Fuel pressure regulator for TBI

[dlivewyer]

I have a '94 c1500 that had a stock 5.7. I recently replaced the engine with a Blueprint 355 dynoed at 390 HP with a holly 600 CFM carburetor that it came with. It has aluminum heads with .202/.160 valves, roller cam and lifters and aluminum intake. I did not want to change to the carb, so I put the stock TBI on it using an adapter plate. I got a 454 TBI unit that I'm gonna put on it and a vortec fuel pump. I got new injectors that "claim" to be 90#/hr. I have calculated that I will need to increase the fuel pressure to 16 to 20 PSI to get the desired flow for the HP, which is way less than the vortec pump puts out. So I need a FPR. I found this one or this one at Summit that replaces the stock regulator. Do you think it will be sufficient for what I'm trying to do? If not, I have seen where people talk about putting in an 18 or 20 lbs spring in the stock regulator. Where would I get one of those? Thanks

[tayto]

GM never made 90# injectors. Post the number that is on top of the injector so we can figure out what they are. a small block big throttle body is probably sufficient for what you are doing but run the BB throttle body if that's all you have. BB throttle body will require more tuning for sure. the rule of them is once you go over 18psi a vacuum referenced FPR is required. if you can find a marine unit you can use it and will bolt on place of the stock FPR. they're discontinued and getting hard to find so a lot of people will run an external FPR and block off the old regulator.

[dlivewyer]

They are standard motor products TJ11. Top of injector has RJN-554 and 1061.

[dave w]

Tuning is challenging. Often the calculated injector flow (formulas used for calculated Injector Flow vs. Pressure) are "course tune" that require adjustment.

Recently I tuned a TBI 502 (SPR Performance Throttle Body – 18 PSI with 80 Lb / Hr Injectors). The calculated injector flow was close, at low RPM's rich and upper RPM's lean. Multiple adjustments to the fuel table corrected the rich / lean conditions.

If the calculated injector flow causes rich for low RPM's and rich high RPM's, consider lower fuel pressure or injectors with lower LB / HR flow.

If the calculated injector flow causes lean for low RPM's and lean high RPM's, consider higher fuel pressure or injectors with higher LB / HR flow.

An AFR Guage is an awesome tuning tool https://www.aemelectronics.com/produ...uego-afr-gauge

I would start with 80 LB / Injectors and Stock Fuel Pressure.

TBI Injector Flow link: http://www.gearhead-efi.com/Fuel-Inj...d-part-numbers

[dlivewyer]

Here is the injectors I have.

[TriumphR3]

https://www.ebay.com/itm/25554940789...mis&media=COPY

It’s a good plan to mod your fuel pressure regulator on the throttle body and make it adjustable.

[dave w]

15 PSI with 80 Lb / HR Injectors . . . calculated flow is 85.9 LB / HR
15 PSI with 61 LB / HR Injectors . . . calculated flow is 65.5 LB / HR

18 PSI with 80 Lb / HR Injectors . . . calculated flow is 94.1 LB / HR
18 PSI with 61 LB / HR Injectors . . . calculated flow is 71.8 LB / HR

[PlayingWithTBI]

Here is the injectors I have.

The crossover part number, 5235231, on Standard's site looks to be 80LB/HR on the link Dave w posted but, Standard doesn't show at what pressure they get 90LB/HR.

http://www.gearhead-efi.com/Fuel-Inj...d-part-numbers

[dlivewyer]

Ok guys, thank you for the input, but no one has commented on the FPR that I was asking about. FPR here Do you think this one will work with a 15-20 PSI spring and the vortec fuel pump (62 PSI)?

Here is the same one with a little more info.

[dave w]

I can't remember tuning a TBI system with an adjustable FPR. Stock FPR with either stock spring, 15 PSI spring, or 18 PSI spring has worked well for me.

Going back in time, just over a decade ago, TBI tuning was mostly adjustable FPR because tuning software was in its infancy. Some TBI owner's resist using tuning software / computers and tune with adjustable FPRs. Unfortunate, but true.

[dlivewyer]

I can't remember tuning a TBI system with an adjustable FPR. Stock FPR with either stock spring, 15 PSI spring, or 18 PSI spring has worked well for me.

Going back in time, just over a decade ago, TBI tuning was mostly adjustable FPR because tuning software was in its infancy. Some TBI owner's resist using tuning software / computers and tune with adjustable FPRs. Unfortunate, but true.

What fuel pump did/do you use?

[dave w]

Of the hundreds of TBI tunes I've helped with, there is a long list of fuel pumps used. Most often the fuel pump used was based on the budget, some TBI applications had very minimal budgets, yet others had very generous budgets. TBI systems are low pressure, allowing a long list of fuel pump choices (factory / aftermarket). One of the performance fuel pump options, with minimal budget, is to replace the factory TBI fuel pump with a factory TPI fuel pump.

The list of pumps I've tuned includes, but not limited to:
Factory TBI fuel pump.
Factory TPI fuel pump.
Factory Vortec fuel pump.
Factory Ford F150 inline fuel pump.
Carter in-tank and inline fuel pumps.
Walbro in-tank and inline fuel pumps.
Aeromotive in-tank and inline fuel pumps.
Plain "White Box" TBI or TPI fuel pumps from Ebay. . .auto parts retailers no longer in business close out
Cleverly fabricated junk yard fuel pump from an 80's 4-cylinder Volvo.

[dlivewyer]

Of the hundreds of TBI tunes I've helped with, there is a long list of fuel pumps used. Most often the fuel pump used was based on the budget, some TBI applications had very minimal budgets, yet others had very generous budgets. TBI systems are low pressure, allowing a long list of fuel pump choices (factory / aftermarket). One of the performance fuel pump options, with minimal budget, is to replace the factory TBI fuel pump with a factory TPI fuel pump.

The list of pumps I've tuned includes, but not limited to:
Factory TBI fuel pump.
Factory TPI fuel pump.
Factory Vortec fuel pump.
Factory Ford F150 inline fuel pump.
Carter in-tank and inline fuel pumps.
Walbro in-tank and inline fuel pumps.
Aeromotive in-tank and inline fuel pumps.
Plain "White Box" TBI or TPI fuel pumps from Ebay. . .auto parts retailers no longer in business close out
Cleverly fabricated junk yard fuel pump from an 80's 4-cylinder Volvo.

Will the vortec pump work for me with an 18lbs spring?

[dave w]

Yes, the vortec pump will work for you with a stock spring, 15 PSI Spring, or 18 PSI spring.

It seems unlikely your engine will require 80 LB / HR injectors with an 18 PSI spring . . . calculated flow of 94.1 LB / HR.

My personal TBI tuning experience does not align with countless internet posts about the "required TBI Fuel Pressures and required TBI Injector flows".

A TBI 502 engine requires using 80 Lb / HR Injectors with an 18 PSI fuel pressure spring . . . calculated flow of 94.1 LB / HR.

If it was my Blueprint 355, I would use 8 port injectors not two TBI injectors. . . see pictures below

Holley 7540.jpg

Holley 300-263_01.jpg

[dlivewyer]

Yes, the vortec pump will work for you with a stock spring, 15 PSI Spring, or 18 PSI spring.

It seems unlikely your engine will require 80 LB / HR injectors with an 18 PSI spring . . . calculated flow of 94.1 LB / HR.

My personal TBI tuning experience does not align with countless internet posts about the "required TBI Fuel Pressures and required TBI Injector flows".

A TBI 502 engine requires using 80 Lb / HR Injectors with an 18 PSI fuel pressure spring . . . calculated flow of 94.1 LB / HR.

If it was my Blueprint 355, I would use 8 port injectors not two TBI injectors. . . see pictures below

Holley 7540.jpg

Holley 300-263_01.jpg

Great, thank you very much. I would love to put an 8 port injection system on it, but I've reached my limit on the budget on this thing. Maybe in the future.