other impedence converters

Not trying to deny LJ of any business... I'm just looking for other options. Any one know of any?

Jesse

ttt

I have a patent pending on the Impedance Converter concept (interfacing a factory engine computer to low-z injectors). The provisional patent was filed in April of last year, the real deal was filed earlier this year. My patent attorney is ready to pursue infringement cases. :)

The current price is as steep as it is because there is a lot of money in the components, packaging, and wiring harness, and they are labor intensive to build. I'm trying to pull cost out of the box to drive the price down and the volume up.

I have one "factory refurbished" box available for $300. It works perfectly, but the black anodized case has some very small scratches. Contact me offline if you're interested.

How about swapping out the MOSFET drivers inside the PCM with higher rated units. I have done this swap on some twin driver batch fired ECMs with good results. But I haven't done a SFI PCM yet. I do beleive I may have a suitable cased MOSFET that would be able to drive a low z injector and still fit on the PCM board.

Anyone want to be a guinea pig?

Originally posted by tjwong
How about swapping out the MOSFET drivers inside the PCM with higher rated units. I have done this swap on some twin driver batch fired ECMs with good results. But I haven't done a SFI PCM yet. I do beleive I may have a suitable cased MOSFET that would be able to drive a low z injector and still fit on the PCM board.

Anyone want to be a guinea pig?
I looked into this before doing the Converter. The PCM injector drivers are physically quite small compared to a 4 amp driver, so space and heat dissipation are big problems. Then there's the lack of peak and hold current control. I think that's fatal.

You might have better luck asking on corral.net... I know splice-in impedance converters have been around for many years now, and there are several out there. Pro-M makes/made one, and I talked to JMSchip.com about their unit a few years back... I think both are pretty pricey, though. Most of them are designed for the ford mustang ecm, so I don't know what it would take to work on the LT1 pcm.

EddieP,

The Pro-M unit is spendy indeed. I saw one on corral.net a while back and even though it was used, it was still 400...

I think LJ's unit is the ****. It is fairly priced and it works. Price out those connectors alone sometimes and you will see what I mean.

LJ won't be the only one in the nines with a stock PCM for long (if the track lets me run that fast without a full cage) ;)

Rich Krause

Yeah, LJ is the only one that can legally make an impedence convertor...

Or you can contact Matt Harlan ( http://www.harlan-engineering.com/ ) or Detroit Speedworks Inc. ( http://www.detroitspeedworks.com/ ) (Greg or Phil)

SC-

jesse, i have a used one i'll sell ya.

Why don't you order a set of high-Z injectors in whatever size you want? RC can make you 75# high-Zs for the same price as their low-z units. As for the benefits of low-z injectors...it would seem to be a factor of pulse width and duty cycle, if both are within the design specification of the high-z injector, I don't know why you wouldn't experience consistent performance (i.e., if the duty cycle and pulse width are the same for a 24# fi and a 75# fi are the same, why wouldn't their performance be similar...amount of fuel being metered adjusted accordingly, of course?). It would appear that low-z injectors become more critical on high reving engines where dutie cycles approach 100%. If you have a low reving <6500 rpm engine, wouldn't a properly sized FI in whatever imp. be sufficient?

Before someone flames me, I'm not saying I know this to be a fact, I'm simply saying I haven't been shown a compelling argument on this subject, as of yet. I really struggled with this issue and eventually purchased a Gen VII to run my 84# low-Z injectors....

Thanks!
CT

Originally posted by brand-x
Why don't you order a set of high-Z injectors in whatever size you want? RC can make you 75# high-Zs for the same price as their low-z units. As for the benefits of low-z injectors...it would seem to be a factor of pulse width and duty cycle, if both are within the design specification of the high-z injector, I don't know why you wouldn't experience consistent performance (i.e., if the duty cycle and pulse width are the same for a 24# fi and a 75# fi are the same, why wouldn't their performance be similar...amount of fuel being metered adjusted accordingly, of course?). It would appear that low-z injectors become more critical on high reving engines where dutie cycles approach 100%. If you have a low reving <6500 rpm engine, wouldn't a properly sized FI in whatever imp. be sufficient?

Before someone flames me, I'm not saying I know this to be a fact, I'm simply saying I haven't been shown a compelling argument on this subject, as of yet. I really struggled with this issue and eventually purchased a Gen VII to run my 84# low-Z injectors....

Thanks!
CT
No flame here! The difference is that low-z injectors get yanked open with roughly 4 times as much current as high-z's. Four times the current results in much quicker opening times. I'm running 95lb injectors on the street these days using the stock injector offset vs voltage table values and "95" as the injector constant. My fuel trims are all near 128, which tells me that these low-z injectors are as "snappy" as the stock high-z 24s, even though they are *4 times* bigger.

By contast, I had to add a lot to the offset vs voltage table to get my high-z 50s to work at all, and they never did work well.

Originally posted by brand-x
Why don't you order a set of high-Z injectors in whatever size you want? RC can make you 75# high-Zs for the same price as their low-z units. As for the benefits of low-z injectors...it would seem to be a factor of pulse width and duty cycle, if both are within the design specification of the high-z injector, I don't know why you wouldn't experience consistent performance (i.e., if the duty cycle and pulse width are the same for a 24# fi and a 75# fi are the same, why wouldn't their performance be similar...amount of fuel being metered adjusted accordingly, of course?). It would appear that low-z injectors become more critical on high reving engines where dutie cycles approach 100%. If you have a low reving <6500 rpm engine, wouldn't a properly sized FI in whatever imp. be sufficient?

Before someone flames me, I'm not saying I know this to be a fact, I'm simply saying I haven't been shown a compelling argument on this subject, as of yet. I really struggled with this issue and eventually purchased a Gen VII to run my 84# low-Z injectors....

Thanks!
CT

Did you ever price injectors from RC? Yikes! I got a set of 93lb low-Z injectors for less than $400. They are on the car, LJ's box is installed, and there is just a little more wiring to do (the tranbrake switch, etc.) then well see how it all works.

The thing that appealed to me about the stock PCM with low-Z box is keeping the factory calibrations for starting, low load operation, etc. Even as odd as my combo was last year, using the stock PCM with 50lb injectors (and the Carroll Superfueler to handle fuel under boost) I never had to do much to get it to run really nice. Most of the tuning was to get the desired AF ratio at WOT. I know there are people out there who insist that an aftermrket ECU is just "plug-n-play". My experience differs - a lot. A big part of the business at the shop consists of debugging and tuning DIY aftermarket ECU installations. People put these things in, and then often can't even get the car to start, let alone run well. More commonly, it will run, but very poorly.

So while there are lot of things about an aftermarket ECU that are appealing, I intend to hold off getting one until if and when it's absolutely needed. I hope you had good luck with your Gen VII, but many people do have great difficulty getting them dialled in.

Like LJ, there were some problems with the 50lb high-z injectors. The 42lb'ers were fine, but the 50's were trouble. This also makes me wonder how well modified high-z units would work. Anyone tried them?

Rich Krause

This is good info guys, keep it coming!

LJ, deal is still on. Should be able to complete the transaction in a few weeks.

Jesse

LJ, I’m curious, can you clarify what you’ve gotten a patent on? The reason that I’m asking is that a few companies have been making similar devices for years. Besides the ones already mentioned, I’d add Accel/DFI.

FWIW, I’ve built one using somewhat different electronics with adjustable peak and hold settings which can be triggered by an ecm or a laptop (I use it for an injector flowbench I’m playing with, with the laptop you can program the driver to go through any routine you want while flowing the injectors, simulating real world use).

FWIW, most ford/fordmotorsport/SVO/denso/bosch pintle style high Z injectors can be modified to flow more, ex:
Ford motorsport (sliver body, in lb/hr):
24- 42
30- 47
36- 77
ford (black body)
36- 65…

The cool thing about this is that when modified their spray pattern and characteristics become much more like the factory GM (lucas) pattern injectors, which is significantly different then the ford pattern, while retaining ford’s tolerance for high pressures.

The disadvantage is that the injector drivers used in gm ecm’s aren’t the best at controlling the injectors and don’t play great with really large injectors anyway. Though I haven’t tried them with the LT1/LS1 PCM’s, which seem to be much more tolerant of big injectors then earlier ECM's.

Originally posted by WS6 TA
LJ, I’m curious, can you clarify what you’ve gotten a patent on?
The patent is limited to interfacing low-z injectors to an *OEM* engine control computer.

but that's been done before with the DFI unit and the older GM style ecms and I thought (not sure, never really looked into it) that was fairly common with ford EEC IV ecms.

I'm mostly curious from an academic standpoint, since my wife is a research librarian and spent some of her grad school time doing patent research less then a year ago...