Nickiphorosn, its all got to do with ifmar rules. the sirio t3 meaning 3 intake ports i legal for state title national titles and world titles providing the you get the ifmar or efra crank version. The 12 5t is faster but its classed as an outlaw engine and not legal to run it events that requrie ifmar legal engines. most countries have classes were out law 12 engines can be used. the Sirio 5t sti is a 5 intake port engine and will produse much more horse power and will be faster over all. If you are in an rc car club ask them if they run a class were outlaw 12 engines can be used. If you just use your car for fun get the 5 port as the paformance difrence is a bit better because the engine dose not have to conform to ifmar engine limations on number of ports and size of crank port. Regards Jeremy.

ok thanks sirio 2127.i just want this engine as a second engine.i participate in two car leagues.the one of them don't have a limitation for the ports of the engine so the t5 sti would be the choice for me at a very good price(225euros).My main engine is a Novarossi 3sct which i use at the main league.i just don't want to ruin my novarossi so fast.the sirio t5 would be i guess(taking in mind your thoughts about this engine) a very good choice.i was searching for a buck up engine arround 200$usd.i was about to pick a jlr red dot or picco,but i checked the repair cost for those engines and is about the same as sirio and maybe more expensive(jlr red dot p/s/c=140$).!!!!
so why don't i pay 20-30euros more to buy a sirio,which is far a better and more reliable engine?thanks a lot my friend

Thats a tricky one, Sirio engines can be a litle tricky some times. It realy depends on what you want. At the moment novarossi has the most relable engines especialy on-road 21 and 12 engines. Its realy up to you nova is very expencive but you do get your money's worth. There are lots of engines to pick from the crf is quite good. I pited for a friend of mine at a local cup 2 day race meet and that engine is well capable of running 10 minets. It is very touchy on the needles but it is not the latest version and one of the fastest engines ive seen and outstanding run time form it and there fairly well priced. Just look around and ask lots of question's of what people think of the engines they prefer to run. Best Regards Jeremy.

[QUOTE=Sirio2127]Thats a tricky one, Sirio engines can be a litle tricky some times. It realy depends on what you want. At the moment novarossi has the most relable engines especialy on-road 21 and 12 engines. Its realy up to you nova is very expencive but you do get your money's worth. There are lots of engines to pick from the crf is quite good. I pited for a friend of mine at a local cup 2 day race meet and that engine is well capable of running 10 minets. It is very touchy on the needles but it is not the latest version and one of the fastest engines ive seen and outstanding run time form it and there fairly well priced. Just look around and ask lots of question's of what people think of the engines they prefer to run. Best Regards Jeremy.[/QUOT

thanks again Jeremy.i 'll go for the sirio t5.

Thanks twiggy and sirio2127 thats the kind of stuff I'm looking for.

I already took the engine down a little bit and noticed those screws were standard. It wasn't a problem most of my vehicles are made by Losi so I have some good standard tools. As far as fuel goes I always ran Wildcat fuel and they only make their 30% nitro with 14% oil content (that I know of). Would this fuel work alright?

Last question where can I get a piston and sleeve for this engine? I don't know if they make it anymore for this one. This is the 2004 limited edition world champion replica (#52 out of 500). I love this engine it would suck if I can't rebuild it.

First off you know the engine we are talking about is an onroad engine? as far as parts go They would be very hard to find i would think no were would have a piston and liner combo instock except maby the factory maby. rods and bearings are as per normal sirio 21 just the racing versions of rear bearing and conrod. The engine will not like that fuel mix the 21 wcr is a stright out race engine and all sirio engine hate lots of oil. Also there is no need to run 30% nitro in this engine its plenty fast use 25% you will get better life and the paformance will be impressive to say the least. Exspect around 5 min run time from this engine same as most high end race 21 on-road engines. But the bigiest thing at the moment for you is fuel you need a better fuel a race brew and parts will probaly be very hard to get apart from bearings and conrods. Regards Jeremy.

Yes, I do know this is an on-road engine and I have it in a PRP XR8 (I'd much rather have a serpent!). Fuel wont be a problem I would just rather stick with having one fuel for all of my vehicles but oh well. The engine came with extra crank bearings and a con rod so I'm sure I'm set on that untill the sleeve wears out.

Thanks again for the info.

defnatly not you eill need to replace the conrod and bearings at the first hint of the bearings getting noisie and replace the conrod and piston pin and clip or clips when the conrod starts to get excessave play. Ive said it befor sirio piston and liners are very good the last a long time even the aac ones. You could run the 14% oil fuel but it will slow the engine down and make it run hotter. the oil mix in fuel can make a huge difrence to running temp qute ezaly 20 deg C form some oil mixes to outers. Just check the engine regulary for ware and condishion and clean and after run it. and tune it well and it will last a long time. Best Regards Jeremy.

Does anyone have the stock needle settings for the Sirio STI EVO3? Thanks.

can anyone assist me in define the difference between a long stroke and a short stroke engine? (in every angle) TQVM

i read somewhere that short stroke engines rev harder while longer stroke engines have more torque.

Bro..if you don't mind can u please direct me to this source?TQVM

short stroke = bore is larger then stroke say eg; bore 15mm stroke 13mm
square engine = bore and stroke are the same say eg; bore 14mm stroke 14mm
long stroke = bore smaller then stroke say eg; bore 13mm stroke 15mm

short stroke engines tend to give more RPM and less torque, long stroke engines tend to give slightly les RPM but more torque - this is just 2 stroke 411.

just in case you dont know i think this is how the bore/stroke relate, someone who knows for 100% certain can correct me if i'm wrong; the bore is the size of the sleeve that the piston pumps up and down in and the stroke is how far the piston moves from TDC to BDC in one revolotion.

the capacity of the engine is worked out by how much displacement the cylinder has from the top of the head button to the top of the piston when it is at BDC this measurement gives you a volume of the cylinder.

by changing the bore/stroke size they can create short/square/long stroke motor when you are restricted to a certain sized capacity.

TDC = piston @ 'top dead center'
BDC = piston @ 'bottom dead center'

hope this helps?

stroke is right
bore is the diameter of the sleeve

It's the internal diameter of the sleeve