel injected for two reasons, simplicity and safety. Thank you for the report. Montblack |
#34
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Corvair conversion engines
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#35
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Corvair conversion engines
I enjoyed it.
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#36
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Corvair conversion engines
On Fri, 20 Jan 2006 08:06:33 -0600, Cal Vanize
wrote: I don't think there's any dispute over the relative cost of engines. This issue is longevity and whether one wants to fly an airplane with an engine that might not make it to the next airport. You mean like a Lycoming? or an old Franklin? |
#37
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Corvair conversion engines
clare wrote: On Fri, 20 Jan 2006 08:06:33 -0600, Cal Vanize wrote: I don't think there's any dispute over the relative cost of engines. This issue is longevity and whether one wants to fly an airplane with an engine that might not make it to the next airport. You mean like a Lycoming? or an old Franklin? Can't speak for Franklins. But I've never had even a skip on Lycomings with with over 400 hours flying PIC in plances with Lyc engines nor with any Conti with over 500 hours PIC in those. These weren't in homebuilts. |
#38
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Corvair conversion engines - cracked crank link
On Wed, 18 Jan 2006 22:49:19 -0600, Cal Vanize
wrote: Morgans wrote: "Cal Vanize" wrote The article does indicate that the cranks were from engines in planes that were flying. That's the good news. But does that also mean that the engines need a teardown and inspection as part of every oil change? If you are running a conversion that is different from William's conversions, it could be a good idea. g If people take the time (yeah, lots of it) to read the whole article, you will notice a few things, and I will attempt to point out some of the more significant (to me) points. Biggest point. Do not use corvair engines outside of the recommended operating parameters. Some sub points. Biggest one, don't use longer prop extensions. Big time no-no. Others include, don't use heavy props, or hand carved props. Don't overstress the prop with some aerobatic maneuvers, or hard landings. Make sure the crank is properly ground. Oil systems must provide for consistent oil flow to all parts, at all times; stay away from two line cooler and filter systems. Use low RPMs and big props, rather than smaller props and higher RPMs. Avoid detonation, which is easy to let happen, if treated like an aircraft engine. Obey all points of his conversion manual. Nitrated cranks are a good way to add an extra margin of safety, when obeying the conversion manual, but the other examples that have followed the manual have been OK for long operational periods, even without the nitrated cranks. Avoid other's add ons, like extra bearing hubs, as they have not been tested. I am sure I missed some points, or miss stated some, but if you are using corvair power, it would be wise to investigate what this man has to say, and not take my word on it. I remember saying a long time ago, that I would feel better (or something like that) if a redrive was used to take the stress off of the crank. I think I will still stand by those words. Of course, It would need to be a properly researched and tested redrive, which at this time, does not exist. Good points all. The point that stood out most for me was the part about the crank from the engine that William built for his own demo 601. From the article: "This engine represents a standard installation, albeit one that was flown at its limits by Gus"... "showed stress fractures on both sides of the area in question." at 200 hours. "no nitride" Note with particuclar interest the phrase "represents a standard installation" regardless of how his pilot flew the plane (it was HIS pilot after all). The statement goes on to say that the engine "was flown at its limits" not beyond its limits. What William wrote is that an engine he purposefully built himself for his own 601 demo plane had a not insignificant crank issue. If he was following his own recommendations, why did he use a crank that wasn't treated? He may be the Corvair conversion expert, but I'd like to read an explanation as to why he wasn't following his own specs. I have read every word on William's web site. It would appear that he has done his homework and research. He may be the most credible source for Corvair conversion aircraft engines. But yet, this discrepency sticks out sorely. It was built BEFORE the crack issue came up and BEFORE the recommendation to use a nitrided crank. VERY simple. |
#39
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Corvair conversion engines - cracked crank link
On Thu, 19 Jan 2006 09:05:51 GMT, Richard Lamb
wrote: Morgans wrote: "Cal Vanize" wrote Good points all. \ Yes, that paragraph does seem to run contrary to the rest of the _long_ website's information. So what gives, others in the know? Or could it be that it's just taken a few years to rack up 200 hours? I didn't catch a time span reference on any of the example engines. But I thought it has been years? About one year of flying - MAX. |
#40
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Corvair conversion engines -
clare at snyder.on.ca wrote:
On Fri, 20 Jan 2006 08:06:33 -0600, Cal Vanize wrote: I don't think there's any dispute over the relative cost of engines. This issue is longevity and whether one wants to fly an airplane with an engine that might not make it to the next airport. You mean like a Lycoming? or an old Franklin? Oh for Pete Sake...ok. A couple of years back, I picked up an Aeronca Chief down in Florida and flew it home. Real nice airplane, and a real bargain - because - the engine wasn't all that great. Continental 85 with metal prop. It had been "overhauled" by one of the club members (not A.P.) and they (the sellers) were honest about it up front. It leaked (a bit). And they were right reasonable on the price. So a deal was offered, $1000 earnest money sent. And Leo and I went down to see?/fetch? We flew it around for a while and determined that the plane was rigged nice and straight, stalled straight ahead, and with the 85 and a climb prop, it could for sure and certain - climb! The little engine ran strong. Checking the oil level shortly after landing (yeah, I know) showed it had indeed lost some oil, but we found it - all on the belly. Oh well, I'm not going to have to clean it. Not part of the deal. The seller offered to "wipe her down and top off the oil and gas". (yeah, I know - now.) So, next morning, oil and gas are full and we headed off for home. It took 3 days to get home and about 12 hours flying. Two hour legs left an hour fuel reserve for the Chief. And the climb prop doesn't go anywhere in a hurry - except up. This engine leaked so much oil it would embarrassed a Harley. I mean really! But something else was wrong. The engine ran fine, but it felt a little sharper than normal during climbs, but smooth out fine at cruise. For the next three days (over swamps, timber, and once VFR on top, I could actually hear/feel/taste it getting worse. A little sharper at first. Then louder. Each takeoff. Only while climbing. On the last leg home I thought maybe an exhaust muff was opening up maybe? And then thought - or a cracked mount? But it smoothed out at cruise. When we rolled out at home, I was glad to be there, because I had decided that the engine was indeed failing and needed to be looked over. Very carefully. BEFORE flying it again. It still ran strong, but something was really major league wrong somewhere during climb out. When Bob (A.P.) tore it down he found the bad seals, sure, and some other minor stuff, and one cylinder with a crack about 1/4 of the circumference of the flange. The crank and cam were ok. Mags ok. A (as in one each - count it) new jug, bearings, seals, etc. signed off major overhaul cost 4 grand. Grandpa, the new owner, it totally tickled with his Chief. He learned to fly in it. Took his PPSEL check ride in it. Took his _wife_ flying in it! Someday his boys will have their chance to learn to fly in it. So, what exactly is the point, you ask? This issue is longevity and whether one wants to fly an airplane with an engine that might not make it to the next airport. Right Hell if I know. But it was a fun trip otherwise... Richard |
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