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0-320 h.p. increase, help wanted

Luke_theDrifter

Registered User
Dillingham, Alaska
Hypothetically, if I'm wanting to build another 0-320 with the intent to get as much h.p. from the engine as posible, and still keep it as legal as posible, what steps would I take? I realize keeping it "as legal as posible if like being kinda pregant", thatswhy this is strictly a hypothetical question.

The way I understand compresion ratio's for an 0-320 the 7:1 should produce about 150 ponies, the 8 1/2:1 produce's around 160 ponies, 9 1/2 : 1 should put it in the 178 h.p. range, and the 10:1 around the 184 h.p range.

Ly-con seems to be producing good results w/ their head work.

There seem to be two popular carbs, from memory the last two digits in one of themis a -13, and the other is a -8. A factory Presision Carb guy told me once that one flows more fuel than the other, meaning making more ponies. I need some help in this area. Any carburator suggestions are more than welcome. Any work to be done to the intake/oil pan?

How about making all of the intake tubes the same lenght, comments on h.p gains?

Nearly all 0-320 that are in common use seem to use the same ignition system, either bendix or slick mags. Is there any other options to put more fire into the engine? I'm already sold on the Iridium spark plugs, anything else to gain ponies from the ignition system?

Nearly all race cars use some type of direct drive system for the accesories. I'm just sure the standard alernator belt is pulling some h.p. from the engine, as small as it may be. I have ask this question before, any calulations to figure what you might "gain/save" by running the small atlernator (direct gear drive) from the assy. case?

Is there anything else I'm NOT thinking about? A well balanced engine w/ every aspect built w/ performance in mind. I'm fairly certain I'm up to date w/ most of the weight saving issues, now I need more power!

good flying..>Byron
 
Byron don't forget about the exhaust system part of the equation. It would have to be upgraded as well. Each upgrade would come with pros and cons be sure that you understand the all of them as a whole.

Matt
 
1) Center carb sump.

2) 0-360 equal length, larger diameter risers.

3) Machine the case deck height down to the minimums (lowers the cylinders and gains about 1 comp. ratio)

4) Alternator field on a "breaker switch" so you can have it free wheel during take off. Good for 5 hp right there.

5) Light weight "everything". Cut all the unnecessary carp off and throw it away.

6) 82/42, well balanced and tuned Borer prop.

7) Go on a diet and loose 20 lbs.

8) Buy 500 gallons of gas and go fly, fly, fly.

Best wishes! Crash
 
Thanks to all for the help so far......

Cub37..>I forgot to mention in the original post that I'm familar w/ the two hot-rod exhaust systems on the market.
In fact I'm already running one of them, on an engine that does "good" (producing well in excess of 170+ hp, "on paper", in real-life its' the strongest 0-320 I've ever ran), but I want to build a real stomper engine!

Through much research I have greatly narrowed down the field of the many options/parts & custom work and know some of stuff I'll use; I know what type of head work to be done and who will do the work, machine work & valve train, I know what pistons to use, brand-type and specs. of camshaft, and so on.

I think there is more work to be done w/ the ingintion system, and carb-intake area. If anyone has specific knowledge in these two area's I'd be greatful for the info.

PA-12..>I'll call Monte Barrett, thanks for the contact info.

Crash..> I got number 3-7 covered, plus LOTS of avgas.
Kindly explain more of what you mean in #1 and #2. Keep in mind of course this is an 0-320.

Anyone got an opinion, or real-life knowledge, of how much h.p. is "robbed" from spinning the alternator & belt (already using a switch to shut it off ), versus running a direct drive, (gear driven Alt.,) from the assy. case? In other words, NO belts, plus a flywheel that has been machined to remove the belt pully, which also would be a good time to dynamically balance it. Would it be reasonable to assume you could re-capture 2-3 h.p?

good flying..>Byron
 
If you hand prop you can get rid of the flywheel altogether and install the spacer that is listed in the O-320 parts. The spacer is no larger than the crank flange, and could easliy be machined out of aluminum as a owner produced part. The "flywheel" really isn't a true flywheel, it is a support for the starter ring gear.
 
Luke; A popular local Cub re-builder has this set up on his PA-18 and has it signed off as legal. It's an O-360 sump that centers the carberator on the engine and makes all the riser tubes from the sump to the cylinder intake ports the same length. This is part of the difference in an O-360.

The O-360 riser tubes are also larger in diameter then the O-320 risers. This lets the engine breath easier on intake. He has a 3" tail pipe on an Atlee Dodge stock muffler. I personally think 2 1/2" is large enough on the tail pipe, 2" is stock. With an 82/46 borer prop he claims it turns 2800 rpm wide open and 2500 static.

Shaving the cases to gain compression ration with legal pistons came from another source but is still legal.

There is a lot more you can do to an O-320 if you were experimental but this is about it in a certified Cub. As for me I have gone the O-360 route and still really like it. I have another friend that built up a hopped up O-320 PA-18 like mentioned above. He then built up another PA-18 with an O-360 in it. He sold the hopped up O-320 Cub a while later. He told me the O-360 Cub "did everything better". In my opinion (other then landing, and here they are about the same) it does. Take care. Crash
 
True...but.....they open it up to flow more fuel. I am not sure what this really means but thats what I was told by a reliable source.

Bill
 
Bill Rusk said:
True...but.....they open it up to flow more fuel. I am not sure what this really means but thats what I was told by a reliable source. I dont know what they do. You would have to talk to Ken at Ly-con. He would tell you.

Bill
 
Byron wrote:
>The way I understand compresion ratio's for an 0-320 the 7:1 should >produce about 150 ponies, the 8 1/2:1 produce's around 160 ponies, 9 >1/2 : 1 should put it in the 178 h.p. range, and the 10:1 around the 184 >h.p range.

Byron, the 150 actually puts out slightly more than 150 hp at rated rpm (from memory, something like 151 hp). For simplicity, let's assume that it is exactly 150 hp at rated rpm.

The hp increase with compression ratio is simply the increase in thermodynamic efficiency, and it doesn't increase linearly.

So, raising the compression to 8.5 gives 159.51 hp, to 9.0 gives 162.18 hp, to 9.5 gives 164.64 hp, and 10 gives 166.93 hp..... More or less :-)

This is substantially less improvement than you are assuming you would get. I have an O-320-E2A that I have increased from 7.0:1 up to 9.00:1, and the difference in climb matches closely what would be expected from the difference in thermodynamic efficiency that I quote above. Personally, I'd be leary of going more than 9.5:1 in a daily runner, due to the increasing liklihood of detonation. And I wouldn't recommend to anyone that they increase compression above stock, due to liablility concerns should they have problems with their engine.
All the best,
JimC
 
I put 12:1 pistons and flow matched cylinders in an IO-540. Made a big difference. Lycon has been using those pistons in the O-360s.
 
12.0:1 in an o-320 would give 16.4% more power than the 7.0:1 pistions in a 150, for 174.7 hp.

I would expect that it would need to run full rich at all times to minimise the chance of detonation (in automobiles, 11.2:1 is considered to be the detonation maximum for premium auto fuel).

JimC
 
It is just a hunch, but if you look at sustainable torque (which is really important for a climb). The increase in compression will result in a non-linear relationship with regards to torque less attractively than horsepower. I know it can be done, but it is very tricky and less predictable (when the fine line is crossed over you get $$$$).
Again, there is no replacement for displacement!
 
LY-CON has put High compression pistons in engines that were hooked up to read cylinder pressures with special made sparkplugs while on the dyno and found that the cylinder pressures were less than stock compression at cruise RPMS! But at full power the pressures were a lot more than stock. I found this interesting. Palhal
 
I've asked this question before, and didn't get an answer. I'll try again.
At any given compression ratio, what is the octane rating fuel that is required?
Lets say I want to run 10 to 1 compression ratio, what octane rating fuel do I need?
 
Another sincere thank you to all who have contrubiuted info....

It seems like a MAJOR contributing factor in keep the ponies so low on an engine of 320 c.i.d, is the RPM. Once again, through much research, it is pretty well agreed by most enegine guru's that a guy shouldn't run more than about 3,000 RPM. Simpily stated there is just to much steel (heavy) revolving around inside this opposing cylinder engine to safely spool up the RPM's....

...>Jim, point well made on the compression ratio, versus the h.p. increase. I have also learned that there are a fair number of people that throw around some very generous numbers when talking about h.p. Your numbers are consistent w/ other educated engine folks I have spoken to.

The "generous horse power" numbers don't seem to be as bad as some of the "lightweight" airplanes numbers I've seen, but I can definatly see a pattern... :lol:

Of course in building an engine of greater than stock h.p. there are many aspects that make-up the entire package. Some of the major influences include; c.id., compresion ratio, cam & valve train, delivering the fuel well & in proper quanity, iginition system, exhaust, and some other less important factor's.
At this point I have a lot of "proven data" to draw from, plus some other stuff that will be unqiue to the engine I'm building.
That said, and taking everything into consideration, I think it is very plausable to obtain a true 176-182 ponies at the prop. Which, by the way, is more than most stock 0-360's deliver to the prop, on a Cub, plus at considerable weight saving's. If it all works out as planned it should be a great preformer....

Now its time for me to get building and quit chatting about it! I will glady post the full results once the engine is built, running, and all the bugs are worked out, stay tuned!

Good Flying...>Byron
 
I'm not an educated engine folk, but the compression thing is just everyday thermodynamics, so is fairly straightforward. As you say, there are other ways to further boost an O-320's horsepower. As an aside, I think Lycoming may be coming out with a retrofit for roller lifters into older engines. That should help at higher rpms.

My own 9.00:1 O-320-E2A turns 2780 to 2790 rpm in cruise with a 62" pitch prop, so can produce more than the 160+ hp that it would produce at the rated 2700 rpm. I wish I'd gone 10.00:1 -- I'd be leary of anything more for my own use.
 
TJ, I don't know the answer to your question but the 12:1 pistons I installed in the IO-540 are being run on 100 LL with no detonation and a 6 cylinder JPI engine anyliser.
 
Byron

As you get into this thing you may be tempted to run your baby on a dyno to see what you got. Be very selective regarding which dyno you run on or you may spend a fair amount of money and get no useful data. Most of the dyno's are not calibrated and are really only useful to give comparative data, ie ...."well it is stronger than other 0-320's I've run". You will get a feel for the operation when you ask how they compensate for density altitude and how they get the performance numbers back to standard day. They will also bolt on their exhaust system, ask what the performance penality is for that and again they will start tap dancing. Lycoming used straight 10" pipes. If they are bringing the pipes together, especially on one side, then they will be exhausting into a pressurized chamber and choking the engine. The question is, how much?, and again you get into the zone of useless data. You will probably find that there are two dyno operators that seem to have some engineering experience, Lycon and Barrett.
It would be most helpful if you could run your engine, tweak it, run it again to see what affect that had, and repeat that several times. The dyno operators will probably be too busy with their own engines to give you that time.
You may find that your best option will be to back door the operation by bolting several different props on and seeing what it will swing. If you put a std 0-320 prop on that it should spin to say 2300 RPM static and it spins it right to 2700 RPM plus then you know you need more prop. This will eventually give you the optimum prop and give you some insight to both your Hp and torque. This is purely static which is also an incomplete picture.
Barrett wants 750 to run his dyno for a morning session. Usually about 2 hrs run time, for warm up then power runs. Others are usually in the 500 dollar range. I don't know about Lycon as shipping there and back is just too costly for me.
It is a very interesting field but you will find a huge void when you get there. I have an 0-320, narrow deck, built with Lycon parts, that should be about 190 hp, but I have no firm data on that. 9 to 1 comp ratio. Feel free to call and I'll share what little I know. Steve Tubbs at Performance air is quite knowledgeable as is Ken at Lycon and also Monty Barrett. Best of luck.

Bill Rusk
815-985-9544 cel
 
When I looked int this a couple years back, I found a disturbing fact. I spoke to four people who had done it and one mechanic who had maintained some of these hot-rods. They all liked the performance, but they wouldn't advise doing it, since they had too overhaul too soon. Some not even a thousand hours.
Does anyone know actual people they have spoke to that got 2000 hours out of one? It would be great to here feedback better than what I have heard.
Given the above info, after spending the extra $'s. does hot-rodding increase or decrease the resale value of a plane?
How much is all the extra costing these days?
 
I have not spoken to anyone personally re TBO. But I've also not heard anyone complain re TBO.

The cost to hotrod was about 1500 dollars. The cyl work was about 1000 and all the rest about 500, mostly in incremental cost. For example I was going to OH my carb during the rebuild. Cost 350. Bought a rebuilt carb, hotrodded for 500. Actual cost then to hotrod was 150.
The outright cost were the cyl work and a different sump. Everything else was either incremental or no factor.

Was it worth it? Don't know yet!

I'm off to the Hatz fly-in. See ya....

Bill
 
How about the Pitts exhaust; Is this a doable thing? I assume that people would use the 4-1 exhaust discarding any muffler or heater funtions. Any one see this mod done on a cub? I was speaking with a maint. fed last week who was very open to supercub mods, very much so engine builds done within reason (Actually learned some neat little pieces of info from him). Kind of like to get something put together (paperwork wise) while the climate is good. He suggested an car altenator "nimpco"? Sold at Stoddards, needs external CB to prevent overvoltage.
 
I assume that people would use the 4-1 exhaust discarding any muffler or heater funtions. Any one see this mod done on a cub?

The Pepsi Cub has a 6 into 1 cluster, about 4-5" wide at the outlet, then a straight pipe that runs back behind the left gear. The long pipe is for skywriting, gets the smoke exiting behind the pilot. Makes it sound great too :up I'll try and get some pics next time it swings through our shop.
 
There was a vender at the EAA-Arlington Show that would build a 4-1 exhaust system, he supplied the collector and the flange pipes and enough PVC fittings to build a mock-up, then you sent it back to him. maybe someone else got his info ? His workmanship looked impressive!

Dennis
 
What engine modifications would become possible if the engine was to be operated in the Experimental catagory?

Stephen
 
Byron,

What was the final outcome on your O-320?

Did you get the HP you were wanting??

Thanks

Benflyn
 
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