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"Best" engine for power / weight

TShort

Well Known Member
I've spent tons of time thinking about the best engine for the -8 (obviously, as I have had the project for 15 years now ... )

I'd like to keep the plane as light as I can. Not super interested in an angle valve motor or a -390.

I'd like to know what is the best combo of weight / power available - specifically, manufacturer / engine shop and specific options. I'm planning on a constant speed prop. I'm guessing this will be an IO-360 of some variant, though I am totally open to some of the other options out there (-340, -375, -380, etc)

I'm sure others have pondered this and was wondering what people have come up with.
 
The IO-360-M1B is used by more people in the RV-8 than any other engine.

IMHO, that is because it is the best power for its weight.

The IO-360-M1B from Van's is the baseline engine for my RV-8 project.
 
You might consider the TCM/Titan IO370 with 9.6 CR rated at 195HP but most shops see 200+. Big performance jump over my 'old' 360/180hp.
 
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My -8 has a Titan IO370 and a WW prop. It is the smoothest engine I?ve ever flown behind. No lack of power.
 
Titan 360 or 370

The Titan is lighter by way of the magnesium oil sump which saves 6.5-7 lbs. and the taper cylinder barrel fins that reduce each cylinder weight by .4 lbs.
It also has the Nickel + Carbide (NiC3) cylinder plate surface that will not rust, roller lifter valve train, dynamically balanced assembly, and many other beneficial characteristics.
 
Like what he says :D:D:D

There are one or two Gents who pass this way. In the day, Mahlon was the Guru. As he retired, I listen to JB !

Bought parts from him and had plenty of advice of him.

He owes me beer, has yet to pay, but heck - he is a few miles away

:D
 
The -390 announcement certainly caught my eye, but now that it's had a few days to age, I think I'm still in the camp that the Titan -370 is the sweet spot. Not really convinced that the extra ~10 horses for the -390 are worth the 30+ pounds.

Still bums me out that Whirl Wind quit supporting the stroker engines, though I checked this week and they've now raised their prices so going with the Hartzell composite isn't so much of a price jump.
 
The -390 announcement certainly caught my eye, but now that it's had a few days to age, I think I'm still in the camp that the Titan -370 is the sweet spot.

That was my thought as well. My IO-370 HC Cold sump arrived a few weeks ago. Order early!
IMG-4498.jpg
 
Best Pwr/Wgt

I think you gotta go with a tricked out parallel valve 360. The dudes at Lycon claim to get 230 hp on their (maybe a little generous?) dyno.
 
That was my thought as well. My IO-370 HC Cold sump arrived a few weeks ago. Order early!

That's almost exactly the engine I have in mind. IO-370, cold sump, high compression, with dual SDS CPI2 in lieu of magnetos.
 
I've spent tons of time thinking about the best engine for the -8 (obviously, as I have had the project for 15 years now ... )

I'd like to keep the plane as light as I can. Not super interested in an angle valve motor or a -390.

I'd like to know what is the best combo of weight / power available - specifically, manufacturer / engine shop and specific options. I'm planning on a constant speed prop. I'm guessing this will be an IO-360 of some variant, though I am totally open to some of the other options out there (-340, -375, -380, etc)

I'm sure others have pondered this and was wondering what people have come up with.

Another data point for you. I’m having a Superior IO-360-B1AC2 engine built by a local performance engine builder. This is a carb to injection conversion on a flying RV8 and wanted to minimize conversion work so I’m sticking with the vertical induction. He will port and flow balance the heads, cut special valve seats, balance the crank and rods, and use 9.5 pistons. He will test run and dyno it when complete and expects around 210hp. According to the builder, the head work alone provides around 20hp over stock and the balance comes from the increase in CR. I believe Lycon does similar head work with comparable results. Pushing these for extra HP is controversial as it adds additional stress, etc. Your actual mileage may vary.
 
Beat me to it. There are some nice engines listed above. I?d pick one of those if funds allow, if not a rebuild parallel valve -360 and take it to Lycon. Their head work is amazing. Really wakes up the engine.

I think you gotta go with a tricked out parallel valve 360. The dudes at Lycon claim to get 230 hp on their (maybe a little generous?) dyno.
 
Beat me to it. There are some nice engines listed above. I’d pick one of those if funds allow, if not a rebuild parallel valve -360 and take it to Lycon. Their head work is amazing. Really wakes up the engine.

Yeah, sure seems to wake them up!

Stu has a video clip of his IO-360-A1B6 at Lycon on the Dyno delivering 239.4 hp (this is an angle valve, but impressive) Finding someone that knows how to do head work is really important to making these little engines deliver.

See around the 6:30 min point in this clip. https://www.youtube.com/watch?v=_B84Cek50t0
 
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