383 with TBI - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**GSOUTHERN** · 04-21-2018, 07:48 PM

Is anyone running a 383/ 425 HP with the factory TBI setup

bennylava · 04-21-2018, 08:07 PM

Just a quick question,

how did you determine that the engine's output is 425hp? That may be important to know when determining if the factory injector size is up to the task

**GSOUTHERN** · 04-21-2018, 10:27 PM

Quote:

Originally Posted by bennylava

Just a quick question,

how did you determine that the engine's output is 425hp? That may be important to know when determining if the factory injector size is up to the task

It is a GM Performance crate engine, so give or take a few hp
Posted via Mobile Device

72MARIO · 04-22-2018, 11:32 PM

I cant directly answer your question but I went from a carbed 383 to a LS 6.0 from a 2004 gmc truck. I will tell you its the best thing you can to to your truck. the stock 6.0 with a good tune makes better power than my 383 ever did. I have now swapped both my trucks to LS engines.

Mattchu60 · 04-23-2018, 08:31 AM

The stock TBI would not be able to handle 425 hp in my opinion without major modifications to the fuel system, TBI and injectors. Your fuel pressure would need to be cranked way up to handle that kind of hp. You would also need a custom ECM with tuning capabilities.

I am running a "custom" 350 with TBI using Dynamic EFI ECM- great system and works well, but I'm probably only about 275ish hp and already hitting the limits of the stock system, Holley TBI and running around 17 psi fuel pressure.

**GSOUTHERN** · 04-23-2018, 11:59 AM

Well I was hoping nobody would get my wheels turning on the LS!! I have a 416 CI/ 550 HP LS sitting here that I could use, then that will lead to my next question, which mounts/ conversion kit is the best for a 88 squarebody 4x4 Suburban? This was supposed to be a quick inexpensive project using some leftover parts, I bought the Suburban wrecked with 52000 original miles, front clip was trashed and I was going to take the interior out of it but once I started looking at it I decided it was too nice to scrap so I decided to put it on another frame. Looks like here I go with another project!!

bennylava · 04-23-2018, 11:55 PM

Sell the other stuff and get the LS

04-21-2018, 07:48 PM	#1
GSOUTHERN Active Member Join Date: Nov 2014 Location: ALVA, FLORIDA Posts: 113	383 with TBI Is anyone running a 383/ 425 HP with the factory TBI setup

04-21-2018, 08:07 PM	#2
bennylava Registered User Join Date: Jul 2017 Location: Texas Posts: 396	Re: 383 with TBI Just a quick question, how did you determine that the engine's output is 425hp? That may be important to know when determining if the factory injector size is up to the task

04-22-2018, 11:32 PM	#4
72MARIO Registered User Join Date: Nov 2000 Location: Huntsville Ontario Canada Posts: 4,052	Re: 383 with TBI I cant directly answer your question but I went from a carbed 383 to a LS 6.0 from a 2004 gmc truck. I will tell you its the best thing you can to to your truck. the stock 6.0 with a good tune makes better power than my 383 ever did. I have now swapped both my trucks to LS engines. __________________ 1968 Suburban numbers matching all original truck now equipped with 6.0/4L80 on Accuair http://67-72chevytrucks.com/vboard/s...d.php?t=625017 1967 C/20 6.0/4L80 Roofing Truck 1990 V2500 Suburban "Plow Truck" 2005 TAHOE DD

04-23-2018, 08:31 AM	#5
Mattchu60 Registered User Join Date: Jan 2014 Location: Swaledale, IA Posts: 485	Re: 383 with TBI The stock TBI would not be able to handle 425 hp in my opinion without major modifications to the fuel system, TBI and injectors. Your fuel pressure would need to be cranked way up to handle that kind of hp. You would also need a custom ECM with tuning capabilities. I am running a "custom" 350 with TBI using Dynamic EFI ECM- great system and works well, but I'm probably only about 275ish hp and already hitting the limits of the stock system, Holley TBI and running around 17 psi fuel pressure.

04-23-2018, 11:59 AM	#6
GSOUTHERN Active Member Join Date: Nov 2014 Location: ALVA, FLORIDA Posts: 113	Re: 383 with TBI Well I was hoping nobody would get my wheels turning on the LS!! I have a 416 CI/ 550 HP LS sitting here that I could use, then that will lead to my next question, which mounts/ conversion kit is the best for a 88 squarebody 4x4 Suburban? This was supposed to be a quick inexpensive project using some leftover parts, I bought the Suburban wrecked with 52000 original miles, front clip was trashed and I was going to take the interior out of it but once I started looking at it I decided it was too nice to scrap so I decided to put it on another frame. Looks like here I go with another project!!

04-23-2018, 11:55 PM	#7
bennylava Registered User Join Date: Jul 2017 Location: Texas Posts: 396	Re: 383 with TBI Sell the other stuff and get the LS



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