Ok here's the story, last August I had a 350 Long block motor (wich was rated at around 300HP) put in my '86 Trans Am. Before it had the LB9 305 TPI. I bought new Accel 21lb fuel injectors, and had him use the old 305 TPI set up with the new injectors. He also put in a 268* comp cam. When I got the car back I found out that I needed a custom chip because it was running really rough and only getting about 8mpg and really liked to overheat. After the chip it ran and performed like new, the only downfall is the MPG only went up to an average of 12-13MPG. Also when the chip work was being done they dyno'd the car and the numbers were not good at all. It only put down 160HP and 275FT Lb TQ to the wheels on a Mustange dynometer. The guys who dyno'd the car said that on any other dyno the HP and TQ rating would be an added 20%.

My question is, could some of this be due to a clogged fuel filter? As soon as i get my car back im going to change it but im not sure when im getting my car back (its in the shop getting new 3.73gears with lots of goodies).

Oh and ignore the sig where it says 285HP i had the sig done before i had it dynoed when i was just estimating the HP, i figured it wasn't quit 300HP but reall close and aparently WAY OFF!

 

About 80% of power losses on the dyno are fuel related. I don't really know the exact percentage, but most of the time a fuel pump, filter, or regulator problem will be what's killing the power. And the crap about other dynos showing 20% more power, :lala: yeah right. A DynoJet might show another 3-5% at most. Your symptoms definitely point to a fuel filter or fuel problem. Sounds like your car was missin about half its power.

 

If i change my fuel filter and that is the problem would i have to have my chip re-burned? That would be cool if this is the problem that way I could actually put down some decent numbers.

 

When you dynoed did they use a five gas analizer? If they did what was your A/F ratio? That should give you some idea if fuel starvation is a problem.

 

Where did the 275FP peak? Is the torque line just falling flat after the peak?
I mean 275FP is pretty stout...Looking at the Compcams dyno sheets, you would need an induction system to support good flow up to 5K to produce max HP...
I thought TPI was terriable above 4K???

Ron

 

275FTLBs TQ peaked at 2500RPMs, Im not sure what the horsepower peaked at. It seems to have power all the way up to about 5300RPM from the looks of the dyno sheet. I'll have to go find it again to see if there was an AFR graph on there.