S

s4lorne

Member
Hi All-

I am in the throws of building my 7A and I am that point that I need to order an engine. this has given me more fits than the canopy choice or tailwheel vs tri.

I have always thought I would do a IO-360-A1B6 but they are hard to find used and at $37K+ new, they are even harder to swallow. I am not thinking of the 390 since it is cheaper but I need to look to those of you who have made these choices for advice. I would also love to hear any arguments toward for or against the 180HP vs. the 200 or now 210 HP.

I have spent a fair amount of time looking at different options including Dan C's site.

Thanks in advance-

Dan R
 
The IO-360-A1B6 is not hard to find used. Call AeroSport Power and have them give you a quote. You don't have to worry about finding one (they'll just build you one) and it surely won't be $37k. I paid $28,260 for mine a few years ago. Overhauled w/new crank & new cylinders & new accessories. Balanced extremely well to say the least. May technically be an "overhauled" engine but I feel it's better than a factory new Lycoming. At a much lower price.
 
I would argue that the little performance gain with larger engines is offset with expense, complication of installation, heating problems, weight, fuel burn, and extra maintenance. My 7A with 180 hp 0-360 A1A and Hartzell Blended Airfoil prop gives me a 204 mph cruise @ 8000msl and plenty of climb rate (1800 fpm+). Van's provided engines using their FWF kits makes installation simple without having to reinvent the wheel.

That's my position,

Roberta
 
Engine Selection

Dan:

The first thing to consider for engine selection is how you intend to fly your airplane. Short hops around the field, cross-country trips, do you live in cold weather, etc.? All of these (any many more) will factor into your decision.

The p/h 360 runs right on target at 180 hp with standard compression and is well suited engine for the RV-7. A word of caution, if you intend to do cross country flight, avoid bumping up the compression too much to try and attain additional hp, as you will see a shorter TBO and really high compression doesn't manage well on long trips.

The A1B6 is a 200 hp rated engine, but they don't usually make that right out of the box. There is a fudge factor there of +/- 5%, so you're more likely to see about 196 out of a stock a/h 360. Cores are getting more and more difficult to find due to the increase in experimental building over the years, and good cores to have rebuilt are even more difficult to find. The shops providing the new experimental Lycoming engines (including us and Aerosport) can provide you one for less than 37K, but I'd like to tell you a little bit about the 390.

This particular engine was developed in our shop for an aerobatic customer in the late 90s. We've been selling it for about 3 years now and have more experience with it than anyone else in the field. It weighs 8 lbs more than the A1B6 and produces 15 more hp based on the fudge factor discussed above. The engine produces a solid 210 hp at 2700 rpm, and we've seen them as high as 217 on our dyno (standard compression, which is 8.9 due to the cylinder bore.) You're looking at 15 more hp for 5K less than the 37K A1B6, and the 390 is still cheaper than the experimental version. Based on those facts alone, I'd pick a 390 over a a/h 360 any day.

As far as firewall foreward mods with the IO-390 on the 7, I can't say. Ross Schlotthauer was the first to put one in a -7, and I know he's not active on this list. He has since sold his plane, but we recently heard from the new owner at annual, and he said the engine is great for the plane and has no squawks. We've heard no negatives at all from the field on this engine. None of them have been affected by the current ADs or SBs on the Lycoming crankshafts either.

Hope this helps you. Please feel free to contact us if we can help answer any additional questions or give you any help.

Rhonda Barrett-Bewley
Barrett Precision Engines, Inc.
2870-B N. Sheridan Rd.
Tulsa, OK 74115
(918) 835-1089 phone
(918) 835-1754 fax
www.barrettprecisionengines.com
 
No need to Agonize

There are so many viable options from US people. Barretts, ECI, etc...

I personally went with the ECI because I had immediate support locally. The price was excellent through Attawayair.com. Support from the company has been excellent.

If you can make OSH you can see them all. Don't agonize. You've seen positive reports on many, so just pick one and finish the plane!!! Once you are flying you'll wonder why you got bunched up on some of these decisions.
 
Hartzell Recommendations

Hartzell actually did a prop analysis on the 390 on a Sportsman 2+2 and approved a couple of props for it. I don't have the analsysis results, but below are the Hartzell props that have been approved for use with the 390

1) The Hartzell Propeller Model HC-C2YR-1BFP/F8477-4 is considered satisfactory vibrationwise mounted on Lycoming Engine Model IO-390-X rated at 210 HP at 2700 RPM (standard compression ratio) installed in normal category type single engine tractor aircraft with the following restrictions:

"Continuous operation is prohibited above 24" manifold pressure below 2250 RPM, and below 8" manifold pressure between 1950 and 2300 RPM."

The propeller diameter limits are 80" to 78".

--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
2) Hartzell Propeller Model HC-C2YR-1BF/F7497

2-BLADE PROPELLER; Available in 74"

HARTZELL "BLENDED AIRFOIL" DESIGN PROPELLER FOR USE WITH LYCOMING IO-390-X 210HP ENGINE

Specifications:
Compact Series Propeller
Aluminum Hub/Aluminum Blade Construction
Constant-Speed
Non-Feathering
 
Thank you-

Hi all-

I think I love the RV's as much for the great community and support as I do the aircraft itself.

I can get the 390 for just under $30K but those 180 prices dure do look attractive.

Thanks for all of the input so far- I really appreciate it and can't wait to get this thing in the air.

Dan
 
This is a difficult decision. Here are a few data points.

1. Although I don't fly an RV, I have flown Dan's RV-7 and it shows NO ill effects of the angle-valve 360's extra weight. I'm sure the factory or those with finely tuned senses will tell you that the big engine somehow dulls the airplane's responses, but I sure couldn't feel it. On the other side: The performance of his airplane is very, very good, with enough to spare that he can run LOP (lean of peak) at high altitude and still have strong cruise performance at amazingly low fuel burns.

2. The economic incentive is not as strong as you think. Run through the options list of a parallel-valve 360 and tally up the extras that are standard on the IO-360/390: counterweighted crank, forward facing induction, roller lifters (on the 390), etc. If you ordered up the parallel-valve engine to the same spec, you might be surprised how close it comes in final price. It'll still be higher in some small multiple of $1000, but it's not huge.

3. Prop vibration. I flew the vibration survey on the 390 with two props, an older design Hartzell 80-inch floatplane prop and a new blended-airfoil 74-incher. Time and again, the engineers said that having a counterweighted crank made all the difference, despite the 390's extra power and higher compression ratio over the parallel-valve 360. After the flights, they determined that the 74-inch was very happy on the 390 (and so, presumably, would the popular 7666 prop; though that's my supposition not Hartzell's) and that the 80-incher required a very minor low-MP limitation.

4. 390 vs angle-valve 360. This is a no brainer, in my view. The 390 weighs the same--essentially is the same engine except for bore--and is 10-15 hp more powerful. (Some say more; I've heard that the angle-valve 360 is not quite a 200-hp engine.) And Lycoming has priced the 390 kit parts aggressively enough to undercut the 360. Less money, more power, same size box; no discussion.

5. Performance at a price. I can't speak for the performance increases on the 7, but can tell you that in the Sportsman the 390 is a massive improvement over the O-360. My airplane was flown in formation with the factory prototype (with the O-360) from Sun N Fun; at the same speeds, leaned similarly, it burned the same amount of fuel. Clearly the slightly better fuel specifics of the 390--from a higher compression ratio and ever so slightly more advanced combustion chambers--offset its extra weight in the airplane. But, again, we're talking airplanes with a max gross of 2350 and typical empty weights above 1400.

This is a difficult decision, as I said. But after nearly 90 hours behind the 390 in the Sportsman, I have absolutely no regrets.

Maybe the best thing is to cadge a ride in a 7 with the big 360 and a ride in one with the O-360 parallel-valver. Any excuse to fly...

--Marc
 
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