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I'm looking for honest input on a MVVS Q-500 engine. I have one NIB & was concerned about comments made on this site reguarding this as not the best Q-500 engine choice for max speed. Was going to put it on a Q-500 plane or a Diamond Dust if I can find one for all out speed. I would appreciate all honest input good or bad.

I also have a Fox Q-500 special NIB. Is that engine any better? Thanks, Mike

HighPlains

My Feedback: (1)

Fox came out about the same time as the Nelson. A day late and dollar short. Would be about the same as the MVVS, so didn't see too many.

bob27s

My Feedback: (19)

MVVS was not too bad. At the time it came out we used it in SEMPRA for a while, went up against the Rossi 40s Webra .40 Q-500 engine at first, later against the Jett .40SS and also the ST40-q500. The MVVS proved to be just a bit off the established mark in performance. In the right hands it was competitive. So an equitable comparison to the above mentioned engines is reasonable. Not in the league of the Jett or Nelson 428 engines.

Runs well. Its downfall, if any, was the muffler design it came with.

The Fox engine was an interesting experiement. Design wise, they were on the right track. It was the first Q-500 428 rules engine that came with a more obvious tuned exhaust system (rossi muffler was the first real mini-pipe). It ran, turned rpm, but didnt have the torque needed for the right Q500 racing prop. It liked 8" and 8.5" diameter props ... sometimes a 9x6. Didnt turn the heavier prop the contemporary Rossi 40 could. Plus they proved to be (ambient) temperature sensitive. Lots of these flew a handful or races, and were relegated to the drawer. For sport use, if you are patient and do not over prop it, it can make for a fun toy.

SSGSPEEDMAN

The best prop would be the apc 8x9 if you can get it on the pipe. I have a the Mvvs Q-500
that was on a V-Vector.
The info on the prop, I got it from Robert at Morris Hobbes in Houstin that sells Mvvs/Rossi. I really like the engine, you can spin an APC 8x5 prop @ 23,000rpms.
There is also a mod you can do on the exhaust port. You can polish it a little and get 300-400rpms. Polish it till its flush with the piston on the bottom stroke.
I did it to mine. But like "bob27s" said the Jett and Nelson are untouchable compared to the Mvvs.

Kevin

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Thanks guys for the honest info.

What speed do you feel is possible with the MVVS Q-500 on a Viper, Skat Cat,Diamond Dust if I ever find one, or a Model Tech Mach Racer?

Is there a better pipe for the MVVS?

Thanks in advance, Mike

bob27s

My Feedback: (19)

You should find level flight speeds in the 140-150 range on something like a Predator, Viper or other sport Q-500 design.

For those I'd suggest the APC 8.75x8W as a starting point.

Prop selection, based on the application, is key. The best prop for each different plane will be similar, but different. But in general, you will be looking at a standard blade 9x7, or APC D-1 series prop from 8.5x7 up to 8.8x8.5 --somewhere in that range. Target 17,000 peak ground rpm as a minimum.

SSGSPEEDMAN

The fastest I could get my Vector with the Mvvs Q500 engine was 148mph.

Yes, there is a better pipe you can get, But don't get the performance pipe.
I tried it and lost 500rpms. Contact Robert from Morris Hobbes, and get a full lenght pipe for your engine. I don't know how much it is. Even with the full pipe, you may get 600-700 rpm. So if you make the mod I told you about, and the full lenght pipe you may gain 1000+ rpms.

Kevin

You would get better speed with a Nelson though.

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Bob & Speedman, Thank you very much for your suggestions.

Robert suggested the GRRT pipe. Is that the one that worked for you Speedman?

Thanks again, Mike

SSGSPEEDMAN

Well that one would work or one from macs pipes. My dad has the Grrt engine. But its also rear exhaust. Hopefully the pipe will fit the hedder.... I don't know if that is going to be a problem.
Ask Robert if the pipe will fit the hedder. It might not be a problem if you use rubber tubing to join the two together. Did you buy the engine new or used? If new, there should be a little booklet that will show you differen't types of exhaust.

ps. You might have to tune the hedder to the prop you want to use.

Kevin

Kevin

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Speedman, My motor is NIB. I also have the round adapter to run as a rear exhaust.

thanks, Mike

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Speedman, My motor is NIB. I also have the round adapter to run as a rear exhaust.

Robert said the GRRT header will fit right on my motor & he was suprised that somebody actually had one of these motors NIB & with the correct adapter for what I'm going to do with a Dust or a Viper or Skat Cat.

thanks, Mike