I have a holley 58mm tb I want to put on my car. I plan on getting the car dyno tuned in the next month or two. I have heard that the 58mm will cause low line pressure problems in a 4l60e if the computer ins't programmed for it. I have a transgo shift kit set up with 3 washers. Will this make any differance? i don't want to burn up the trans.
Any thoughts?
Thanks,
Kory

 

I may run a bit crappy with out programing for a bigger TB A/F ratio etc... You bumped up your line pressure with the shift kit so you should not have any worries there i suggest that you either use the shift kit or the computer to up the line pressure DO NOT USE BOTH! I did and blew a seal in the trans and fried the clutch packs. Good luck . Steven

 

Thanks for the input.
Does anyone else have an opinion?
I think I will probably put it on but I would like a little more input.
Thanks,
Kory

 

I tried a 52mm, with a Transgo, and it caused part throttle shifting problems. Most people don't have problems with a 52.

 

I gotta disagree with the 58mm causing problems with the running of the car other than A4 shifting. The PCM should correct A/F ratio regardless of what size TB you have to my knowledge.

You do run a risk by running the 58mm throttle body without programming but, IMO, on an F-Body the risk is minimal. I ran a 58mm throttle body on my A4 Vortech supercharged 94Z for several years with NO programming changes! The shifts were weak but my tranny didn't immediately burn up I had the car to the track several times and drove it around town quite a bit. I think I put around 25k miles on the car with the 58mm throttle body and no adjustment in PCM programming. I did, however, have a Trans Go shift kit installed with 2 washers and I'm sure that helped some.

 

I have three washers in mine. I think that I'll try it. I can always go back to stock if it seems too soft.
Thanks for the input.
Kory

 

another thing to look at it the intake port size. If your intake is not ported to 58mm..there is not a lot of reason to go with the 58, unless of course, you plan on porting it.

 

I ported it a while back when I had the heads off.
Kory

 

OK, what would changing tb size affect that would necessitate programming changes?
I don't quite understand why a larger tb would need any change in line pressure or anything.

 

yeah i wonder too what does a bigger tb have to do with the trans? i noticed no difference when i went to a ported stocker from lpe.

 

The 4L60E shifts according to vehicle speed and throttle position sensor. With a bigger TB, the sensor will show less of an opening for a given speed, unless reprogrammed, and shift softer.