The Super Efficient engine project- 40+ MPG- 110HP!

dstar · Post by **dstar** » Thu Apr 14, 2005 8:43 am

I have a mechanical inj unit for a Porsche 6 on my desk, currently
using it as a paperweight. (I do lots of paperwork....

)

Would this be considered sequential? There are 6 outlets and I'm sure it was timed to the crank, since it is a toothed gear.

Jake?

Don

raygreenwood · Post by **raygreenwood** » Thu Apr 14, 2005 4:03 pm

It is pulsed mechanical injection (Bosch high pressure right?). I do know that timing wascritical...but I don't knowwhat its timing was referenced to. Technically it is sequential. Just don't know how or if its synchronized. It may not matter either. At those pressures, as long as the valve is at some point open, as the injector injects, that system can easily be made to deliver a full injections worth. Those injectors were huge.Ray

j-bro · Post by **j-bro** » Thu Apr 14, 2005 7:10 pm

I used to service a 71 911 with that system but never had to work on the fuel system. The toothed gear is driven by the crankshaft with what looks like a miniature timing belt. The fuel line routing from the pump to the injectors and the appearance of the injectors was so similar to CIS that i took for granted that it was a continuous injection system, pressure being relative to crankshaft speed. Having since read a bit about bosch mecanical systems I know it was probably more complicated than that. The pumps are similar to diesel pumps. Fuel is forced into the line by a piston whos bore and stroke determine injection quantity. There is also some valving to take care of enrichment wich is linked to a lever in the car for cold start, much like a maual choke. I believe it was sequential.

I'm no expert on it by can say with some certainty that it was one of my absolute favorite cars to work on and test drive.

j-bro · Post by **j-bro** » Thu Apr 14, 2005 7:20 pm

Forgot wich thread/forum I was in. Kind of veered off topic...

It's all dstars fault!

Wally · Post by **Wally** » Thu Apr 14, 2005 11:37 pm

j-bro wrote:... The toothed gear is driven by the crankshaft with what looks like a miniature timing belt.

FYI, the injection pump with the Bosch mechanical FI on 'E' and 'S' cars from that period, is being driven of the left side cam, not the crankshaft

BMW had a similar system with a Kugelfisher pump on their Tii versions.
These 4 cylinder Kugelfisher pumps were later used on a lot of type 4's in buggy (dirt track) cross competition. The mechanical injection gave more power than carbs, but used enormous amouts of fuel! so its not really in its place here in this thread

Regards,
Walter

dstar · Post by **dstar** » Fri Apr 15, 2005 8:30 am

j-bro wrote:Forgot wich thread/forum I was in. Kind of veered off topic...

It's all dstars fault!

YEP!

But I can still sleep at night.......

It is ALL relevant, and a LOT of info in these posts can contribute to the super efficient engine project!

If mech FI BETTER than electronic FI?

I've been thinking, I might make a *trophy* out of this FI unit(though it's prolly worth$$$ to SOMEONE) and *present it to Jake one day!

Course, he' prolly got enough *trophies*(junk) in his yard TOO!

Don

914fan · Post by **914fan** » Fri Apr 15, 2005 8:17 pm

Ray
I was referring to raising the top ring to shorten the crown. However taking the top of the piston down would also work if you changed the stroke or rod to compensate for the loss in height.
I was trying to say that I thought that a smaller crown helps the engine run more clean.
Can anybody confirm this?

Jake,
Thanks for the answer. I'll update my sheet to include those dimensions.

raygreenwood · Post by **raygreenwood** » Sun Apr 17, 2005 4:24 pm

I'm not sure I really understand the concept here of moving the top ring...but....are you speaking of the length...of the remainder of the piston...above the top ring? I take it you mean by having a custum piston made? Just a total guess...but I could "speculate", that since the outward force of the rings below....keep the piston somewhat centered in the bore, the piston to bore clearance allows gap equivalent to that clearance at the edge of the piston. Th longer the distance is bewteen the top of te piston and the top of the first ring....may allow more gasses to "wedge" between the piston and bore....possibly causing poor efficiency. But...I would also think the more "wdging" force those gases have at the ring land.....the better outward force you get on the rings. Ray

HAM Inc · Post by **HAM Inc** » Mon Apr 18, 2005 8:22 am

The area between the the top of the top ring and the top of the piston is called "crevis space". Reducing this area does promote a cleaner burn as the charge occupying this area rarely reacts completely, if at all. However, moving the top ring closer to the combustion chamber quite often reduces the life of the ring. The crevis space on an aircooled engine can be reduced slightly, though this should be approached with caution.

dstar · Post by **dstar** » Mon Apr 18, 2005 8:35 am

Isn't the *crevice space*, the reason the Weisco pistons are *threaded* in
that area?

To *throw*, or cause the turbulence to *suck*, the unburned fuel charge
trapped in this area back into the combustion chamber?

Just *asking*!

Don

HAM Inc · Post by **HAM Inc** » Mon Apr 18, 2005 10:21 am

I'm not familiar with those pistons, dstar. Not sure what the logic is behind the grooves.

914fan · Post by **914fan** » Mon Apr 18, 2005 2:29 pm

Ham
That is exactly what I was reffering to. Thanks. Maby Jake will try playing with this seing as hee does a lot of custom stuff already. Imagine a 2.8L Honda clean type4
Waiting Jake.......

raygreenwood · Post by **raygreenwood** » Mon Apr 18, 2005 3:15 pm

Thanks HAM. i learned something new today...and though my explaination was poor....thats aboutwhat I figured raising the ring would cause. Cool! Ray

HAM Inc · Post by **HAM Inc** » Mon Apr 18, 2005 3:31 pm

You're more than welcome gentleman.

vw505 · Post by **vw505** » Tue Apr 19, 2005 12:01 pm

Len , when i send you my "Q" heads feel free to experiment with them for for you flow # . i think we are useing the same valve sizes .