another bad day at the track.

first the worst....

2.21 60'
6.88330
10.64@66mph
would not pull above 4000rpm
fouled the plugs...left a smoke cloud and unburned fuel behind.
i tried to add too much fuel.


second the least bad....

2.16 60'
6.43 330'
9.81@74



previous bad run
3.0 60'
9.5@82



this is what happens when i fool with too many things at one time.

my guess besides fuel, is the cams gave up about the time the intake started working. rev limiter set at 5600. intake works at 6700. the intake gets shelved until the motor catches up. the tuner i have has failed. the memory went bad. so it has the stock timing. that hurts a lot also.i have to get off my butt and get hypertech to get me another tuner.

i tell the good and the bad.

i lost 16 mph or about 100hp on my worst run. it could happen!!!

i have another unmodified untake.

15 second 1/4 times.

if nobody tries anything new there can be no innovation.

i am going to add a tapered divider between the runners. the effect on other manifolds is to make them operate at even higher rpms. usually tapered runner intakes don't lose much at the low end, and make moderate gains in the ~4500+ range depending on taper angles and length.
for example a tapered runner intake with 12" runner and say 4 degrees of taper and a final 1.8" runner diameter makes power at ~7200. that's why true tunnel rams have long runners. they don't really make power down low, but mid to upper power is unmatched.

there is an issue with the published flow characteristics and bore/stroke of 5.4's. they have a noticable dip in the torque curve from 2700-3800 rpm. as the runners get shorter the loss is more and more evident. obviously a stall 3800 rpm converter get past the area, but i can surely testify it's there. i leave the line pretty hard and it falls over until 4000. dyno sims show the loss removed mostly with long runners , to include tapered runners, but pure straight runners long enough to eliminate it die at 5500. hilborn injection uses different runner lengths to tune the flat spot out in big block chevy.

i'll make the changes and test it at the track this fall.

i put the long runner stocker back on.

i start tomorrow adding the tapered partitions between the runners.

here is a pic of the manifold as it is now...



note the area between the runners.

in a perfect world a runner has a trumpet with contours that are even all the way around. what i have is a high wall on one side and a 1/2" partition between runners.
in mt opinion the air enters the runner with some tumble. the outer runner area has more velocity than the area between runners. the air has to bend and enter. i don't feel like it kills the airflow, but it can't help. i am going to extend the area between runners to form a wedge. it will create a taper to the actual runner. i'm hoping to get more laminar flow into the entry and more velocity. tapering the runners allows lengthening without changing the rpm band from high to low. i also feel like it will isolate the opposing runners from syphoning effect.