ptuomov

Group --

Two injector resources that you may be interested in and then a question.

First, here's a catalog of most all fuel injectors know to man. It will not answer all your questions, but it can be used to rule out some definite non-matches. I don't think I've seen this resource posted here yet, but if someone has already done it my apologies:

http://users.erols.com/srweiss/tableifc.htm#tabtop

Second, in case someone is thinking about making their own intake manifold, here are some injector bosses that are available both in aluminum and in steel. The look pretty cool and should weld reasonably easily to a runner:



They aren't cheap, though. $40 per boss plus shipping.

Now, then to questions. I've read most if not all injector threads on the forum. There's a lot of info about replacement injectors. However, I would like to know more about the largest injectors that people are succesfully running with the LH computers. So far, I've found short Siemens Deka high-impedance 60 lbs/h and 83 lbs/h injectors that might work. However, I'd very much appreaciate any comments based on actual experience with very large injectors.

RyanPerrella

the injector boss is very simple, those look overly complex, very large and would lead to a very high profile fuel rail

Actually, i am looking for a low profile injector, something like 2/3rds the height of the current 928 injector. Do you see anything matching that description in their product line?

BC

The shorties are in some fords and chevy cars and trucks.

BC

http://suprasonic.org/public_html/so...rs/RCtech.html

John Speake

The Sharktuner should cope easily up to the 62#. I don't personally know of anyone going over 42# yet with ST but I am sure 62 will be OK.

RyanPerrella

John,

How does the shark tuner work with twin mas air metering devices and twin throttle position sensors?

I know the twin screw setup by DR does this, it is critical to my intake design, im just not exactly sure how the LH handles the signal when it comes from a pair of MAF's and TPS's

90 S-4

Ptuomov,
I'm interested in those injector bosses, who sells them, great find, Thanks..

ptuomov

So the short Siemens Deka #60 high-impedance injectors would work with the reprogrammed '87 fuel computer? My guess is it would. Given the manual transmissions we're forced to live with, I don't think the #83s are necessary.

John Speake

DR uses only one MAF in one of the intake channels. The other "MAF" is just a dummy.

I am working on a way to combine two active MAFs for the ST.

John Speake

Yes, I believe they would be OK, at rated fuel pressure.

RyanPerrella

would you also use 2 TPS switches, or since they would be linked to the same cable from the throttle pedal, you would really only need one TPS sensor reading off a single throttle body?

John Speake

As the WOT switch part seems so failure prone, maybe it would be a good idea to have two connected in parallel :-)

ptuomov

I can't hook up a toaster the right way, so please bear with me on this question: Why not just "average" the two MAF signals? What I am thinking about here is

MAF1 -> resistor -> output terminal <- resistor <- MAF2

Wouldn't this about "average" the two signals voltages? I don't think this MAF signal has to "drive" anything so maybe this would work.

See http://www.allaboutcircuits.com/vol_3/chpt_8/8.html

If the plenums are connected at some point, the LH / sharktuner should then function as before.

Completelymisunderstoodthisagain?

dr bob

I think you need the SUM of the two airflows, not the average. Your average signal would give you half of actual total Assuming that they are both passing exactly the same amount of air, then doubling the 'average' would hardly be the right way either. I'm sticking with SUM, final answer.

ptuomov

Sum could be produced with an op amplifier. However, I don't think SUM is what we want. The stock fuel computer goes nuts with over 6v, since it expects 0-5v. That's why you always have to feed in 0-5v.

Now, as you correctly point out, with stock maps the computer feeds in only half the fuel. But the map can be changed to feed in more for a give MAF signal level.

Effectively, the hardware is fixed to accept 0-5v, but that can then be internally mapped to whatever desired by changing the fuel maps.