Help, Losing Power Too Early

[wido78]

Well, I finally got my car to the track and needless to say, I was...disappointed! The fastest speed I was able to trap was 105 MPH, I had NO power on the top end.

So today I went to the dyno to do some tuning and the following where my numbers:

1st Run: Max Power 377.5 @ 5200 Max Torque 429 @ 4300
3rd Run: Max Power 458.7 @ 4800 Max Torque 489 @ 4800
4th Run: Max Power 402.2 @ 5200 Max Torque 451 @ 4600

The tuner didn't include run 2 on the graph, but it was about the same as the first. There was a decent cool down period between each of the runs, with the exception of the 4th, which he only waited a minute and a half before making the run.

The following are my mods and I would think that I should be making more horsepower as well as longer in the RPM range.

331 Stroker
TFS TW Heads
1.6 RR
Vortech V1 S-trim around 6PSI
Ported Cobra Upper/Lower
FMS 42 lb injectors
X-303 Cam
Crane Ignition
Autolite spark Plugs @ .035

The tuner is thinking the spark is being blown out on the top end and wants me to go back to stock ignition and make some more pulls.

I was wondering what everyone's thoughts are as well as where other's are making power, I would think it should go into the 5500-5800 range for this type of setup.

Thanks in advance.

 

[TC93]

The 105 is very low with that combo My (8.5 to 1) 331 ran that MPH before adding the blower. And when I added the Powerdyne with 9#'s of boost, it went to 118.

What are you running for fuel pump(s)??? What was you tune as far as fuel pressure and timing?? Also are you runnign an aftermarket chip or anything??? Also what plugs are you running(39xx???)??

 

[wido78]

I am running a Walbro 255 LPH intank fuel pump at 40 PSI. As for the timing, it is currently set at 15 degrees initial and I am not sure what the tuner has the timing set through out the band on the chip. The runs that I listed are the runs during the chip tuning...

I am also running Autolite 3922s.

 

[wido78]

I also have a set of 3923s that I might try, any thoughts?

 

[TC93]

That sure does seem like high initial timing to have achip in there. When JMS sent my chip the recommended setting it back to 10*. You can swap the 23's in but don't think that is the problem.


My combo is close to yours:

331 8.5:1 compreesion
Twisted Wedge Heads
Ebrock RPM intake(box stock)
42# injectors
AFM B-31 cam
Crane ignition (HI -6)
Autolite 3923's at .035 gap

Are you using an FMU?? Does the chip have any fuel added in the upper RPM's?? I run a 255 HP in-tank with a T-rex inline with my 42's and no FMU with fuel pressure at 40#'s.

On the dyno how is the mixture on top end?? I would take out the chip , set timing around 8-10* and set FP around 40-44#'s and see how it responds...

I don't think it's blowing out spark.. With my Powerdyne making 9#'s of boost and NO chip with plugs at .035 and crane box, I didn't have a problem blowing out spark. I added an S-trim with the JMS chip and still have the .035 gap on 3923's with the crane and seeing 13#'s of boost and haven't had the sprark blow out.

 

[wido78]

I do have an FMU set at 4:1, as for the chip adding fuel at the top end I am not real sure how he has it programmed. I am however going to back the base timing down to 10* and go from there.

As for the A/F ratio on the top end, I am right around 11.8 to 12.1, which I think should be about right?!?!

I did pull the plugs and they look great as far as I can tell, so I think I will pull the timing and see what happens.