DIYEFI.org Forum

I read something Fred wrote about Free EMS being able to work at up to 18,000rpm. This got me thinking and I had the idea of using an old go-kart engine I had sitting around as a test mule.
It's a 100cc single cylinder air-cooled piston-port 2-stroke "ReSa" class engine.
Easily does 18,500rpm (although one time I miss-geared the kart at Eastern Creek and took it up to 22,500rpm several times )
I then thought about making a test-stand with a waterpump as a load, maybe oil injection to the bearings and that also led to the idea of computer control, logging, dyno, engine run-in function etc...

I think I'm getting too many ideas and not enough time to work on them.

Anyone in Oz following these forums and thinking of mucking around with the EMS?

The max rpm is 65535/2 , but the type of trigger and the number of cylinders will come into the practical max. Unless you run out of time for all the interrupts it should run sweet up to the top just updating the numbers less often the higher you go (less often relative to the cycles, but similarly often at all rpms).

ca7 is another ozzy, not sure who else, but there are doubtlessly a few on here :-)

Fuel management/tuning maybe tough for a 2-stroke since O2 sensors get fouled with oil very quickly .......

Even if the injections aren't 100% accurate as long as it is slightly rich to be safe.
There is no way I would consider tuning a two-stroke with an EGO sensor. Exhaust temp. and plug colour are the way to go, the exhaust note is useful too. You can hear when they "Four stroke" (too rich), sound crisp or the change when they are about to seize (you have a split second which is long enough to realise it is going to seize but not enough time to react and save the engine ).
I think the hard part would be sizing the injectors for idle to WOT control.

"Fuel management/tuning maybe tough for a 2-stroke since O2 sensors get fouled with oil very quickly ......."

Even worse, 2-strokes spit out about 20% of their air/fuel charge making the O2 reading worthless. MAF would be the beter way to tune a 2-stroke.

-sean

I had a bit of a search around and found a few people who have made their own inertial engine dyno's.

A good write up on this page http://www.wotid.com/dyno/
has a link to a few other dyno projects as well as explaining the why's andhow to's of inertial vs brake dynos.

Am I going to get in trouble for putting the idea of a home made dyno in your head Fred?

longracing wrote:Am I going to get in trouble for putting the idea of a home made dyno in your head Fred? ;)

You can't, it was already there, has been for years ;-) WAY down my list, but start a thread and get cracking :-)

Here's a link to 'Burgermans' plethora of sites, much of which i have found informative and entertaining over the last few years, included it here because of his info on his own dynos that he built and opperated for some time, lots of other stuff including a pile on nitrous, and his drag racing days..

http://www.fatnfast.com/

look for his home pages there, and have a looksie, plenty of tales about his exploits too, including his downfall and other accidents, the one involving avgas and a lightswitch is a bit of a shocker..

JB

(gonna try and find out all my other automotive links i've collected over the years, some of it must be of use to you gents. )

Hey! I'm JB!

Piffle and fie JB, I am the true JB, JB!