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Another LT1 throttle body topic

Old 07-05-2017, 07:54 PM
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Another LT1 throttle body topic

I'm finally closer to getting TPI in my truck (95 silverado 5.7).
I was watching LT1 videos on youtube and something caught my eye - the TPS on the side of the TB looked almost identical to what the truck TBI units used. So I looked up part numbers on autozone (95 camaro LT1 vs 95 5.7 TBI) and they are different, but the connectors look the same. Does anyone know if they are in fact the same? If so, could I just use an LT1 throttle body, reuse the truck's factory TPS connector (picture attached) and call it good?

I also only have pedal and cruise control cables (4l60e). Assuming an LT1 never had a 700R4 then most of the TBs out there would not have a provision for a TV cable if I am correct? if so I suppose this would also make for a cleaner install.
Attached Thumbnails Another LT1 throttle body topic-img_0460.jpg  
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Old 07-07-2017, 03:54 PM
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Re: Another LT1 throttle body topic

Same tps connector. Iirc no provision for a tv cable but a stud tv stud can be added. The iac passage is open between the tb bores and will work on any tpi plenum.
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Old 07-07-2017, 07:25 PM
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Engine: 5.7 TPI and 5.7 TBI to TPI convert
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Re: Another LT1 throttle body topic

Sweet then. Being that its 4L60E the TV is a non issue. And I am 1 year away from no emissions, I will ignore the no vacuum port for EGR.
But looking closer at the LT1 IAC, it looks completely different that the TPI and TBI. TBI/TPI looks like:
Amazon Amazon
LT1
Amazon Amazon

I dont have a wiring diagram so I dont know which wire is which.
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Old 07-09-2017, 01:27 AM
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Car: 1992 Z28 and 1995 Silverado
Engine: 5.7 TPI and 5.7 TBI to TPI convert
Transmission: 700R4 and 4l60E
Axle/Gears: G80 3.23 and open 3.42
Re: Another LT1 throttle body topic

I noticed this for the IAC. Hopefully they did it correctly. If so, that makes it easy, and looks pretty.
http://www.ebay.com/itm/301537517333...item4635095f15
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Old 07-11-2017, 07:56 PM
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Re: Another LT1 throttle body topic

That would do the trick. Or you can use a tpi lower iac plate on a lt1 tb.
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Old 07-12-2017, 09:59 PM
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Re: Another LT1 throttle body topic

I thought I read somewhere that using a tpi lower would require opening up some passageways.
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Old 07-12-2017, 10:00 PM
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Re: Another LT1 throttle body topic

I e used a lt1 iac hosing on a tpi tb zero modifications same gasket.
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Old 07-13-2017, 08:37 PM
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Re: Another LT1 throttle body topic

I bought one today and things appear to check out.
-The TPS connector is the 3 pin triangle style none adjustable and connects with the truck.
-The lower plate i swapped out so I dont have to wire in the LT1/LS1 style IAC, and everything lined up fine. One part of the IAC air passage way is a little taller than in the TPI, which is weird, but hopefully does not mess with the computer. The coolant inlet/outlet lines are different on the plate, so I suppose those in the north that want a heated TB will have to modify their lines.
-EGR vacuum is missing, but wont care soon
-TV cable provision is not there, but is fine for 4L60E
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Old 07-14-2017, 10:11 PM
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Re: Another LT1 throttle body topic

I spoke too soon. In regards for throttle and cruise hook up.
Look at TBIcruise.JPG and TBIthrottle.JPG. Then TBI1, 2, and 3. I had 2 studs of identical size on the TB.
Then on TPI1.JPG, 1 stud is of identical size, which would fit either the cruise or accelerator fine (but no place for cruise). But on the LT1, there is only 1 stud, which is thickest of them all. I suppose it can be grinded down, assuming there is even enough room for the clip to hold it in place. But there is still the question of where a cruise control hookup would go.
Attached Thumbnails Another LT1 throttle body topic-lt11.jpg   Another LT1 throttle body topic-tbi1.jpg   Another LT1 throttle body topic-tbi2.jpg   Another LT1 throttle body topic-tbi3.jpg   Another LT1 throttle body topic-tbicruise.jpg  

Another LT1 throttle body topic-tbithrottle.jpg   Another LT1 throttle body topic-tpi1.jpg  
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Old 07-15-2017, 08:09 PM
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Re: Another LT1 throttle body topic

If you do need two studs cruise and tv you can use a 93 lt1 tb.
http://m.ebay.com/itm/93-Camaro-Z28-....c100408.m2460
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Old 07-15-2017, 08:50 PM
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Car: 1992 Z28 and 1995 Silverado
Engine: 5.7 TPI and 5.7 TBI to TPI convert
Transmission: 700R4 and 4l60E
Axle/Gears: G80 3.23 and open 3.42
Re: Another LT1 throttle body topic

That one wont work either. The truck TBI cruise and throttle both pull, and that top stud looks like it needs to be pushed in order to open the blades.
That would then just leave me with that bottom stud, which looks to be the same size as the LT1.
I could modify the bottom stud (make smaller), hook the accelerator cable to it, and then modify the cruise control cable similar to the LT1 cable circled here:
http://shbox.com/ci/ci16.jpg
Or just brand new cables from some other company out there.
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Old 01-02-2019, 06:16 PM
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Re: Another LT1 throttle body topic

Old thread, but did you end up using the lt1 Throttlebody on the tpi ?
Any interference between the iac coolant pipe and the thermostat housing ?
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Old 01-02-2019, 08:40 PM
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Engine: 5.7 TPI and 5.7 TBI to TPI convert
Transmission: 700R4 and 4l60E
Axle/Gears: G80 3.23 and open 3.42
Re: Another LT1 throttle body topic

Yes, the pipe had to be shaved away. I think the vortec housing didn't interfere (or at least not as much) but I didnt want to have a radiator hose wrapped all the way around pointing the other direction.




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Old 01-02-2019, 08:55 PM
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Re: Another LT1 throttle body topic

Thanks for the image, your install is very nice. I like the air intake setup .
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Old 01-12-2019, 09:21 PM
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Re: Another LT1 throttle body topic

what is the advantage to using an lt1 tb on a tpi? i picked one up to adapt the iac housing and iac. i also picked up the connector adapter. is the lt1 iac better than the tpi?
im running a 91 speed density tpi with smog delete
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Old 01-12-2019, 09:56 PM
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Car: 1992 Z28 and 1995 Silverado
Engine: 5.7 TPI and 5.7 TBI to TPI convert
Transmission: 700R4 and 4l60E
Axle/Gears: G80 3.23 and open 3.42
Re: Another LT1 throttle body topic

I don't think the LT1 flows any better than a TPI, if that is what you are expecting. But I could be wrong. Personally, the primary reason I bought it was because it was available to me when I put a little too much cleaner on the TPI one I had, and the aluminum got extremely stained. But once I found that the LT1 ones were a little cheaper (at least the one I found) I saw a few advantages (which are only advantages because it was going on a truck). There is no spot for a TV cable, since my truck has a 4L60E (so I suppose it looks a little cleaner). The trucks also have the same TPS sensor as the LT1, so that makes it nice to be able to carry it over (although the IAC is the same as an LS1, whereas the truck IAC matches the thirdgen...). Also, it has 1 less vacuum port, and I wasn't planning to use EGR anyway, so again a little cleaner of an install.
The only downside is that the drivers side coolant port smacks against the thermostat housing. With a little dremel cutoff wheel, I trimmed off the port (which is about an inch) plus an extra few milometers. Its aluminum, so it cut easily and clean.
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