but the thing is most people assume that they lack up top but are better down low. Set up correctly they make a good but more down low and loose little to none up top. look at race motors that run them. would not figure they would unless they paid off up top as well. I would be interested in tryin a set of the 1 3/4 sets

 

That would only be true "if" the primary tube size was sized for max rpm/hp of the engine size .........typically the 1 5/8 primary sets with a small diameter collector will not make the HP past about 4500 rpm a larger tube / 4 tube will .......but it will make the same or more torque and torque is what moves the truck.......

 

Keep in mind though, just like with HP, one needs to look at average torque not just at the peak. A strong average Torque band will move these heavy sleds far better than a peaky torque curve

 

So will a big converter

 

Not pissing here. But where have you seen these used on a High rpm race engine? I have always seen big primary big collectors on race set ups, or just zoomy's

 

from burns website

While typical off-the-shelf street 4-into-1 headers do not have secondary pipes, Burns' research has proven repeatedly that his Tri-Y designs make more overall power over a broader rpm range. While traditional lines of thought have street enthusiasts knowing Tri-Y pipes make more bottom-end torque, further research by Burns into the design have resulted in headers making more power all across the rpm range. With more components as part of the Tri-Y design, more tuning possibilities exist, and therefore more potential lives within.

 

I agee a flat torque curve is what you want but these stock to mild 5.3 dont have a flat torque curve with only 325ci so you want to move the torque peak down low to get the mass moving ........ and small diameter primary tube tri Y will do that better than a 4 tube thats all I'm saying ......... its all about exhaust velocity .for a street truck I will give up some torque at 4500 to have more off idle to 3000 where most of us drive .........if your building a drag race deal then its a different deal .....ti Y headers are a good design for small motors in heavy cars .......big inch high rpm motrs dont need tri Y ......they can use differnt sized collectors to tune the torque band


Yes agree withthe Burns web site but you cant compare a quality $$$ header like Burns to the street design Thorleys, Thorleys wont pull all the way thru to redline and be equal to a 4 tube and were not designed to ........ Burns stuff is tuned to the engine rpm band you build the motor for

 

You see them On high rpm road race / oval track cars .........not so much on drag race cars as they just go WOT ......... I run big tube 4 tube headers on my dragrace car but we do change collector length / diameter to tune the torque band

 

So then you can look into a stepped header, that starts out with a small prime and gets bigger.. I have never seen anybody post before and after dyno's of the Tri's vs a standard header, def none of a stepped header.. Dyno graphs would be nice to see for sure..

 

yup you are completely right cdn I was just saying at the start of the thread that there needs or should be more people build tri y headers. That way for our trucks and motors people could have a more happy medium. Torque down low but still make good power up top. As far as I knew thorley was the only one that made them but I am glad to see at least there is an option between 1 5/8 for the smaller motors and a 1 3/4 for some of the bigger motors. I just think they are a good design for our heavy trucks but thats just me. Not tryin to start anything or say anyone is wrong just a little info on them so maybe some people can see there is a middle ground.