[DeTomaso] retrotek speed - long

Asa Jay Laughton asajay at asajay.com
Mon Jul 26 00:15:53 EDT 2010


Justin,

Thank you for the great write-up.  It actually answered a lot of 
questions I've personally had but not researched.

Greatly appreciated,
Asa Jay

Asa Jay Laughton, MSgt, USAFR, Retired
&  Shelley Marie
Spokane, WA
******************************
http://www.racingagainstautism.com
http://www.teampanteraracing.com


On 7/25/2010 17:48, Justin Greisberg wrote:
> Someone asked about the system, so here I go...
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> i have the powerjection 2 system, I think
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> long message for those interested in this.
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> when it comes to electronic fuel injection, there is mass-flo (most modern cars) and speed density.  Mass flo is very sensitive to pressure changes, and old fashioned radical cams (lumpy idle) are notorious for messing up the mass flow readings.  to do mass flow correctly, you have to have long intake track (look at any modern car with long air snorkel), which I think does not look right on old car.  One company, mass-flo EFI has a very nice slim mass flow sensor, and basically adapts 87-93 ford mustang system to any engine.  they do not offer any self-programming option, so I did not go for that system.  They say it is fine for any cam, but everyone else says it cant be.  who knows?  i wanted to program myself a little (maybe just fooling myself, as these systems dont seem to need my input)
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> I think all other retrofit fuel injection systems are speed density.  Not as good for compensating for changes in air pressure (altitude), but most of these systems these days seem to be self learning, constantly looking at wide band AF readings to adjust fuel mixture.  Port fuel injection is what is on all new cars (one injector for each intake port).  There are plusses and minusses to this for the engineers, but for me, these systems require either buying a modified intake manifold, or modifying it yourself.  Forgetting about the fact that it may not be ideal to reverse engineer a carb intake manifold this way (that is why the same engine will always produce a few more peak horsepower with carb than with port fuel injection), these systems tend to be more expensive.  retrotek and FAST make nice controllers for these systems, and many modern intakes can be converted.
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> However, if you think about it, we should all be tuning our carbs with jet changes, and accel pump changes, and thinks like that to have optimized power and efficiency.  I have never done that, only bought a carb and put it on and hope for the best.  And those cars run like old cars -- hard to start in cold days, sometimes bogging when you hit the accelerator...
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> The retrotek powerjection (and the FAST EZ EFI) are both throttle body fuel injections, so the throttle body contains 4 injectors, and it is basically a computer controlled carb.  I mounted an electric fuel pump under the gas tank, used the tank drain to provide fuel to the pump, added a fuel pressure regulator, and a return line to the original tank output.  I had to add a few sensors as well, but really easy to do.
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> The powerjection 2 system has a self contained computer which I mounted behind the passenger seat.  lots of wires right behind the bulkhead cover panel.  I wanted to put it in the glove box, but the wiring harness was not big enough.  The powerjection 3 system from retrotek has the computer mounted along the throttle body, so less wires to deal with, but otherwise the same.
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> The retrotek system allows you to hook up a computer and play with all the settings  idle mixture, accelerator enrichment (like an accel pump on a carb), and fuel map.  If you use a ford electronic distributor from a 460 truck engine you can even control spark, although I am not doing that.  The FAST EZ EFI only has a handheld controller, and does not offer as much personal control.  I am not sure you need it, since you just start the car and let it self tune.  It has taken some time for me to get my car to self tune, so the jury is still out on it for me.  BUT, when I remember to put fuel in the car, it starts right away every time.  And I have far more control over the engine than I would with a carb.  And I got to make a lot of AN fuel lines!
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> I still think this is the best system available for this purpose currently.  I am surprised the EZ EFI from FAST cant be hooked up to a computer, but it cant.  I hear Accel has something new that might be better, offering more control over disributor, but I dont know.
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> And the polished retrotek throttle body looks real nice!  better than ugly old fashioned throttle bodies.
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> For those interested, I got the 1200cfm unit with four 75lb/hr injectors because I am running CHI heads and intake.  If you have stock heads (esp 2v) and stock displacement, can use their smaller unit with 60lb/hr injectors.  For stroker, or bigger heads, bigger unit seems right.  For those really interested, the computer has had to do a lot of adjusting from the base map that comes with it  -- my cleveland combination seems to have very different needs than generic small block V8.
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> Of all the glitches I have had trying to get my car to run the last year, the fuel injection has not been one of them.
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> i hope this has been helpful.  justin
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