Question about the TBSS / NNBS intake upgrade

[Sam Harris]

So I’m finally getting ready to buy the rest of the parts I need to do this upgrade.

I apologize, as I know this topic has been well-covered, but I haven’t seen an answer to my question regarding flow of factory FF injectors.

I have a 2003 (DBW) 5.3, Flex engine.

I have the intake manifold, and (hopefully the correct fuel rail (12621662).

Trying to decide if I should also do the injectors while I’m at it, and it would also be easier to install and check for clearance etc.. if I can install the injectors and rail into the manifold, while still being able to drive the vehicle.

I know the FF injectors have more flow than the non-flex injectors, but can anyone tell me what their volume / flow is rated at?

I’m looking at a few options on this Glenn’s auto site 36 & 50 LB injectors. (Can either do new Delphi or injector clinic) also, assuming my factory fuel pump may need an upgrade if I did decide to go with larger injectors.

Also, there’s a reference to “EV6” style injector plugs, not sure if that’s what I have or not. I believe I already have them.

So far, I’m looking at this Throttle Body:
https://www.glennsautoperformance.c...-90mm-dbw-throttle-body-4-bolt-ported-by-chuy

X-link:
https://www.glennsautoperformance.c...ue-rush-performance-trp-x-link-adapter-module

Evap adapter kit:
https://www.glennsautoperformance.c...oard&utm_medium=product-links&utm_content=web

Corvette filter / regulator:

C5 Corvette Filter/Regulator - Return Fuel System Adapter - LS Swap/TBSS Intake

New C5 Corvette Fuel Filter/Regulator This filter/regulator assembly is commonly used when converting return style fuel systems for use with return-less applications. Popular for simplifying the fuel system for LS swaps or standalone EFI systems such as Holley, FiTech, or FAST designed to...

www.glennsautoperformance.com

Any thoughts / recommendations are greatly appreciated!

 

[iamdub]

So I’m finally getting ready to buy the rest of the parts I need to do this upgrade.

I apologize, as I know this topic has been well-covered, but I haven’t seen an answer to my question regarding flow of factory FF injectors.

I have a 2003 (DBW) 5.3, Flex engine.

I have the intake manifold, and (hopefully the correct fuel rail (12621662).

Trying to decide if I should also do the injectors while I’m at it, and it would also be easier to install and check for clearance etc.. if I can install the injectors and rail into the manifold, while still being able to drive the vehicle.

I know the FF injectors have more flow than the non-flex injectors, but can anyone tell me what their volume / flow is rated at?

I’m looking at a few options on this Glenn’s auto site 36 & 50 LB injectors. (Can either do new Delphi or injector clinic) also, assuming my factory fuel pump may need an upgrade if I did decide to go with larger injectors.

Also, there’s a reference to “EV6” style injector plugs, not sure if that’s what I have or not. I believe I already have them.

So far, I’m looking at this Throttle Body:
https://www.glennsautoperformance.c...-90mm-dbw-throttle-body-4-bolt-ported-by-chuy

X-link:
https://www.glennsautoperformance.c...ue-rush-performance-trp-x-link-adapter-module

Evap adapter kit:
https://www.glennsautoperformance.c...oard&utm_medium=product-links&utm_content=web

Corvette filter / regulator:

C5 Corvette Filter/Regulator - Return Fuel System Adapter - LS Swap/TBSS Intake

New C5 Corvette Fuel Filter/Regulator This filter/regulator assembly is commonly used when converting return style fuel systems for use with return-less applications. Popular for simplifying the fuel system for LS swaps or standalone EFI systems such as Holley, FiTech, or FAST designed to...

www.glennsautoperformance.com

Any thoughts / recommendations are greatly appreciated!

My FF injectors are #12594512 which are 36lb. Yes, mine's a GenIV, but the FF injector volume would still apply. EV6 is the type of injector, which has its own specific electrical connector, mostly, but not always. Mine are EV6.

If your pump is adequately feeding your engine now, then it should even with larger injectors. You'll have to have the tune adjusted to dial back the injectors so they supply the same as the current injectors do. The larger injectors will just be headroom for future mods. If your mods outgrow your fuel supply and the injector duty cycle is still well in the safe zone, then, yes, you will need a higher output pump. I think a stock FF pump would be appropriate if you were running FF injectors. IIRC, 36 lb/hr injectors are said to be safe for up to 500 WHP.

 

[Sam Harris]

My FF injectors are #12594512 which are 36lb. Yes, mine's a GenIV, but the FF injector volume would still apply. EV6 is the type off injector, which has its own specific electrical connector, mostly, but not always. Mine are EV6.

If your pump is adequately feeding your engine now, then it should even with larger injectors. You'll have to have the tune adjusted to dial back the injectors so they supply the same as the current injectors do. The larger injectors will just be headroom for future mods. If your mods outgrow your fuel supply and the injector duty cycle is still well in the safe zone, then, yes, you will need a higher output pump. I think a stock FF pump would be appropriate if you were running FF injectors. IIRC, 36 lb/hr injectors are said to be safe for up to 500 WHP.

Thank you. Sounds like no current need to upgrade them. Though, I may be approaching 500 with the current setup. Wish I had a dyno run or two. Basing my estimate on some dyno videos from Richard Holdener. After doing the intake mods, I should be pretty close to that number. Although, that’s likely at the crank, not whp. I’ll have to ask BBP where the duty cycle is for these injectors, after tuning for the intake.

 

[Sam Harris]

Hmmmm.. turbo

 

[iamdub]

I saw this earlier. Not sure if it's anything useful for anyone collecting parts or if the price is good:

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[Sam Harris]

Hoping I ordered the correct one..

 

[iamdub]

Thank you. Sounds like no current need to upgrade them. Though, I may be approaching 500 with the current setup. Wish I had a dyno run or two. Basing my estimate on some dyno videos from Richard Holdener. After doing the intake mods, I should be pretty close to that number. Although, that’s likely at the crank, not whp. I’ll have to ask BBP where the duty cycle is for these injectors, after tuning for the intake.

Stage 2 and the heads, headers, etc... I'd say ~420 at the crank. Mine is similar to yours, just with nearly-stock, mildly-shaved heads. Calculating the ET with the weight, etc., 400ish at the crank is a close estimate for mine. It's right in line with the '09 6.2/2WD Tahoe. It's difficult to say for sure what's lost through the trans. Actually, mine might be doing a little better than I'm thinking cuz it's matching the 6.2 Tahoe with a 4L60. The 6.2 has a 6L80. Richard's figures are always high cuz his dyno mules are with no accessories and an electric water pump, a cool ~75° dyno cell, etc. His before-and-afters are for comparing the mods themselves and not for relating to real-world figures.

 

[S33k3r]

Stage 2 and the heads, headers, etc... I'd say ~420 at the crank. Mine is similar to yours, just with nearly-stock, mildly-shaved heads. Calculating the ET with the weight, etc., 400ish at the crank is a close estimate for mine. It's right in line with the '09 6.2/2WD Tahoe. It's difficult to say for sure what's lost through the trans. Actually, mine might be doing a little better than I'm thinking cuz it's matching the 6.2 Tahoe with a 4L60. The 6.2 has a 6L80. Richard's figures are always high cuz his dyno mules are with no accessories and an electric water pump, a cool ~75° dyno cell, etc. His before-and-afters are for comparing the mods themselves and not for relating to real-world figures.

I thought the rule of thumb for loss through automatic transmissions was ~33% ?

 

[iamdub]

I thought the rule of thumb for loss through automatic transmissions was ~33% ?

You have transmission problems if your losses are that high! It's more like 18%-20%. This is why I used 1/4 mile times for a baseline and after mods comparison. The E.T. and vehicle weight are used to calculate what's actually getting to the ground, which would include the losses in the trans and differential. I don't recall the numbers, but adding in the 20% losses from the calculated RWHP was right at what the 5.3 should've been making both stock and modded. Actually, the figures were a tad high. But, word on the street is GM technically underrates their engines since they advertise their output with all the accessories loaded up- A/C compressor pumping, alternator powering the fans, etc.

 

[S33k3r]

You have transmission problems if your losses are that high! It's more like 18%-20%. This is why I used 1/4 mile times for a baseline and after mods comparison. The E.T. and vehicle weight are used to calculate what's actually getting to the ground, which would include the losses in the trans and differential. I don't recall the numbers, but adding in the 20% losses from the calculated RWHP was right at what the 5.3 should've been making both stock and modded. Actually, the figures were a tad high. But, word on the street is GM technically underrates their engines since they advertise their output with all the accessories loaded up- A/C compressor pumping, alternator powering the fans, etc.

I'm either misremembering, or my knowledge on the topic is old. Thank you for the correction! And the details are really appreciated too!