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hotrodding the 4.3 V6 (tips & tricks)

197964 Views 190 Replies 52 Participants Last post by  sixsix
G'day, mates!

For those of you who have the venerable 4.3 v6, but want more power as well as throttle response this post is for you.

First off, I know how frustrating it is to have to work with all of the limitations built into the Astro engine: the small choked up t.b.i., or the weirdo c.p.i. "spider" intake manifold, mild cams, and weak ignitions, etc. :crying: There isn't one day that goes by that I don't think about how can I make my engine PERFORM better.

I will admit, a v-8 option SHOULD have been offered. As well as a turbo (look at the syclone/typhoon), or at LEAST take the tuned port intake (instead of cpi) and chop two ports off of it and tune it! (Would make an awesome project). But, since I rent an apartment, most projects HAVE to be done within a day or two.

So, most of these tips are Very doable with minimal downtime. 馃崒 Also, throwing big money at hipo parts doesn't always pay off. (Not in this day and age, anyways) Only the parts that are reasonably priced will be mentioned.......

1. Ram-air: bringing in COOLER air makes it easier for the engine to make power. (Try driving your van without a/c with the windows up on a 90 degree day, your engine is in the same scenario ) This can be made at home with dryer ducting with an aluminum sheets and some clamps. Cheap Cheap! :dance:

2. K&N filter: (8-10 horsepower). If you are in a dusty area, add a foam filter as a buffer. Paper filters restrict your airflow and most people forget about them and they get progressively dirty.

3. Morosso or Proform Air cleaner base: smooths out the airflow and allows removal of the stock "restricter" ring underneath it. This thing is TERRIBLE for performance.

0000tbi choker.jpg

4. Raise the TBI injector pod: this allows more air to get in past the injectors. Turbo city has some goodies. View attachment 4 This spacer/gasket raises the injector pod 1/4". I raised mine to 1". :layrubber:

5. Adjustable fuel pressure regulator: Add more air, add more fuel. Raising your fuel pressure on late models is akin to changing jets on a carb.

0 1000 cfm adjregulator.jpg

6. Fuel pressure gauge: for proper fuel pressure tuning. I set mine to 15 psi. these are fairly cheap.

7. Throttle spring modification: Removal of the stock throttle spring, and replacing it with a SOFTER old-style return spring(s) will increase the opening speed and improve overall throttle response.

8. Throttle enhancer: Casper electronics has a piggyback sensor that when the throttle is at 70% open, it tricks the computer into thinking it's at 100% open, increasing throttle response. (This product DOES work very well, I have one on my Fiero as well)

0 1000 tps enhancer.jpg

9. Bigger TBI: Stick with the stock one...UNLESS you add an edelbrock aluminum intake with a 7.4 liter TBI with the 2" bores. ( This is just a backburner idea at most)

10.1" Throttlebody spacer : (fits under TBI) will add torque by increasing the intake volume. Swirl-type spacers also help mix the fuel and additional air before it's combusted. Unfortunately, swirl types don't work on CPIs....they're port-injected already. I currently have the helix 1 1" spacer. I thought I remembered seeing a 2" trandapt spacer years ago but, I think they discontinued it. Just a while ago, found out CFM technologies has a spacer that's supposed to allow the engine to pull air/fuel from either tbi bore (if it's a duel-plane), offering a more balanced air/fuel mix resulting in more power. Not sure if ours is a dual or single plane, but it's worth mentioning.

0 1000 supersucker.jpg

Most of these parts , together as a whole and with tuning, should net 20+ horsepower. :rockon:

This concludes part ONE for now..........stay tuned for more.

Thank you


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With my 2000 AWD LT all it took was swapping to the 0411 pcm and a bit of transmission shift/lockup tweaking to make the van feel significantly faster along with netting an easy 2+ mpg. However, after doing a bed mounted turbo 4.3l s10, I'm not satisfied with where the van is and thankfully I have another brand new gm8 turbo on hand which will find home where the Astro's muffler currently resides. For the sake of reliability and ease, I'll probably run a maximum of 7psi of boost so I don't need to run an external fueling system (the ol dime had an injector preturbo that came on at 5psi spraying methanol. Felt like vtech kicking in when that happened). My only concern is where I'll put the turbo air intake as I'd rather not have it at the bottom of the van and risk hydrolocking during heavy rains.
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sixsix said:
Have you considered the area in the inner fender - where the OEM air intake resides...
- going to be quite the plumbing feat. "Laws of Subtraction" may come into affect.
I for one, am looking forward to any build info and or pics, etc.

Welcome to the forum - Fresh Blood always Welcome...!!
Thanks for the warm welcome!

I'll need to make a point of trying to remember to take pictures while working on the van, it's something that I've always been bad about. So far all I've done is swapped in a DR44G 140+amp alternator (manually controlling the output via PWM signal generator), removed the factory pin stripes, removed the cracking black vinyl decals around the windows and am currently in the middle of replacing the body bushings/rebuilding a completely rotten lower radiator support. Since that part will be hidden I'm going to essentially copy what Chevymankevin did. Thankfully the metal donuts arent that rotten and have been coming out of the electrolytic rust removal cooler looking better than I expected.

I mention the body mounts as I am planning on gaining some much needed room for plumbing via a 2in (maybe 3in) body lift. Doing the s10 build I learned that a mere 2in ID pipe that was over 10ft long was more than enough to push 15-17 psi down a 4.3's throat. With that said, the turbo's intake was literally 6in long so I'm not sure how much a longer/more restrictive intake will change things.

Doe_nStein said:
So what just a better tune with the 411? Funny you mention this as I am planning this mod on my Cadillac LT1 and bought two 411s from the junkyard. So I could have one for the van too.
Basically I turned off any of the "abuse mode" items, reduced the torque management trans tables by 2/3rds (that is how much power via timing the computer pulls just before shifting), adjusted the TCC lockup pwm minimum to 90%, maximum to 100% (by design the TCC normally never fully locks and almost always will have a 30-50 rpm slip. Allowing it to fully locked dropped my trans temps quite a bit, especially combined with allowing lockup to occur as early as 15mph in 2nd. Other gains came from the 0411 having a high and low octane spark map table, leaning out the PE mode along with lowering the entry point from 90% throttle to 60%. If you use a 12212156 OS you can change the platform from van to holden to allow for activation of "lean cruise" which will pull fuel and add timing at highway speeds (or lower if you desire. Mine is set to activate at 40mph and deactivate below 30), at 50mph I'm crusing at 16.3:1 afr which makes a very noticeable difference in avg MPG. Once my coworker is done borrowing my laptop I'll be able to get some logs and hopefully make a slightly more aggressive lean cruise table.

With that said, I'm a complete amateur when it comes to tuning and have only been messing around with the 0411 pcms for about a year, 90% of which was on a 5 speed so figuring out the 4l60e stuff has been quite the adventure.
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How did you go about tuning the 411? Send it off? Do it yourself? IF so how and what did you need to do it?
Get yourself an "okayish" obd2 Bluetooth module (elm327, vicar, obdlink) and using either a laptop or a desktop with a hella long usb extension you can connect to and pull a copy of your PCM's OS using PCMhammer. From there just download and install tuner pro, then head over to the TunerPro OBDII forums, and find the XDF that matches your OS. In my case I ditched the stock OS and /changed to the 'universal 12212156 os (only OS that will work for any gm v6/v8 platform) and simply copied my stock tables into a 'lean burn' 12212156 copy I had from an s10.

2156 is a nice version to use since that one has the best XDFs available (the most adjustable parameters) not to mention a user on the pcmhacking forums released a patch for it that gives you 2 step launch control (with optional boost building timing retard) up to a 3 bar MAP table among a few other things.

The best part is that the only barrier to entry is a ~$20 obd scanner (I recommend the obdlink lx or mx), anything with an 0411 512k p01/p59 1mb PCM (or one that has been swapped in, it's really not that hard) and some form of a pc/laptop with bluetooth. Everything is essentially open-source and is simple to use once you get the hang of it. Nothing sweeter than perminately disabling a nuisance SEL code, and lowering trans temps with no more than 5 mins of dicking about.

It's one thing to throw on a better flowing intake and exhaust, along with some better injectors, it's another thing entirely once you've adjusted the tune to take advantage of them. I managed to make a ~400hp 4.3l s10 out of maybe 500 in parts and most of that was spent on stuff I didn't use/need. All thanks to open source tuning (and amazon warehouse discounts <3 my pair of GM8 turbos I got for ~75 each).
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Sent a PM, I paid lextech on the gmt forums for my copy as when I tried doing it on my own the first time on an s10, it didn't go so well. There are 5 dark green wires that are easy to get mixed if your're not careful.

EDIT: Forgot to mention the snail has been mounted under the van for a few days and even at 5psi it's like a different van. I'm holding off on pictures for at the moment as much of the cold side looks like hell since I was running a cheap 120v inverter welder on cheap harbor freight wire, connected to one of those thin lamp extension cords. Spent more time grinding than I did welding. The gist of the setup is I made a pie cut 90 that goes straight from the plastic bonnet down to the lower pass side of the motor where a regular 90 is welded, then there is a single silicone connector for the long af single welded piece(s) of steel that directly attach to the turbo with the 2nd of two silicone couplers. Due to half assing the pipe to bonnet (misplaced my coupler but had an exhaust adapter that fit snugly so that was temoorarely epoixed into the bonnett. Accidentally hit 14-15 psi despite the waste gate having no boost refrencel but thakfuly no harm was done and glue has broken away some leaving me with a near perfecf 5psi of boost.
Until I get my old 'is that a f***ing injector on your pre turbo intake elbow' setup going again, I temp rigged up a cheap inline 'bosch' style fuel pump that draws from a jug of VP Racing 80% ethanol hand sanitizer that I have like 30 gallons of and that runs to a single mister nozzle that is clamped onto the one connector on the bonnet. I\d MUCH rather have it spray preturbo but I did this as a bit of a stopgap until this weekend. Should be getting ~30g of methanol for next to nothing and I plan on spraying some amount of 50/50 - 70-30 meth/water into the turbo intake. Also this weekend I'm going to finally cut the cat converter out and replace it with a test pipe, thefts are bad around here, I could use the cash but most importantly: the damn thing is robbing my turbo of heat That and I'm like 90% done building from the turbo to the stock exhaust. its been a challenge due to the inlet and outlet on the gm are on the same side. once that is on my goal of a mostly sleeper astro will be compete. I feel no desire to see what the 4.3l in the astro can take as I know my same year s10's motor held 15-17psi all day no problem
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