Turbo Satoh S373 Beaver III

GrocMax · Oct 12, 2017

Removing it is a really bad idea rack could jam stuck wide open.

Ilikeurtractor · Oct 12, 2017

Keep some rags handy to shove in the intake

GrocMax · Oct 13, 2017

I'm having evil thoughts about making an aneroid/boost compensator out of a Holley 4 bbl carb vacuum secondary unit, its about the right pressure range to do it.

Ilikeurtractor · Oct 14, 2017

Do you have any data showing how much fuel the pump can supply at full rack (without limiters)? It would be interesting to know how much theoretical power you could achieve from it. I suspect the same pump was used on all K3 engines with different configurations of limiter linkages being the only difference. If that is true then the pumps should be capable of delivering a lot of fuel. Maybe the pumps had different available cylinder sizes though (?)

GrocMax · Oct 14, 2017

We know the plunger diameter is 6.5mm, take the total injector cam lift subtract about 3-4mm, compute volume, compute mass per stroke, multiply by RPM/2 and multiply by 60, there's the mass per hr, divide by BSFC (mass per HP per hr) = HP.

A WAG estimate at 6mm plunger lift and .330 BSFC is between 80-100HP sticking to a 3000 RPM rev limit.

I suspect they used the exact same pumping element on a wide variety of engines of various sizes and just changed the stopper lever and injectors.

Ilikeurtractor · Oct 14, 2017

Well that gives something to work with for sure.

GrocMax · Oct 14, 2017

You need to know what the exact effective stroke (fill port close to spill port open) is, that guess could be off quite a bit.

Ilikeurtractor · Oct 14, 2017

I wonder if the effective fill/spill is the same for all series of engines? Or if they are more closely matched to the particular engine? Seems like the cost to make them unique probably wouldn't justify it. Easier just to limit the rack I suppose.

Ilikeurtractor · Oct 14, 2017

According to the manual I have the fuel injection rate for a K3A at "smoke set" is given to be 20.5 mm^3/stroke (+/- 1mm^3). At "start set" it's 30 mm^3 (+/- 5mm^3). I don't know how much this changes as the rpm varies but it must to some extent otherwise it wouldn't be specified I suppose (although I would think it would be pretty independent of speed). If we assume the engine to be 30% efficient and the fuel to have a heat energy content of about 140,000 BTU/gal then the power available at smoke set would be about 24 hp. At start set 35 hp. In the extreme case of 35 mm^3 it would be 41 hp. All of these values are at 3000 rpm. So plenty of gain to be had just by getting to the smoke set value. I wonder what the actual power of the non-turbo'd engine is at smoke set? It should be close to the 24 hp unless the efficiency tanks as it gets there. Then the next questions would be how much boost would be required to get a 30% efficient conversion of the fuel at the start set and is this possible without grenading the engine in a short amount of time?

GrocMax · Oct 14, 2017

Ilikeurtractor said:
I wonder if the effective fill/spill is the same for all series of engines? Or if they are more closely matched to the particular engine? Seems like the cost to make them unique probably wouldn't justify it. Easier just to limit the rack I suppose.

Can't be, they vary widely in size thus max fuel requirements. Just switching the stopper lever you can set max fuel for a wide variety of cylinder sizes. K3M is twice the size of the K3A.