Understanding marine dbw vs cable misc.

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wwilson

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First time post and first build. My topic had an abundant amount of information except for one specific variant I can't seem to wrap my head around. I'm building a 96 k1500. 383, 202 and 160 stainless valves, new injectors 1.6 rockers 10.5 ish to 1 comp. Pretty standard build. Specifically for towing so the builder did his best on the cam. (I don't have those specs on me) I have the 411 computer already installed and the factory lb injector conversion. But it's showing that I need more fuel across my curves according to my tuner. That being the case I'm trying to decide if installing bigger spider injectors, or, doing the marine intake would make sense. I found one complete for a couple hundred bucks. Only pitfall is the marine intake I found is a 4 bolt throttle body style.
-Do any of you know the differences in those specific 4 hole throttle body 5.7 vortec marine intakes?
-Am I wasting my time trying to install the marine intake to begin with as its not going to see high revs most it's life?
-If it's worth swapping over, can you interchange either the top half of the intake?
-or do they make a 4 bolt to 3 bolt throttle body adapter that I can't seem to find?
I appreciate any information or opinions on this stuff.
 

1998_K1500_Sub

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I need more fuel across my curves according to my tuner

How did he come to that conclusion, e.g., were the Long-term / Short-term trim values indicative of this, or wideband O2 measurements or... what?

What was his recommended solution? Did he say to you "You need bigger injectors" or "You need overall greater fuel delivery potential" or "You need to tweak the fuel map so the Long-term trims are closer to neutral" or... what?

Specifics will help refine the solution to the problem :)

You might want to take a look here for @L31MaxExpress remarks:

 
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wwilson

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His exact words were "larger injectors would help this thing immensely, your injectors are working at their maximum output and we still have more power to squeeze out of this build" based on that comment on the article you referenced, it sounds like he's getting better performance out of a "ported" stock manifold. Do you happen to know what he means by that exactly? Because if that's the case I will happily purchase the larger injectors and not have to mess with anything else. Injectors are 7-800 bucks vs the cheaper used intake. If the intake would be better then I don't mind doing the changes necessary. If however he's getting better numbers and I don't have to do anything but swap the existing injectors for larger ones, there's really no point to the marine swap. I think the comment about being ported might have something to do with that?
 

1998_K1500_Sub

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His exact words were "larger injectors would help this thing immensely, your injectors are working at their maximum output and we still have more power to squeeze out of this build". Based on that comment on the article you referenced, it sounds like he's getting better performance out of a "ported" stock manifold. Do you happen to know what he means by that exactly?

No, I don't, and I would like to know myself!

Hopefullly @L31MaxExpress will read and respond.
 

L31MaxExpress

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His exact words were "larger injectors would help this thing immensely, your injectors are working at their maximum output and we still have more power to squeeze out of this build" based on that comment on the article you referenced, it sounds like he's getting better performance out of a "ported" stock manifold. Do you happen to know what he means by that exactly? Because if that's the case I will happily purchase the larger injectors and not have to mess with anything else. Injectors are 7-800 bucks vs the cheaper used intake. If the intake would be better then I don't mind doing the changes necessary. If however he's getting better numbers and I don't have to do anything but swap the existing injectors for larger ones, there's really no point to the marine swap. I think the comment about being ported might have something to do with that?
If you are not reving it out the marine intake is not a huge benifit. The used marine intake itself may be cheaper used. That being said by the time you clean or replace the clogged marine injectors that have been sitting with old fuel in them for months or years, modify the intake, modify the injector wiring, add the injector connectors and modify the fuel system as well as all the other bits you will be over the cost of the bigger spider. You will need a 3-bolt upper. I believe the uppers interchange but have never tried it myself. The 4 bolt marine throttle body has a different bolt pattern than a Ls throttle body, so unlikely to find an off the shelf adapter and I have only seen drive by wire 4 bolt throttle bodies on those intakes. Not saying a cable application does not exist, but I have yet to see one and that goes for the 4-bolt 4.3s too. The direct bolt-on approach of the upgraded high flow spider will save time and money, especially if you lack the tools to drill, tap and otherwise modify the intake. If you are in an area that requires EGR, that is further modification. Requiring custom fabricated EGR tubing, a remote mounted EGR base from an early LS and fabrication to mount the EGR bracket.

I do not know the history of your truck, but given most of these trucks now, I suspect that your old clogged fuel filter, old fuel pump, and fuel pump wiring is likely the cause for weak fuel delivery. My 383 even with stock injectors was not climbing to the 90-100% duty cyle range until 5,200+ rpm and it is moving a ton of airflow through it. I have a newer Delphi pump, a Racetronix hotwire and a new K&N fuel filter. I put larger injectors into mine to run E85 when I upgrade the pump. My regulator was adjustable and was set to 75 psi on the stock AC Delco upgrade spider. Its good for a another ~2 lbs/hr fuel flow vs the 58 psi it is set at to start with. 2 lbs/hr might not sound like alot but over 8 injectors given a ~0.45 lb/hr/hp brake specific fuel consumption it is another 30-40 hp worth of fuel. My van at 85K when I changed the stock pump and wiring was dropping to just under 50 psi at WOT and was running out of fuel with the old heads/cammed 350. Changed the pump and wiring and instantly held 75 psi all the way to redline and was drowning the 350 in fuel. My stock fuel pump connector was burned at the pump on both sides of the connection. The Racetronix harness provides full alternator voltage to the pump basically supercharging it and reducing amperage draw. I started using K&N fuel filters because they are constructed better than cheap parts store filters and have a higher flowing media with more surface area. Less resistance to flow means the pump does not have to work as hard to supply the necessary pressure, increasing the volume and pump life. Getting adequate volume to maintain pressure at WOT is often overlooked even by the so called pro tuners.

What was the injector duty cycle and what was the air/fuel ratio? What was the fuel pressure when the engine was under load at WOT? I can tell you first hand the PCM sometimes mis-reports the duty cycle reading and 110-115% duty cycle will often still add additional fuel as well on the 0411s.
 
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JeremyNH

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I put in a marine intake early last year. It is a superior intake to the stock vortec, there really can be no question on that. It is free of all interior obstructions and absent the spider has an enormous volume which is advantageous for torque building. It has a standard fuel rail system which means you have many options regarding fuel injector selection. Having said that, for a truck motor the end result performance gain is pretty minimal. It's not nothing, but it's minimal. I would expect it to be a more reliable fueling solution (look at all the posts of people who have issues with their spiders vs the hundreds of millions of vehicles with standard fuel rail injectors which run without issue through their service lives) which was my aim when I went through my motor last year. Lastly, if the spider had any advantage over fuel rail injectors why didn't any other manufacturer, including GM, copy it? If you do get an intake try to get it with the accessory bracket (kind of an S shaped steel bracket that spans the manifold) because it makes it much easier to mount the canister purge valve and attached wire loom to keep the install clean. If you convert to cpc ignition at the same time as I did you won't have to worry about the ICM mounting either and what you'll end up with is a cleaner than factory installation.

With regards to your questions:
-Do any of you know the differences in those specific 4 hole throttle body 5.7 vortec marine intakes? No, mine had the same 3 hole tb as stock but on the PPED forum there is some discussion about getting an adapter for it. Given the dates of postings though there may not be adapters available any more.
-Am I wasting my time trying to install the marine intake to begin with as its not going to see high revs most it's life? You don't need it since the stock manifold is sufficient. But as mentioned it is superior to the stock manifold. May be easier to tune too.
-If it's worth swapping over, can you interchange either the top half of the intake? The top halves are not interchangeable. Beyond the big hole where the spider penetrates the upper manifold the stock also has carveouts in the upper manifold for pcv and canister purge valves. So they're not the same shape.
-or do they make a 4 bolt to 3 bolt throttle body adapter that I can't seem to find? As mentioned, take a look at the PPED forum. I know it was discussed.

The EGR tube is really easy to fix. You need two 5/8-3/4 flare adapters, two 3/4 flare nuts, and one 5/8 flare nut. The stock EGR tube is 5/8 and the middle foot or so of it is smooth SST so you cut it in the middle and flare it for a union. The 1999 Silverado uses a "divorced" EGR which can be mounted outboard of the AC compressor (basically where the pulley of a whipple sc would go if you had a whipple sc). Cut the adapters off of the 1999 EGR tube ends which leaves enough SST to flare (the 1999 EGR uses a 3/4 tube). Feminize the 5/8 end of one of the 5/8-3/4 adapters and put it in the manifold and then use the other adapter and flare nuts to put it all together. If you do the EGR this way you can keep the stock coolant hoses. Never could figure out why the author of the original procedure thought you needed a radiator hose from a pre-96 truck anyway.

The marine intake isn't hard to do and you don't have to abandon anything a stock truck has to put it in. You can buy new 24# Denso injectors for about $150 for 8 on ebay which are intended for use in marine engine overhauls (they made a lot of Marine Magnums). My intake came off of a 2005 Mercruiser with a 305 and cost $550 to the door. Probably spent an extra $400 on everything else (new injectors, injector harnesses, wire, 16 pin metripac, vac tubing, thermostat, canister purge valve, water neck, tb spacer, egr fun (not fun - easy solution after a half dozen failed solutions), etc). So it isn't a cheap thing to do. But it does work exceptionally well done right. Is it worth it? I have no regrets but it certainly isn't something you need for a 383. But by that logic a 383 isn't something you need either.
 
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L31MaxExpress

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I put in a marine intake early last year. It is a superior intake to the stock vortec, there really can be no question on that. It is free of all interior obstructions and absent the spider has an enormous volume which is advantageous for torque building. It has a standard fuel rail system which means you have many options regarding fuel injector selection. Having said that, for a truck motor the end result performance gain is pretty minimal. It's not nothing, but it's minimal. I would expect it to be a more reliable fueling solution (look at all the posts of people who have issues with their spiders vs the hundreds of millions of vehicles with standard fuel rail injectors which run without issue through their service lives) which was my aim when I went through my motor last year. Lastly, if the spider had any advantage over fuel rail injectors why didn't any other manufacturer, including GM, copy it? If you do get an intake try to get it with the accessory bracket (kind of an S shaped steel bracket that spans the manifold) because it makes it much easier to mount the canister purge valve and attached wire loom to keep the install clean. If you convert to cpc ignition at the same time as I did you won't have to worry about the ICM mounting either and what you'll end up with is a cleaner than factory installation.

With regards to your questions:
-Do any of you know the differences in those specific 4 hole throttle body 5.7 vortec marine intakes? No, mine had the same 3 hole tb as stock but on the PPED forum there is some discussion about getting an adapter for it. Given the dates of postings though there may not be adapters available any more.
-Am I wasting my time trying to install the marine intake to begin with as its not going to see high revs most it's life? You don't need it since the stock manifold is sufficient. But as mentioned it is superior to the stock manifold. May be easier to tune too.
-If it's worth swapping over, can you interchange either the top half of the intake? The top halves are not interchangeable. Beyond the big hole where the spider penetrates the upper manifold the stock also has carveouts in the upper manifold for pcv and canister purge valves. So they're not the same shape.
-or do they make a 4 bolt to 3 bolt throttle body adapter that I can't seem to find? As mentioned, take a look at the PPED forum. I know it was discussed.

The EGR tube is really easy to fix. You need two 5/8-3/4 flare adapters, two 3/4 flare nuts, and one 5/8 flare nut. The stock EGR tube is 5/8 and the middle foot or so of it is smooth SST so you cut it in the middle and flare it for a union. The 1999 Silverado uses a "divorced" EGR which can be mounted outboard of the AC compressor (basically where the pulley of a whipple sc would go if you had a whipple sc). Cut the adapters off of the 1999 EGR tube ends which leaves enough SST to flare (the 1999 EGR uses a 3/4 tube). Feminize the 5/8 end of one of the 5/8-3/4 adapters and put it in the manifold and then use the other adapter and flare nuts to put it all together. If you do the EGR this way you can keep the stock coolant hoses. Never could figure out why the author of the original procedure thought you needed a radiator hose from a pre-96 truck anyway.

The marine intake isn't hard to do and you don't have to abandon anything a stock truck has to put it in. You can buy new 24# Denso injectors for about $150 for 8 on ebay which are intended for use in marine engine overhauls (they made a lot of Marine Magnums). My intake came off of a 2005 Mercruiser with a 305 and cost $550 to the door. Probably spent an extra $400 on everything else (new injectors, injector harnesses, wire, 16 pin metripac, vac tubing, thermostat, canister purge valve, water neck, tb spacer, egr fun (not fun - easy solution after a half dozen failed solutions), etc). So it isn't a cheap thing to do. But it does work exceptionally well done right. Is it worth it? I have no regrets but it certainly isn't something you need for a 383. But by that logic a 383 isn't something you need either.
You just helped prove my point. Cost and pain in the butt factor are up there.

Also I took it as if he were asking if the two different marine upper intakes would interchange, not the truck one.

As far as performance. If the stock lower intake is ported, it will out perform the box stock marine intake. The stock intake is very beefy and the aluminum grinds away like butter with some decent long shank carbide cutters. Mine is matched almost exactly to the 210cc runners in my heads. IMO the stock manifold also has a plus of having the injector spraying directly on the back side of the intake valve. Aiding in vaporization and keeping the intake valves free of any carbon buildup.
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wwilson

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Thank you for all the information. It helped make my decision easy. I purchased larger injectors and I'll be done with it. I didn't finish posting the rest of the build as I'm working a ton ( just got off and start at 6am. Every day for months) but to the fueling issue the pump has been replaced with the Delco factory pick up unit and I'll use the k&n as their cheap. Just to be safe. Everything I could think of when rebuilding this was replaced. Radiators and e fans, every sensor sender belt hose, computer throttle body water pump spark plugs aluminum distributor, wires plugs, transmission by flt stage 5 new coolers, lines, clamshell mount inserts trans mounts the entire front end while the engine was out. I've went through this with a fine tooth comb and tried to get everything done the right way. If you name it under the hood I've replaced it less the AC compressor and power steering pump. Also when I was asking about upper halves it was specifically marine upper to marine upper because the mounting dimensions I found for the dbw marine throttle body seemed different then the standard 4 hole LS TB. Like you guys mentioned the holes in the 3 hole need those ports for my iac stuff. But with the information I've got I just figured I'm about done with throwing anything else at this until I at least get some more miles under it. It's going to tow. It's getting a gear vendor and 12 bolt rear, end of the year, stock tires no lift. It's a tool more then a toy for me specifically. So if the gain is only seen high rpm and I can't easily replace a part from AutoZone on the side of the road......i won't do the marine intake. To answer your questions about why he said what he said fuel running lean? I don't know exactly. He didn't elaborate only told me a bigger injector would help us out immensely and probably keep it together longer as running lean pulling 7500 lbs up hills all day is going to eventually run this into the ground. Again I didn't ask as I'm an automation electrician. This is the largest mechanical endeavor I've ever done. I sincerely appreciate all of your knowledge as well as you're patience. I'm sure a lot of this has been beaten to death but I searched a large amount and couldn't find the answer to the 4 hole question and wanted some legit real world opinion on my application. So again thank you!
 
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