25 June from Hartmut.... some editing by stainless
Got the sprockets this morning from the hardening shop - promised to put stickers on the bike. The did a spot-on job as all my parts were handled perfectly and no matter how soon I needed them - they did it! The sprockets are just barely sliding on the shafts. I guess you can sandblast them a little more - on the other hand a little warmth would make them slide onto the shafts - that's what Bernhard says - he made them to his gearbox tolerances so I guess he is right.
The box is completely loaded - I had it on a weight scale - 308,5 kg - I guess the motor and gearbox should be around 250kg.
I have put in all spares that we might need, a couple bearings for the outrigger plate and clutch axial bearings and the good pistons that you sent.
The special PTFE seals have arrived this morning - no time to fit them so they are included in one of the boxes. Have to ask them for a sticker or two - they forgot to send them. They deserve it. I have to go and have some stickers made too - haven't got any...
Will send all the stickers in an envelope in the next couple weeks.
There are several things going on in my mind what I need to tell you but here is the biggest issue:
I do think that compression will be much higher now in the cylinders due to the earlier opening of the inlet. If it were my engine I would go and get a smaller pulley for the crank and drive the blower about 25% slower. If it doesn't give way over 500 hp on the dyno you could always go back to the bigger pulley. My fear is that the blower load will be so high in the chambers that the thing will grenade. I might be wrong but I just wanted to tell you my thinking.... I will sleep better if you tell me you have a pulley laying around and will try it before using the big pulley.
Max's reply
Your concern about the blower pressure increase by cam timing change is unnecessary. Cam timing before was 60o before TDC, .020 off the seat. You said that you achieved a 4o on the rear engine, and a 6o on the front engine advance before TDC using 70o before TDC opening. The difference between 60o at .020 off the seat and 70o opening doesn't affect static compression pressures that much. The static compression ratio of the engine with the dished piston design, even though the stroke has been increased by one inch, the static compression ratio is about 7 to 1. Using a compression gauge, removing all spark plugs except for one cylinder, and spinning the engines to 600 rpm with the starter, blower belt on, injector hat butterfly open, the compression gauge reads between 110 lbs. pressure, and 120 lbs. pressure. To get pressure to a minimum of 150 lbs. pressure static at 6500 rpm, which is the minimum amount of pressure for an alcohol motor to make power, the boost required is two atmospheres. The 180 cu. in. engine requires a 1.6 to 1 ratio to achieve the equal of a normal aspirated engine running alcohol, showing a pounds pressure of 150 to 175 on the gauge, which is very much the equal of our engines running the size of blower we have at the ratio we have. A 25% reduction in the blower ratio would probably reduce the horsepower to maybe 350. That's just a guess, but it would definitely kill the horsepower needed to meet our goal of 322 mph with the car attached. If it seems that the blower pressure is too high at 6500, we can simply reduce our at speed rpm to 5500, and equalize by putting a taller gear on the bike. We can do this to the extent that the bike will no longer pull at the lower rpms.