Van's Air Force
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which IO-540?
- Thread starter smenkhare
- Start date
w1curtis
Well Known Member
TT,
After you have added fuel injection and provisions for C/S prop to the O-540- B2B5 engine. What was your savings over over a standard D4A5 producing 260 HP (8.5:1) since the B2B5 at 7.5:1 compression only produces 235 H?
B2B5
Hi William,
The 235 spins slowest of all those series, in addition to the lower compression. Since the crankshaft, camshaft, are capable of spinning faster, I chose to do just that. It also required a change in counter weights, to match the prop (from a Lance), and balancing, to help out as well. Without a dynomometer, I can only calculate power and it should be 250 to 255. I also changed base timing, from 22 to 25 deg. I plan to use mogas as much as possible. Having done so with my Arrow, FI, mogas and LASAR was short of an eye opener, results of which were astounding.
In my racing days, I lowered compression (after having raised it as was the standard practice) on 3 different engines, with improved results, so why not a slug like a Lycosaurus. A dyno was available at the time, and it proved to be true. There were other minor changes to go along with the drop in compression.
Since reliability was the object, the drop in compression, was called for. Surprisingly, and with the help of the dyno, we gained the reliability and a boost in performance.
At this time, I can only predict, but based on 900 hrs of "tinkering" with the Arrow, there should be an improvement in power over the 235 of at least 15 hp, which, though calculated, is conservative, but a significant improvement in fuel consumption with mogas and a measurable improvement with AV gas (mogas was better consumption and power wise).
Like the Arrow, I'm planning engine speed at cruise at 2400. With six cylinders (better balancing than 4) , and lower compression, I believe it will be reliable and economical to operate. The joys of experimental.
TT
RV10
N968TP
Hi William,
The 235 spins slowest of all those series, in addition to the lower compression. Since the crankshaft, camshaft, are capable of spinning faster, I chose to do just that. It also required a change in counter weights, to match the prop (from a Lance), and balancing, to help out as well. Without a dynomometer, I can only calculate power and it should be 250 to 255. I also changed base timing, from 22 to 25 deg. I plan to use mogas as much as possible. Having done so with my Arrow, FI, mogas and LASAR was short of an eye opener, results of which were astounding.
In my racing days, I lowered compression (after having raised it as was the standard practice) on 3 different engines, with improved results, so why not a slug like a Lycosaurus. A dyno was available at the time, and it proved to be true. There were other minor changes to go along with the drop in compression.
Since reliability was the object, the drop in compression, was called for. Surprisingly, and with the help of the dyno, we gained the reliability and a boost in performance.
At this time, I can only predict, but based on 900 hrs of "tinkering" with the Arrow, there should be an improvement in power over the 235 of at least 15 hp, which, though calculated, is conservative, but a significant improvement in fuel consumption with mogas and a measurable improvement with AV gas (mogas was better consumption and power wise).
Like the Arrow, I'm planning engine speed at cruise at 2400. With six cylinders (better balancing than 4) , and lower compression, I believe it will be reliable and economical to operate. The joys of experimental.
TT
RV10
N968TP
w1curtis
Well Known Member
TT,
In these days of $5 avgas, that sound like a pretty good idea. So in the end you left the compression at 7.5:1, and upped the max RPM to 2700-though you cruise at 2400. For us with the D4A5, reducing the compression to 7:5:1 may also allow the safe use of mogas.
Interestingly on my Cardinal, I find I take off and climb at 2700, I cruise at 2500, and I let down at 22-2300. Not sure how I will do it on the -10. Many cruise at the -10 2250.
In these days of $5 avgas, that sound like a pretty good idea. So in the end you left the compression at 7.5:1, and upped the max RPM to 2700-though you cruise at 2400. For us with the D4A5, reducing the compression to 7:5:1 may also allow the safe use of mogas.
Interestingly on my Cardinal, I find I take off and climb at 2700, I cruise at 2500, and I let down at 22-2300. Not sure how I will do it on the -10. Many cruise at the -10 2250.
w1curtis
Well Known Member
Any model of the parallel valve 540. I think there is one flying with an angle valve 540 but this would require a LOT of modifications. You also have to make sure you have the correct mounting ears for the Van's mount. These supposedly vary even within the parallel valve engines but can be interchanged.
D4A5
Will,
I doubt that running the D4B5 on mogas would be much of an issue. It's basically a 6 cylinder IO 360, that shares the same barrels and compression.
Originally the IO360 B1E 180 hp, 8.5:1 used 89/91 octane AV gas, no longer available. Mogas will be an improvement, so unless warranties are an issue, I'd use mogas.
I fly 3 ACs that use mogas, one before it was legal, and considering it's age, at the time of it's birth (46 T craft), AV gas was an "option". The other is a C182, and an oil guzzler, it's STCed for mogas 87 octane. The difference between AV and mogas performance and economy are very noticeable. With mogas, consumption drops, as well as oil consumption for equivalent power settings. In addition it's JPI, displays near stable temperatures as opposed to AV gas where they bounce all over the place.
The 3rd is a Searey amphip with a 912S Rotax. With AV gas, oil changes are to be tripppled, the engine speed at cruise is unstable, and power is down. Plugs (now with more than 400 hrs.) glazed up almost immediately.
For me. it would be mogas.
TT
RV10 N968TP
Will,
I doubt that running the D4B5 on mogas would be much of an issue. It's basically a 6 cylinder IO 360, that shares the same barrels and compression.
Originally the IO360 B1E 180 hp, 8.5:1 used 89/91 octane AV gas, no longer available. Mogas will be an improvement, so unless warranties are an issue, I'd use mogas.
I fly 3 ACs that use mogas, one before it was legal, and considering it's age, at the time of it's birth (46 T craft), AV gas was an "option". The other is a C182, and an oil guzzler, it's STCed for mogas 87 octane. The difference between AV and mogas performance and economy are very noticeable. With mogas, consumption drops, as well as oil consumption for equivalent power settings. In addition it's JPI, displays near stable temperatures as opposed to AV gas where they bounce all over the place.
The 3rd is a Searey amphip with a 912S Rotax. With AV gas, oil changes are to be tripppled, the engine speed at cruise is unstable, and power is down. Plugs (now with more than 400 hrs.) glazed up almost immediately.
For me. it would be mogas.
TT
RV10 N968TP
