more hp required

[Robert Bradbury]

Here I go again!

I'm finding the c-90 to not be enough when it comes to takeoff and climb, especially given that I am on 1650 floats. Oh and my empty weight is 1020 .

I'd like to either go with a bigger engine or crank up( scuz the pun) the output of the c-90 as is being done with the 0-200.

I know going to 9.2:1 pistons on the 0-200 yeilds an immediate 10% gain
but I'm not sure on the C90 . Can anyone shed some light here?

I bought the Aeromatic Prop last fall thinking it would help, but it hasn't been
easy getting it setup just right . I ran out of time and had to shelve the
tests until spring. Anyone with any experience regarding the Aeromatic ?

Robert

[Forrest Barber]

Re: more hp required

maybe a PT-6 turbine?? The aeromatic is a good prop for the 150 Franklins and up. Can you find a 150 hp Lyc??

[astjp2]

Re: more hp required

You need to look at the 90HP cub, they run a 74-76" diameter prop and a real flat pitch when on floats, somewhere around 38-40", that will get you off the water but makes for slower cruise. Skip the aeromatic prop, I got to see the results when one of the blades seperated from the hub on a freshly overhauled and yellow tagged prob. The blade took out a 6" diameter chunk of concrete from the runway and the inbalace ripped the engine from the mount. The only thing left attached to the engine as it was laying in the cowling was the fuel line. Tim

[Robert Bradbury]

Re: more hp required

You need to look at the 90HP cub, they run a 74-76" diameter prop and a real flat pitch when on floats, somewhere around 38-40", that will get you off the water but makes for slower cruise. Skip the aeromatic prop, I got to see the results when one of the blades seperated from the hub on a freshly overhauled and yellow tagged prob. The blade took out a 6" diameter chunk of concrete from the runway and the inbalace ripped the engine from the mount. The only thing left attached to the engine as it was laying in the cowling was the fuel line. Tim

I was running a 74-39 but it still doesn't cut the mustard . I can get out of the water with two guys, full fuel on a good day and that is it . I cruise around the 75mph mark which is just too slow. If I could get 85-90 and a little better performance out of the water I would be happy enough. I think
I may have to go to a 150HP to really get what I want or try a hopped up
0-200 making 120 hp . The 0-200 would be the cheapest and simpliest but
would it be enough?? Probably better just to sell and move up at this point.

Robert

[gcgilpin]

Re: more hp required

Don't bother going from C90 to an O200 if you're looking for off the water performance.

C90 will do better... more torque at low RPMs. O200 would be a step backwards.

You may want to consider high compression pistons. Either C85 pistons or Lycon high compression pistons. They will make some difference... although it won't be earth shattering.

[Forrest Barber]

Re: more hp required

go to 150 hp OR get rid of the 1650's , I stay underfloated at 1320 and live with it! Tell the tribe about your wing span and empty weight.

[perryv1]

Re: more hp required

I have the C-85 to O200 conversion with a 74-42 prop and 1320 floats and this thing goes GREAT! At last years Greenville flyin I beat 3 outher planes including a 150hp PA 12 the best time from closed throttle was under 12 Seconds! and it still cruses at about 90mph.I have to throttle back to about 2000 rpm when Im flying with a PA 11 or PA 18
Get rid of those Heavy Floats if you want it to go better.
PV

[clipit]

Re: more hp required

what cam dose your c-90 have? i use the 530788 cam and a mccualy 75-35 to 38 pitch on a cub and baby ace. great preformance!!! greg

[gcgilpin]

Re: more hp required

what cam dose your c-90 have? i use the 530788 cam and a mccualy 75-35 to 38 pitch on a cub and baby ace. great preformance!!! greg

What's your static RPM? Is your prop a 35 or 38 pitch?

[Ragwing nut]

Re: more hp required

How did you set the Aeromatic up initially? What rpm do you get at static?

Mike

[wlas]

Re: more hp required

I am running a 0-200 with 85 HP pistons and its a big jump from the 90 that I changed from, using the same prop, which is a 74-41 I gained 100 RPM on take off. I can take a 300 lbs load off my lake, which is 2500 feet long. the load is in addition to myself, with minimal fuel. thats with 1320 floats. With a set of 1650 floats it wouldn't do as well. I installed a 0290 D2 135Hp on the 46 model T-craft for a guy a few years back and he sure could have used 1650 floats. I flew it on 1320's and told him to get bigger floats, but I think he is still using those 1320's. I sure liked the power that 135 had and a 150 would be even better. The 1650's are the same float as a 2000 only a little shorter, they need lots of power.

[Robert Bradbury]

Re: more hp required

go to 150 hp OR get rid of the 1650's , I stay underfloated at 1320 and live with it! Tell the tribe about your wing span and empty weight.

I am talking to someone with a 0290 firwall forward which would do the job nicely.

Wing span is stock at 36' and my empty is 1020lb.

[Robert Bradbury]

Re: more hp required

I have the C-85 to O200 conversion with a 74-42 prop and 1320 floats and this thing goes GREAT! At last years Greenville flyin I beat 3 outher planes including a 150hp PA 12 the best time from closed throttle was under 12 Seconds! and it still cruses at about 90mph.I have to throttle back to about 2000 rpm when Im flying with a PA 11 or PA 18
Get rid of those Heavy Floats if you want it to go better.
PV

The floats would be the easiest change if I could find a set. Oh and I guess I
would have to go to high compression pistons and thus require 4 new cylinders. Now its starting to get expensive again. I have a chance to buy a
0-290 firewall forward which I think would be the best option given the floats
that I have. The extra speed, likely in the 100 mph range would offset the
fuel economy I was getting at only 75mph. As I've always said " there's no
replacement for displacement".

Robert

[Robert Bradbury]

Re: more hp required

what cam dose your c-90 have? i use the 530788 cam and a mccualy 75-35 to 38 pitch on a cub and baby ace. great preformance!!! greg

I really don't know what is the cam number except that it is the stock cam for a C90. My prop is a Sen 74-39 at present. I think the static with this prop is 2250 or 2300. Hard to remember now with all the changes and props I have
been trying. Another factor is that my tach is reading wrong. I have been using a handheld electronic through the window to get more accurate results.

Robert

[Robert Bradbury]

Re: more hp required

How did you set the Aeromatic up initially? What rpm do you get at static?

Mike

The Aeromatic is a long story which is still unresolved. The instructions and setup as it arrived were a contradiction. I was told the prop was tweaked for the C90 however he had all the spare weights on there so when I tried it I had a static as you would expect of about 1500. I wasn't too happy when I
discovered this and the fact that the weights were really not secured well.
He should have bagged the extras and or tagged the prop . I never really did get a good balance between static and cruise before running out of time. I will resume this spring.