Ok, you decide Carbs, FI, or DI

[2T Institute]

I know this is straying off the DI debate a bit but I'm not sure you can apply that as a hard and fast rule across the board.

I don't care if you stray off, the info you gave was awesome.

Back in 1993, there was a certain NSR500 with EFI. Shinichi Itoh rode it, and Doohan said he wasn't a R&D rider, he was racing to win. Well it first debuted in the Japanese GP, Wayne Rainey said the bike sounded like a cruise missle coming up and going buy. He also said his YZR500 was being pulled towards Itoh's bike when he was coming from behind him, and then he would rocket by and Wayne would try to get behind him to draft. 9 out if 10 times Rainey couldn't draft Itoh because the bike was fast and would gain about 7 bike lengths. But after the end of 1993 Honda pulled the plug on EFI, not because it didn't work but because of Mick Doohan who wasn't into testing new stuff. Also the NSR 500 of Itao was the first to break 200 mph at Hokenhiem. Funny stuff ain't it?

The problem with open loop fuel injection on a race engine is the hot/cold pipe dynamic in the engine. Worked OK at Hockenheim and Suzuka but never worked when mid range part throttle fueling was of importance.

[Chris2T]

One thing that doesn't seem to get discussed much in DFI threads is volumetric efficiency. A DFI engine can make substantially more power than an identical EFI or carbureted engine, because of greater volumetric efficiency. The fresh air being drawn into the DFI engine is ALL air, there is no fuel to displace any of the air. So the engine is capable of drawing in more air with no other changes than simply switching to DFI.

Very true, hadn't thought about it that way. Plus, each drop of fuel is undiluted by oil. pure air + pure fuel!
Also, i was looking at the bore/stroke ratio of the e-tec direct injected marine engines and was blown away by the piston dimensions. For instance, on one of their engines which has 432cc cylinders, it has a 91mm x 66mm bore/stroke. Hugely oversquare = high revving screamer! can't recall a 2 stroke ever being this oversquare

[Out of Order]

Your still going to get a little bit of oil in the combustion chamber no matter what. Why? Because if the main bearings are oiled through lets say the gearbox oil (Bimota V-Due) all that's left is the rod bearings which aren't going to need a lot of oil. But you can now run oil ratios like a RX-7 wankel engine which are like in the 1000 range, maybe not that drastic but you get the point.

In the end, is the engine going to be cleaner? Yes. Is it going to be more efficient? Yes. Will it need less oil to run? That's a positive. Is it going to make more power? Now that depends. No one will know with out R&D, because you just can't assume these days, you need facts to back it up. To be honest I think a DI engine will work for motorcycles we just need someone to build the damn thing.