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Old 01-26-2020, 05:59 PM   #1
vht
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94 Chevy truck Question

Looking at a 94 chevy C1500, wondering what has been done to gain a little more power from the 5.7 TB motor? Truck runs out great, already has a performance exhaust and also should mention it's a 4x4. The trans even shifts really nice. Wondering if the TB is a limiting factor since I've never done any performance mods to one of these.
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Old 01-26-2020, 10:13 PM   #2
1976gmc20
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Re: 94 Chevy truck Question

Well if it's a 4x4 then it's a K1500 and not a C1500.

I've got a 1989 and it seems to have plenty of power to me, but it's a five speed.
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Old 01-27-2020, 08:37 AM   #3
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Re: 94 Chevy truck Question

I always felt the TBI versions also seemed a bit "weaker". I went from a 96 with Vortec 350 to an 83 with a carbed crate 350 to a 94 TBI 350. and like you said it ran great, just seemed to be less powerful. I didn't notice much change on the 94 when we put in a new cat. It wasn't my truck at the time, but it did seem to help. I have not done any "modifying" to a TBI motor, nor do I know any one that has, short of cat back exhaust. All of the above were 2WD trucks with automatics.
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Old 01-27-2020, 12:21 PM   #4
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Re: 94 Chevy truck Question

Seems to me like the power on the carb and TBI is about the same, except the TBI is more consistent. There is no "flat spot" at certain RPMs like you sometimes get with a carb.
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Old 01-27-2020, 07:43 PM   #5
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Re: 94 Chevy truck Question

I was wondering if the TB cfm or injector size would limit a cam change or even if I went with a 383. I'm just interested in torque for some towing.
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Old 01-27-2020, 09:45 PM   #6
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Re: 94 Chevy truck Question

I think most of the difference is in the heads. The engine in my 83 was a 70's era 350, and the vortecs is way better flow than the TBI. I am sure you could tune up a TBI, just not sure how much control you have or tweaking that can be done with the factory one.
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Old 01-29-2020, 12:21 PM   #7
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Re: 94 Chevy truck Question

https://harristuning.com/Tbi/
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Old 01-29-2020, 02:32 PM   #8
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Re: 94 Chevy truck Question

The TBI motor's limitations are the tbi (450 cfm stock), the cam (it's ****), and the heads (also ****). The 450cfm isn't too bad and can handle and upgraded cam to a degree but the computer and manifold vacuum are limiting factors in upgrading the cam much.

the link above for Harris Tuning will give you a wealth of info on the TBI setup and what can be done short of swapping the entire setup.
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Old 01-29-2020, 10:50 PM   #9
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Re: 94 Chevy truck Question

Thanks, I found that link, I figured with a RV type cam, headers and a good exhaust it ought to run decent. Of course I'd get a chip done for it, the only thing that would hold it back is the heads but since I'm not concerned about revving the crap out of it they might be ok.
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Old 02-28-2020, 11:45 AM   #10
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Re: 94 Chevy truck Question

Im working on building my 350 tbi, its getting vortec heads, and rv spec cam, and a new chip burnt to change the tune. im going for pulling power as I am on 35s with a 6 inch lift.
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