L03 TBI 305 to Vortec 350 L31 keeping the cpfi?
10-13-2013, 03:58 PM
#1
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L03 TBI 305 to Vortec 350 L31 keeping the cpfi?
Hello Afficianados & third gen experts,
For a mild-build '96-'00 5.7 Vortec swap into an '88 IROC T5, has anyone retained the factory fuel injection?
I know you'd have to swap fuel pumps for more pressure, use the Vortec ECM & wiring with something like a Howell kit.
If just 300 hp (a 100% improvement over the 305!) was all that was needed, mild cam & spring swap, headers, and a mild tune from somewhere, would this be a feasibile lower cost alternative to a $2700 F.A.S.T. EZ EFI kit?
Oh, the "improved" part. Delphi mpfi conversion assembly, new true multiport conversion for the problematic poppet valves in the original vortec cpfi.
Thanks
For a mild-build '96-'00 5.7 Vortec swap into an '88 IROC T5, has anyone retained the factory fuel injection?
I know you'd have to swap fuel pumps for more pressure, use the Vortec ECM & wiring with something like a Howell kit.
If just 300 hp (a 100% improvement over the 305!) was all that was needed, mild cam & spring swap, headers, and a mild tune from somewhere, would this be a feasibile lower cost alternative to a $2700 F.A.S.T. EZ EFI kit?
Oh, the "improved" part. Delphi mpfi conversion assembly, new true multiport conversion for the problematic poppet valves in the original vortec cpfi.
Thanks
10-13-2013, 07:11 PM
#2
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Re: L03 TBI 305 to Vortec 350 L31 keeping the cpfi?
Are you talking about "retained the factory fuel injection", or are you talking about the conversion?
2 VERY DIFFERENT things.
And you "know" this .... how? The injectors that come in the conversion use the same FP as any other port injectors.
Why? Your existing ECM will handle all that, as long as you can figure out a way to plumb in your MAF.
Don't forget: THE ENGINE couldn't care less what shape the chunk of aluminum plastic and whatnot that's stuck on top of it happens to be in. The ECM doesn't give a rip either. Once you boil it down to injectors and a distributor, all that "Vortec" just stuff kinda disappears into the noise. All THE ENGINE cares about is, getting the right amount of fuel for the amount of air it's taking in, and getting a spark at the right time. All the rest is irrelevant.
2 VERY DIFFERENT things.
I know you'd have to swap fuel pumps for more pressure,
use the Vortec ECM & wiring
Don't forget: THE ENGINE couldn't care less what shape the chunk of aluminum plastic and whatnot that's stuck on top of it happens to be in. The ECM doesn't give a rip either. Once you boil it down to injectors and a distributor, all that "Vortec" just stuff kinda disappears into the noise. All THE ENGINE cares about is, getting the right amount of fuel for the amount of air it's taking in, and getting a spark at the right time. All the rest is irrelevant.
10-14-2013, 07:06 PM
#3
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Re: L03 TBI 305 to Vortec 350 L31 keeping the cpfi?
Hi Sofa, Thanks for the reply.
I should have said "kept the cpfi on the L31 5.7 as I swap the 5.7 vortec into the car".
The TBI pump can only generate about 12-15 lbs & I would like to use the cpfi, so that's what I wasn't clear about.
I had read that the cpfi requires 55lbs, unless the info I have there is wrong.
Would the '88 TBI computer run a "96-'00 cpfi?
Thank you, appreciate your expertise.
I should have said "kept the cpfi on the L31 5.7 as I swap the 5.7 vortec into the car".
The TBI pump can only generate about 12-15 lbs & I would like to use the cpfi, so that's what I wasn't clear about.
I had read that the cpfi requires 55lbs, unless the info I have there is wrong.
Would the '88 TBI computer run a "96-'00 cpfi?
Thank you, appreciate your expertise.
10-14-2013, 07:33 PM
#4
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Re: L03 TBI 305 to Vortec 350 L31 keeping the cpfi?
Are you talking about "retained the factory fuel injection", or are you talking about the conversion?
2 VERY DIFFERENT things.
And you "know" this .... how? The injectors that come in the conversion use the same FP as any other port injectors.
Why? Your existing ECM will handle all that, as long as you can figure out a way to plumb in your MAF.
Don't forget: THE ENGINE couldn't care less what shape the chunk of aluminum plastic and whatnot that's stuck on top of it happens to be in. The ECM doesn't give a rip either. Once you boil it down to injectors and a distributor, all that "Vortec" just stuff kinda disappears into the noise. All THE ENGINE cares about is, getting the right amount of fuel for the amount of air it's taking in, and getting a spark at the right time. All the rest is irrelevant.
2 VERY DIFFERENT things.
And you "know" this .... how? The injectors that come in the conversion use the same FP as any other port injectors.
Why? Your existing ECM will handle all that, as long as you can figure out a way to plumb in your MAF.
Don't forget: THE ENGINE couldn't care less what shape the chunk of aluminum plastic and whatnot that's stuck on top of it happens to be in. The ECM doesn't give a rip either. Once you boil it down to injectors and a distributor, all that "Vortec" just stuff kinda disappears into the noise. All THE ENGINE cares about is, getting the right amount of fuel for the amount of air it's taking in, and getting a spark at the right time. All the rest is irrelevant.
10-14-2013, 09:06 PM
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Re: L03 TBI 305 to Vortec 350 L31 keeping the cpfi?
no, put in a high pressure pump and convert the vortec black pcm to a ls1 411 pcm and get hptuners and custom tune yourself
10-14-2013, 10:05 PM
#6
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Re: L03 TBI 305 to Vortec 350 L31 keeping the cpfi?
Thanks for the info wyochimneysweep.
Didn't mean to sound like a know it all in my original post, wasn't articulate enough at the start.
What is the learning curve like for someone that's never done programming before, to do the above, assuming I get the proper 411 ECM and HP tuner software?
Thank you
Didn't mean to sound like a know it all in my original post, wasn't articulate enough at the start.
What is the learning curve like for someone that's never done programming before, to do the above, assuming I get the proper 411 ECM and HP tuner software?
Thank you
10-14-2013, 10:14 PM
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Car: 92 chevy 1/2 4 wheel drive
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Re: L03 TBI 305 to Vortec 350 L31 keeping the cpfi?
if your using most stock items you wouldn't need to do much in terms of tuning but if you do change things you would have the ability to do easy changes or send tune and log files via email and have someone do it for you. or buy books and videos and take small steps and you can learn to tune......search here for tpi obd2 thread just that instead of doing tpi you are keeping the vortec intake
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10-15-2013, 05:59 AM
#8
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Re: L03 TBI 305 to Vortec 350 L31 keeping the cpfi?
wyo,
Thanks for the direction.
Thanks for the direction.
10-17-2013, 06:50 PM
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Re: L03 TBI 305 to Vortec 350 L31 keeping the cpfi?
I have a 305 92 rs I want to build a 350 I need help some one message me please 
10-17-2013, 08:06 PM
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Re: L03 TBI 305 to Vortec 350 L31 keeping the cpfi?
I forgot how to make a thread lol
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