EJ 22 in Zenith 750 STOL

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rv6ejguy

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People routinely get around 100hp from EA81s with a cam change in atmo form. Turbo engines, done properly, gain hp not directly proportional to MAP as boost overcomes the pumping losses on the intake stroke as well. I've seen a nearly a doubling of hp at only about .6 Bar of boost on several engines I've built.

The long block weight of of an EA81 is around 140 lbs., the EJ22/EJ25 SOHC 188lbs. The figures on my website assumed a heavier and more expensive PSRU like the M300 which is not needed at these hp levels. The SPG gearboxes are about 25-30 pounds lighter than the M300. With attention to detail, both of these conversions would weigh well under 300 pounds which is the target FF weight.

91%? not sure where you get that figure from? Check your math. 165 X .82= 135hp which is more than 120. Even at 5000 rpm, we'd be over 120hp. Also, the latest atmo EJ25s put out 175hp so theoretically 143hp at power peak rpm at 5500 feet. Also account for reduced exhaust back pressure with altitude which adds a couple percent more hp.

As a reference, the component weight of my engine, gearbox, turbo, intercooler, oil cooler, rad etc. including starter and alternator is around 324 lbs. I have some rather heavy turbo brackets and a steel intake manifold. The EA81 with SPG gearbox is around 80 pounds lighter and would also require lighter coolers, smaller turbo etc. because of the much lower hp.
 

rv6ejguy

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Ross, is there a reason for not mentioning the reasonably common EA82T (turbo)?

And by EA81 Turbo I figure you mean to turbocharge one rather than the very rare actual EA81 Turbo?
EA82s were heavier and had more head issues.

The factory EA81T is preferable due to it's head design which has proper injector placement low in the ports. I'd use the FlyGas dual port heads if I was doing one.
 

Victor Bravo

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The reason that I did not start a new thread about the O-320 (being an off-topic engine on this thread) is because I was asking about the relative advantage of the on-topic engine versus other traditional (off-topic) choices.

As for identifying and quantifying that advantage, I believe I have found my answer.
 

rv6ejguy

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The reason that I did not start a new thread about the O-320 (being an off-topic engine on this thread) is because I was asking about the relative advantage of the on-topic engine versus other traditional (off-topic) choices.

As for identifying and quantifying that advantage, I believe I have found my answer.
Done right, the price point is a fraction of an O-320. This is probably the main driving force on many auto conversions.
 

mcrae0104

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People routinely get around 100hp from EA81s with a cam change in atmo form.
I'm surprised that a cam swap increases the power output by 30% but I'll take your word for it. I'm still not entirely comfortable with asking an engine to reliably put out 150% of it's rated power, but to each his own.

Turbo engines, done properly, gain hp not directly proportional to MAP as boost overcomes the pumping losses on the intake stroke as well. I've seen a nearly a doubling of hp at only about .6 Bar of boost on several engines I've built.
Interesting. I was not aware of that. Thank you.

91%? not sure where you get that figure from?
Yes, you're right. Somehow I was thinking 150 hp at 5,500 was the goal. It was 120. (150 is 91% of 165)
 

rv6ejguy

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I'm surprised that a cam swap increases the power output by 30% but I'll take your word for it. I'm still not entirely comfortable with asking an engine to reliably put out 150% of it's rated power, but to each his own.
Hundreds of EA81s used Stratus or Formula Power cams, a bit more compression, bigger carb and less restrictive exhaust to get around that 100hp mark. RAM builds a 115hp EA81 for aviation use (atmo) and a 160hp supercharged version.

The Subaru is very strong with a stiff block and 5 main bearings. 100hp is not going to hurt anything.
 
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