Spraying the 4.3L V6
01-13-2006, 04:01 PM
#13
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if you were using a DP intake system i could see doing a dry shot that big, but unless you find a way to raise the fuel pressure i see a cracked piston in your future.
01-15-2006, 01:11 AM
#17
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On the 4.3 Vortecs, they use a 19 lb/hr poppet injector, the Vortec engines actually run at 58-60 psi at WOT. The 19 lb injector is actually flowing like a 22.1 lb/hr injector.
In a 350 the 19 lb/hr injectors are goof for 400 hp at the engine, since a 4.3 is a 350 minus 2 cylinders, that 4.3 should have enough fuel for 300 total hp.
The 4.3 in the fullsize trucks is rated at 190-200 hp(200 hp in 1997).
Lets say 200 hp + the 80 hp shot = 280 hp, you souldnt have a problem IMO, you have a 20 hp margin of saftey there. If you wanted to spray any larger of a shot, it would have to be a wet shot.
Adding a larger fuel pump WILL NOT help with the dry shot, with the stock FPR, the limiting factor here is the stock 19 lb/hr spider injectors system.
A larger fuel pump will only help your cause IF you install and external adjustable fuel regulator and raise you WOT FP over 60 psi.
If you added a Marine V6 intake manifold and some larger fuel injectors, the stock PCM will drive ANY high impedance injector, the limit will be the engine strength and not the fuel system.
I wouldnt spray any more than an 80 hp shot on your truck as is.
Since you are spraying an 80 hp shot, I know I will be safe spraying a 107 hp shot on my Vortec 350. If you divide 80 hp by your 6 cylinders, that gives you 13.3 hp/cylinder, I take that 13.3 and multiply that by my 8 cylinders and I get 107 hp. I think I roughly have 300 hp so if I add that 107 hp dy kit, I will go over that 400 hp magical number. But since I have 28 lb/hr injectors I can actually spray to a total crank hp of 480 hp. If I had my stock intake manifold with the 19 lb/hr injectors (exact same rating as yours, just 2 more in my truck) I would have to observe my 400 hp ceiling (300hp in your V6) since the injectors wouldnt be able to properly fuel the nitrous shot.
I am glad that you go so aggressive with the your stock setup, that gives me confidence in my setup.
When you install your V8, you might want to add a little larger injector than you need NA, just in case yoiu ever need a little extra hand from thatdry shot again.
Dry shots are awesome IMO, no nitrous backfires and excellnt cylinder to cylinder distribution of nitrous, these intakes were never designed to flow liquids.
peace
Hog
In a 350 the 19 lb/hr injectors are goof for 400 hp at the engine, since a 4.3 is a 350 minus 2 cylinders, that 4.3 should have enough fuel for 300 total hp.
The 4.3 in the fullsize trucks is rated at 190-200 hp(200 hp in 1997).
Lets say 200 hp + the 80 hp shot = 280 hp, you souldnt have a problem IMO, you have a 20 hp margin of saftey there. If you wanted to spray any larger of a shot, it would have to be a wet shot.
Adding a larger fuel pump WILL NOT help with the dry shot, with the stock FPR, the limiting factor here is the stock 19 lb/hr spider injectors system.
A larger fuel pump will only help your cause IF you install and external adjustable fuel regulator and raise you WOT FP over 60 psi.
If you added a Marine V6 intake manifold and some larger fuel injectors, the stock PCM will drive ANY high impedance injector, the limit will be the engine strength and not the fuel system.
I wouldnt spray any more than an 80 hp shot on your truck as is.
Since you are spraying an 80 hp shot, I know I will be safe spraying a 107 hp shot on my Vortec 350. If you divide 80 hp by your 6 cylinders, that gives you 13.3 hp/cylinder, I take that 13.3 and multiply that by my 8 cylinders and I get 107 hp. I think I roughly have 300 hp so if I add that 107 hp dy kit, I will go over that 400 hp magical number. But since I have 28 lb/hr injectors I can actually spray to a total crank hp of 480 hp. If I had my stock intake manifold with the 19 lb/hr injectors (exact same rating as yours, just 2 more in my truck) I would have to observe my 400 hp ceiling (300hp in your V6) since the injectors wouldnt be able to properly fuel the nitrous shot.
I am glad that you go so aggressive with the your stock setup, that gives me confidence in my setup.
When you install your V8, you might want to add a little larger injector than you need NA, just in case yoiu ever need a little extra hand from thatdry shot again.
Dry shots are awesome IMO, no nitrous backfires and excellnt cylinder to cylinder distribution of nitrous, these intakes were never designed to flow liquids.
peace
Hog
01-15-2006, 01:16 AM
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Originally Posted by therat1989
The 4.3 isn't that weak. In fact my friends lazer with the 4.3 and a "custom" cold air will only trail 4-5 car lengths back from 0-90.
those Vortec 4.3's arent weak at all. They are in ecsb 4wd's but a 4.3 rcsb with a TC, 4.10's and bolt ons could be made to run pretty good, with nitrous, anything is possible.
peace
hog
01-15-2006, 10:58 AM
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Formulated, congrats on your dry hit, another success story for all the dry nay sayers. There is one thing you can do, or think about, that's running a hot wire kit to your fuel pump. A 12v heavier gauge wire directly from alternator to your pump. What this does is insures the highest voltage at peak demand so pump can work at it's fullest. I know on the vette's this will keep pressure up and flow at max, actually IIRC it's up to about a 20% gain in pump performance. So, for those that think pump can't help a dry shot, it can, espec when high demand area and you lose a few pounds of pressure.
Hog, some very good input. I just wanted to add that the limits of injectors can be extended past the rec safety limits rec. I have run and dynoed 480 rwhp on 28lb'ers. A co ls1techie is running his 28's at 140% duty cycle, so the 80% duty cycle is long term wear/tear rec. However, myself I try to stay away from static or 100% duty cycle, but not afraid of the 90% area.
Robert
Hog, some very good input. I just wanted to add that the limits of injectors can be extended past the rec safety limits rec. I have run and dynoed 480 rwhp on 28lb'ers. A co ls1techie is running his 28's at 140% duty cycle, so the 80% duty cycle is long term wear/tear rec. However, myself I try to stay away from static or 100% duty cycle, but not afraid of the 90% area.
Robert