[Lowspeed Lowside]

@all: big thanks for all the replies

Originally Posted by TnNinjaGirl

Also, if it were the least bit of a good idea someone would have already done it.

If that were true, we'd still be using candles, I mean: torches, I mean: rely on moonlight.

With all this new found horsepower you (we) are going to need a stiffer frame, larger front tire (read wider rim and new forks/front end) and a larger rear tire (read wider rim and wider swingarm). So by the time you get an engine you can boost and all of the ancillary items to keep the bike physically together and stable.... you don't have a Ninja 250 anymore.

The main misunderstanding is that you, like many others seem to think a turbocharged ninjette is/should be equivalent to a 600cc sportbike.

Keep in mind, that you'll always be able to ride in a way that will exceed the limits of what your motorcycle can do. For example, if you're going to attempt a U-turn with a radius of 30 feet @ 65mph on a ZX-6R you're going to be in much, much more trouble than cruising @ 130mph on a long, empty, straight, smooth, clean street with a turbocharged Ninjette.

Drag shouldn't be a big deal with an intercooler up front. The bike is small. Bigger bikes do 170mph with no aerodynamic issues. As long as it is sitting in front of the radiator and not hanging off the side of the bike it should be fine. Another problem to worry about it heat soak. Once that intercooler gets heat soaked, say goodbye to your coolant temps.

Which is exactly why I don't think intercoolers should be put it in-front of the radiator and drag could represent a problem. Anybody willing to think about whether a spring-loading mechanism for the intercoolers can be made for $20? The idea would be that they fold back at speed and guarantee constant airflow...

If you do end up running boost, I wouldn't do more than a couple 3 psi. The heads and head bolts aren't exactly the best engineered pieces in the world. The bottom end has already been mentioned. These motors are alot like glorified Briggs and Stratton go-cart motors (which I used to build and race).

In your experience, what gives up its ghost first? The head? Or the head-bolts? Remember we have a very limited budget, so it would be nice to know which part is the most likely to fail first, in which case there might be a cheap way to monitor it. If it's a bolt, is it feasible to modify one and treat it as a safety fuse? Probably not...

Originally Posted by greg737

I wasn't suggesting you re-invent an ECU for an EX-250 fuel injection system, the Bowling & Grippo MicroSquirt ECU will do quite nicely. I was thinking of all the other items that you need for fuel injection.

I think you entirely missed the point!

Programmable Engine Control

Now, how cool is that!

Unfortunately, there is so much interesting stuff to do and so little time to do it. For example, a Bowling & Grippo MicroSquirt ECU is $250 (http://www.diyautotune.com/catalog/m...v22-p-381.html), whereas a tracfone with much more powerful hardware is $10 (http://www.tracfone-orders.com/bpdir...sionId=9428759). Taking the phone apart is free, solder is 2c, electronic parts are $2, putting linux on it is free, writing a driver is free. If you don't rev up the engine 2x long and 1x time short within 10 seconds of ignition, make the engine play Yankee-Doodle-Dandy! Or make flames shoot out of the exhaust, in case you need a lighter! Arrrrgh! The possibilities! Stop teasing me!

Back on-topic...

I'm having a hard time accurately modeling intercooler behavior. The difficulty is that the compressed air cools gradually, therefore some parts of the intercooler will be cooler than others.

We know that there is thermal conduction within the material of the intercooler, i.e. the hotter parts are slightly cooled and the cooler parts are slightly heated, which is why two coolers in series connected by a thermal insulator should provide better cooling, than the same two coolers connected in parallel, at the cost of decreased boost. What we don't know is how a pair intercoolers X by manufacturer Y will behave at Z psi, W cfm and T° - I hate that.

It should also be noted that the (non-super/turbo/atomic) combination of engine tricks Mike developed for his EX-250 G Force racing engines cost thousands of dollars per unit in parts and machine shop hours to implement, including his super-secret tweaks to the oil system that were necessary just to keep it from grenading right away; it wasn't a simple matter of bolting on a few parts or overboring the engine.

I do not doubt that Mike Norman is an top-notch expert on motorcycle engines in general and has lots of experience with the EX250 in specific, and we do learn a lot about Mike Norman's upper limit, but - I know this sounds rather arrogant - it makes immediate sense to treat Mike Norman's upper limit as our theoretical lower limit: we definitely know that 35-40hp at the rear wheel is doable.

Also, I don't think you have considered that as a group we might have a big edge over Mike. Not all EX250 engines are created equal, so if the maximum power we can get out of the average EX250 engine is X and the standard variation is Y, (Warning! Gaussian! I assume too much!) we'd expect 1 in ~50 engines to generate at least X+2Y and 1 in ~700 (I think) to generate at least X+3Y. Someone might even own a Goldilocks!

Last but not least, I do not think highly of people (even professionals) who like to keep tweaks super-secret. They are protecting a monopoly, which guarantees a suboptimal allocation of resources (sorry about that, but I did mention that I'm a boring economist). Real geniuses are intelligent enough to stay ahead of the curve by coming up with tweak, after tweak, after tweak...

If you consider the massive collection of cool DIY-stuff here, individually we might not be geniuses, but the DIY section generates tweak, after tweak, after tweak...