I have the option to flip my computer to sequential to batch firing. I also hear all you need is crank trigger to run the batch fire system. Just looking into the advatages/disadvatages.

Thanks

 

Sequential is better but not by a whole lot. My understanding is the primary advantages to Sequential are lower emissions during cold starts and a slight improvement in idle quality. Virtually no difference in power between the two.

 

It makes no difference at WOT and very little anywhere else. Sequential may idle a little better, lower emissions at very light load, etc. I don't think sequential is really worth bothering with for a high performance car.

Rich Krause

 

Do you guys know if its true that all you need is a crank trigger in order for the batch fire to work? Does it just send fuel 4 cylinders at a time(bank to bank)

 

BtB does not need a crank trigger. It just alternates bank to bank (cylinders fire alternately from one side to the other).

Rich Krause

 

There are definite advantages in running sequential in very high HP applications, but only if you keep the duty cycle on the injectors relatively low. That way you can time fuel flow to compliment air flow in the runner. Aftermarket systems like the MoTeC provide a "timing map" for the injectors. Not a lot of HP there, but keeping the fuel atomized in a flowing air stream can prove beneficial when compared to dumping batch fire injectors against a closed intake valve.

As Rich points out, batch-fire (or bank-to-bank) fires the complete bank of injectors on each crank revolution, so all it needs to work is the crank position = crank trigger. Sequential requires cam position, so it knows which cylinder is going to fire next. The Opti turns out to be a superb, high resolution cam position sensor, and can be used easily with most of the aftermarket computers. Getting the hihg voltage stuff out of the Opti, and going to an 8-coil setup will also be possible with this approach. And that appears to prolong the life of the Opti.

 

Good post...


On a fairly tame street car you wont hardly notice a difference...one of my best friends has a 93 and I can't tell a damn bit of difference in the idle of the two cars. I get better fuel economy but I attribute that soley to the 6 speed vs his auto...

 

Im running the fast bank to bank system right now. Since I have the bank to bank system why does the ecu still want to see the cam sensor? Its a jumper harness so I no longer need the speedo. This is actually to help a buddy out but i might be on the same track. He has the edis box from fast.

Thanks

 

Fred's right, padon my dyslexia. Got my cam and crank positions mixed up. My context is forced induction though, where sequential is not an advantage for peak power over bank-to-bank. NA, Fred makes a good point about the fuel and air flow, but this would refer to NA and I have not seen it verified,

Rich Krause

 

Rich:

You can also make a very good case for sequential injection with dry nitrous. The dry system has the advantage of flowing nitrous only when the valve is open. A direct port wet setup is going to spray nitrous and fuel all the time - and that means cold fuel and nitrous impinging the back of the hot valve. I've seen the NOS NOSzles used to advantage in a dry system - and the NOSzles are only there to admit nitrous - on a sub 7-second Pro 5.0 car. Obviously, all this thinking is way over my head, and I have spent a bit of time learning from people who do this stuff for a living...

Fred

 

FAST typically recommends the sequential systems to applications that are over 1000 hp. They may also be beneficial in those applications that have a large disparity in cyl-to-cyl EGTs. In those cases you can get the MACK Daddy FAST sequential ECU with Individual Cylinder Tuning Capabilities. Cool stuff!
Kevin

 

Hey guys,
Speaking with a college (ok the kid that lives 2 houses down and works for Boshe)

There was a guy there that brought in his personal vehicle and tuned it himself.

He got the best results by setting 100% duty cycle and adjusting fuel pressure. He was spraying gainst a closed valve and open valve (720* of crank rotation)

intresting huh?


another thing for BF VS SPFI-

although SPFI has a lower cycle duty given the same conditions, the flow rate is typically higher. thats why they went from 19# to 24# injectors from 93 to 94