Going to have a friend build a Patirot forty size from a kit I bought last year--Have a Rossi 45 Sport with a mini tunned pipe and a Super Tigre 61 with a Macs tunned pipe-Name that motor and why??

Oodles,

Do you have sound regulations at your field? My experience with the Super Tiger is that they don't hold up to high revs. Generally the bearings fail. It may also be a little heavy? I've no experience with the Patriot and how much muscle you can put up front. I have three Rossis, a 40, a 61, and a 91 and have never had any trouble with any of them.

I would go with the Rossi. You would have better performance even though it is a little heavier than most 40s it is lighter than the 61 and you could turn more RPMs more reliably.

Kaos1

If you are asking which engine we would recommend, the Rossi-45 with a 9x8 APC will gt you VERY good performance on the Patriot-

This airplane usually comes out nose-heavy, and you need RPM's so ditch the 61

I have used:
Webra-50GT
OS-50SX
ASP-46
Irvine-53
Jett-50

The best performance was the Jett-50 with a 9x9 APC

Your best performance will be with a Jett. 50 .

If you have the Rossi 45 on hand, go with that. As noted, the plane tends to come out nose heavy. Smaller engine will be better.

Although, the ST61 probably weighs about the same as the Rossi. Use care in either case when building - do what you can to keep things light.

You do not want a big pipe on the Patriot .40. Looks bad......adds to drag. Kinda defeats the purpose.

As razor noted, 9x8 up front.... let it turn.

If you are running the stock Rossi mini-pipe, perhaps consider switching to a jett-stream muffler. Does not require any sort of support (bolts firmly to the engine), no o-ring to leak/wear, provides some additional backpressure the rossi really needs, and i tend to find that its better for the higher RPM applications.

Keep us apprized of your project!
Bob