Konstantin

where can I find infos on the Link 2. ?
why is better than the Link 1?
Danno, when will be the Link 2 available?
Is it already available from Huntley or SFR?


Konstantin

Danno

Hi Konstantin, the main difference between Link1 & Link2 is sequential fuel & ignition. This primarily makes for easier fuel-metering at idle and off-idle transitions when using large injectors. Maximum power should be the same in both configuration.

The Link-2 has closed-loop knock-control, although you don't want to rely on that. It also has additional outputs such as a second RPM-switch for VTEC, shift-light, etc. A water-spray switch to activate water-injection pump. Another output can be used for progressive nitrous injection. The computer will also adjust the injector duty-cycle
to meter additional fuel to match the amount of nitrous injected.

So the Link-1 will suffice if you want to replace all of the DME/KLR's function with a programmable plug & play unit. The Link-2 would be the choice if you need the additional functionality.

More info here:

Link-1: <a href="http://www.link-electro-usa.com/link1.html" target="_blank">http://www.link-electro-usa.com/link1.html</a>
Link-2: <a href="http://www.link-electro-usa.com/link2.html" target="_blank">http://www.link-electro-usa.com/link2.html</a>

Konstantin

then set me up for the Link 2
I want this water injection sequential Injection and want to use bigger Injectors like 55 lbs at least.

Konstantin

Huntley Racing

You will want to run at least 80# or larger injectors. With sequential you need more injector to make up for the single injector fire per cylander. We are putting a link 2 on a HR 2.8 ltr in the shop right now and another on a 2.5 ltr right afterwards. We will post the results.

Alan C.

If Konstantin is talking about full sequential then the injectors will only fire half as many times since batch fires 2 at a time.
Alan

tazman

I don't know what Derrek said makes sense to me. Lets say all 4 injectors have 4 seconds to fire. If you fire 2 at one time then you have about 2 seconds that each injector can be fired. Now if you fire each one separately they only have 1 second each unless the Link2 can fire more then one injector at a time.

Danno

"If Konstantin is talking about full sequential then the injectors will only fire half as many times since batch fires 2 at a time."

"Lets say all 4 injectors have 4 seconds to fire. If you fire 2 at one time then you have about 2 seconds that each injector can be fired. Now if you fire each one separately they only have 1 second each unless the Link2 can fire more then one injector at a time."

You have to keep in mind that it's DUTY-CYCLE PER 4-STROKE CYCLE that we're talking about here. Batch fire would fire all 4 injectors simultaneously once per 4-stroke cycle. Sequential would fire 2 of them at a time twice per 4-stroke cycle. However, the total amount of time available to fire is still the same. And the total amount of time the injectors are on is still the same.

So at 6000rpm, you have 20ms per 4-stroke cycle. Let's say you're firing the injectors at 80% duty-cycle. The firing pattern would look something like this:

BATCH 1-4: 16ms-ON, 4ms-OFF

SEQUENT.1&4: 8ms-ON, 2ms-OFF, 8ms-ON, 2ms-OFF
SEQUENT.2&3: 2ms-OFF, 8ms-ON, 2ms-OFF, 8ms-ON

Notice that in both cases, the ON times and OFF times are identical. Check out the pictures I drew up comparing the two here: <a href="http://members.rennlist.com/951_racerx/SequentialVsBatchFiring.pdf" target="_blank">SequentialVsBatchFiring.pdf</a>

Now that was theoretical, in reality the injectors have a latency period as they open. Low-impedance peak & hold injectors tend to be 3-5x faster than high-impedance saturated injectors. The actual fuel-volume delivered vs. time looks more like this:
<img src="http://boards.rennlist.com/upload/Injector-Pattern.gif" alt=" - " />

So you have to account for the latency period in both firing schemes. With sequential injection, you have to account for two latency periods per 4-stroke cycle. And at higher-RPMS, the latency takes up a larger percentage of the total time available because it's a fixed amount regardless of RPM.

EDIT: Whooops, didn't add up my OFF times correctly... fixed...

RLefebvre

Danno, I don't have a Link or a Porsche, but I recognize good tech when I see it, so wanted to ask you something.

I'm running a Pectel system on a Focus. It has an automatic correction, where, if I should ever have a cam sensor failure, I lose sequential firing and revert to batch. It has an automatic correction where it would basically fire the injectors twice as often (batch) with a multiplier of 0.550. So basically it would give about 10% more total pulsewidth.

Your graph there seems to show the amount of latency would be more than 10%. Where did you get the numbers in that graph? Just want to get an idea if I need more for safety.

If I ever get a 951, I'll certainly go to you for engine management. You on cc.com by any chance?

Danno

"Your graph there seems to show the amount of latency would be more than 10%. Where did you get the numbers in that graph? Just want to get an idea if I need more for safety."

Yes, the latency is more than 10% because of the very short pulse-width of only 4.5ms. This was a simulation I ran to test how large 75-lb/hr injectors will work with the stock Motronic DME computer at idle. So this pulse-width represents only a 3% duty-cycle and the response-time of the injectors are quite apparent between the low-impedance P&H types vs. high-imp. saturated.

However at mid-range operating ranges with pulse-widths of 15-30ms, the latency becomes a much smaller percentage of the total ON time.

At high-RPM near redline with very little time per complete 4-stroke cycle, even at 100% duty-cycle, the low-imp. saturated injectors' longer latency becomes a major limitation in delivering adequate fuel.

Steve Lavigne

</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Originally posted by RLefebvre:
<strong>If I ever get a 951, I'll certainly go to you for engine management. You on cc.com by any chance?</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Aaah, P51. That lsd thread was almost worth a cross post to cc.com.

BTW, Danno posts as DannoXYZ, but he only pops in from time to time. Look in his profile on cc.com and you will find some good tech from when he used to post more.

Danno

"That lsd thread was almost worth a cross post to cc.com"

Yes most certainly! Almost as good as the cross-drilled brakes thread from the Altima board... heh, heh.. <img border="0" title="" alt="[Wink]" src="wink.gif" />

Haven't had too much time to check out C-C.com lately since taking on this GURU Racing stuff. I've been concentrating on the Porsche 951 stuff. But I have been getting a lot of inquiries from the Mustang-SVO and Turbo-Chicken crowds. We might pursue that market with our MAP kit eventually.

RLefebvre

I really ought to look into this Link Systems. The Focus crowd is RIPE for the picking at that price point.

I had read some posts on a Miata forum, where one guy who was promoting Haltec systems, was complaining about "spark scatter" on the Miata. Now, I don't know if this was because it was running through the distributor, or if it is something in the Link itself. Do you know anything about this?

Danno

Spark scatter is typically cause by mechanical mis-alignments in sequential timing. One set of plugs would be referenced from the crank-trigger and the other from the cam-trigger (both have to be exactly X-degrees before TDC). But with the stretch of a cam belt at various RPMs, this can affect the timing of the second set of plugs.

The other area that contribute to scatter is the internal clock on the computer. Exact positioning resolution is based upon the number of teeth in your timing wheel. A 60-2 wheel is common in aftermarket EFI systems. By using the 132-tooth stock wheel in Porsche's Motronic system, we can double the resolution. The internal clock then divides down the time between 'hard' pulses from the teeth to generate 'soft' interpolated positions in between. The more teeth you have, the less you have to rely on interpolated values in between.

I'm not too familiar with the scatter issues on the Miata, if you can link me to some, that may shed some light onto whether that issue is present on our systems as well. Thanks