I would like to ask you racing guys. What is the current state of the art S2K NA engine? Urge has posted insane results with Endin engine that they were developing - something in the reagion of 340-360ho at the crank. https://www.s2ki.com/s2000/topic/645...t-track-build/ Honestly I find it hard to believe... Is it really possible? Is there any real owners of full URGE build engine making close to above numbers (crank)?

I just found that unlike some time ago (3 or 4 months sinse I saw it) URGE designs doesn't offer engine builds anymore...

Thanks
Ted

 

I would call Patrik and ask him, personally I've never heard of anyone reliably putting down more then 250whp...

 

Someone in Europe had it, lasted him a few minutes before it took a dump. Urge stopped using endyn shortly after...I believe its real difficult running high HP N/A reliably, toda seems to have a good motor, but they are around 300hp though

 

https://www.s2ki.com/s2000/topic/109...ngine-failure/

Mine is now running reliably after rebuilding with a standard crank and much lower redline (at my own cost - Urge didn't offer anything) and putting out good power. I will update my post at some point soon.

 

The French TT guys are making ~300 out of the AP1 engines, reliably too, they do a full season without being touched.

 

In the linked thread, the OP's "F1 guy" and "URGE" both argued their case about engine balance, regarding mods done to the original crankshaft in that Endyn engine, and neither of them were correct in their argument for or against what was done.

An inline 4 has two pistons going up and two pistons going down together, so in total the two going up always cancel out the two going down, right? So why do you even need counterweights?

The problem is that the forces going up and down aren't directly opposed to each other, so they rock/bend the crank across the main bearings like a see-saw. The counterweights on a fully counter weighted crank are directly in opposition to the reciprocating pistons and work in opposition to the see-saw affect by trying to zero out these forces acting to bend the crankshaft and crush the main bearings. Cutting down the counterweights without reducing the reciprocating weight of the pistons & rods and reduced their effectiveness.

Half counterweight crankshafts are better than nothing, but have the opposing forces farther apart than the fully counterweighted crankshaft.

For higher RPM engines, removing reciprocating weight reduces stresses. Removing rotating weight improves acceleration.

This is just the basics. There are second order vibrations that can only be cancelled with "balancing shafts", and rotational vibration caused by acceleration/deceleration of the crank between combustion events and rocking caused by differences in the forces caused by the con-rod big end going up vs. down, etc., that can be partially dampened by increasing the rotating weight and/or the use of harmonic balancers. I won't attempt to explain the rest, because it's over my head.

 

Can you post a link so we can read about them?
Thanks

 

Yep both myself and the engine builder are aware of the balance forces in a 4 cylinder. If you have a crank totally in balance, removing most of the counterweight and nothing from the other side will throw the balance out in a rotating scenario. The balance forces in a crank aren't just up and down with the pistons, they are 360 degrees of full rotation, and any significant imbalance will manifest itself onto the bearings. I study machinery vibration / balancing at work but hadn't had to apply this to cranks before, only pump / compressor / turbine shafts.

We found the crank to be out of balance, and that along with an advised 9500 Rev limit is what killed it.

The proof is that I've now got an OEM unmodified crank in there with all the other internals unchanged and it's lasted 7 races, 4 qualifying sessions a track day and a test day.

Anyway that's for another topic, but it still riles me that as a buyer, I got blamed for the failure after paying a shit load of money for a 'race' engine

 

The guys running in the Tout Terrain series, engines are Foucart built, but you're not going to get much info without phoning and ordering one to be honest. He's a pure race engine builder so he doesn't really aim/market at forums/trackday group, people know his engines well enough over there to just go to him.

 

Vincent Foucart, the guy running the 2 liter V-16 made with a custom CNC block and 4 CBR600 heads? Yep, he sounds a little on the fringe. (In a good way)