[Diy_efi] Sequential fire setup

[Dave Dahlgren]

The straight scoop. This is not the cheapest way but i suspect a 1200 hp BBC is
not cheap either. What does it cost if you do nothing but ship the engine to
someone and have it done. Manifod, rails and injectors about 6000
ECU, harness and tuning about 12,000
If you do it yourself about 8000 plus dyno time where ever. Just make sure the
dyno has a servo to run the brake so you can do all the load points foe each
rpm. If you have a limited knowledge of EFI then make sure someone on the crew
has a good knowledge or the dyno operator does. Also make sure the dyno operator
thinks efi is a great idea as most want to make a half dozen pulls and call it a
day and that is not going to happen with your engine.

My ideas mixed in with the questions below.
Dave Dahlgren

> mazak wrote:
> 
> Hello
> After much thought my best friend & I have decided to put sequential fire EFI
> on our drag car.
> I found this---> http://yarchive.net/car/fuel_injection.html
> Very nice information---I learned more from this than anything else I've read.
> 
> We've already built a 91 Corvette drag car with a L98 TPI (batch fire) & had a
> little success. The owner didn't want to dyno the engine so everything has
> been a hit-or-miss considering our limited knowledge of EFI. We're fully aware
> of the basic theory & operation but since I read the post about sequential
> fire I've begun to wonder if there's any advantage over batch or bank fire.
> 


Lots of advantage to it. For starters you can trim the fuel for each cylinder if
all the 'soldiers' are not of equal power output. it also aids in injector
balancing. I get injectors flowed and just enter the differences in the cylinder
trim tables to start. they are flowed at a duty cycle and period to correspond
to max power output.

> Here's what we're planning......
> The car will weigh 2250-2350lbs & we're hoping for 1200hp @8500rpm from our
> 565 BBC.
> The throttle bodies (4) each have 2 two inch holes located directly over the
> fabricated intake runners.
> The injectors we're starting out with are 88lb & the ecm is a FAST sequential
> fire. (http://www.fuelairspark.com/)
> 

If i were to spec out the induction for this engine it would be an IR setup. 8
butterflys 8 stacks 1 for each cynder. A kinsler or hilborn casting will do just
fine. Run in Alpha N mode. Plenums are for carbs you don't need one for a race
engine and EFI. The same goes for MAP sensing, use alpha N and the map sensor
for baro compensation and get on with it. i have done it a zillion times and
with a sequential ecu it is very nice. An added bonus is the injector placement
can now be tailored for the application. general rule of thumb is higher in the
runner for more power and closer to the valve for more response. The trade from
highest to lowest positions is about 10% in torque with the high one being the
winner. In the WSC/ALM/Petit Le mans  cars we have the injectors out of the
stacks completly hanging on a rail that sprays the fuel into the stacks.

> I guess I'm asking any of your personal opinions of this since you seem to
> have full knowledge of EFI systems.
> It seems everyone we've spoken with so far gives us vague information-----for
> example: What injector angle ? 

I generally run them to point to a high speed area of the runner in in a
straight section about 30 degrees from parallel.

>How much fuel pressure ? What is the optimum

More is better up to a point with electric pumps if an NA car then 75 to 85 is
about the limit. If you have a mechanical pump then I have run up to 125 on some
injectors.

> EGT ? 
Depends on compression ratio.. the higher the compression the lower the EGT it
also varies with timing as well. More timing EGT goes down for a while them goes
way up. retarded timing makes things hot and then hotter.
Typical NA EGT for a 13.0/ c/r is about 1350 with C-12 and 36 degress of lead.
This is probaly not the peak but it is what you will see with the typical
response time of most k-wire sensors. At Bonneville that same engine will be at
1500 at the 4 mile mark and still going up.

Open or closed loop if the engine is only run at WOT ?

Open loop definately! All feedback is reactive not proactive. There is always a
delay invloved. So no matter how fast the feedback it is always history not
current conditions. You need to do the tuning on the dyno and the racing on the
track.

> I've got some general ideas about the answers to these questions but no
> rock-solid advice.
> We would gladly compensate the right person that would work closely with us to
> get maximum HP.
> Weeks could be spent on the dyno without some sort of baseline information.
> Also, any tips or links to other online information & articles would be
> greatly appreciated.
> Anyone interested in helping please contact me asap.
> 
> Thanks in advance
> Ray Roberts
> 
>


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