Originally posted by Top Gun 777
there was a hundreds of Novas engines and we will nevr find out how many blew up, but even if it was 20 out 100 it is only 20% failure, but 2 Sirios out of 6 is about 33 %. I think no need extra explanation.
To change head clearance from 0.0175 to 0.029 is realy huge difference ( about 0.025 cc head volume increase), I agree with that. But I am very certain that detonation came mainly not from compression ratio. If I will be asked what to do first, I will sugest to glue sleeve to crancase. I explain many times what happening with AAc sets and will do it again. Sleeve sitting in all Sirio engine pretty free and during the work sleeve has micro vibration and create a lot of microscopic debry. That debry goes to combustion chamber and light up during the combustion process and create a lot of temperature, which is creating abnormal detonation. I will be agree to slow down detonation if you change head volume on 0.012, but if it was reqired to rasise further, for me meaning-it wasn't compression ratio. It is my assuming and I will start from it. I also can sugest to use Ferrocene in this kind of case, it will remove detonation completely, but it will keep combustion speed at the same rate. Again if it is detonatin cause by compression ratio-it is easy solve by couple different ways, but if detonation create by other issues-it will not help.
TopGun, thanks, now we are talking more constructively. Regarding the % numbers I unserstand what you are saying. I was just talking about the guys in our team. There were more LCM engines there. The difference realy I think (and I think that you will agree with me) is that most normal drivers do not push their engines as far as what we (people running at A main national levels of racing) do. (guys, don't take me wrong, I'm not trying to sound like a snob). But what I'm saying is that when at this level people are pushing the raw limits of what any engine can do both in terms of HP and longevity. Most normal drivers will never push their engines this far in regards to compression, RPM and general strain, a 1 hour main at this level is simply torture for any brand of engine. I still stand by my beliefs that having 2 engine failures for 6 drivers under these conditions is good. Heck look at Sal, the only TOP driver to make the main. He blew his engine so this equals a 100% failure rate for them. Are their engines unreliable? I personaly don't think so, it was probably just pushed too far. As you are aware of it can be any numbers of variables, clutch engages too late causing engine to bog= excessive strain on engine= raising temp on engine, engine possibly a little too lean, pipe gets damaged causing engine to go lean, tires wear down too much=over rev engine, clutch starts slipping, tank leaks, engine is over compressed etc. etc. etc.
Regarding the aluminum particles that you mentioned it is possible. However the issues that we experienced were only with the drivers running this 1 particular type of fuel. The rest we could run at the lower deck heights and had no failures or engine related tuning issues. This leads me to think that it is fuel related. In hind sight having to make such a dramatic deck height change just to run this fuel without detonation should have been a warning sign. Something I guess we ignored.
daniz24 you said "Yes, the LCM indeed has a ton of HP. But how much is it? I believe it is almost twice (maybe over) than Sirio Evo2 price. So you can't say Sirio produce higher performance engine with less price compare to Novarossi. Sirio with Sirio-based LCM is totally different story..."
When you say Evo2 I think that you are talking about .12's which I do not know a lot about as I'm involved mostly with 1/8. I have however seen the new LCM .12 engines and there is a lot of neat stuff that they are doing. Regarding prices I think they said they are supposed to street around $300 and should be available in a month or so. Is this twice as much as the Evo2's?