rcpilot

I want to purchase a motor to get modded by a good tuner but i'm stuck in choosing one. I am picking between Roar legal 3 port motors and my choices are Sirio, mt-12, mr-12, rb x12, rs 12.

I will be racing at rather large tracks. Is the Sirio a faster motor compared to the Nova bases motors? Do they last a long time?

Thanks for any help.
Martin.

rod_b

Well, you can pretty much take your pick of that group. If someone is gonna mod it, you should pick an engine they are familiar with. If it doesn't matter to them, I personally would pick a Novarossi based engine. The Sirios, I heard, are quite fast in general and modded I would assume would be ballistic but the new MR12 really shocked me as to how fast it was. I had an RB X12 before that and people used to ask me if it was modded. Either of those 2 would be my first choice. The MT12 is good and you can find it for relatively cheap. The new engines are faster out of the box but a modded MT12 can still be pretty fast.

rcpilot

Thanks for the reply, I'm actually leaning more to the short stroke motors and am stuck more between the Sirio and mr-12. I have heard before though that the long rod mt-12 can take a little more abuse as its long stroke isn't being able to seize up as easily.

Does anyone know if the Sirio can take the abuse in an 1 hour main? How long does it last compared to Nova motors? I was getting around 10 gallons with mt-12's last year running 30 and 40 fuel. So I want to try the Sirio but I'm not totally convinced yet.

Ron C.

iTrader: (2)

I agree with RodB...

The nova based would be the choice.
I would take the MT12 due to its durability.
The new RS12 S3 is a very promising motor
too, it seem.

Bounty Hunter

Well if you are talking about the TRP 3 port ABC then I would say yes. Actually the Sirio is a long stroke motor (13.80mm Bore - 14.00mm Stroke). I have been running one in my V One RR for the last 5 months now. I have gotten almost 3 gallons of Odonnel 30% through it. I have broken down the motor once so far and it is pretty clean. As far as out and out performance, well I consider the Sirio to be amounst one of the new gen motors and can keep up with an MT/MR12 out of the box, if properly setup and tuned of course. That plus I am getting 6+ minute tanks with it as well (Race day temps at 265+). Anyways I think I have put it through its paces and it has done pretty well. For a non modified 3 port it is pretty fast out of the box. Once you bring mods into the mix, however, it is a whole new ball game!

InitialD

The length of the stroke you mentioned has got noting to do with a motor being categorised long rod or short rod type. The length of the conrod determines this. This is what Dennis Ritchey (bless his soul) has mentioned before if I'm not mistaken. However, I do not know if the Sirio is a short or a long rod based motor. But from the characteristics, I gather that is a short rod motor like the rest of the Novarossi bunch.

popsracer

Everything being equal, Bore and Stroke in an Engine.
A longer Connecting Rod (and Piston to match) will shift the power band to a lower Rpm. A Shorter Rod in the Exact same Engine, will have it's Power band up in a Higher Rpm range. In our .12 size engines, it may hardly be noticeable though.
This has long been a tuning 'Trick' on Full size engines. Change the Rod length to shift the power band closer to where you need it.

rcpilot

Thanks for the replies. Does anyone got an opinion on the Sirio motor?

Ron C.

iTrader: (2)

I have not used a Sirio .12 motor but have
seen a few of them run. I must say, they seem
to be pretty competitive with the others...

theRED5

I have been helping 2 new guys at our track with Sirio engines. We have had the bioggest problem trying to get them broken in, after 12 tanks of fuel, they're still getting stuck TDC, and have even broken 2 Associated starter boxes...burned the motors up. I don't reccomend them, not from a performance standpoint, but because they come from Trinity.

nova racer

night and day in the punch dept.

JPHRacer

In full size motors rod leangth has very little to do with the powerband. Almost nothing infact. They wil tune motors with different stoke's and bore's, square, oversquare, undersquare... In a crank-inducted motor, where the intake timing is in the crank, rod length changes the relationship between the piston position and the crank position. A shorter rod will effectively increse the crank timing, giving more RPM, and less Torque. Besides a few motors out there, all the .12's have the same bore and stroke. Rod leangth is a cheap way to use exsisting parts to make more timing in the crank. The problem with it is that somtimes you dont want the crank to open any sooner, just later, It all depends on the motor, and what has been done to it on the insides.

Ron C.

iTrader: (2)

I have the .21 Sirio and had 2 gallons of 30% fuel
thru it and its still tight enough to get stuck at
times. But I dont mind that at all because to
me it means that compression is still good. My
only worry is that how long can the rod hold up
with this tightness. ? Yet it is so far so good with
this motor.

I hear you about where the motor comes from.
Its a pretty decent motor, in my opinion as well.
Too bad its distributor has a "not so good rep to
back it up.. "

Ducati998

I have the Sirio 3 ports on my ntc3, and I couldnt love it anymore. Although hearing that is can burn up the motor on my starterbox kind of scare me. The motor fires right up everytime. Still breaking it in, so I would recommend this motor.

patelladragger

mr12 is incredibly quick as a stock legal motor. Will keep you in the mix unless everyone is running STRONG modifieds and the track is huge and all driving factors are thrown out the window. I'd go mr12 and call it a day. I've ran them all and it felt like the best legal non-mod out there to me.