O360.... Squeeze out more power?

[RoscoeT]

You're either an MMO devotee or you ain't.

I can lead you, but I can't make you drink.

You gotta hand it to those old MMO creators - they were marketing geniuses. Mix up some mineral oil, pain thinner, dye, and perfume and call it "mystery" oil. The only thing mysterious about it is what it's actually good for. Therein lies the genious. There are some fervent true believers out there, though. Faith is much more powerful than science.

 

[poadeleted20]

Mill .030 off the the both the case and cylinder mating surfaces.

Is that something which is authorized in the O-360 maintenance manual? I kind of doubt that method of increasing compression ratio is actually authorized, but it's the sort of thing some air racers used to do before some race organizers started doing NASCAR-type tech inspections on airplanes with unexpectedly good performance.

 

[poadeleted20]

It would be far easier to just buy 10:1 pistons and throw those in.

Exactly what Maybelle Fletcher did in her Tiger in the old Powder Puff Derby -- until she got caught.

 

[poadeleted20]

How about a constant speed prop? I have seen a Archer with one.
Looks like MT has a STC for a three blade constant speed composite prop.
http://www.mt-propeller.com/en/entw/stcs/pa28_2.htm
Dave

I can't speak directly to this choice in the Archer, but the Tiger has virtually the same engine and also has that prop STC'd for it. My experience in side-by-side Tiger flight tests , and the before/after data when the only change was the prop, suggests that this gives no significant speed improvement in Tigers that had the 63-pitch Sensenich prop which was STC'd for AA-5B's and standard on AG-5B's replaced by that MT 3-bladed prop. The only apparent benefits were the ability to descend at cruise power without exceeding redline RPM, about a 10% reduction in takeoff roll thanks to better initial acceleration (up to about 40 knots), and reduced cockpit noise.

The problem on cruise speed is that 75% power only gives you so much thrust no matter what prop you're turning unless the prop gives you better efficiency, I think the reduced efficiency of the three shorter blades on the MT prop compared to two longer blades counterbalances any improvement otherwise obtained.

Of course, that's a different airframe, but I still think it suggests some caution in expecting any significant increase in cruise speed if you replace the original Sensenich prop on an Archer with the MT 3-bladed prop.

 

[Ted]

Agreed..... And finding pushrods to get the proper valve lash will be
"interesting"............. Actually that would be proper hydraulic lifter preload...

Exactly what Maybelle Fletcher did in her Tiger in the old Powder Puff Derby -- until she got caught.

My point was if you're gonna break the law, why go to that much effort? And no, I'm not endorsing breaking the law.

 

[N801BH]

My point was if you're gonna break the law, why go to that much effort? And no, I'm not endorsing breaking the law.

I understand sir....
I was just pointing out to Henning the complications of milling the case and cylinder barrels shorter to raise the compression...

 

[Ted]

I understand sir....
I was just pointing out to Henning the complications of milling the case and cylinder barrels shorter to raise the compression...

Agreed as well!

 

[Jimmy cooper]

Why not call Don swords and ask him?

 

[JHW]

if you're going to cheat then there is no partial credit, might as well cheat big. Swap the data plate onto a 390 or at least get the cylinders.

 

[Ted]

Problem with a 390 is the cylinders are about $2k each last I checked, only available from Lycoming. Plus then the crankcase would need to be machined for the cylinders, and angle valves are wider so I don't know if they'd fit. Much cheaper to buy a set of illegal pistons, although it won't get you the same power improvement.

 

[Unit74]

I called AOPA and asked how much insurance would be on a 5 place Bo today, 110k hull... She said about $4500 a year with PPL-IA., no HP or retract time. Thats insane. A mooney M20j, same value was $3k.

Based on what I have now, that ups my fixed costs $400/mo to just over $1100 and that's not even getting off the ground. All in, no MX reserve I'm at $685 on the Archer.

That's a hard pill to swallow.

 

[N801BH]

Problem with a 390 is the cylinders are about $2k each last I checked, only available from Lycoming. Plus then the crankcase would need to be machined for the cylinders, and angle valves are wider so I don't know if they'd fit. Much cheaper to buy a set of illegal pistons, although it won't get you the same power improvement.

Yup...

No substitute for cubic inches...

 

[Ted]

I called AOPA and asked how much insurance would be on a 5 place Bo today, 110k hull... She said about $4500 a year with PPL-IA., no HP or retract time. Thats insane. A mooney M20j, same value was $3k.

Based on what I have now, that ups my fixed costs $400/mo to just over $1100 and that's not even getting off the ground. All in, no MX reserve I'm at $685 on the Archer.

That's a hard pill to swallow.

AOPA and Avemco are not good insurance companies. They are high cost. Get a real broker and tell them to pound sand. That's more than my Aztec insurance was when I had 0 MEL time and 225 total.

 

[poadeleted20]

I called AOPA and asked how much insurance would be on a 5 place Bo today, 110k hull... She said about $4500 a year with PPL-IA., no HP or retract time. Thats insane. A mooney M20j, same value was $3k.

Either way, it goes down a bunch the second year when you have some significant time in type.

 

[poadeleted20]

No substitute for cubic inches...

I think "Big Daddy" Don Garlits' actual line was "There's no replacement for displacement." But doing what Henning suggested or putting in the 10:1 pistons doesn't change displacement, only compression ratio.

 

[Ted]

I think "Big Daddy" Don Garlits' actual line was "There's no replacement for displacement." But doing what Henning suggested or putting in the 10:1 pistons doesn't change displacement, only compression ratio.

Which improves your utilization of that displacement.

 

[Henning]

It would be far easier to just buy 10:1 pistons and throw those in.

Do both and you may end up at 11.5:1 and take advantage of 100LL, or better weld up some domes and get 12.5:1.

 

[N801BH]

Do both and you may end up at 11.5:1 and take advantage of 100LL, or better weld up some domes and get 12.5:1.

Actually, I "think" Lycon offers 12:1's and has them in stock.. And if you run 100LL it should not detonate........... too bad...

 

[Henning]

Actually, I "think" Lycon offers 12:1's and has them in stock.. And if you run 100LL it should not detonate........... too bad...

I never had problems running 12.5s on premium pump gas.

 

[Ted]

I never had problems running 12.5s on premium pump gas.

Were you doing it on a Lycoming?

 

[Stewartb]

I think it's accurate to say that increasing compression improves volumetric efficiency so there is a gain to be had. The problem in airplanes is the long durations at high percentage of power output at relatively low RPMs and air cooling. That's a tough combo. I have several experimental Cub buddies running higher compressions but none exceeds 10:1. A couple use nitrous and they've accelerated component failures. The response has been to increase displacement to make up for not using nitrous. Funny how guys go full circle.

If you're going to use very high compressions you'd probably better have a well tuned fuel injection system. Updraft carbureted intake systems don't feed fuel all that well. But I'm jaded. I have an 0-520.

 

[Ted]

My experience is that 10:1 compression is about the max that is reasonable for use on our engines. If you had a particularly odd application (like being based at Telluride and limiting yourself on manifold pressure) then I could see an argument for 12:1, but I could see a better argument for forced induction.

Aside from detonation, you also get into crankshaft longevity issues. The crank really doesn't care what power you're making, it cares what peak forces it sees. The two aren't entirely linear as far as relationship, and higher compression increases peak pressures.

Detonation is a real concern, although that can be mitigated with proper use of the mixture knob.

 

[nrpetersen]

That particular O-360A4M model Lycoming engine has no damper on the crankshaft rear whose job would otherwise be to reduce torsional vibration in the propeller/drive system. Whatever you do, be sure the exact prop-engine combination is approved by those who know about these things.

I don't, but I have heard bad comments from those who do.

 

[moonshine]

I fly the same engine on my DA40-FP Diamond
With the more aerodynamic airframe to pull along and a power flow exhaust, I very rarely fly at max open throttle below 10k, since the tach will redline.
I have the same chunk'o'metal prop, pitched a bit more (forget the numbers, same as Tiger), with a new style Donaldson filter (no k&n stc for my plane) I get 2300rpm at static (used to be 2250 with stock filter)
138Ktas at 7-8k at 75% lean at peak all day long with no wheel fairings and 600x6 mains.
Point being, smooth out the airframe and put some rejex on top.

 

[flyingcheesehead]

Anything that fills the micro-pores of the cylinder bore wall is going to help out with compression IN THEORY.

And MMO will do neither. Even if it did "fill the micro-pores" the compression ratio would go from 8.5:1 to 8.49999999999999:1 and you wouldn't get any noticeable performance improvement out of it.

You're either an MMO devotee blind believer in marketing lies or you ain't.

FTFY.

I can lead you, but I can't make you drink.

Seeing as how bull**** is a solid, it's pretty hard to drink.

Mill .030 off the the both the case and cylinder mating surfaces.

An interesting idea, with some flaws as discussed by others, but again a relatively insignificant increase in compression from 8.5:1 to 8.9:1, resulting in about 1.32 hp added and a speed increase of about 0.3 knots, presuming you solved the flaws. Nice try though.

I have been researching the idea of stepping up to a Saratoga or A36, but I just don't want to get rid of this Archer. It will fly 129kts all day and if I could squeeze a few more out, I'd probably be convinced to do the interior, paint it and drop in a 540 and gpss roll stering.

Consider yourself lucky - You already have the fastest Archer I've ever heard of. Best I've seen myself was 122, and that was on a nice clean 80's model with the fully-faired gear, which I presume you already have - Not sure if there's a way to add that after the fact? If not and there is, that'll buy you some speed.

However, at this point you've already got one of the fastest examples of the type and you'll likely be spending several thousand dollars per knot. If your plane still isn't fast enough, you need to switch types. If you like Piper and could use another seat, go with a PA32R (Lance/Saratoga).

 

[poadeleted20]

I fly the same engine on my DA40-FP Diamond
With the more aerodynamic airframe to pull along and a power flow exhaust, I very rarely fly at max open throttle below 10k, since the tach will redline.
I have the same chunk'o'metal prop, pitched a bit more (forget the numbers, same as Tiger),

The allowable prop pitches for the Sensenich 76EM8S10-0 prop on the AG-5B Tiger are 61/63/65. On the AA-5B, the STC for that prop (replacing the OEM McCauley) allows 60-65, with most folks using 62 or 63. Early Archers use the 76EM8S5 prop at 60 pitch IIRC, but I don't know what the difference is between the EM8S5 and the EM8S10-0, so I don't know how comparable those are. Later Archers use the 76EM8S14-0-62 (the 62 being the pitch), but again, I don't know how comparable the EM8S14-0 is to the others. However, the DA40F uses the same Sensenich 76EM8S10-0 as the Tigers, pitched at 63 (middle of the Tiger range).

 

[bluerooster]

The Only way to get more power is to burn more fuel.
Either by putting more fuel through the engine, or burning more efficiantly the fuel that's already being put through the engine. problem with the latter is that with our aircooled engines, the temps resulting from burning a stoic mixture 100% of the time will cause problems. So you must run either a bit rich, or a bit lean. Either way is a reduction in power from burning a stoic mixture.
So ya gotta burn more fuel. In order to do that, ya gotta feed it more air, or change fuel types.

You may want to contact Power Flow and ask them why they don't offer the STC for the Archer. You may offer then the use of your airplane as a testbed for the STC. A friend of mine has a Sundowner, which was the testbed for developement of the STC for the C23. End result was he now has a powerflow on his C23 at a reduced cost. And other C23 owners can now get a Powerflow.

 

[Pilawt]

You may want to contact Power Flow and ask them why they don't offer the STC for the Archer.

I believe it's because of the location of the muffler in the cowl. Cherokee 180s with the old pre-1964 blunt cowl, which had the muffler mounted rearward near the firewall, do have a Power Flow STC.

 

[Unit74]

Consider yourself lucky - You already have the fastest Archer I've ever heard of. Best I've seen myself was 122, and that was on a nice clean 80's model with the fully-faired gear, which I presume you already have - Not sure if there's a way to add that after the fact? If not and there is, that'll buy you some speed.
.

I don't know how much money the previous owners threw at it, but it has the whole Knots2U pa28-181 catalog on it minus the wingtips, which are stock. A fresh engine and rigged tight help too. But firewalled and leaned up a bit, it will do 129. I usually pull it back to 125 and burn around 9.6 or so at 7k.


I'm really on the fence about selling, or keeping. I really only need the 5th seat maybe, 3-5 times a year at most. If there was a club I could get into locally with a Toga/Bo/ 6 seater I would be dumping 20k in the Archer panel right now and keeping it! I am looking at the IDF540 really, really hard right now.

 

[poadeleted20]

The Only way to get more power is to burn more fuel.

That's not true, as you point out yourself.

Either by putting more fuel through the engine, or burning more efficiantly the fuel that's already being put through the engine.

...problem with the latter is that with our aircooled engines, the temps resulting from burning a stoic mixture 100% of the time will cause problems.

That's also not true. Things you can do to reduce power losses (like a tuned exhaust system or optimized ignition timing like a LASAR ignition system) will allow you to send the same power to the prop on less fuel or more power to the prop on the same fuel, and those can do so without excessive CHT's.

 

[Pilawt]

Things you can do to reduce power losses (like a tuned exhaust system or optimized ignition timing like a LASAR ignition system) will allow you to send the same power to the prop on less fuel or more power to the prop on the same fuel, and those can do so without excessive CHT's.

No free lunch with a LASAR. My 172N/180 (with Power Flow) came to me with LASAR installed. I had to carry a special tool kit around in the airplane because few mechanics in the field have the equipment to service the oddball mags. It ran roughly at idle. Then I read in the manual (below) that the LASAR system increases CHT by 20°F. The first time a mag even cleared its throat I had the whole system taken out and returned to normal configuration. Now it runs better and cooler.

 

[Henning]

Were you doing it on a Lycoming?

Hell no, 350 Chevy done my way instead of Chevrolet's, 4-1/8 (400)bore block and 3-1/4 (327) stroke crank using 6.3" rods (rather than 5.7 to decrease the rod angle).

The IO-360 I did that ended up in my Midget Mustang was 11.7:1 though with a custom cam Ed Iskendarian did for me himself. It never had a problem on 100LL and I ran it at 2900 rpm almost exclusively.

 

[RichNY]

Hell no, 350 Chevy done my way instead of Chevrolet's, 4-1/8 (400)bore block and 3-1/4 (327) stroke crank using 6.3" rods (rather than 5.7 to decrease the rod angle).

The IO-360 I did that ended up in my Midget Mustang was 11.7:1 though with a custom cam Ed Iskendarian did for me himself. It never had a problem on 100LL and I ran it at 2900 rpm almost exclusively.

Wait till Rotor and Wing reads what you just wrote.

 

[RichNY]

I believe it's because of the location of the muffler in the cowl. Cherokee 180s with the old pre-1964 blunt cowl, which had the muffler mounted rearward near the firewall, do have a Power Flow STC.

When I had my Archer, I was told by Power Flow that they couldn't improve on the stock system enough to get the performance gain they wanted.

 

[poadeleted20]

Wait till Rotor and Wing reads what you just wrote.

I suspect his Midget Mustang was E-AB, and that's a lot different from the production airplane which started this discussion when it comes to tinkering with the design. So, I don't see what R&W could object to about it, at least on a regulatory basis.

 

[RichNY]

I suspect his Midget Mustang was E-AB, and that's a lot different from the production airplane which started this discussion when it comes to tinkering with the design. So, I don't see what R&W could object to about it, at least on a regulatory basis.

The point that Isky himself made Henning a cam.

 

[poadeleted20]

The point that Isky himself made Henning a cam.

Not sure that's an issue on E-AB regarding it not being a certified aircraft part, and aircraft owners can contract out spare parts manufacture.

 

[Ted]

No free lunch with a LASAR. My 172N/180 (with Power Flow) came to me with LASAR installed. I had to carry a special tool kit around in the airplane because few mechanics in the field have the equipment to service the oddball mags. It ran roughly at idle. Then I read in the manual (below) that the LASAR system increases CHT by 20°F. The first time a mag even cleared its throat I had the whole system taken out and returned to normal configuration. Now it runs better and cooler.

The LASAR wasn't a very good example. It worked, but not very well.

The newer setups that are now certified I'm much more interested in. On my list the funds come in.

Hell no, 350 Chevy done my way instead of Chevrolet's, 4-1/8 (400)bore block and 3-1/4 (327) stroke crank using 6.3" rods (rather than 5.7 to decrease the rod angle).

The IO-360 I did that ended up in my Midget Mustang was 11.7:1 though with a custom cam Ed Iskendarian did for me himself. It never had a problem on 100LL and I ran it at 2900 rpm almost exclusively.

Angle valve or parallel valve?

That is high compression. And on 100LL when operated normally, I'd expect it to be ok. Plus I recall you saying you flew your Midget Mustang highish altitude and longish trips, which will also lessen the burden on the crank.

12.5:1, egh... I wouldn't do it. But 10:1 would be my normal limit.

 

[RichNY]

Not sure that's an issue on E-AB regarding it not being a certified aircraft part, and aircraft owners can contract out spare parts manufacture.

Sigh...

 

[Henning]

The point that Isky himself made Henning a cam.

Ed and I went back to when I was a kid, he was buddies with one of the guys that had the engine machine shop I would work for and would stop by when he was in St. Louis. There was a great man, if you asked him a question about designing a cam, you better have a half hour for the explanation, he was very liberal at giving out his information and tricks. He was also a consummately upstanding business man and stood behind the quality of his products, he even bought a $20,000 engine when his new cam broke on a dyno run and lunched the engine. All he asked was that I find every piece of the cam I could and send it to him. The racing world is as small as the aviation world.