I thought I'd start a similar thread for GT engines, since the market now looks really competitive. With Maxima announcing their GT engine, the current selection is:

-OS Speed 21XZ-GT
-Reds R5T GT and R5R GT
-Picco EMX-GT
-Novarossi Mito GT, replacing the Ison GT
-different Nova based engines, such as Ielasi and Tesla
-one-off engines from respected tuners

...and reportedly more coming from respected manufacturers.

What's popular at your track? What are your experiences with them?

There is one more really good GT engine available on the market, still a bit restricted as it has to launched offically still on a global level, but it's available. The WERKS GT engine was launched early this year exclusively in Brazil and has already achieved some impressive results. The engine is definitly on par with the top GT class engines, is very durable and has an excellent cost / benefit. I have now over 5 gallons on the prototype engine (which by the way won the State Championship), and it's still going strong. If you want to see some pictures, please visit us on facebook under https://www.facebook.com/werksracingbrazil/ and if you would like to get such an engine, please get in contact with me on facebook.

How much off the pace are buggy motors for GT racing?

you will be lacking topspeed, unless you do some modifications. You can get some more out of them, but you need to work on the manifold and pipe. The general problem with offroad engines is that they are not made for such long full throttle, high RPM operation. They tend to overheat, and once they start overheating, temp goes up real quick.

I have been racing both standard as well as modded buggy and truggy engines. You can compete with them, but you need to be careful with carburation, and if there are pure GT engines in the field, you will see that they spool up just differente from your engine. On a tight track though you might be ok...

As thommi said, a GT specific engine will have considerably better top end than a buggy version. That being said you don't need to be discouraged because gearing, pipe and clutch setup are really important in GT. But for serious GT racers looking for a new engine a specific one is worth it

I am thinking about getting into GT as a second class when I run nitro sedan and I have 3 buggy motors so I was just trying to see if I could skimp. I have a keep off 21-4, a murnan P5 and a reds R5r. Which of these would be best?

On what track are you planning to use the engine? If it is a tight technical track, I would try the R5R. I have seen the 21-4 on a medium sized track and honestly, was not impressed by it. As said before, the danger in using offroad engines is the temperature, as more than often, to be able to stay close to the faster engines, you will end up leaning the engine out too much and overheating it. If you use an offroad engine, put minimally an onroad pipe to it (2068 for example) and try a short manifold. Use an onroad plug as well, OS RP7 or even RP8, with 25% Nitro. This is what you can do with offroad engines before you start modifying the internals. If the engines are new, then there is something you could try out without actually taking a dremel to alter the sleeve...

Cool, thanks.

Most likely Toledo and Cincinnati.

I am from Brazil, so no idea about these tracks...

They are both pretty long, so I will most likely need to get a GT version motor.

If you are looking for a GT engine, I can get you the WERKS GT engine with 2068 pipe...

Picco GT is by far the winningest engine in the class. It won GLC, ROAR Nats, Nitro Cup, Pan Am race, Winternats... To top it off, street price is only $299

The Picco GT engine is fast, but be prepared... the WERKS GT is coming

How much is it? Anywhere in Asia I can get this?

Go to facebook page https://www.facebook.com/werksracingbrazil/

You can see more information there and you can get in touch with me.