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86 TPI onto 93 350

Old 05-17-2018, 09:47 AM
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86 TPI onto 93 350

Hello, long time lurker, worked on other cars FI, etc.

Looking to put an 86 TPI in and onto a 93 Chevy 350 in a Van.

Plan on running the TPI Stock (no hop ups) and with its MAF system. What I am looking for is better MPG over its TBI system. Do you know of anyone having done such a set up?

Only problem I am going to run into is the center bolts. My understanding is my 93 has the newer bolt angle vs. the 68s.

I am also told I can hog out the intake bolt holes a little and use a set of special angled washers.

Can anyone tell me where I can get these angled washer?

Thanks.

Rich
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Old 05-17-2018, 11:27 AM
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Re: 86 TPI onto 93 350

I put a TPI in a 92 ish truck back in the day, IIRC It would be easier to modify a couple connector lengths for tpi, use the factory tbi computer/harness and skip the MAF system.
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Old 05-17-2018, 12:27 PM
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Re: 86 TPI onto 93 350

Everything I have read a MAF is the better system FOR WHAT I WANT...I want MPG, and again everything I have read said MAF is a more responsive and finer tuning live system.


I have the complete factory system PCM, harness, MAF and a couple spare MAF sensors to boot.


I am very much aware the RPM limits of the MAF but I read it can flow enought for a 500HP 5800RPM so it is well above my engine as it is a stock 93 Van 350.


Thanks for you input.


Rich
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Old 05-17-2018, 02:55 PM
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TBI to TPI In 93 Van, using old PCM??

Sorry got cross eyed reading for this answer:

Why can I not swap out a TBI in a 93 Chevy Van, and add three injector plugs to each of the two old injectors leads and as I saw a hint just swap my eprom to one for a TPI?? Leaving all other stuff as is…running on a MAP or speed density?


Rich
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Old 05-17-2018, 03:33 PM
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Re: 86 TPI onto 93 350

The rumors about MAF being a better system mostly come from the 5.0 Mustang crowd. The 5.0 Mustang MAF system is better than the 5.0 Mustang MAP system for the same reason the Fbody MAP system is better than the Fbody MAF... The newer system is more refined and works better.

The only truth in the rumor as it applies to TPI is that MAF measures the actual air flow into the engine, so in theory it compensates better for mods that increase air flow. But really you'll want to tune any non-stock setup for best results anyway.
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Old 05-17-2018, 03:35 PM
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Re: TBI to TPI In 93 Van, using old PCM??

Unless the Van in 1993 used a different computer than the TBI thirdgens, the TPI prom won't even swap into the TBI computer.
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Old 05-17-2018, 03:45 PM
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Re: 86 TPI onto 93 350

Truth^
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Old 05-17-2018, 06:04 PM
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Re: 86 TPI onto 93 350

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Old 05-17-2018, 11:03 PM
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Re: 86 TPI onto 93 350

For gas mileage intents and purposes i can GUARANTEE you switching from TBI to TPI stock for stock won't help your cause. TBI was excellent on gas mileage.
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Old 05-17-2018, 11:12 PM
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Re: 86 TPI onto 93 350

I haven't seen an improvement on my truck. Then again its not tuned 100%.
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Old 05-17-2018, 11:29 PM
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Re: 86 TPI onto 93 350

​​ TPI does look great though. Would look cool!
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Old 05-18-2018, 05:53 AM
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Re: 86 TPI onto 93 350

Further, TPI (sometimes known as "Torque Producing Induction") might be more suited to a heavier vehicle, like a truck which doesn't require a lot of top-end performance.
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Old 05-18-2018, 06:29 AM
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Re: 86 TPI onto 93 350

If you want better mpg, use vortec heads, find a vortec tbi intake, install a nice set of headers and a free flowing exhaust. Then tune that bad boy.
Your TBI will breath way better.
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Old 05-18-2018, 11:20 AM
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Re: TBI to TPI In 93 Van, using old PCM??

Originally Posted by racprops View Post
Sorry got cross eyed reading for this answer:

Why can I not swap out a TBI in a 93 Chevy Van, and add three injector plugs to each of the two old injectors leads and as I saw a hint just swap my eprom to one for a TPI?? Leaving all other stuff as is…running on a MAP or speed density?


Rich
Rich,
You CAN use the TBI PCM to run the TPI. It does take a modified Memcal and modifications to the PCM board to properly control the TPI in batch fire mode and disable the peak and hold circuit in the injector drivers. Even if you could run the Van engine on the TPI memcal which you cannot, you would still need to pull alot of timing from the TPIs tuning to work with the swirl port heads and weight of the van. You wire 4 TPI injector pigtails to each of the original TBI injector wires. Lengthen the IAC wiring, the CTS wiring and TPS wiring. A carbureted van accelerator cable is a direct swap for your current throttle cable and works on the earlier TPI throttle body and plenum bracket just fine. I used a remote mounted cruise control servo from a 1987 2.8 S10 and mounted it on the passenger inner fender. I swapped out the control solenoids from the V8 cruise control on the van since the metering restrictions caused the V6 servo to be very aggressive on the V8. A 1992 CPI Vin W Astro/Safati van pump is a direct swap for the TBI in-tank pump. While I first used rubber high pressure fuel line to feed standard Camaro/Firebird rails, I ended up revising the setup and using A/N line from the hard line on the frame rail at the back of the bellhousing area to feed a TPI fuel rail modifed for rear feed and return. The Vans OEM accessory drive setup cleared the TPI just fine. Used a 1997 Vortec 350 thermostat housing I drilled out the bolt holes on to match the larger TPI bolts and matching Vortec upper hose. I modified the oil fill tube by attaching a mounting bracket to bolt to the rear of the compressor bracket.

Last edited by Fast355; 05-18-2018 at 11:36 AM.
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Old 05-15-2019, 11:52 PM
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Re: 86 TPI onto 93 350

i need some help with a prom for a 1992 pontiac trans am 5.0l
PROM DELCO AXXB 3063
any info would be helpfull
looking for new old stock if possible
but anything would help
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Old 05-16-2019, 01:45 PM
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Re: 86 TPI onto 93 350

Originally Posted by tcntx View Post
i need some help with a prom for a 1992 pontiac trans am 5.0l
PROM DELCO AXXB 3063
any info would be helpfull
looking for new old stock if possible
but anything would help
If you have a memcal already I can fix it or reprogram it to axxb.
I do have a new old stock axxb for $165 shipped in the states.
see your other post for a ebay link.
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