Carb vs injected

gsimatos · Post by **gsimatos** » Sun Dec 17, 2006 2:05 pm

What do you guys think about Carb VS Injected engines?? My experience with Cessna all carb'd engines, old technology but relaible. I have a buddie here on the field build who has built several airplanes and he says injection is the only way to go. Also wondering if there would be issues with space in the engine cowl for RV7 which as the additional nose wheel attach on the engine mount. I will look forward to your comment G

captain_john · Post by **captain_john** » Sun Dec 17, 2006 4:49 pm

Gary,

This is another one of those time where you build what you want.

Carb
*simplicity
*lower cost
*reliability

FI
*better fuel managing
*no icing
*a touch more power

Either way, you will have a nice RV!

What are your mission requirements?

CJ

gsimatos · Post by **gsimatos** » Sun Dec 17, 2006 6:59 pm

I am thinking simplicity and reliability are real important. Plan is some local zooming around but 500 mile cross country is really what i am interested in. The RV is a huge departure from my experience with cessnas so I am inclined toward the carb'd engine which is "the devil I know". Of course I am just at the empenage stage so it is way early to decide but just trying to get a rough working plan in my head, Thanks G

Post by **Spike** » Sun Dec 17, 2006 10:41 pm

Ive flown both and have to say that I have not found much difference, except, a carbed engine was easier to start when warm. Ive had about 80 hours in FI & 200 or so in carbed.

My RV will be carb'ed due to cost and simplicity of the fuel system.

svanarts · Post by **svanarts** » Sun Dec 17, 2006 10:54 pm

I can't add to what Spike just said so I'll say... me too.

cjensen · Post by **cjensen** » Sun Dec 17, 2006 11:16 pm

Me three...

gsimatos · Post by **gsimatos** » Mon Dec 18, 2006 12:37 am

OK you guys sort of looks like lots of support for the simplicity of the carb'd engine. Since I got ya on the phone another thing that is sort of" build what ya want "is the issue of LYC 320 or 360. The cruise speeds are very close and while the climb for the o-360 is impressive the o-320 is pretty nice also. Is the extra weight and fuel burn worth it?? I am thinking it ain't that 150/160hp is plenty but again what do I know other than drilling out ratty rivets from my HS. Wadda ya think????? G

captain_john · Post by **captain_john** » Mon Dec 18, 2006 6:49 am

G,

What are you building again? A -7A, as I recall?

The -7's can't carry a full 100 lbs. of baggage if you go with a light engine/prop combo.

They more or less seem to be made for the 360's.

My $.02!

CJ

Post by **Spike** » Mon Dec 18, 2006 9:15 am

To me, the question of 320 vs 360 revolves almost soley around the prop. If you want the fixed pitch Sensenich then I would say stay away from the 320. The RPM restriction with that prop and the 160HP engine will be a thorn in your side. I have a friend that is prop limited on his 8A because of this.

I was going to go FP sensenich on my RV-9A, but because of this restriction will probably end up with a CS whirlwind if I can swing the dough.

gsimatos · Post by **gsimatos** » Mon Dec 18, 2006 7:38 pm

I wasn't aware of a problem/prop restriction with the O-320.( By the way I am thinking about building the 7A). Ran into a buddie today who flew the RV-7 demo when it was here in BC, Canada and he talks to the Van's factory pilot who seems to feel the O-360 is the way to go as you guys pointed out above. Man that is one honking big engine on that plane but I guess there ain't no replacement for displacement. I have a cessna 170 with the 145 hp engine and its fun to 5000 ft then the lack of power really dictates what you can do beyond this point so I guess I will keep an eye on the 360 situation/prices Thanks agaion you guys G

tshort · Post by **tshort** » Mon Dec 18, 2006 8:20 pm

G-

How 'bout some pics of your 170? I have a ragwing '48.
Why are you looking at building a -7A instead of a -7?

(maybe this should be a new thread ... creeping a little)

Thomas

svanarts · Post by **svanarts** » Mon Dec 18, 2006 11:27 pm

An O320 RV-7 has greater range than a comperably equipped 0360 RV-7. You will burn less fuel and be able to fly farther on a tank of fuel. You will still have a very nice performing airplane.

I was gung ho for a 180 horse motor on this new plane. The more I consider it, the more I'm leaning toward an O320 with a CS prop. The 180 makes it more of a muscle plane and ... uh... why else would I want an 180 horse motor?

gsimatos · Post by **gsimatos** » Mon Dec 18, 2006 11:29 pm

T,
Mines a '52. I put a photo in Gallery just search cessna and i think it should come up. Still trying to negotiate around this site, little slow. My problem with this RV stuff is too many choices, tail wheel nose wheel, engines, slider or tip up top. Actually it is good to have choices. To answer your question, tho I am OK on the 170 I am a little worried about the overall step up in performance in the RV as a tail dragger so i am leaning to the tri-wheel RV7. Don't want to change too many things at once. How that for the waffling??
G

cjensen · Post by **cjensen** » Tue Dec 19, 2006 12:09 am

From what I hear, Gary, the RV series taildraggers are amongst the tamest of tame for the little wheel in the back crowd...I certainly hope so, since I don't yet own a TW endorsement...

svanarts · Post by **svanarts** » Tue Dec 19, 2006 1:02 am

gsimatos wrote:I am OK on the 170 I am a little worried about the overall step up in performance in the RV as a tail dragger so i am leaning to the tri-wheel RV7.

If you want a tri-gear airplane that's fine but don't let the performance put you off. If you can land a 170 you can land an RV-3,4,6,7,8. The only caveat is that once you have been flying a conventionally geared RV for a while you may have trouble going back to the 170. It will feel like a truck that's lost its power steering.

If you have any recent hours flying tailwheel you will have NO trouble landing the RV.

gsimatos · Post by **gsimatos** » Tue Dec 19, 2006 1:51 am

I did the tail wheel check out with the 170 in march then did about 75 hours on it. The 170 is pretty predictable, just gotta keep it straight. So on the 170 I am getting there. I am just going to think about what i want in an RV a little more. I need to make some decisions as you all know because I figure I can order up the wing+/- the feuselage in a month or so. I would like to have a plan for the gear and engine in my head by then. Thanks for your help you guys, G

Post by **Spike** » Tue Dec 19, 2006 9:51 am

One thing that Im not sure I buy when comparing carb'ed engines to FI engines, is that the FI engines create more power. Anyone care to defend it?

cjensen · Post by **cjensen** » Tue Dec 19, 2006 10:21 am

Just because it's FI DOES NOT make it create more power. Compression ratios, as well as porting and polishing and cold air induction make the power differences. An FI parallel valve -360 engine makes 180hp, just like it's Carb'd brother. They both run 8.5:1 pistons. The angle valve engine is FI only (correct me if I'm wrong on that, but I've never seen an angle valve carb), but runs something like 9:1 or 10:1 pistons, to get 200hp. Of course displacement can make a big difference since -320 and -360 engines are being discussed here as well.

Take the OX-340S and the IOX-340S for example. Both are parallel valve engines, both run 9.0:1 pistons, the O puts out 177hp, the IO puts out 185hp. The ONLY difference is cold air induction.

captain_john · Post by **captain_john** » Tue Dec 19, 2006 5:07 pm

cjensen wrote:Take the OX-340S and the IOX-340S for example. Both are parallel valve engines, both run 9.0:1 pistons, the O puts out 177hp, the IO puts out 185hp. The ONLY difference is cold air induction.

...AND Fuel Injection!

The "I" in IO-3X0 means fuel injection.

Great research Chad!

CJ

jim_geo · Post by **jim_geo** » Tue Dec 19, 2006 5:52 pm

Can anyone give me a before and after on porting and polishing.