ml258-89iroc

what the differance between the two. if I wanted to use a lt1 throttle body what would I have to convert?

1989GTATransAm

iTrader: (3)

What year LT1 throttle body? Next question is why?

Z28cross-fire

I think they are roughly the same and can be switched. I believe they are both 48mm too. And again, why? If they are the same there will be no gain from changing.

kubihibi

He asked what the differences were, which means he didnt know they were the same. Thinking the LT1 was better he was thinking about putting that one on instead

Vader

Your '89 uses an adjustable TPS, whereas the LT1 does not. You may have a bit of a chore adjusting the TPS output.

The IAC on your TB is threaded into the opening, while the IAC on the LT1 TB is bolted in at a flange. You would have to rewire your harness to connect to the IAC that is already installed on the LT1 TB. Electrically, they are the same.

The coolant passages on the LT1 TB have much smaller hoses connected to them. That may present a minor plumbing problem. If you've bypassed the coolant for the TB or plan to do so, that is not an issue.

Comparing gaskets for each. the mounting holes appear to be a match.

The throttle cable belcrank is different, and the cable connections are going to change. I'm not sure if the belcrank could be changed easily of not, or if it would be easier to alter the cables.

Vader

Another possibility is that the TPI TB is worn out, and rather than bush the throttle shaft, an LT1 TB may be available as a replacement. Don't make too many presumptions. That's exactly how I've been tripped up in the past.

ml258-89iroc

I just found a good price on a 52mm throttle body. what i was wondering was the throttle cable will it connect or do you have to take the throttle arm off of the l98 throttle body or use a lt1 throttle cable? thanks for the help.

Z28cross-fire

I said they can be switched, then I just asked why. Then stated there is no gain in switching. I was not saying he can't or that there are no other options. I didn't assume anything.

Why do people always miss-interpret my posts???

Vader

I don't believe I misinterpreted your statement. You are absolutely correct that there is no benefit in changing the TB simply because it was once bolted to an LT1. I was merely exploring the possible reasons why anyone would try it, since it makes little sense as an improvement.

vwdave

Holley makes a throttle body that has nitrous provisions already in it, but they dont make one for the L98.

Maybe thats why too....(although he already answered)

Shagwell

also, some of the 89 up TPI's came factory w/ the progressive throttle cable linkage which is the same as the LT1. mine did...

Spharticus

I was wondering the same thing. I have a 95 Formula Firechicken with a 52mm BBK TB. I also have a 90 Vette. I wanted to put the TB from the Bird, onto the Vette, so I didn't have to spend the money to buy another TB. I must do a little more reasearch on this topic.....

Vader

The '90 Y-Car should have a fixed (non-adjustable) TPS, so that is compatible so long as the connectors are interchangeable.

If the throttle cable bellcrank is similar, it might work, but the TV cable attachment and position might trip you up since the '95 didn't use a TV (electronically shifted). The TV spool on a 700-R4 is very sensitive to starting position and overall throw. Of course, if it's a manual trans, that's not a problem.

More research, comparison, and measurement would be a good idea.