Are the fuel lines that go from the engine back to the tank the same in a TBI as a TPI?
I know they are highter pressure, but what about the fuel line diameter?

Thanks,
Chris

 

I'm not positive, but I think TBI lines are 5/16 and TPI are 3/8. There are a lot of people out there who will tell you that you must change your fuel lines when switching to TPI. I recently found that to be a myth. All 5.0 Mustangs have 5/16 lines and they're around 38 psi. I also have contacts to someone who put a 454 w/hilborn converted to DFI in an 89 IROC. The car originally had a TBI 305 and he claims he is using the stock fuel lines except for a splice where he put an inline pump. Don't believe everything you read.

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'88 IROC TPI 355, fully balanced, 9.75:1 compression, fully ported '70 truck heads(for now), Harland Sharp Roller Rockers, Comp Cams TPI cam, fully ported '90 speed density TPI with '86 base so it fits older style heads, Crane AFPR, Flowmaster 3in. exhaust, Edelbrock TES headers, all emissions equipment is still intact, plan on burning my own chips, many more mods and parts on the way as time and money permits =(
Best E.T. with TBI 305: 16.11 @ 82mph
Haven't been to track with new motor
Won bracket races at Numidia Raceway with my '70 Nova
In memory of Dale Earnhardt, I'll miss cheering for that black #3 on raceday!!!

 

IROCZ88 is right about the size of the fuel lines.5.0's may run 38psi but the a TPI runs on alot more psi than that don't it?i'm switching to -6 braded line for my 305 TBI to 350 TPI converssion.

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1991 banditt2 #130 of 600
Project 350 TPI Banditt II
http://www.street-dawg-racing.cityslide.com
http://photos.yahoo.com/tonysams72
http:/discussion-board.com/GreaterCincinnatiFBodyAssociation

 

TPI will run between 40 & 50 psi. Depends on what you set it to if you have an AFPR. Stock is from 42-44psi. It isn't a bad idea to swap, but it is not necessary unless you're running a turbo or blower and need extreme fuel flow. Traxion's article on swapping from TBI to Speed Density TPI states that the TBI lines won't cut it. That's a myth. My physics teacher hear at PSU helped me do some bulk modulus and fluid dynamics equations and difference was .000324 g/cm^3 for pressure. Remember, pressure and flow are two different things. The difference in flow is a little bigger. If you plan on running a power adder than you have to consider it, but there is PLENTY of flow even from a stock TPI fuel pump to supply a mild to moderate TPI 350 even with 5/16 fuel lines.

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'88 IROC TPI 355, '69 truck 4-bolt, fully balanced, 9.75:1 compression, fully ported '70 truck heads(for now), Harland Sharp 1.6 Roller Rockers, Comp Cams CS 252AH-12, ported '86 TPI converted to speed density, Crane AFPR, Flowmaster 3in. exhaust, Edelbrock TES headers, all emissions equipment is still intact, plan on burning my own chips, many more mods and parts on the way as time and money permits =(
Best E.T. with TBI 305: 16.11 @ 82mph
Haven't been to track with new motor
If you have any questions on converting from TBI to TPI email me at jdkchevy70@yahoo.com
In memory of Dale Earnhardt, I'll miss cheering for that black #3 on raceday!!!

 

I'm trying to verify with a coworker who converted his '90 RS from TBI 305 to TPI 350, but as I recall, he said the lines from the tank to the engine compartment were exactly the same. The flex lines were all he changed, and that was primarily because he was using a '91 speed density system.

My '82 carb'd V6 had 3/8" lines. If I recall correctly what I've heard, all 3rd gens had 3/8" lines.

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R. 2.93 limited slip. Cat-back from '91 GTA, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 w/'87 LB9 block, ZZ3 cam and intake, World 305 heads, Hooker headers & y-pipe, 3" Catco cat).
57 Bel Air, my 1st car. 0.030 over 396, Weiand Action+, Edelbrock 1901 Q-Jet, Jacobs Omnipack, 1-3/4" headers, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Best 15.1 @ 5800' Bandimere. Daily driver while Camaro was being put together.

 

I've been talking to someone who claims when GM switched over to SD in '90, they put 3/8 fuel line on all cars wether it was TBI 0r TPI to lower production costs. Can anyone verify this? Mine is an '88 so that's no help.

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'88 IROC TPI 355, '69 truck 4-bolt, fully balanced, 9.75:1 compression, fully ported '70 truck heads(for now), Harland Sharp 1.6 Roller Rockers, Comp Cams CS 252AH-12, ported '86 TPI converted to speed density, Crane AFPR, Flowmaster 3in. exhaust, Edelbrock TES headers, all emissions equipment is still intact, plan on burning my own chips, many more mods and parts on the way as time and money permits =(
Best E.T. with TBI 305: 16.11 @ 82mph
Haven't been to track with new motor
If you have any questions on converting from TBI to TPI email me at jdkchevy70@yahoo.com
In memory of Dale Earnhardt, I'll miss cheering for that black #3 on raceday!!!

 

can any one say weither this is true or not?



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1991 banditt2 #130 of 600
Project 350 TPI Banditt II
http://www.street-dawg-racing.cityslide.com
http://discussion-board.com/GreaterC...dyAssociation/
http://www.cincyspeed.com/

 

back from the dead... ttt

 

but why ?

 

ok wait actually i have a good Q =D

approx. how much does it cost to re-tube the entire length of the fuel system with stainless braided, from tank to head ?

 

not sure about steel braided but rubber fuel injection hose is like 14cents/inch