srthompson1980

Hey, I was wondering what is restricting the torque on my 305 TBI setup. The 305 with a TBI was rated with 255 ft/lbs, but the 305 TPI of the same year was rated at 295 ft/lbs.

I know all there are alot of differences between the TBI and TPI engines, but is the torque hidden in the heads, exhaust, cam, intake?

Thanks

91interceptorZ

iTrader: (3)

a lot of it would be the tuned port injection itself.......don't know if heads are any diff. Exhaust is the same. Cam is different but small like your tbi cam.
Are you wanting to change it out??

Stephen

iTrader: (12)

The long TPI runners are a big part of the torque TPIs make. Notice how the LT1s are essentially a short runner TPI? The toque # comes down, because of that.

bluers91

The heads are different and in some the cam is different too.

Fast355

iTrader: (2)

Exhaust and Tune....Fix BOTH and your TBI will make the TQ of a TPI engine with the exception of the 2,600-3,600 rpm band.

thomas1976

TPI Heads are different. TPI Exhaust is alot different, better by much. TBI cam is smaller.

bluers91

Some TPI's run the same peanut cam as the L03 TBI. Some run the L98 cam with more duration.

thomas1976

No 90-92 TPI has the penut cam for sure.

Stephen

iTrader: (12)

Yep. 1987 got the peanut cam. Guess what year my GTA is?

BUT, even with 210,000 miles on mine, I can still roast my 315s so.....

srthompson1980

I knew at least 30 h.p. is hidden in the exhaust. Today I picked up a used set of headers and 3" y-pipe and a 3.27 BW posi rear end. After I install everything, I want to get the car to a dyno, and I will see if the torque numbers increase along with the h.p.

After this, I want to try the Edelbrock TBI intake manifold and see what happens.

With 3 kids, this will be a process finding time to install everything.

kkingsrulee

Stephen is exactly right.

With headers short headers provide more low end and long headers provide more top end, high speed power.

Intake runner lengths are the exact opposite, short runners provide more high speed power, long runners provide more low end torque.