Dual TBI units - another idea - I wanna burn my own chips! - diesel airplanes

[KasaRyan at aol.com]

After all my complaining troy with howell-efi.com is helping me finally get 
my 4bbl holley TBI on 425 hp 383 operated by factory 1994 ECM straightened 
out.  It operates 2 injectors in series off of each factory driver.  The late 
model computer WILL NOT fire 2 injectors (holley or GM) in parallel.  It is 
imperitive to get a heated o2 sensor as part throttle response could be much 
better when in closed loop.  The biggest problem with this setup (as others 
have mentioned) is that the tbi doesn't do well at figuring fuel flow when 
you have relatively small throttle openings and high map due to increased 
engine size, cam, 4 instead of 2 holes.  At about 1/4 throttle you have zilch 
for manifold vacuum - so it takes forever to get the fuel curves straightened 
out.  A TPI type system with a mass airflow sensor would work much better at 
dealing with altered engines.  I am on chip iteration 6 and still not there 
yet.  But at least now I can get rubber at 30mph just by smashing the gas and 
mpg is almost 18 in a full size truck.

The bores and injectors in the holley 700cfm TBI are the same as 2 350 truck 
TBI units.  So by my figuring - it should support twice the horsepower - 420 
instead of 210.  You could probably use dual TBIs if they will fire in 
series.  Just hook both trhottles together and use the TPS off one of them.  
You will have to burn your own chip and that will be the fun part.

On the subject of making my own chip just - I am a controls engineer and 
would have no problem burning my own chips and it would have made this 
project go one hell of a lot smoother that is for sure - what I need to know 
from the GMECM folks is what exactly I need to do it, where do I go for 
information, and how much do these things cost?  I have tried looking thru 
the archives but about a million posts come up when I try to search on 
anything like this.  I can breadboard a little something up if that is 
required - here is what I think I need:  Some blank uveproms - 2764?  An 
eprom burner that hooks to the serial port of my computer.  Some sort of 
windows based software to convert what is in the chip to an understandable 
table.  I can then go out and run what i made and watch the int and blm 
numbers on my autoxray scantool.  It would be nice to have one of those 
laptop scan packages that would let me record runs and then look at all the 
numbers later.  I could then modify the values - burn another chip - and run 
again.  What's availible out in the world as far as these sort of things go 
(I dont want to deal with machine language type stuff)?  

Diesel aircraft engines - yes the packard dr980 made 225hp at 1950 rpm in 
1928 and weighed 510 lbs.  The germans build gobs af aircraft diesels in the 
30's - some for the Hindenburg - Daimler Benz LOF6 - v16 -1200hp-at 1750rpm 
from 3299 cubic inches but weighed 4400lbs.  But the main reason it was used 
was because it was stone block reliable and specific fuel consumption was 
only 0.37pounds/horsepower hour.  Most gasoline aircraft engines are in the 
.5 lb/hp*hr range.  Quite a few late 30's Lufthansa ju52's were powered by 
OPPOSED PISTON two stroke turbodiesels.  from 560 to 1000 hp from 1525 cubes 
and similar economy.  The british right before the jet engine wiped piston 
aircraft development off the map built a 3570 hp flat 12 2stroke diesel with 
250 lb of exhaust thrust, power recovery turbines and hoped it would power 
the p[lanes of the 50's.  - all of this is from A HISTORY OF AIRCRAFT PISTON 
ENGINES by Herchel Smith.  

Thanks for listening to my electroyappin!
Ryan Hampl                             kasaryan at aol.com
139 Hoover Ct. 
Salina, KS  67401
phone  (785) 825 5831