When to go from 40 to 46?
 

I am building FW190 from scratch from a set of plans that I purchased from AMA. The aiplane is 58" ws and should weigh 5 to 5.5 lbs. The plans call for 35-45 engine. However, the room provided under the cowl looks like will only accomodate a 40. The author stated that he flew it with a "healthy 40" and an 11x6 or 12x4 prop. I dont want to spend all this time building for a 40 size then not have the power to enjoy warbird performance. What do you guys suggest? Will a 40 work? I had a TT gp42 sitting back for this plane but now I am not so sure.

Thanks
Jim

RE: When to go from 40 to 46?
 

A 45 of the same make as a 40 will be built in the same case, ergo the 45 will fit. Generally all 45s and 40s are interchangeable installationwise with the exception of the mounting holes. Generally you won't notice the difference in power except for cases where the 45 is specifically a high performance engine and the same manufactures 40 is a sport 40.

A 5 to 5.5 lb airplane will be no problem for any 40 out there. For your application I would focus on running reliability and ease of operation. The TT42 with it's airbleed carborator would not be my first choice. But if you have it running with a high degree of reliability in another plane, then use it.

Denis

RE: When to go from 40 to 46?
 

[b]Jim:

The biggest difference between a 40 and a 46 engine is a toss-up. Could be the snob appeal being able to say 46, or it could be just the price.

Price? Hobby People sells the Magnum XLS 40 for about $20 less than the LS 46, but all the parts except the sleeve, piston, and cylinder head interchange. Includiong the crankcase other than the "40" or "46" on the side. If there is any difference in the production cost, the 40 has to be the more expensive to produce as it has slightly more metal with the thicker cylinder wall.

There is not enough difference in the power for me to notice.

I have several Magnum 46 engines, but since I got my first XLS 40 engine I have bought no more Magnum 46s. Not worth the higher price, and the 40 is an excellent, powerful engine.

What I'm saying is, it will be time to go from the 40s to the 46s when they sell for the same price.

Bill.

RE: When to go from 40 to 46?
 

Thanks for the replies.

I also have a TH 46 and it is quite a bit larger than the TT gp42 that I have. It also seems to have a significant more power. That is the main reason why I put forth this question. I originally put the TT 42 in a Seagull Spacewalker II and it would fly the airplane but just barely. The TH 46 seems to fly it with much more authority. Taking those results and applying them to my question on the FW 190, which will probably be lighter but have less wing area, I could not decide if the TT gp42 would have enough power to fly the plane the way I wanted to fly it. And if it doesn't, will I be able to switch to the 46 without doing a lot of surgery. I would like to use the TT 42 since I now have it sitting on the shelf.

Still confused.


Jim

RE: When to go from 40 to 46?
 

[b]Jim:

That comparison is pretty much apples and oranges. The GP42 is what I call a "Starter" engine, one to learn with. The TH 46 is what you "Graduate" to, much more power than the GP 42 as you noted. If there is a TH 40 that would be the one for comparing with the TH 46, just like the Magnum XLS 40 and the XLS 46 I mentioned.

Sound to me that you should go ahead and buy the Magnum XLS 40 - save money and have good power.

Bill.

RE: When to go from 40 to 46?
 

When you compare 40 & 46 of the same manufacturer and the same model what everyone has said is true. 46 engines are often the same size and slightly lighter when compared to their 40 siblings.

There are also 50, 53, and 55 two stroke engines that are the same size/weight as their 40 counterparts.

Bill, I'll put a Webra 50 or 55 up against the 40 of your choice. :D

RE: When to go from 40 to 46?
 

IMHO an OS .40LA cannot compare to an OS.46 FX when it comes to power. With the OS .40 I flew a trainer mostly at full throttle, with the OS .46 I flew the same trainer mostly at 1/4 throttle. GL

RCF esq.

RE: When to go from 40 to 46?
 

[b]All:

I was overly simplistic in my original comparison, I should have specified engines that were similar other than the total displacement. The two Maggies I used as an example are in effect the same engine, differing only by a few thousandths inch bore, and the selling price.

Eric:

Webra 50? Depends on the application. Purely grunt power? Your 50 is going to wipe my 40. All out speed? I'll use a Q40, it will not only out turn your Webra, it will at least keep up with it also. And just might walk away from it. With our normally grossly overpowered planes a 40, in most cases, can't be told from a similar 46.

Going from a 40 to a 55, an engine that's almost 40% larger, you're almost guaranteed a difference you can see.

Fiend:

Going from an OS "LA" engine to an "FX" is again not a valid comparison. Even though the LA is ridiculously expensive for a "Starter" engine, that's all it is. The FX was a fairly good and powerful sport engine. Had it not been overpriced and ABN construction it would have been an excellent engine. Absolutely no comparison the the LA.

Bill.

RE: When to go from 40 to 46?
 

:) ok maybe not the same, but at least the same manufacturer. and the OS .46 was pricey

RE: When to go from 40 to 46?
 

[b]Fiend:

I said that.

Bill.

RE: When to go from 40 to 46?
 

easy does it,I was agreeing with you on the price ;)

RE: When to go from 40 to 46?
 

[b]FIEND:

Sorry, I misread the "Tone" of your voice.

Bill.

RE: When to go from 40 to 46?
 

Jim,

The entry level engines like the TT GP 42 and the OS .46 LA are smaller physically than their ball bearing counterparts, as you have pointed out. The significant measurement is the distance required between mounting beams: typically about 32mm for the GP and LA versus 36mm or so for the ball bearing .40s and .46s. Apart from this, I'd imagine there is not a lot required to fit a ball bearing engine where once a GP or LA was installed.

My recommendation is to try the GP, see how you go and if necessary upgrade to a .46.

If you are in the market for a new ball bearing engine, check the prices. Tower's prices indicate that the premium to go from a .40 ball bearing to its .46 equivalent is very small: GMS .40 to .47, $5; OS .40 FX to AX46, $5 and TT .40 Pro to TT .46 Pro, $4.

Call me old fashioned, but a 15% upgrade in capacity for $5 seems like a cracking deal to me!

Let us know what you decide.

RE: When to go from 40 to 46?
 

Thanks guys.

Lots of info. Although I am a long way from finishing the 190, I am pretty sure that i will invest in a 46. Or a ST 51. After the finickyness I have found with the ABC engines that I have and the smoothness that I have had with an OS 91 FX, I think that I might prefer to have a ringed engine. Anyone have any opinions of the ST engines?


Thanks
Jim

RE: When to go from 40 to 46?
 

The ST engines I have owned had good power and were reliable. The stock mufflers are big, heavy and ugly. I can live with big and ugly, but I try to stay away from heavy.

RE: When to go from 40 to 46?
 

Go for a TT Pro 46, good price and excellent power.

Cheers,

Chip