i need some help. i am buying a viper within the next two weeks and i am looking for an engine for it. i was thinking about the the mvvs-40 or a rossi 53 or 40 or a jett 40. i kno all are good engines but im really torn. please help.

Flyboy:

Look in the yellow pages under "Psychiatrist." Sorry, couldn't resist.

Any of the engines you named should do well. Are you planning to run the plane in a particular racing class? If yes rhen get the biggest Jett that will comply. If it's for fun I'd go with the Rossi. Similar performance to the Jett 40 for a lot less money.

JMO.

Bill.

As Bill noted, if you plan on racing, check with your local organization or club for their engine rules.

If this is just for sport, no problem - pick an engine you are comfortable with.

Any of the engines you noted will work well. The Rossi .40 is a good value these days.

The only concern with the Rossi is that it is heavy, and you will end up with a nose-heavy aircraft - its hard to balance a Q-500 with a great deal of mass no the nose. Also make sure to support the tail end of the muffler.

The best 'econo-speed' setup you can put on the nose, is a Thunder Tiger .46, with a Jett-Stream muffler added. For about $140 you will have one heck of an engine. Use a 8.75x8W prop and you will have all the performance you might want, with limited expendature.

For a Jett product, the standard SJ-46 or SJ-50 is the way to go if you are just flying for sport. .... and if you do want more, the Jett SJ-50 with an SS muffler is the way to go. Similar performance to the Q-500 .40 racing version, but throttles and idles well - and is very user friendly.

You will want a backplate mount for any engine you chose. Jett offers replacement backplate mounts for TT, Jett, OS, and a few others.

LCSPERFORMANCE.COM offers backplate add-on plates that are sometimes more conveninent.

Take the time to search the Pylon Q-500 and Extream Speed forums for modification/reinforcement information on the Viper.

I hope this is helpful.

Bob

Hi Bob

Amazing as it may seem I weighed the Rossi 40 with the tuned (black) muffler and the TT40 with the stock muffler and the weights were within a 1/4 oz. The Rossi the heavier. I also compared RPMs on a apc 9/6 prop and of course the Rossi had the TT40 by about a 800 to 1000 rpm. But with a perf specialties tunned muffler the TT40 matched the Rossi on the ground. I don't know about air. Of course the TT40 with PS muffler costs more than the Rossi with tunned muffler. I've been running the Rossi 40 and 53 on 3D planes and they are well worth the money

Denis

Denis, no argument there..

As I noted, nothing wrong with the Rossi - other than being a tad heavier than most. Ran them in Q-500 for a few years. Good value for $130 as sold by Morris.

TT46 is $80 - UT/JS muffler $50ish..... about $130 as well. So its a toss up of sorts. Id give the edge to the Rossi maybe all things aside.

You are correct though. The TT engines are not super lightweights. Real brass and chrome adds up Drove me nuts last year when I went 424 racing - after swapping out the 428 QJ-40 engine (AAC), I fogot about the weight was about an ounce ligher on the QJ, and I had some serious battery pack relocation to deal with.

Since I was curious - thought Id take a look back at some of my notes..... this might be helpful for original poster and others along the way...

the Rossi I have listed is about 16 oz ( 430 g) without the muffler. I did not have a weight listed with the black muffler. Total weight depends on the muffler I guess. (any have that info handy?)

The TT40 pro is about 17oz (487g) with the stock muffler.
I know TT46 is a few grams less - did not have that weight handy.
The OS 46AX is about the same 487g.
The Jett SJ-46 with the prop spinner nut and muffler is 487g as well - and I know the muffler alone weighs about 130 g (4.5 oz or so).

Bob

Hello!
As has been said earlier if you intend to compete in a certain pylonracing class get the rules first and find out what engine is allowed. In the US the foremost national Q-500 pylonracing class is the AMA 428 class where 6,5cc Nelson and Jett reign supreme.
For club racing many other sport 6,5cc engines are used like the TT .40.

Over here in Sweden we race Q-500 pylon using standard 6,5cc engines running ordinary plastic glassfilled 10x6 props and no nitro (80/20) fuel.
Webra .40 GT is and has been for the last 15 years the most popular engine used.
It easily outperforms any other engine, including the Rossi (which is sooo heavy) and which has a very poorly made silencer.
The Webra turns a 10x6 a black Graupner Cam-prop at around 14000rpm on the ground and easily rews up some more in the air.
So if you want the most powerful standard engine with a silencer, running a 10x6 prop (unmodified) on 80/20 fuel; Get a Webra .40 GT!

Regards!
Jan K
Sweden

Bob

Boy did I screw that up. I weighed the TT40 at 539 grams with stock muffler and the Rossi 40 with their stock tunned muffler at 547 grams. But the TT had a spinner nut and Perfspec radial back plate mount. I just went and compared apples to apples and the TT is 465 grams, about 3 ozs lighter than the Rossi. I'd have to mount my battery in the "V" of the tail. The Rossi muffler is 103g and the TT is 102g. The Ultra thrust racing muffler for the TT is also 103g. Locally the Rossis sell for 109 to 119 and the racing Ultrathrust for about 65. 20 bucks either way is not a real ** breaker.

Jaka
I've flown one of my racers with an old Q500 Webra with an ultra thrust and it was fast. I don't know how the GTs compare with the old Q500 and I can't remember what rpm I was getting with a 9/6 apc but I believe it was over 18k and I didn't have to rebalance the plane. Took a TT40 off to make room for the Webra. The cg moved back a little as I recall I had to switch to a pylon prop to take advantage of the power though.

There is a guy in Germany that is modifying Rossi 40s and putting his own name on them and racing them in their Q500. He says they are strong but won't run like a Nelsen though.

Denis

this is just for sport flying at my local field and maybe racing people that are spped freaks like our club president. i didnt really here anything about the mvvs 40 u all talked about rossis and jets. how does a mvvs hold up to all of these. it says it turns 20,000rpm. I think im goin with the mvvs 40 or a rossi but not sure which rossi to chooses if i go that way. one person at my field said a rossi 53 but wouldnt that be to big. anyway lemme kno what u guys think. this really helps. thnks guys.

The MVVS will run with the rest of the strong 40s but not with a Rossi 53. I've only compared the Rossi 53 with a Rossi 40 on a 12/4 apc and the Rossi 53 is good for about another 1000 rpm on 5% nitro. The Rossis don't like much more than that. But then the 53 is closer to 200 bucks than the 40 is to a 100 bucks. They are both great running engines.
But did I mention they are both LOUD, LOUD, LOUD on their stock mufflers. I did compare a Webra 50 with an Mvvs 40 on my Balsa Nova and the MVVs gave up nearly a 1000 rpm to the Webra also on a 12/4.

Denis

Jaka
I forgot to mention I think you are thinking of the old Rossi mufflers. The new ones seem to be well made and durable. They do use this screwy spring to hold it on. I don't use that. I use a fuselage stand off. Oops more weight.

Denis

Denis

A Rossi 53 is the same size as a Rossi 40, probably a little lighter because of more material removed from the cylinder. It's a bunch more power. Make sure you have your Viper beafed up in the right spots. Go to the Q500 forum for info on that.

Denis