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hotrodding the 4.3 V6 (tips & tricks)

197967 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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In order to find concise info about your van the best source is the FSM, (factory service manual). You can find them on fleabay.
What I would suggest is to start your own build thread and look for feedback on ideas there. Any hotrod thread posted here will likely be on that one van, like lumpy did with his lift or chevymaher did with his rebuild. (those are two gifted pups right there!) (lumpy picks a mean guitar) :rofl:
Max attempted a general guide but there are so many variations over the years and differnt ways to get from a-z so you get this- :banghead: and then turkeys like me add our :2: and you get this- :blah:

I would encourage all new guys here to start a thread on their van and in that way you get the feedback and share the wealth of knowledge you pick up along the way. If you do a write-up of one specific task with lots of pics I'm sure it will get stickied, If you gather the info on hotrodding the 4.3 v6,,, It will be sticked, don't forget the pics.
Lump doesen't sleep well w/o is daily ration and then goes out painting camo on everything,,,,
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Sandwich, a thick aluminum gasket, in fact you want to get a gasket for the template. search EGR here and you'll find chevymaher"s pics. The EGR has a piston that needs to be allowed for so that gets a hole drilled but you block the other hole.
You can use thinner material but I would be hesitant to use something as thin as a soda can. An old piece of heat duct would be OK IMO.

Yeah CM, you're gettin' slow in your old age,,, 14 min. Did your walker break down?
You're correct Doe, but the tips and tricks need to be viewed in perspective as a whole, just recently on the other forum a fellow mentioned the cold air intake,

"The K &N kit 57-3017-2 fits S10 truck but not exact fit for Astro. k&N claims 7.42 hp increase at 4671 rpm."

My reply was simple,
"A.P., When is the last time you had your astro to 4500 RPM?
You see most of the things like this are unsuited for our uses. Your rig is setup for off road use mostly correct? Which would be better for you if you're out boondocking and have trouble with a dirty air filter? Are you likely to have the things to clean an oil filter or have a spare oiled filter handy? A spare stock is convenient and clean if you needed to carry it along. And where is that 7 hp useful? maybe when you kick it down on the highway for passing, maybe..."

My '93 has a 350 with a stock paper filter pulling cool air from the front of the grill. Underhood heat is not an issue.
My '05 w/ a 6 liter lq4 has a K&N sucking in the hot air from under the hood. I bought it that way and it was tuned as is. At some point I would like to modify a stock airbox and filter to again draw fresh cool air from outside but will then need to have it re-tuned as the air temps will be drastically reduced.
I don't do much off roading but if I did this would be a necessity.
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