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hotrodding the 4.3 V6 (tips & tricks)

198334 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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You know, I appreciate your efforts here. There are two very important things that should be mention, first.

Most importantly, proper maintenance. Not enough can be said for staying on top of the maintenance. That includes all fluids, tune-ups, tires, and just keeping everything clean.

Second, the exhaust. The most restrictive part of these vans (and many other cars out there) is the exhaust. It doesn't matter how much air and/or fuel you shove down the intake, if the exhaust holds it up, its all for not. Its the hourglass effect, weakest link in the chain, etc. A lot of people don't like headers but they are the best bang for your buck, period. But there is something else that can be done, replacing that stock catalytic convertor with an aftermarket version. All catalytic converters do the same thing but aftermarket versions flow 3, 4 or 5 times as much as the cheap stock equivalents.

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gtkane said:
2.5" would probably work well enough.

I over-killed mine because that's what I had in the shop- shorty headers(unknown make) with 2.25 y-pipe into 3" pipe to the Cherry bomb extreme muff., and dual 2.5" out the back. It's noisy as ****, and the wife hates it!
Yes but the exhaust would have to be done right. True dual exhaust for a 4.3L would make it run worse. The exhaust flow would decrease because the exhaust would cool too quickly and slow down in the pipes. You would need a X-pipe at best to help with the scavenging and maintain some of the heat. The same thing would happen if too large of pipes were used.
madmax said:
Thanx 4 the props, astro 355! Actually, I mentioned that this was PART ONE of a series. Exhaust upgrades are TOO obvious (next to air filter upgrades). I'd rather start off with fairly low-buck tricks that are often over looked on a late model (sort of late ). :lol: As far as exhaust size 2 1/4 is the best. I like big exhaust too, but v-6s NEED that back-pressure for torque! Thankfully, my vans emissions exempt here in Michigan , dont need the cat. :dance: But, duals can help open her up. Avoid "turbo" mufflers of dubious design , as well as "one in two out" types (unless its from SLP)............STRAIGHT THRU only! A thrush "cherry-bomb" (25-30 bones), works very well with y-split duals on the year. I've used this set up for four years now, and its JUST now wearing out!!! Soundwise, sat right next to johnny 5 oh in traffic.....never pulled over for sound. :D I think the second "y" in the exhaust , muffles the sound a bit more before exiting. Anywho, onto part 2. :sci-fi-beamup:
Well, the obvious upgrades are the ones that should be done first. The aftermarket for any vehicle or engine is overloaded with "low-buck tricks" that often don't work because the obvious upgrades are skipped.

Secondly, dual exhaust is the worst thing you can do if you are concerned about backpressure. Catback exhaust "one in two out" are a very effective way of increasing torque.

Listen, I'm not trying to rag on you. Its just that somethings you are saying I don't agree with and other things have been mentioned over and over. If you do a search in the archives, you can find it there.

Ok, but the first obvious upgrade you would do to any vehicle would be to make sure its in tip top shape. You can't just start throwing performance mods and expecting to get the full advertised benefits out of them if your engine is running at only 75%. That's the reason I said something in the first place.

We can debate this forever, there just needs to be consistency. You can't suggest that an "obvious" mod would be a carb (old school) when you talk about modding a throttle body, reprogramming the ecm or adjusting the fuel pressure. Sure, we can get away with that in our older vans but suggesting that OBD II vehicles (which have the majority on this board) change over to carbs is not feasible or legal.
"Well I'm not here to entertain, I just hope you learned something"

-Michael Ironsides, Starship Troopers
Madmax, I appreciate the effect you have put into copying and pasting this information into one place that's easily accessible but really we should keep this about stuff that can be done to our vans and available powertrains. I'm sure someone can put any engine they want into an astro/safari van, while I'm pretty sure that the overwhelming majority has a 4.3L (which is a 350 minus two cylinders) and a combination of 305 and 350 blocks. Don't get me wrong, I'm one for oddities and things that haven't been done before.
Again, changing and/or modifying any emission controls is illegal. I'm surprised at seeing companies still offering these kinds of products since the EPA is actively going after companies for these types of mods.
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