[speyers]

Does anyone have some data concerning RV-8 (or other models) performance with 160 vs. 180+ horsepower? My loose understanding has been that more HP gives you better climb and shorter T/O distances, but not as much gain on the speed end. Is there any data or experience out there other than VAN's numbers? I am thinking about a 0-320 in my -8 and was wondering how much cross country speed I would be giving up. Thanks.

 

[RV6_flyer]

There is a 200 HP RV-8A a few hangars down from me and I have another friend that sold his 180 HP RV-8A. The 180 matched the numbers quoted by Van. The 200 HP is a few MPH slower than Van's numbers. The 200 HP airplane is over 100 pounds heaver with all the creature comforts in the airplane plus the pilot is also about 75 pounds heavier. There is 175 pounds more weight to carry around in this one 200 HP 8A compaired to the 180 8A that I am comparing to.

One of my friends that is a CFI in Sacramento, did a BFR in a 150 HP RV-8 and it also preformed to Van's numbers.

The bottom line, if you built it per plans, you should get the numbers published by Van.

http://www.vansaircraft.com/public/rv-8per.htm

 

[casper]

Does anyone have some data concerning RV-8 (or other models) performance with 160 vs. 180+ horsepower? My loose understanding has been that more HP gives you better climb and shorter T/O distances, but not as much gain on the speed end. Is there any data or experience out there other than VAN's numbers? I am thinking about a 0-320 in my -8 and was wondering how much cross country speed I would be giving up. Thanks.

If you are going cross country by your self you wont know the diffference. But if you team up with some 0360 powered RVs you wont like it. The first airplane I built was a 6A with 0320. i couldn't keep up with the other guys. So i built me 7A 0360, now I'm happy. To each his own.

 

[Martin Sutter]

160 vs 180 vs 200 hp

The o-360 has become pretty much the standard for the RV6, 7, and 8. This engine is only about $1500 to 2000 more expensive but the big kicker is when you try to sell the airplane it will be worth $10,000 more if you have the 180hp engine as that is what most buyers want.

Martin Sutter

 

[gmcjetpilot]

20 HP?

http://www.vansaircraft.com/public/rv-8per.htm

I think the above Van's link is all you need?

The other difference is in purchase price and weight. From my data base the
average empty wt. of RV-8's (actual finished RV's)

......IO360; 320/cs; 360/cs; 320/Fix; 360/Fix
Avg..1151;...1118;...1079;...1053;...1089
Max.1178;...1168;...1106;...1106;...1149
Min..1116;...1080;...1059;...1032;...1044

IO360 is 200HP with constant speed prop.

No surprise that a IO360 w/ C/S prop is heaviest and a 320/Fix is lightest.

Other wise the difference is 20 HP and Van's specs address that.

If you have never flown a RV before and are only use to Pipers and Cessna's, a 150 HP RV will roll your socks down. The comment about resale above is a fair one. The IO360 does cost a lot more, but assume you have priced engines. If buying new I would go O360. If buying a used engine you might need to take what you can get. It depends on your budget. Your answer in a nut shall is impossible to answer except in the most basic terms. Go out and do your homework. Good Luck

 

[praterdj]

I am going with an IO-360 primarily for two reasons....weight (I'm 6'-4" 250) and I have also been told that the 360 can be converted to Gas if they phase out 100LL. I'm not sure if the angle valve 200 can run on gas.

I have flown in a 7 with a IO-360 and an 8 with 200hp. Top end speeds are close but you do lose a little on the V.S.

I believe you will find the 180 HP will still leave you smiling and impressed on climb out.

 

[Low Pass]

It's a money question. Get more hp if you can afford it. My 160-hp -8 performs as Van advertises.

Also, your prop choice makes a big difference! My 160 CS -8 will fly as fast as some 180 hp FP RVs. I know, I know - it depends on the FP prop (and a thousand other things). Just think about these other variables - they make a difference.

 

[Skyhi]

Handling - not speed

The RV4 handles better than the 8, mainly because it is 200lbs lighter.
My RV8 just tops 1100lbs with XP-360, MT CS prop, Inverted systems and VFR panel and performs OK in terms of speed, but I think it would handle much better if I had been able to build it lighter. If builidng again I would go for an 0-320 with 3 bladed fixed prop, and drop the inverted systems. I think the handling would improve, the shortfield would be as good (with the loss of weight), and the slightly slower cruise would be more economic - (which would also be moving with the times in environmental terms).
Nic

 

[RV6_flyer]

The RV4 handles better than the 8, mainly because it is 200lbs lighter.
My RV8 just tops 1100lbs with XP-360, MT CS prop, Inverted systems and VFR panel and performs OK in terms of speed, but I think it would handle much better if I had been able to build it lighter. If builidng again I would go for an 0-320 with 3 bladed fixed prop, and drop the inverted systems. I think the handling would improve, the shortfield would be as good (with the loss of weight), and the slightly slower cruise would be more economic - (which would also be moving with the times in environmental terms).
Nic

After 1,892 hours of flying my RV-6 with more than 500 hours of formation with other RVs, not a signal one of the smaller engine fixed pitch RV ever got a lower fuel burn than the larger engine constant speed birds. You are also dreaming about the lighter weight lower horsepower fixed pitch bird having the same takeoff performance. (unless it may be an RV-3 against an RV-8A)

 

[Skyhi]

Gary - I think you are missing the point. The best aircraft are built light, they handle and perform better. See the Sportcruiser - 130mph at 15lph on 100hp.
Nic

 

[Ironflight]

Gary - I think you are missing the point. The best aircraft are built light, they handle and perform better. See the Sportcruiser - 130mph at 15lph on 100hp.
Nic

Respectfully Nic, you might be missing the point of a "discussion group". The idea here is to share ideas and information, not necessarily convince others that your own opinions are "right". In this case, you are defining "best aircraft" in terms that others might not share. I have never found a single aircraft that does everything perfectly - which is why there are so many types in the world.

I have found that my 180 HP -8 does exactly what Van's says it will do (plus one extra knot which I can be convinced is instrumentation error). That is typical of Van's - they give you just what they say they will, nothing less, and nothing more.

Paul

 

[N941WR]

I guess I'm not like most hot-rodders as I value handling over straight line performance. Thus my selection of a Miata for SCCA events and probably the reason I elected to build an RV-9 over the -7 was the option of putting a small, light engine in it w/o giving up much in the way of performance. Ok, I did give the loop and roll option and will probably miss doing those things.

What this meant is that the O-290-D2 I'm installing in my -9 cost me all of $3,500 and by the time it is hung the total cost will be around $8K for a 0 SMHO 140 hp engine, complete with duel PMags.

Granted it will not run as fast as an O-320 powered RV-X but then I probably won't race one of those, unless it is CAFE type race where I can throttle back and really sip fuel.

What does this have to do with the 160/180/200 hp question? Pick the options that you want for the plane you are dreaming of and start building, if you select options others want, it will never be your dream plane. Just keep in mind the options might have an impact on the future sale of your craft, this may or may not be an issue for you.

As someone stated earlier, the O-360 has become the standard engine for the -8 (O-320 for the -9) and selling an -8 with the O-320 might be an issue down the road. Either way, remember you will still have some outstanding performance as that lowly O-320 is pulling a lot of four seat 172's around the sky.

 

[Skyhi]

Changing times

Thanks for your moderation Paul; the lesson that I learnt from building my RV8 is that weight has big drawbacks - poor low speed handling being one of them. The marginal benefit of slightly higher straight line speed is not important for me flying in Europe, I tend to fly my 8 at low power settings to get max range and cruise at 150mph @ 21/21. I dont fly formation with heavy 8's with 200hp and never feel the need to keep up. So my choice would be, just as N941WR suggests, light and nimble and moderately fast - as I too value handling over straight line performance.
Nic

 

[Skyhi]

Icebergs

I have found that my 180 HP -8 does exactly what Van's says it will do (plus one extra knot which I can be convinced is instrumentation error). That is typical of Van's - they give you just what they say they will, nothing less, and nothing more.

Paul

Paul - you are a great advert for Vans - but performance figures are the tip of the iceberg.

Every Vans builder I meet tells me how fast his aicraft fly's - So what !

The big question is how does it handle at different speeds. Nic

 

[rv8ch]

How does it handle?

The big question is how does it handle at different speeds.

As you already know, it handles somewhere between a Piper and a Pitts.

 

[dan]

For what it's worth, I agree with Skyhi about keeping it light. The airplane is much more fun to fly when it's light...half fuel & solo, compared to when it's got full fuel & a big warm body in both seats, etc.

That said, since we're projecting our individual priorities here, I gotta play devil's advocate and ask about aircraft capability. Which aircraft is more "capable" -- the one with 100hp that is incredibly light and nimble, or the one with 250hp that is heavier and not as nimble, but has the power to do just about anything?

Given the "I learned about flying from that" situations you've been in, which applies more directly to saving your bacon?

I'd personally rather have the HP. I don't ever recall hearing somebody say, "If only I had a smaller engine."

 

[zav6a]

Engine Choices - How about...

One of the choices that I have not heard discussed for the -9 is an O-235 - but with a turbo or supercharger. Should be very light, with a Airflow Performance FI it would be fairly straightforward to supercharge. Stick some 9:1 pistons in it, add electronic ignition, turbonormalize up to 15,000 feet or so, run lean of peak, work on making it as slick as possible and would be the most efficient RV in the sky while outrunning 0-360s at high altitudes.

If you live at high altitude, and fly there most of the time, you give up nothing. At an 8000 density altitude, typical for many western airports in the summer, The most we get out of an 0-320 is 120 hp anyway.

It all depends on the mission and with fuel prices where they are, this would be a cool, fast, lightweight, efficient cruiser!

As Paul pointed out, there is no perfect airplane, only the airplane most perfectly suited to mission. That is why we really need two of them!

 

[Yukon]

Really Really BIG Motors

Paul - you are a great advert for Vans - but performance figures are the tip of the iceberg.

Every Vans builder I meet tells me how fast his aicraft fly's - So what !

The big question is how does it handle at different speeds. Nic

With all due respect Nic, get with the program! This discussion group is for guys with really big motors to agree with each other about how really great really big motors are for things like formation flying, overhead breaks, vertical climbs etc. Did I mention I like formation flying???? If you talk about efficient aircraft, you will be violating the rules of the forum!!!!

 

[Yukon]

One of the choices that I have not heard discussed for the -9 is an O-235 - but with a turbo or supercharger. Should be very light, with a Airflow Performance FI it would be fairly straightforward to supercharge. Stick some 9:1 pistons in it, add electronic ignition, turbonormalize up to 15,000 feet or so, run lean of peak, work on making it as slick as possible and would be the most efficient RV in the sky while outrunning 0-360s at high altitudes.

If you live at high altitude, and fly there most of the time, you give up nothing. At an 8000 density altitude, typical for many western airports in the summer, The most we get out of an 0-320 is 120 hp anyway.

It all depends on the mission and with fuel prices where they are, this would be a cool, fast, lightweight, efficient cruiser!

As Paul pointed out, there is no perfect airplane, only the airplane most perfectly suited to mission. That is why we really need two of them!

I've been daydreaming about turbocharging my 0-235 someday. Strong lower end and beefy case, I imagine it would hold up well. I think though you will find 7 to 1 pistons (or so) in turbo engines.

 

[RVbySDI]

What this meant is that the O-290-D2 I'm installing in my -9 cost me all of $3,500 and by the time it is hung the total cost will be around $8K for a 0 SMHO 140 hp engine, complete with duel PMags.

Bill, can you tell me more about your O-290-D2 installation. I have an opportunity to buy one of these engines for my RV9A and am very interested in it. I have been kicking around the IO320/IO340 engine for a while now but buying new pushes these engines in the 25-30K range with FP prop. I have the chance to pick up a good O290D2 engine for $3500. This would probably mean I can have a complete install for $8-10K. That sounds much better to my pocketbook. If you would like to PM me, please do. I would love to hear more about your O290D2 install.

 

[praterdj]

I'd personally rather have the HP. I don't ever recall hearing somebody say, "If only I had a smaller engine."

Perfect quote that pretty much sums it up.

Also..power can get you out of trouble. It's not just about the top end speed because I doubt there is much difference simply due to horsepower. It certainly has an effect but how straight the plane is built and how many things you can do to reduce drag would make the most significant change to the top end giddy up.

Even though there are 200FP+ engines available I want the 180 HP. Minimal weight, Climbs like a beast, fairly good fuel economy, better resale. But that's me....ultimately you need to decide what you want.