This morning I was watching horsepower TV and they had a 350 out of a truck that put down 298 horse and 337 torque. NOw that was a carb'd motor with no accessories, electric water pump, shorty headers and moroso pan. They didnt specify which carb and intake they were using. Then they installed Dougs Long Tube headers with 1 5/8 primaries and they noticed no peak horsepower gain or torque but did get some torque through the lower rpm band. I just thought this would be coool to post for anyone with this question. This makes me feel good because I have shortys.

 

Here's a dyno sheet when I switched from Hooker Shorties to 1 3/4" longtubes in my Y-Body. It made very little peak hp gains, but some decent gains in hp/tq down low.

 

If you go strictly by "theory", that's the purpose of the longer tubes... it tunes the exhaust to produce better scavenging at low RPM, boosting torque. But the longer tubes may increase pressure loss at hight RPM/higher flow volume. Shorter tubes boost the scavenging at higher RPM.

 

ya but also like you said those longtubes were 1 5/8...all lt1 longtubes are 1 3/4

 

Yea understandable, but how much increase is there in an 8th of an inch. Thats an interesting dyno sheet with that much torque increase. What other mods did you have done to it.

 

At that time I had CNC Cylinder Heads, 212/224 521/533 cam, 52mm TB, Meziere EWP, 4.10 gears, and stock lower end.

 

Ok now my next question. Do you think that increase would be seen in a mainly stock or light bolt on car.