ok i tried both TB at the track last night

made 2 runs with stock TB (no airfoil) trapped 110mph
let the car cool for 2 hours and....

made 2 more with the BBK 58mm TB, both trapped 110mph.

interesting......

any thoughts?

jesse

 

In no way does that make me want to shell out $350.

Thanks.

 

Yeah thanks for the research, I won't worry about that one.

 

Thank you ! Post like this are what make this site worth going to !

 

Is your intake manifold match ported to the 58mm TB?

 

of course

 

if you do a search, there is some good info like that would tell you that without big CAM & heads you won't see much gain, with AUTO trannies you might experience other problems aswell if you do a search, thing is I noticed a slight AFG increase for MAF readings with 58mm, nothing much, maybe 5-10rwhp worth with GM847/heads etc... Did you port your intake manifold as in the ports? I belive the stock intake if not ported would never need anything bigger then 48mm airflow wise. Only reason to really get a 58mm TB is for those extra few horses & to fix the SPLIT BLM issues assiciated with big cams, but only if you buy the holley, no other TB will fix it unless you do the SPLIT BLM FIX mod.


bla bla bla tried going to bed.

 

my intake was ported by lloyd E. and yes i did have to the split blm "mod" and have my pcm programmed for the 58 TB. tuned by pcmforless.

 

Thank you for posting your results. It will help some of us save some money for mods that do work instead of the ones that see little or no gain.

 

i dont think your car is making enough power to benefit from the larger TB.

i remember awhile back their was a discussion about the CFM requirements of different power levels, and it was around 400-450rwhp i think where the 58mm became necessary.

 

if you have your car tuned to a 58 and your intake ported to a 58 then putting the 48 on will not work right unless the car is setup for a 48......if you changed the computer settings and put a stock intake then you might see a change.

 

Interesting... You must have lost too much low end with the 58 to benefit.

I know tb upgrades aren't real popular here, but there have been several people who have bored the stock 48mm out to 52 on their Impalas, and have gotten about 2mph trap speed and shaved almost 2 tenths off a 1/4 time. This was also with bolt on motors. This was over in www.impalassforum.com If you could get yours bored at a local shop for cheap and fabricate butterfies to fit, I still think this is a worthwhile mod. It definitely is on a Chrysler 360 in a R/T Dakota or 5.9 Grand Cherokee even with the stock beer keg intake manifold, and they have twin 48mm openings like the LT1's.

Jason

 

That is really wild. Was there any change in your times? 60ft or 1/4? Im getting ready to do the LE2 and hate to drop the 320 for the TB. Ive read many places the 48 w/airfoil is worth over 400hp. Now Im confused.

 

What was your before and after air:fuel?

I hate to nitpick, but I have heard from reputable sources that the 58mm changed the a:f. Only after tuning were gains seen.

However, this does show that if you aren't going to tune the car after a TB swap, you should save your money.

Ryan

 

96speed no idea on the a/f ratio

the times varied (track was slick) and i couldnt get my DR to hook at all, but all passes were 110mph traps.

48mm
1. 13.2 (2.34)
2. 12.8 (2.09)

58mm
1. 13.0 (2.1)
2. cant remember at 4am

jesse