Wasnt looking for my horsepower----but---

I just said the other day I wasnt looking for anymore horsepower....but.....when you discovered what I discovered last night...you may eat your words like I am.

I was doing a routine flight controls inspection...then I went to the throttle. I set it at full throttle in the cabin...and went back to the intake manifold...and could not believe that I could rotate it about 3/4 of an inch more.....I rechecked it...and began to think about it.

Somehow while I was putting my Subaru engine all back onto its mounts etc...I must have changed...pulled..or whatever the adjustment on my throttle. I measured it exactly and I was able to move the arm that had a radius of 1.25 inches...exactly 11/16 of an inch....that computes to 31.5 degrees of travel.

I readjusted it ...and could not wait to go test fly it.

If you remember I originally pulled 5400 rpm on take off with my stock cam.

I was ecstatic when I tried my new cam and it pulled 5750 rpm on takeoff.

Well now...I took off this morning and it pulls exactly 5900 rpm now....way too much...but I will add pitch to the prop to keep it at 5600 or so.

I can tell my top end and my rate of clumb are going to be much more over what I was happy with.

I now will include checking that throttle linkage on all pre-flights.

All my prop pitch data collecting will now be obsolete...my top end will be quite a bit higher.....and when I add pitch to pull that EJ25 down to 5600 and climb out...its much better.

I have basically been running my new cam with a 2x 4 under the throttle pedal so to speak.

I wasnt looking for this extra horsepower..but now that I "found" it...I aint giving it back.

The first picture shows what my full throttle setting has been since I put the new cams in.

The second shows the actual full throttle setting. The tip of that arm moved 11/16 of an inch on a radius of 1.25 inches......31.5 degees of travel.

Hindsight says I should have checked the throttle and all controls after any engine movement from its mounts. Hey...Ifeel kind of dumb for not doing that but am patting myself on the back for constantly checking over my machine and finding quirks like this.

How many out here check their full throttle movement every pre-flight? every month? never?

Cant wait to see what these extra ponies that I should have had in the first place feel like.




Gold Member
Cool. Now how sure are you that it wasn't like that before you took the engine apart for the cams :p



Senior Member

I assume the Magnum requires the same 5 inches clearance on the prop.

I think if you had the Medium IVO you would have been in trouble. Look at the pic of my prop striking the tail brace.


Any comments if this engine was on a non CLT? Or how about the partial RAF drop keels?

I think it is great if the gyro is setup to handle the power.
Rusty: Good question..and I was expecting that from someone..:yo: ..yes...I do know for a fact that my throttle was wide open before..because I check it every month. I just failed to check it after my cam job...

Larry: The Magnum prop is much stiffer...and only requires 4 inches of fore and aft clearance. I have exactly 5 inches to the front...and 4 inches to the rear.

When you consider the arr of the prop tip...its even more clearance than that.

Jim Mayfield had advised me NOT to get a medium prop. I wouldnt have anyway as they are rated at 100 horse..where the Magnum is up to 700 horse. I think that now that I have 180 horses....I wont be exceeding the limits of this prop. :yo:



Senior Member

I believe you have the best setup you can get on a 2.5L Sparrowhawk or the modified RAF.

IVO was pretty clear on the Magnum for the 2.5L. They were less specific on the model IVO to use for the 2.2L due to the difference in HP. The Magnum on a 2.2L with a Delta grind is probably the way to go with the 2.2L.

Your fuel consumption must not have changed much with the Delta grind or you would have noticed the difference by now.

The extra rpms with the Delta grind does not surprise me after reading the Hot Rod Subaru forums. The same forum seams to favor the 2.2L as being able to handle the most abuse. The common problem with the 2.5L is the head gasket which you have already delt with. I am still amazed at these Subaru engines.

Are you using the stock Subaru engine computer?
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Larry: I believe its a stock computer. It came with the kit....I am in a learning mode all the time and someday maybe I will be able to tell just by looking.:party:

I would like to say that I am always going over my machine trying to look at it from a different set of eyes. I am a stickler about my basic controls,,,such as the throttle. Like I said...I check that probably every month. It takes just seconds. I just happened to be all lathered up with the new cam that I didnt even check the throttle control after putting it al back together. I guess I figured that since I never disconnected the throttle...the thought never went through my mind.

But now I am glad it worked out this way. Here I was all very satisfied with my new performance numbers.....and this throttle being only 90% open was a gift. I will admit that I was a little surprised that my top end only increased 3 mph when I initially started testing my new cams performance. My flat out top end GPS averaged speed over a 180 degree course change was 94 mph with the stock cam....and 97 mph with my new cams. I think I will be pleasantly surprised what my new top end will be with my new cams with the throttle at 100%.

To be fair to my numbers...I have to have the doors on and its too freakin hot the next several days to do that. Next week will be a cool down...and I will slip the doors on and go see what she does now.

I am not "looking" for any more horsepower.....but if I "find" it...I am keeping it.:whoo: Hey....I wonder if all 4 plug wires are on? :der:




Sling-Wing Pilot
Hey Stan is you find any extra horsepower laying around, under the stairs or behind the toolbox, let me know, I think you have enough already. :)


Gold Member
Stan. I am thinking about adding the baddest engine on a gyro to mine this winter. A turbo EJ-20 WRX STI. 245 at 6500. Redline 11000 RPM. But I like my EJ-2.2. They say it can take the abuse so I hit mine with a hammer once in a while just to let it know who is boss!


Senior Member
Stan. I am thinking about adding the baddest engine on a gyro to mine this winter. A turbo EJ-20 WRX STI. 245 at 6500. Redline 11000 RPM. But I like my EJ-2.2. They say it can take the abuse so I hit mine with a hammer once in a while just to let it know who is boss!

I was looking at the EJ-20 at 227 hp. It requires an intercooler which I was not sure if it could be mounted on the motor and still clear everything. I have also noticed that they seem to have alot of problems. The EJ 2.2 is the most durable of all the subs and was considering a turbo 2.2 at 165 hp.

I talked to Delta cams today about the 2.2L Stratus cam grind. In both the 2.2L and 2.5L you gain about 15% hp. Stan must be sitting with about 190 hp which is dang good. They claim you will also have higher end rps..which is something Stan also mentioned. The 2.2L with the Stratus cam grind is about 165 hp...which is what you begin with on the 2.5L.

It would be interesting to see the 2.2 turbo with a stratus grind. If you gain 15%, you are still at the same 190 hp on Stan's.

The simpliest solution looks like purchasing a 2.5L closed block (elminating the head gasket problem), and doing Stan's cam grind for $83.50 per cam.

If you can find a 2.5L DOHC turbo, you talking about 300 HP. I think Stan has found just the right mix at 190 hp with the IVO.

Larry, is your mod centerlined? I would think getting up in the 190 hp range and not being exactly centerlined would be risky. But that is my uneducated guess.
Larry: Delta Cams told to expect about a 10% gain. So at 165 to start...I am conservatively saying I have 180 horsepower. They said I would notice the torque more in the area I want to cruise at.

I tell you one thing...whatever it is ....it sure kicks that SparrowHawk in the pants like it never has.

Its kind of weird....you know how you get money in the bank...and you dont want to touch it until you need it? ....I am finding that with this extra horsepower. I am flying around more and more at lower rpm's saving on that motor. I couldnt be happier with it now...and I just want to save them ponies..until I want to flat out and cruise somewheres fast.

Larry Boyers EJ20 engine swap out is going to be one interesting machine when he is done. 245 horses...I cant wait to see what it does.

Mark Knight has this awesome 4 cylinder yamaha snowmobile engine....155 horses....and it weighs ....NOTHING at all. He is going to put it in his single place Air Command. I believe he will have more horsepower per pound than anything out there.


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Platinum Member
Good for you Stan! That's an easy way to get more power....get rid of that throttle governor !
Thom: I dont want to race.....because I know Pat Mcnear, Duane Hunn, and Jim Logans RAF's are faster. I am weight challenged and the aerodynamics of that comfy cabin takes horsepower just to stay even. I always said it takes a 2.5 in my SparrowHawk to do what a 2.2 did in my RAF.

I am competing against myself and what I "had". I love to feel the improvements as I do these changes.

So....I record data....and "race" against "my" numbers....and I am winning.:peace: :whoo: :plane:



Senior Member
Stan and other,

After reading these posting I got to wondering. What effect do these high horsepower ( 245 hp) and controllable pitch propeller fit into the regulations? It is my understanding that any horsepower greater than 200 hp and/or controllable pitch propeller required additional training and logbook endorsement.



Senior Member
A pilot operating with sport pilot privileges has no horsepower limit but can not operate an in-flight adjustable propeller. CFR 61.303

A recreational pilot is limited to 180 horsepower. CFR 61.101

A private pilot or higher needs an endorsement from an instructor for more than 200 horsepower but no additional training for the propeller. CFR 61.31e.

Chuck Roberg

Gyro's are more fun
It is my understanding that any horsepower greater than 200 hp and/or controllable pitch propeller required additional training and logbook endorsement.
That only applies to airplanes not rotorcraft.

61.31(e) Additional training required for operating complex airplanes.

61.31(f) Additional training required for operating high-performance airplanes. (1) Except as provided in paragraph (f)(2) of this section, no person may act as pilot in command of a high-performance airplane (an airplane with an engine of more than 200 horsepower), unless the person has—

Dave Patrick

Hi Stan just learning this site...

Hi Stan just learning this site...

so this is a test more than a response :usa2: