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acroeric
11-08-2005, 10:32 AM
Besides using C-85 pistons and the p/n 530788 35 degree overlap cam (approved cam - just hard to find) what other mods are being done to increase the power from the C-90's? Mine is a -12. I have heard that using a intake spider off an A65 and grinding it to make it flow better also helps. I do not want to do anything that has not proved reliable.

Cub junkie
11-08-2005, 04:06 PM
I think you answered your own question. I have heard about the A65 manifold trick. The C90 is my favorite small Cont.

marc krier
11-08-2005, 07:30 PM
the pistons will give quiet a boost also use gapless rings.

bob turner
11-08-2005, 07:33 PM
What are gapless rings? How do you get them on?

bob turner
11-08-2005, 07:33 PM
What are gapless rings? How do you get them on?

Ron Babos
11-08-2005, 07:51 PM
Gapless rings are not really gapless. They are two piece with one thinner ring slipping on to the bottom of the other main ring. The gaps are staggered and thin ring covers the gap of the main part.
I have used them in VW aircraft engines, and seem to work ok. No better, no worse. Do not use them in both compression grooves as they may scrape too much oil off the cylinder, and the cylinder may run dryer than it should. This is caused from the thin ring causing a much higher pressure point than a thick stock ring would . The thin ring section is almost identical to an oil control ring in some engines.
Ron

Nathan K. Hammond
11-08-2005, 08:29 PM
Straight pipes, with no muffler (to take advantage of the cam). Port and polish all the cast intake pieces.... spider, elbows, intake side of Cylinder. Take special care to line up the intake tubes with the elbows and spider. Venturi the 65 spider. Internally balance EVERY reciprocating part, doesn't really gain anything in hp, but will make it an exceptionally smooth engine. Run a Metal prop. Nitrous?

nkh

Ron Babos
11-08-2005, 10:27 PM
While at it, go with a four into one tuned exhaust. Make that puppy breathe.
Ron

fireball111
11-08-2005, 10:45 PM
HI I GOT J3 WITH CONT WHEN INCREASING POWER ON DEMAND
ENGINE SPUTTERS OR MISSES WAT COULD BE PROBLEM
RUNNING GOOD AT CRUISE BUT SCARY WHEN NEED TO THROTTLE
UP FAST TEMPERATURE GOOD MAGS NOT THAT OLD .

Steve Pierce
11-08-2005, 10:47 PM
What is the difference in the C-85 pistons and the hot rod pistons Lycon is selling?

Fireball, does your carb have an accelerator pump?

behindpropellers
11-08-2005, 11:03 PM
What is the difference in the C-85 pistons and the hot rod pistons Lycon is selling?



Probably spark plug clearance. I think the original C85 cylinders had the spark plug boss raised up just a bit.

Tim

R. JOHNSON
11-08-2005, 11:37 PM
What do you guys think is the best carb for the C90. Also does anyone know who makes four to one exhaust for the 90.

Thanks, Ryan

Nathan K. Hammond
11-09-2005, 12:37 AM
C85 pistons are flat topped, and are about 1/8" taller than O-200 (pin to top). Normal compression is about 6-1 with O200 pistons, running C85's takes it to about 7/7.5-1?....sorry I don't know the exact number. LyCon's are a domed top piston that run up to about 10-1 and take special rings.

Fireball- We need a little more info. Is it sputtering as you accelerate the throttle on take off? Through what RPM? From what I've gathered, sounds like it's coughing at about 1300-1500rpm? If so, it's getting caught where it changes from the idle jet to the high jet, and you need to en-richen the carb a little. Or change your rhythm while pushing the throttle.

Ryan- Best carb? Whats the best truck? Some people will say Stomberg, and other will say Marvel. Strombergs occasionally have a problem leaking while on the ground, but it's not a problem if you use a new steel needle and seat and lap them together. Personally I think it's what you can get your hands on. :wink:

nkh

Ron Babos
11-09-2005, 05:25 PM
I have a Stromburg on mine, but if I had deep pockets I would go with a Marvel if for no other reason it has a mixture control that works. The accelerator pump will also stop that hesitation you have now.
Try setting the idle screw richer, as this may help with the transition when you open the throttle. Make sure you have no intake leaks before doing anything.
Check the location of the cable attachment on the carb arm. It should be as far away from the shaft as possible.
When properly set up the Stromburg will not cough on acceration, unless you are a real animal with the throttle :lol:
Ron

JP
11-09-2005, 08:25 PM
I have the Marvel with the accel pump. Sometimes I get a bit of stumbling/roughness and occ. rpm drops shortly after I 've gone to full throttle. My guess is that accel pump is just shooting too much up in...

What's the best fix?

fireball111
11-09-2005, 11:03 PM
Is there a screw to increase mixture or a lever ,i've never worked on
one but i do see a lever tied and locked with wire. I don't know if there
is an accelerator pump . The sputter or miss is between 1200 approx
1600 and yes im pretty aggressive with throttle . do you know wat gap supposed to be on plugs .I know you check intake leak on car with
propane but how do you check on airplane any sugestions.Can i take
accelerator pump without taking all carb apart if there is one.Is there
a place were i can get break down of carb.

Nathan K. Hammond
11-10-2005, 12:09 AM
Check for leaks physically and visually, make sure all the hose clamps are tight and the rubber tubing (inner and outer) are in good shape....i.e. no cracking, splitting, etc. Don't know about using propane, hell I've never even heard of it.

The lever you see tied off is the mixture control. And it's really not much of one, called a "Back Suction Mixture" Best to just leave that alone.

Your problem with the sputtering is mainly with the advancing speed of the throttle. Slow it down to about a 3 count....ooooone tttwo thrrrrree, stop to stop. REMEMBER airplane engines aren't built like cars! You've got to be easy on them if you want it to last.

There's a knob on the back side, I think, of the carb, thats gonna be your idle mixture. Screw it out a little at a time to en-richen the idle mixture, only if you still have hesitation problems with the slower throttle speed.

Spark gap 18/22 go/no-go

nkh

Nathan K. Hammond
11-10-2005, 12:13 AM
JP, I've got about "0" experience working on small Marvels, most is on the Stromberg. :roll: But I bet Ron will be able to give you some idea's.

nkh

acroeric
11-10-2005, 07:12 AM
Thanks for the replies. I am most likely going to run a 76-AK-2 Sensenich prop pitched pretty low (43) as well. Performance Propellers out of Arizona makes a wood prop that all the acro guys are crazy about- it is supposed to be as good or better than a metal prop. I guess I would have to fly one to believe it.

I have been struggling trying to decide between the 0-320 and a little C90 with some performance mods. The airplane is a 750 pound clipped wing Tcraft. The addition of the 0-320 adds so much cost and weight- more fuel, more structure, better brakes, electrical system etc. I think the C90 is my best bet in keeping it simple and light.

For an exhaust I use a simple 2 into 1 Luscombe 8E set up, no muffler.

Thanks for the replies again. BTW- I build all wood clipped Tcraft wings- if anyone wants a set for a CWC project let me know- I will be glad to share my jigs and drawings. Mine come out at 55 pounds per side, for reference a stock wing is 80-85 lbs so you eliminate alot of weight. I am currently designing a set for a J-3 with an 0-200 and Tcraft wings.

JP
11-10-2005, 07:34 AM
JP, I've got about "0" experience working on small Marvels, most is on the Stromberg. :roll: But I bet Ron will be able to give you some idea's.

nkh

Gosh, I hope so. I'm sort of mystified. She runs a bit rough and drops off on rpm about 60 seconds or so after full throttle is applied. Doesn't matter how fast or slow I apply. It only happens at 2250 and above. The engine also has a hard time sometimes getting to full rpm (2525) and will lag and then surge. I've seen how much fuel an accel pump can squrt and the duration for which it does it, so that' what I suspect. I hope Ron let's me know what he thinks.

I've also discovered that the C-90 carbs can ice in a hearbeat.

What sorts of props and model number stroms and marvels is everyone using on a C-90?

behindpropellers
11-10-2005, 08:41 AM
Jeff-

The correct stromberg is on the c-90 TCDS.

http://www.cub-club.com/tc/Continental/E-252,%20C90%20&O200.pdf


Can anybody give the comparisons between the stromberg and marvel carbs? The C90 I have for the J-5 has a stromberg on it. I can get a marvel if I want one. Thanks

Tim

Nathan K. Hammond
11-10-2005, 11:16 AM
eric, 750# WOW thats gonna be a hoot to fly! If I was in your shoes, I'd most likely stick with the C90. If you do all the tip and tricks, getting 120hp out of it with good reliability isn't a problem. I didn't think about it before, but an Aeromatic prop would be a REAL BIG advantage. It's basically a constant speed prop without the need for any controls. Great thing about them is you get full RPM for T/O and can get a good cruise too. Had a guy tell me about a Clip Wing Cub with a C90 and an Aeromatic.... he swore he could get off the ground in 50 ft. and out cruise a Citabria! DANG! There pricey at around $4200 but for what you get, it's worth it. www.aeromatic.com

JP, in the case of the Stromberg, it's a NA-S3A1. But that carb is the same for A65's up through O-200's, what changes is the ventrui. Example: the A65 setup may have a 1 1/8" diameter venturi, and a C90 may have a 1 7/8" diameter venturi. (THESE NUMBERS ARE NOT CORRECT, JUST AN EXAMPLE).

nkh

Cub junkie
11-10-2005, 11:26 AM
At 750#s empty wt. I would stick with the Cont. too. Sounds like a fun aircraft. I have ridden in a Swick with O-320 and it went well despite my lard in the right seat, about like a Decathalon.

Ron Babos
11-10-2005, 06:45 PM
fireball111: I assume the main problem is hesitation when advancing the throttle? This is cause from a lean condition from either an intake leak, or insufficiant fuel mixture. Late ignition timing will cause this symptom also.
The propane is a good check normally, but too much of a prop hazard and too windy to be successful with an aircraft engine. Do a check on the intake rubbers for no splits and the clamps tight. Check the intake elbows at each head. Make sure the carb is tight on the spider. Everything must be perfect for the Stromberg to work with-out hesitation.
If all this checks out several things with the carb may cause this hesitation. The mixture control should be wired full rich, cause the damn things never worked right anyway. The fix was to leave them wired rich.
The big screw at the back of the carb is the idle mixture screw. Open it 1/2 turn at a time while checking throttle response. The engine will still idle reasonably smoothly with just a slight touch of richness. It will run lumpy with black smoke puffing out the pipes if you go too far. Idle speed should not be below 600 rpm when hot. Lower than that , you may be looking for trouble, especially when cold weather comes. (ice) Mine is set for 700 rpm hot, and cold start it runs around 500 rpm.
If that doesn't do it , the float level may be too low, which has the effect of having to draw fuel from a lower , further point, which will make all rpm ranges leaner.
The overall condition of the carb will have major effects on things. If the throttle shaft bushings are too loose, vacuum needed to draw fuel will be lost, again causing it to lean out, especially at lower rpms. The carb may have dirt in the idle jet not allowing sufficiant fuel to be delivered. If turning the idle mixture screw out has not effect, this may be the culprit.
It's hard to fix the problem with a key-board, but this would be where I would be looking for the problem. Good luck.
Ron

Ron Babos
11-10-2005, 07:16 PM
jrussell: See fireball111 post for some ideas. The fact it is losing full rpm is a bit of a concern. Pull carb heat at full throttle and see what happens. If you get a drop ok , but if it stays the same or increases back to where it started before dropping, you are really lean. First thing I would do is make sure fuel flow is what it should be. Sounds like you just have enough to keep it running, but no extra at full throttle. Don't rule out a sticking valve. Probably would have some clattering happening at full throttle if it is. If it's a Marvel with a two piece venturi, this could be causing some of the problem. Not familiar with it that much, so hopefully others could chime in and explain the symptoms of these venturis. I'm quite sure you only have one problem causing the stumbling and power loss. Unless you have a leaking primer I don't think too rich is the problem, as the accelerator pump fuel delivered will burn up is a second or so and have no further effect on the overall mixture. If however, you can see black smoke pouring out of the pipes at full throttle, I will update the info to suit that problem. :D
Ron
Ron

fireball111
11-10-2005, 08:19 PM
Thanks ron and guys i will check all these things starting with leaks on
intake and throttle shaft
then spark plug gap ,mixtures .Just one more thing no sure about.
The accelerator pump does it have one and is there some kind of
carb cleaner i can run true without damaging the engine.I don't think
i was in the right topic but wasn't sure how to do that sorry for interruption
on mods .witch were by the way very interesting.going to work on that this weekend hopefully if it don't snow to mutch.

fireball111
11-10-2005, 08:22 PM
any gas filters somewer on system i haven't seen one

fireball111
11-10-2005, 08:28 PM
Do i check timing with timing light hows that done were the timing marks and how many degrees adv is it supposed to be at

Ron Babos
11-10-2005, 09:17 PM
Fireball111: No accelerator pump on a Stromberg. Normally there are two fuel filters. One is the gaskolator and the other is in the carb. It is behind that big brass nut on the side. Make sure you install the screen in the carb with the open end in toward the carb. If the engine runs fine at full throttle, neither of these are causing your problem, but they should be looked at from time to time anyway. You need a mag syncro- timer to do the job accurately. Don't have the degree settings for c90 , but sure some-one will post it.
Ron

acroeric
11-10-2005, 09:47 PM
I have owned a 180 Hp Clipwing Tcraft and a 0-200 powered clipwing T. like Cubs the lighter you can keep them the better they fly. The 180 did good but it was really heavy(1100 empty) The 0-200 powered plane was around 750.
My engine is a C90-12. I have C85 pistons that have been chamfered and will re-work the A65 intake. I finally found the good cam and will use it along with a 2 into 1 exhaust. I plan to balance everything so it doesn't eat itself. Basically - if I can get a reliable 105-110hp I am happy. Oh yaeh- I will use the MA3-SPA carb until I can find a reliable inverted f/o system for the little continental. The 0-320 A2A ia a good engine it is just much heavier than the C90- by the time I add electrical and all the structural mods I had an additional 150-200 pounds. I would have to build the plane much heavier as well. I think I will stick with the little C90 and have a really fun aerobatic sport plane keep the hard acro for the 180hp Pitts.

If anyone notices any items that are proven that I missed please let me know. Happy flying-

Longwinglover
11-10-2005, 11:17 PM
acroeric,

Check your PM.

John Scott

Nathan K. Hammond
11-10-2005, 11:27 PM
Get an oil filter for it. It's only $200 but by far the best money you spend on the engine! El Reno carries them, so do a bunch of others, I think they're made by F&M.

Other than that, I think you'll have a hell of an engine. :D

nkh

acroeric
11-11-2005, 07:15 AM
Yep- the oil filter adapter is cheap insurance. I have one I plan to install. Not only does it filter the oil it acts a a heat sink and lowers the oil temp slightly if you have ram air plumbed to it.

Champdriver
11-11-2005, 08:45 AM
Eric, Don't disregard the Fuel Injection system if you are wanting to do Aerobatics. The Bosch system can be a little finiky, but once you have it dialed in it works like a CHAMP (Little Pun)... Marc Krier had it on his clipped wing cub, and once the final setup was done worked quite well... Champdriver

JP
11-11-2005, 09:57 AM
Ok, I think the problem is solved. The PA-11 Sage of Minnesota has opined and here's the deal.

The type certificate for the PA-11 calls for a Stromberg carb part number 530726, which has smaller jets in it for the 90 HP...the Marvel is approved for the C-90, but not approved for the C-90 installed in a PA-11.
Ron, your advice and observations are right on the money. Since I now know that I have the wrong carb for the application with the wrong jets I'm going to start by swapping out the Marvel for the correct Stromberg. That seems to be the logical place to start and I am fortunate to have access to the correct Stromberg.

The primer is ok. Induction seems ok. Fuel flow seems just fine via a number 5 hose from the gascolator. In flight it does crank out at 2525 indicated with the current prop and seems to have no problem at that rpm. The fuel system is the Atlee Dodge STC'd application of the PA-18 fuel system with the header tanks. The engine does run rich and black smoke has been reported trailing behind me occasionally.

I will report back in once I've done the swap and performed some test flying. I really appreciate all the advice I've gotten--you all are super.

Roger Peterson
11-25-2005, 05:56 PM
If you really want to pick up some extra HP, put on a electronic ignition.
Did some great things for my 0-200

R. JOHNSON
11-26-2005, 12:56 PM
Roger, what kind of electronic ignition do you have and where did you get it. Thanks, Ryan

Roger Peterson
11-26-2005, 01:13 PM
http://www.lightspeedengineering.com/

I purchased it from Klaus at Light Speed. I put it on the right side and left the mag on the left. I also put the readout on it and it is really interesting to watch the ign timing vary all the way from 30 to 45. It reads the man pressure and the rpm to set the timing.

redrooster
11-27-2005, 10:53 AM
So while the electronic ignition on the RH side is varying from 30 to 45, the mag on the LH side is just firing at 30 (?) every time? I guess with no mixture left to ignite that doens't hurt anything.
Good thinking to keep the one mag. A guy at my airport is building a GlasStar TD with an O-360. It has double electronic ignitions, and so it has two complete and independent electrical systems for safety just in case one fails. Also has a big radio stack, digital FADEC, and a whole buncha bells, whistles, flashing lights,buzzers, etc. Not exactly my cuppa tea but he's a retired airline guy so maybe he's used to all that Billy Whizbang stuff....

Rooster

Roger Peterson
11-27-2005, 11:13 AM
I get about a 200 rpm drop when I switch to the mag on runup. Sure is a smooth running engine, but the loudest one I have ever rode behind.

Ron Babos
11-27-2005, 12:53 PM
Roger: Define loud. Exhaust or Continental mechanical noise?
Ron

Roger Peterson
11-27-2005, 03:03 PM
No more than normal mech noise. The main noise is the four into 1 exhause on a non standard engine.
I started with a standard 0-200 engine. I purchased new continental cylinders and sent them to Light Speed Engineering in Santa Paula Ca. Klaus Savier of Light Speed then installed his forged pistons with a 9.4/1 compression ratio. Did a ring and piston fit. the top clearance on the pistons was accomplished by grinding the combustion chamber on some of the cylinders. The intake and exhaust ports were then ported. The valves were then 3 angle cut on all seats and valve faces. The connecting rod were shot peened and balanced and line-bored to fit the larger wrist-pins and balanced. I then installed a electronic ignition by Klaus in place of the right mag.
The plane is made to standard PA11 plans except for the electric trim, seats, and a full panel. Plus a few other mods.
There are a few pictures of the construction on www.pmmi-inc.com/planes.html.
Don at Sensenich made a 72/50 wood prop for cruse and a 80/20 wood prop for floats. The cruse prop gives me a top speed of around 115 mph and the float prop will curse at about 75 mph. The wings were purchased from Dakota Cub and mounted to the plane using Super Cub Struts. Since I did not install a jack screw for trim, I put double tail brace wires on the tail. Other than that it was std construction. I did use some ultralight fabric to install a fishing rod carrier which you can see in the pictures.
The 4 into 1 exhaust was made for me by Chris Stepp at Aircraft Exhaust Technologies. He has some pictures of it on his web site at http://www.aircraftexhaust.net/. He really did a nice job and it gave me about a 100 rpm adder. I also installed Micro VG's on the plane which lowered the stall by a full 20%.

Roger Peterson
11-27-2005, 03:06 PM
Made a little typo. The float prop is a 80/27.

R. JOHNSON
11-27-2005, 09:18 PM
Roger, do you feel that the increased performance with the 4 to 1 over the stock system is worth the money if you had to do it over? Also if you had to pick either the elect. ignition or the exhaust what would you go with? Also how much horse power is your engine putting out? Thanks in advance for your time, Ryan.

EDIT: I think you answered my exhaust question when I seen in another post you've had three sets. I have another question though, have you thought about trying the J-3 mount for the zero degree thrust angle? Thanks, Ryan.

Roger Peterson
11-27-2005, 10:15 PM
The four into one gave me the most boost for the buck. Picked up 100+ rpm when I put it on. I would not go to the 0 thrust. Have tried it and picked up very little. Like the added performance getting off the water with the 4 deg of look down. If I want to go fast, I get in the 172 with my wife. She won't let me fly, but she lets me ride.
The homebuilts are really nice, because you don't have to guess what works the best, just go try it. By the way, my PA11 can keep up with the 172 but I have it looking at the ground at that speed. I think I am putting out about 120 to 125 hp, but my fish that I caught last summer get bigger when I get back to Texas.

Cub junkie
11-28-2005, 12:40 AM
Roger,Do you like the trim you have opposed to the jack screw system? Were you trying to eliminate some of the headaches associated with maintaining a jack screw system? Kevin

acroeric
11-28-2005, 08:09 AM
Roger- I have been looking at the 4 into 1 exhaust as well. I currently use a Luscombe 2 into 1 setup off an 8E. It works well and is also loud (but I like that). I wonder If I would get any gain over this setup? It is very free flowing.

Any issues with Claus' pistons? I have a set of C85 pistons moly coated that I was planning to use but the 9.5 to 1 sure sounds like it would be a huge gain. The C85 trick probably adds 5-8 hp but only adds a little to the compression ratio.

How much time is on your engine? Any problems so far? You have done all the mods I have been wanting to try-
Eric

Roger Peterson
11-28-2005, 08:26 AM
I used the electric trim just so I could get the control on the stick and have a real fine trim control. The only trouble with my system is that the trim tab is about 4 times as large as it needs to be but don't want to rebuild the elevator.
I think the 4 into 1 collectors that Chris builds reall pull a vacuum on the remaining 3 exhaust tubes and help cut down on back pressure.
I have had no problems with the engine and the pistons seem to work fine. I only have about 125 hr on the engine. Flew it to Canada and back and on floats for the summer. I am getting good oil analysis back but my oil usage is only about 1 qt in 25. Would like it to use a little more oil. The oil does not turn black like my other planes. Will know more in a few years but for now it is really a smooth engine without any vibrations at any speed.
About the only change I would make is to the Float plane prop. Should be a 80/32. I turn about 3,000 wide open and 2850 on lift off.

redrooster
12-08-2005, 02:26 PM
Someone posted this link on another discussion site- it's from the Flybaby website and has some good poop on the small Continentals.

www.bowersflybaby.com/tech/fenton.htm

Rooster

JimC
07-21-2006, 10:49 PM
>C85 pistons are flat topped, and are about 1/8" taller than O-200 (pin to top). Normal compression is about 6-1 with O200 pistons,

7.0:1

> running C85's takes it to about 7/7.5-1?....sorry I don't know the exact number.

8.7:1

? LyCon's are a domed top piston that run up to about 10-1 and take special rings.

Lycon flat-top 9.5:1 ----- can't get 10's for the O-200. I'm running 9.5:1 Lycons in an O-200 that I'm building up now.

Lycon pistons have 3 rings vs. 4 rings for the C-85 pistons.

Gapless rings are made by Total Seal to fit about anything imaginable.

JimC
07-21-2006, 11:00 PM
Fireball, stumble on throttleup and quitting at low rpm during taxi are both often a result of running an A-65 spider on the C-85 and C-90. About a fourth of C-85's seem to be using 65 spiders. You can tell a 65 spider by the abrupt external neckdown in the throat. The 85, 90, and O-200 spiders have a uniform diameter throat. If you have a C-85 spider, polish it.

The cheapest solution is to throttle up more slowly, take about 2 seconds to shove the throttle in.

acroeric
08-23-2006, 09:25 PM
I am assembling my C90-12F engine and am considering leaving the vacuum pump gear and housing out. In looking at the oil flow I think as long as I have a well fitting blank off plate it should work fine- Anyone know of a reason I should not do this? I am sure the engine would pick up a little hp without the friction of the gear plus I loose a pound or two off the engine.

JimC
11-01-2016, 11:09 AM
Quoted -- "Normal compression is about 6-1 with O200 pistons, running C85's takes it to about 7/7.5-1?....sorry I don't know the exact number".

Normal compression for C90/O-200 is 7.00:1
C85 pistons with C90/O-200 crank gives 8.68:1
Klaus Saviar pistons 9.4:1
NFS pistons 9.5:1
9.5 pistons with no changes in timing or jetting will give a 9.76% increase in power and torque.

tcraft128
11-01-2016, 08:17 PM
Make sure you plug those holes where the gear bolts on.

pilotski
11-01-2016, 10:04 PM
Besides using C-85 pistons and the p/n 530788 35 degree overlap cam (approved cam - just hard to find) what other mods are being done to increase the power from the C-90's? Mine is a -12. I have heard that using a intake spider off an A65 and grinding it to make it flow better also helps. I do not want to do anything that has not proved reliable.

why a A65 spider? there a lot smaller throat then the c-90 ?

hotrod180
11-02-2016, 11:36 AM
There's a lot of info on Continental 4-bangers -- what fits what, performance mods, etc-- on this webpage:


http://www.bowersflybaby.com/tech/fenton.htm

JimC
11-02-2016, 02:05 PM
A65 spider has an external and internal stepdown in the throat that the 85/90/O-200 spider doesn't have. Opening the 65 spider up for 'improved' flow will cause it to crack at the stepdown due to over thinning the throat wall.

Read the two paragraphs under 'Cam Design Changes' on Page 1 of SB M49-17 and note that Continental explicitly says that the 24 cam gives more power and better acceleration than the 35 788 cam.

pilotski
11-02-2016, 04:00 PM
that's why I was asking why someone would use a A65 carb spider

JimC
11-02-2016, 04:14 PM
As an aside, the stock O-200 cam gives more power and torque than either of the C90 cams up to a density altitude of about 9400-10,000 feet. At sea level, according to Continental, anytime the O-200 is between 2150 rpm and about 2900 rpm, it is producing more torque than the peak torque of the C90.

Farmboy
11-02-2016, 08:26 PM
.

Read the two paragraphs under 'Cam Design Changes' on Page 1 of SB M49-17 and note that Continental explicitly says that the 24 cam gives more power and better acceleration than the 35 788 cam.

Jim,
Would you say that Continental's statement on the -788 cam is based on the stock engine and exhaust, so depending on what other mods one may install, the -788 cam may well provide a benefit? Most engines benefit from breathing easier, hence exhaust mods are typically first, and then intake mods may follow.

JimC
11-02-2016, 11:45 PM
"Most engines benefit from breathing easier"

I would agree with that, and the 90's 24 cam would also benefit from that as well. As would the 35 cam of the O-200. Continental did not dyno these engines with the J3 or PA11 exhausts installed. My personal preference is for the sharper lobed O-200 cam, but that's because I never have to launch at density altitudes above 10,000 feet. The 90 cams will outperform the O-200 cam when the manifold pressure drops below 21 inches.

I typically prop the O-200 to give a 55 mph climbout between 2500 and 2800 rpm and an 79-81 mph cruise at 2250-2350 rpm. In a J3, I'm leary of a 55 mph climb at more than 2800 rpm with much less than 3 gallons in the nose tank for fear of unporting the tank outlet during the climb. At 2800 rpm and 55 mph, the J3 deck angle is very steep.

I've designed an offset J3 'muffler' that fits within the stock heat shrouds (so looks externally stock with shrouds mounted) but doesn't muffle and flows somewhat better than stock while also clearing the -12 oil screen housing. I haven't built or flown it yet, but am looking forward to doing so. I haven't given any attention yet to the 11 exhaust.

BC12D-4-85
11-03-2016, 01:49 AM
Better suck and blow help performance. Here's my choice for air filters...as close to an open system as I've tested for static rpm on a C-90 with their P10-7150 FFA/PMA element:

http://donaldsonaerospace-defense.com/library/files/documents/pdfs/007217.pdf

Gap

JimC
11-03-2016, 07:19 AM
So, with a volumetric efficiency of about 0.8, at 2800 rpm the 90 and O-200 will pump about 130 cfm. That gives an improvement of 0.4 inch of H2O over the Brackett, for about a tenth of a percent increase in power output. About 0.1 to 0.15 hp. That's about a 2 fpm increase in the J3's rate of climb. Every bit helps.

cubdriver2
11-03-2016, 07:24 AM
I haven't had an air filter on my J4 for the last 900hrs

Glenn

BC12D-4-85
11-03-2016, 11:06 AM
So, with a volumetric efficiency of about 0.8, at 2800 rpm the 90 and O-200 will pump about 130 cfm. That gives an improvement of 0.4 inch of H2O over the Brackett, for about a tenth of a percent increase in power output. About 0.1 to 0.15 hp. That's about a 2 fpm increase in the J3's rate of climb. Every bit helps.

On pretty much a standard August day at 425' MSL, 72F, 29.85" Hg from set to 0' on altimeter...MP gauge read 30.10" Hg. Nosed into the bank on floats...fresh C-90 in a PA-11. Prop Sen 76AK-2-40. Used digital remote sensing Proptach sitting on panel. Here's the WFO static data I recorded with a new Brackett filter element and new Donaldson P10-7150:

Brackett 28.5" 2300 rpm
No air filter 29" 2325 rpm
Donaldson filter 28.9" 2320 rpm

Every little bit helps.

GAP

BC12D-4-85
11-03-2016, 11:07 AM
I haven't had an air filter on my J4 for the last 900hrs

Glenn

Probably not many volcanoes or blowing dust where you live?

GAP

JimC
11-03-2016, 11:28 AM
I agree wholeheartedly about the every bit part.
So, the chart and text in the link was wrong?
(it doesn't jive with your numbers - it gives a half inch of water difference for 130 cfm, and you are seeing a half inch of mercury - big difference)

BC12D-4-85
11-03-2016, 11:47 AM
I agree wholeheartedly about the every bit part.
So, the chart and text in the link was wrong?
(it doesn't jive with your numbers - it gives a half inch of water difference, and you are seeing a half inch of mercury - big difference)

Well that's what went down for me, not sure what Donaldson did but I suspect they used a flow bench and not a real engine. I repeated the test forwards and then backwards the same day...same results. The Brackett has two potential flow issues...the foam element (mine was unused) and the backing/anti-backfire louvered metal plate. Both are restrictions versus an open air box. I didn't try just the Brackett filter without the foam element. The Donaldson and K&N/Challenger filters don't use the metal backing. Later I compared the Donaldson vs Challenger in that PA-11 and saw no detectable difference.

I also compared the Brackett versus the Donaldson on my current C-85 Stroked Taylorcraft w/C-150 exhaust, newly rebuilt tight airbox, and saw similar static results with the same prop...Brackett about 2415 and Donaldson about 2440. The rpm bounces around some but the Donaldson again offered about 0.4-5 "Hg manifold pressure and increased static rpm. Yes the static is above TCDS specs and a hundred or so over my previous PA-11 with C-90. Not all engine installations are created equal.

Edit: I install MP gauges to quickly detect carb ice and monitor MP at idle and WFO. Lower is better at idle (10-11"); higher better WFO (I like to see no more than 1" Hg system loss) and as close to ambient air pressure as possible. It's just a way to note a tight engine and infer volumetric efficiency.

GAP

cubdriver2
11-03-2016, 12:18 PM
On my other cub I still use the original folded media wash and oil type, last forever

Glenn

JimC
11-03-2016, 12:56 PM
I don't like the brackett either (except in very, very dusty conditions).

I typically see about a 25-30 rpm static difference between the Brackett and no filter.

I'm thinking about a C150 exhaust for my O-200 11. How is it working out for you?

BC12D-4-85
11-03-2016, 01:06 PM
I don't like the brackett either (except in very, very dusty conditions).

I typically see about a 25-30 rpm static difference between the Brackett and no filter.

I'm thinking about a C150 exhaust for my O-200 11. How is it working out for you?

The only comparison (and a loose one at best) is between my former PA-11 C-90-8F with the Piper exhaust and my current C-85-12F Stroker with the Cessna C-150 system...static rpm was higher on the latter with the same intake and internals (I have a C-90 cam in the Stroker). I assume Cessna and Continental did their best to get power out of the O-200 while providing heat for the cockpit. So yes I'm happy with the system. The headers can be curved inwards some (Atlee did mine for the builder) to fit a tight cowl.

Another option that may fit better would be the Luscombe exhaust: http://www.acornwelding.com/pdf/Luscombe/Luscombe%20Model%208E_F.pdf or similar. Good reports on these as well.

More on this: http://luscombe.org/technicaldocs/baffling%20facts%20about%20your%20exhaust%20system .pdf and http://dc65stc.blogspot.com/2010/09/taylorcraft-exhaust-conversion.html

GAP

JimC
11-03-2016, 02:28 PM
Main advantage to the C150 exhaust is that I have one lying around.
Are you running the 788 cam in the Stroker?
Or the 24 cam?

BC12D-4-85
11-03-2016, 02:54 PM
Main advanage to the C150 exhaust is that I have one lying around.
Are you running the 788 cam in the Stroker?
Or the 24 cam?

Well if the C150 exhaust is sitting there then have a go at it...might take some fitting and as I mentioned the headers can be bent closer to the engine. I'm running a C-90 forged cam and required lifter bodies in a C-85 case machined for them...I assume it's a 531076 with 24* overlap (others did the work). The SBM47-16 (Rev. 1960 Supp. No.1) and M49-17 discuss this. Magneto timing to the upper range of acceptable tolerance is important.

Edit: I'd also experiment with exhaust stack length at some point. See if exhaust reversion timing can affect power in that installation.

GAP

JimC
11-03-2016, 03:05 PM
"Magneto timing to the upper range of acceptable tolerance is important".

True. In one O-200, I run 28 BTDC with the 9.5 pistons and the 35 overlap O-200 cam. Am thinking about advancing a bit more. Other O-200 is stock.

BC12D-4-85
11-03-2016, 03:27 PM
"Magneto timing to the upper range of acceptable tolerance is important".

True. In one O-200, I run 28 BTDC with the 9.5 pistons and the 35 overlap O-200 cam. Am thinking about advancing a bit more. Other O-200 is stock.

Seeing as how mine's still wearing a C-85 data plate under TCDS E-233, 28R/30L* is the legal upper tolerance range (+-1*) listed for a STC SE00979AT Stroker. Not sure what an O-200 would tolerate. I'm not an A&P so I just throw $ at the builders.

GAP

JimC
11-03-2016, 04:43 PM
I pull a cylinder and look at the pistons ever hundred hours or so. I suspect the 9.5 O-200 would tolerate 28/30, but haven't actually tried it. Wanted to build up a few hundred hours at 28 first. It's also bored 0.015" oversize. So far, so good. Tried Total Seal rings, but couldn't get the valve guides to quit leaking oil due to the increased suction. With them, got a puff of blue smoke every time I cobbed the throttle.

BC12D-4-85
11-03-2016, 05:00 PM
Pre-detonation might manifest itself on the piston tops...pocking and irregular carbon coverage...so if it looks good then fly more. I guess I'd rather have a little more oil on the guides as long as they aren't coking and as a result show offset of the valves. How do the inner valve covers look? Any sign of excessive exhaust blowback through the guides and seals and uniform between cylinders? Are the exhaust valve faces uniform in discoloration and seating/cooling well?

I wrestled with installing higher compression pistons than 7:1 with this latest engine but decided against it as I wanted durability and not to expose the builder to undue scrutiny. Cooling then becomes more critical too. So it works well enough.

They did something to the center main cross-bolting to help it hold hands better, but I expect it wasn't a complete through bolt like the larger engines. The carb is a MS but without jetting mods one has to be careful with A/F ratios feeding power produced.

If I did it again I'd probably try the Luscombe exhaust (maybe with a crossover tube between stacks for a 2-1-2 setup) unless someone has dynoed one and found a loss of performance over a C-150 system.

GAP

JimC
11-03-2016, 05:36 PM
No noticable blowback through the guides. Valves and seats look and seal good (I run 93 octane mogas with ethanol). Carb is an MA3-SPA 10-4115 with brass float. 9.5 cooling is not an issue on a J3 (no intercylinder baffles), but I don't think I'd be comfortable running more than 10.0:1 pistons on mogas at advanced timing.

BC12D-4-85
11-03-2016, 05:49 PM
Ok Jim I missed the J-3 part...so an exhaust external to the cowl is not an issue of fit I assume. Well I'd surely experiment with exhaust to see if there's any benefit to be gained.

How's your mixture distribution between cylinders? Do you see any visible color differences on the internals or EGT spread? If so, how have you dealt with it? I was thinking of having Atlee X the outlet of the airbox to maybe straighten the flow into the carb but forgot when it was time to have it done. I don't have an EGT.

Prop...I've read here and elsewhere about which pulls the best...what's your current preference in a Sen or Mac? Lots of Cattos have migrated north to Alaska but I'm reluctant to try just yet.

Gary

JimC
11-03-2016, 06:43 PM
The C150 exhaust would have been for my 11, not the 3.

Mixture distribution seems OK - no signs of temperature distress, runs very smooth. J3 is non-electric, so don't have good figures on CHT/EGT. Were they bad, I think it would have shown up during recurrent internal inspections.

Mac 7440 seems to outpull everything else up to 2700 rpm. Above that Mac 7535 comes into its own.
I'm curious about Catto, but no experience.