okay,

this is going to sound dumb and is a dumb question but thats what these forums are for

i have an 89 firebird w/ a 305 tbi. i have the throttle body that sits vertically on top of the intake manifold, and has a round filter around it [came stock with a big metal circle thing and snorkle].

whats the difference between that intake, and the intake where it has a horizontal metal box over the intake manifold w/ tubes that run into the sides of the intake manifold.

may sound confusing but let me know if pictures are needed.

 

i think what your describing is TPI ( tuned port injection).
If thats what it is, theres a ton of differences, from the number of fuel injectors, to the way fuel pressure is regulated, to the fuel pressure itself.

 

thats what i thought but a buddy of mine had an 91 tpi rs but it was the same as mine.

what would it take to convert from tbi to tpi?

 

the actually make a kit for that i dont know the name or anything but the kit comes with new intake and all the fittings i think you have to go to a higher pressure fuel pump as well..

the long metel box you describe is where the air goes into and gets forced into the intake manifold and if you look at your friends intake you can count 8 uinjectors

tpi is good but it has its downfalls...for instance the length of the intake runners which take the air such i long time to rreach the intake but this still makes it beter than our cars but not for intake reasons...


all you need in your TBI is a good cam/head setup and you have just a fast car granted you have good gears and posi.

 

its not the length of the runners that hurt the 4500 rpm brick wall, its the width of the runners that sucked...or lack there of. they cant support all the air going through them at high rpms. tpi is killer for low end torque unless you slap on a new intake, and runners. then problem fixed but you are 800 dollars less rich.

 

maybe not so much the length of the runners but the time it takes for the air to go from the butterflies to the intake is what really csucks..

the way the have a solution for this is the holley stelth ram setup where there are no runners the air is transfered right from teh "long metel box" instead of going out the sides and down

 

that stealth ram deal is no joke, that sucker is bad, if i had tpi, id have that. even though its kinda like a ford way of looking at the tpi lol. hat and well, its liek having two manifolds kinda...KINDA,...not really but you know what i mean

 

stelth ram is amazing looking and performance wise... i wish i could afford TPI I cant even dream of 2ooo dollar stealth ram setup!

 

are there instructions on thirdgen for installing a cam into our little 305's?

 

not sure there might be a breif info about it in tech articles there is a post though see if you can search it! i know all the steps even though i havent started it yet thanx to said post