4.3L Vortec Peformance

[chevyman08]

There are a few cheap or free performance tricks for the 4.3L Vortec specifically the 98 and up version. Since the intake gaskets on the newer vortec engines are notorious for leaking, I recomend replacing them with the alluminum gaskets available at your local GM parts department. There a little more expensive but they last forever. While you have the intake off go ahead and gasket match the intake ports on the heads and intake. Next take off the plastic upper intake and smooth the port inlets on the lower intake, just take the raised part out and make a smooth entrance into the port. Then take to throttle body off, remove the baffle that is on the throttle blade, just use some needle nose pliers and rip it off. Fill the rivet holes with JB Weld or Quick Steel, but make sure you leave the big on in the middle because it helps with idle control. Next smooth the inlet of the throttle body just open it up a little, but don't port the throttle blade seat or you'll ruin the throttle body.

[Black Knight]

Descreening the Throttle Body, a Cold Air Intake, and exhaust are the best and easiest mods for a 4.3L. I did all of the above and I gained 6 mpg and a healthy amount of power in a 98 Sonoma.

[chevyman08]

thanks for the information Black Knight that has to be one of the coolest looking grand ams i've ever seen! So far on my truck i've added a round k&n air filter just after the MAF sensor, removed the screen from the mass air sensor, ported the trottle body+ removed the baffle and added a flowmaster delta 40 2 1/2 in/out muffler. The performance gains for these mods was huge and I only spent $50 for the muffler (used) and a friend gave me the k&n. I don't know how much it helped my gas milage (lead foot) but my truck will now light both rear tires up when i shift from first to second under heavy throttle.

[chevyman08]

I finally found a way to bypass the speed limiter on my 2000 S10 4.3L 5 speed I'm not sure if this will work for automatics or full size trucks. This is not a complicated setup all you need is 1 piece of 16 gauge wire around 4 ft. long. Trim about 1/4" from each end of the wire. Start at the underhood fuse block, pull the Fuel pump relay and look at the diagram on the side number 85 and 86 terminals should be for the relay control circuit (the coiled wire on the diagram) find the positive side of the coil by using a test light, if your standing at the drivers side fender it will be the terminal on the lower right corner. Rap one end of the wire around the pos. terminal of the relay coil side and reinstall the relay. Run the wire to the front of the fuse box, trim a small section of the plastic seal on the fuse box lid and the fuse block to run the wire through. Next run the wire along the drivers side fender and through the gromet bellow the power brake booster. Then run the wire to the interior fuse block. Find the park lamp 10 amp fuse, pull the fuse and wrap the other end of the wire around one terminal of the fuse reinstall the fuse. If you have the Auto headlights you realy don't even need to use the headlamp switch. With this setup all you need to do is turn the switch to the park lamp setting and the fuel pump will run and your truck will not shut off, use caution this also eliminates the rev limiter. Also do not turn the switch on with the engine off it will flood the engine.

[chevyman08]

MPFI conversion kits 1996-2006: direct replacement for poppet nozzle injectors (CSFI) $340 uses Multec 2 fuel injectors rated at 19lbs, true MPFI is available from Afordable Fuel Injection (AFI): 600 cfm 2 bbl throttle body system $1950, 700 cfm 2 bbl throttle body $2100, 1000 cfm 4 bbl throttle body $2400 these kits are for stock motors if you have a modded motor, supercharger, turbo, or nitrous it may cost more due to additional programming requirements. The Marine MPFI intake will work with minor mods but it is made from cast iron and weighs a ton, all that is needed are fuel injector connectors with the pig tail attached, a fuel injector wiring diagram some Crimp and Seal connectors and new intake gaskets (the originals may look good, but they fail often its best to replace them while the intake is already off.)

[Eliteweapons]

Where could I find the mpfi conversion kit? will that work on the 94 vortec? I am having o2 lean ses light and I think its my injector so i am looking to see if I can upgrade it at the same time.

[chevyman08]

I'm not sure if the mpfi conversion kit will work on your 94 vortec, both the multipoint and the throttle body of the pre 96 vortec engines are throttle body based which means they rely on two centrally located injectors and the CPI has 2 injection solenoids and 6 poppet nozzels. this presents a problem to true mpfi injection because the injectors fire all the time and are not sequential like the 96 and up models. The kit from AFI (Affordable Fuel Injection) comes with a sequential mpfi setup with a separate ECM for the fuel injection system. the only drawback to this system is if you have an automatic you will have to piggyback the aftermarket ECM onto your OEM computer to retain the programming for the 4L60E automatic, another option would be to convert to a 700R4 transmission. The AFI kit can be found by googling AFI fuel injection systems. on a second note my tip for killing the speed limiter is a bad idea my fuel pump freaked out after a day or two and it never really worked, the quest continues. a computer reprogram may be the only way.

[leadsailz]

To what benefit is MPFI is to the stock TBI? Just curious because I am planning to upgrade my 98 s10. Also, do you have any recommendations on a cam?

[chevyman08]

Sorry I took so long to reply. The Main difference is the upgradable external fuel injectors which allow for higher horsepower to be made. Stock is 19 lb/hr which is good for up to 300 in a V6 engine. If you want more power you have to upgrade to MPFI or get an add on injector system,usually incudes 2 injectors with a separate computer. The down side to these is they are like TBI they saturate the intake charge with fuel as soon as it enters the intake manifold, also they require about the same amount of wiring and fab workas an MPFI upgrade. As far as cams go Comp is the best they have 3 different grinds for the 4.3L and the best one depends on what you want the rpm range to be more lift/duration= higher rpm horsepower with a loss of torque.

[chevyman08]

I'm in pursuit of more power (bang for buck) than a 4.3L can offer. I am currently looking into a Vortec 350 swap backed by my NV3500 5 speed. All that is required is the motor mounts, dual electric fan kit, V8 swap headers, redone exhaust, computer reflash (necessary for any major performace upgrade anyways), new clutch (mine is worn), and a 5.7L vortec with intake, ECM, and harness from a 98+ vehicle. All that is needed from the harness is the injector wires and plug. The ECM can be sent and programmed while you drive the 4.3L around. the imediate benefit is 65 more horse power and 60 lb/ft of torque. The later benefit is aftermarket support and easy future upgrades. Just have some Xtra cash for rear tires because you'll need 'em. lol

[chevyman08]

Just to give you an idea of price. V8 swap mounts and headers (S10 V8 Swap/Conversion Community) $184.95, 2.8L frame mounts (AutoZone) $8.99 per side, ECM reflash $250, clutch $191.99 (AutoZone), spal dual 11" fan kit $359.95 (S10 V8 Swap/Conversion Community). Another option is to look at a salvage yard and find a set of dual electric fans that fit and buy a $24.00 fan controler from AutoZone. Also you'll probley need intake gaskets, $59.99 from AutoZone.

[brokenbird]

where do you find the cams i was looking for one for my seirra but could not find one

[boomer49]

Originally Posted by chevyman08

There are a few cheap or free performance tricks for the 4.3L Vortec specifically the 98 and up version. Since the intake gaskets on the newer vortec engines are notorious for leaking, I recomend replacing them with the alluminum gaskets available at your local GM parts department. There a little more expensive but they last forever. While you have the intake off go ahead and gasket match the intake ports on the heads and intake. Next take off the plastic upper intake and smooth the port inlets on the lower intake, just take the raised part out and make a smooth entrance into the port. Then take to throttle body off, remove the baffle that is on the throttle blade, just use some needle nose pliers and rip it off. Fill the rivet holes with JB Weld or Quick Steel, but make sure you leave the big on in the middle because it helps with idle control. Next smooth the inlet of the throttle body just open it up a little, but don't port the throttle blade seat or you'll ruin the throttle body.

In reference to the baffles on the throttle blade, it sounds like there are two of them as you mention leaving the 'big' one on. I am about to install a TB space on my 99 4.3 and would like to perform this mod but haven't looked at the TB yet. Are the baffles on both the top and bottom, just the bottom, and which one is taken off?

Thanks in advance for your reply.

[Grnnt4]

Originally Posted by boomer49

In reference to the baffles on the throttle blade, it sounds like there are two of them as you mention leaving the 'big' one on. I am about to install a TB space on my 99 4.3 and would like to perform this mod but haven't looked at the TB yet. Are the baffles on both the top and bottom, just the bottom, and which one is taken off?

Thanks in advance for your reply.

He's talking about leaving the factory hole in the throttle blade for idle control and plugging the holes left from removing the baffle. There's only one baffle on the back of the throttle blade. I just did this last weekend while replacing my leaky IM gaskets, and it worked out nice.

[boomer49]

Originally Posted by Grnnt4

He's talking about leaving the factory hole in the throttle blade for idle control and plugging the holes left from removing the baffle. There's only one baffle on the back of the throttle blade. I just did this last weekend while replacing my leaky IM gaskets, and it worked out nice.

Ahh, I understand now. Thanks for the info. By the way, did you notice much difference by adding the spacer and removing the baffle?