I'm looking into the 1/8th on-road class for next year but i can't figure out what motor i need.

Are all 3.5cc motors roughly the same? Are some ported differently for off road maybe?
I was looking at O.S and FX Engines but most come with 180 degree exhaust flanges which i assume are for off road?

If anyone can point me in the right direction or suggest me a good starter motor please let me know.

All competition engines come with a rear exhaust. What 1/8 onroad you want to drive? GT or the pancar type?
Differences offroad/GT and onroad is the size of the cooling head, most offroad/GT are about 60mm diameter and the rotation of the carburettor while with the pancar type the heads are 50-54mm and a switched direction of the carburettor. And yes, technically there are also differences making the needed performance, also with the used exhaust systems (offroad has a longer manifold)

If it is about a GT you basically van use any offroad and GT type engine, if you want to go racing there is a (stupid) limit of 5 ports you need to take care of. Most pancar type engines today have 7 or 9 ports. If you want to start with a decent engine the OS R21max art.nr. OS1B900 is a good start.

What separates the on and off road engines is their timings. On road engines use a more of a L shaped header whereas off road uses a U shaped header. On road GT8 also uses an off road header.

For GT there are much shorter U shaped manifolds giving the exhaust length more an onroad use.

Thanks for all the info, i should have said from the start that it is for a 1/8th pan car.

GT and offroad motors seem to be plenty available at shops like KleinKram, but for pan cars i see nothing specific.
All of them except for two 2.11cc motors come with big heads, 5 or less ports, U shaped exhaust flanges, and carbs the other way arround.

I feel like i am overthinking this, but for how expensive these motors are i really want to get the correct variant.

Edit : https://www.worldchampionproducts.co...efra-2115.html
Something like this seems to be what i should be looking for?

Yep, it is not the fastest motor but for sure very decent and affordable. Probably you are going to run it on 16% fuel, in that case you must remove the 0.1mm headshim. And the ENS set comes I believe with an 8mm insert in the carburettor. If so the replace it by an 8.5 or 9mm (if you are not going to run the ENS or the German Hobbycup.

If money does not matter you can always go for an 05 or 06 engine (VS or OS), they are fast, powerful and competive with all other top engines but also require more attention.
In that range you have also Ielasi tuned, Hasi, ASM, GiMar and Kabuto. All OS based with some extra mods.
Other high rated brand is MAX, only very expensive.....
Then there is Picco currently with their Monza9, this engine is only fast with the latest MAX exhaust.
And there is the FTX line like XRD, Sirio etc but there are not much selling points.

I looked up some of those motors, but i ran into your channel most of the time.

However i settled for the O.S 2115, if i do well and have fun the next season i can always settle for an upgrade the next one.
But i'm sure it'll take me a few seasons to get the most out of this motor first anyway.

My channel????

Another tip. If you are going to use fuel from Energy or the European Maxima (= energy) it is wise for your engine to add 1% extra castor oil. I use Eurol Racing-1 but any racing castor will work.

I assume this is yours? There can't be that many dutch nitro gurus called Roelof
I'll order some trough work, thanks

Ah, my youtube channel....

I have all over the net published some projects. Like this one regarding this blue head OSMAX Modding en mechanica maar dan net iets anders - Modding, mechanica en elektronica - GoT

Everything is coming along nicely but i have the feeling my exhaust is slightly too big?
If i mount it in a specific way i can make it clear the tire and turnbuckle, but just by mere millimeters.

Just move the exhaust on the front side a bit closer to the chassis

Like Roelof stated, your pipe is "Flexible" via the connections at the header and the Pipe, the Pipe Mount Wire allows you to fine tune its location. Also you can turn the header a tiny amount Anti Clockwise which may allow for a loss of 1 mm or 2 in overall length. Either way great setup, and anything Mugen and Rody is ok in my book! (Roelofs too, as he like I are Mugen guys)

Thank you both, completed the kit and everything fits like a glove now.
Clutch came together properly after pulling the crankshaft while mounting the cone as Roelof suggested.

The only thing still left do is cut the body, but i can't find any guides on how to do this properly.
Are there body/chassis specific templates or measurements for this, like petitrc has for 1/10 TC cars?

You can get pre-cut bodies. But yes, there are printable templates to find.