[madmax]

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. 🍌 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.

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.

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)

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.

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

 

[astro355]

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.

:2:

 

[Mr_Bowtie]

Whats the recommended size exhaust piping for a mild 4.3L? 2.5" duals? Headers w/X-pipe or Y it into single exhaust?

Don't forget weight reduction! Remove those seats before you take on a C5 Corvette... :lol:

 

[gtkane]

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!

 

[astro355]

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!

:cheers:

 

[generaljake01]

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!

TRUE THAT!!!! It sounds almost as bad as headers with sidepipes on a ASTRO...OH WAIT NEVERMIND! :rofl: just kidding 355, i had to say it cause i have headers with 2 1/2" with 24" turbotubes that goes straight out the back and i LOVE the sound, of course im not running one of the 4.3's..Id say a v-6 with large dual exhaust does sound like a obnoxious v-6 with dual exhaust...my :2:

 

[astro355]

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]

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. I think the second "y" in the exhaust , muffles the sound a bit more before exiting. Anywho, onto part 2. :sci-fi-beamup:

 

[madmax]

The second wave of engine mods are fairly easy to do as well. (autozone, murrays's, advance auto etc. parking lot approved) :mrgreen: I'll cover fluids next..... (1.) Engine oil : ROAL PURPLE synthetic oil is a prerequisite for performance. (at least 8 horsepower.) Already tried MOBIL one, Amsoil, not impressed. :snooty: First day I used R.P., you could tell a difference. Albeit not earth shattering, but better! (2.) Engine coolant additive : REDLINE "Water wetter"

First used it in my 79 firebird back in 92'.....awesome. Dropped temp 20 degrees. Plus, it keeps your water pump lubed as well. Used it in my 86 fiero gt , and my 91 astro.......this stuff works! :thumbup: (3.) Fuel additive: REDLINE s1-1 fuel system cleaner.

Its measurable at fuel fill ups so you can use it over a longer time period. It keeps your engine clean, and upper cylinders lubed when running. It also lubes your injectors and fuel pump. (4.) FUEL: MOBIL or SHELL....I prefer MOBIL, all though both use high quality detergents in ALL there petrols. There are other brands that have additives in them as well (marathon/STP, texaco/ techron), but could be iffy. :mrgreen: (5.) TRANSFLUID : currently, using dexron 3, plus alittle LUCAS trans additive. Plan to upgrade this year to DEXRON 6 SYNTHETIC plus the NAPA brand trans lube additive. Read on a truck forum a trans mechanic, in passing. said that this is the BEST additive bar none for transmissions. Sorry, cant remember the actuall name......but NAPA makes it. ( A deeper t-pan and cooler would also benefit) (5.) GEAROIL : ROYAL PURPLE

duh. Synthetic 'nuff said. :blah: On to part THREE.

 

[madmax]

Welcome to the inner sanctum, mates.....this is your mission if you choose to accept it. PART THREE. Factory parts removal, and or enhancement. Stock IS a compromise. This is a fact. Most engine emissions systems ( IE: EGR, crankcase vent to filter/ NOT pcv, catalytic converter, etc) are designed to choke and or WEAR your engine down over time. All EGR does is introduce part of your exhaust back into your engine for reburning. Take a lot at a your exhaust pipe and run a finger in there. Or better yet ( if you have any free time unbolt your EGR and look inside. What do you see??? CARBON BUILD-up! This crap eventually builds up on your valves, rings, pistons etc. The crank case vent hose ( that goes to your airfilter ) is just as worst! It has a direct path way for oil vapers to be burned and potentially cause carbon build up. Take a look at your TBI once and awhile....see how dirty it is? Carbon is one of the main causes of power loss. This is probably why people want to use " seafoam". ( Or maybe they just like making smoke signals,and killing small animals, I dont know...) :shrug: :?: Regardless, removal of the two already mentioned items would allow a cleaner burn....... thusly, gaining more power. I made a block off plate from some spare aluminum from a bike project ( 25 gauge, I think). Some metal shears, some drilling, some hi-temp RTV, shazam. For the crankcase vent (drivers side valve cover), I used a stand alone valve cover filter. Unfortunately, due to the PCV valve, you can't totally eliminate ALL the potential carbon-build up :banghead: At least you can minimize it. The CAT is a no brainer. Either cut it off with a exhaust cutter tool, or pay some $$$ and get a hi flow after market cat. Try SLP (street legal performance), I remember ACCEL used to sell one awhile back. Google is your friend (sometimes) :text-google: For "enhancement", TURBO-CITY has an adjustable MAP sensor that piggybacks on your stock one

It has three fixed fuel settings: economy, stock, performance. I tried it out, works pretty good! Bought one for the fiero too........ ( helped the lean out issue of exhaust on it) The "performance" setting just adds additional fuel, but its legit. :thumbup: One last mod that SHOULD be done.......factory clutch fan removal ( plus shroud). By adding an E-FAN (dual fans are the bomb!), you'll net a cool and easy 15-17 horsepower! Additionally benefits: MORE engine bay room, more access to engine , looks better, LESS load on the water pump (!!!!), dead weight ETC. ETC. It did'nt cost me nothing but a little elbow grease due to the fact I had taken it (plus the MSD 6a), off of the 79 firebird before getting rid of it (rustbucket). :rockon: Save your useable parts whenever possible , mates. Also, I prefer using a simple, light-up toggle switch for fan activation. No thermo stat. or circuit-breaker. Just a 30 amp fuse.Less wiring. Its been working for 4 years now, no probs. Almost forgot, the 4.3 also uses a 160 degree stat ( bought that to use the stupid HYPERTECH chip). When the engine runs cooler, it will make consistent power. With it running cooler, I installed a "heated" O2 sensor from a 95' astro (It mainly increases the accuracy of the O2 sensor), but even then I knew this sucker needs a better chip. Although you're gonna be look n at $400 for a reburn!??! :crying: The van runs really hard in part and full throttle with the crap chip, but it feels like it should be cleaner on idle to low throttle. (lil soft due to computer no doubt) Next chapter..... PART FOUR: COMPUTER FUEL REMAPPING! (the other fuel enhancing stuff WAS just affordable bandaide solutions. GOOD, but not the BEST) :sci-fi-beamup:

 

[madmax]

PART FOUR: COMPUTER FUEL REMAPPING! Just found this gem recently......

pretty damn cool! This is a EBL FLASH ECM upgrade.

Its supposed to do away with the "burning" of chips and allows a choice of EIGHT "bins" (fuel maps) that can be chosen from a laptop (which i dont have, but could get used )

, OR you can read your past engine data on your PC!

You can do hi speed datalogging ( how your engine runs, what it is doing etc.)

, has an optional port mod for mpfi tuning, (my 86 fiero), you can tune it with the engine running as well. :dance: Not much of a tech geek..... but, tuning your computer as well as engine is outstanding! You can eliminate the EGR, change the open loop/ close loop peramiters , as well as mph, rpm,and tps thresholds. They also have a "flash switcher"

which can select one of the eight "bins" (fuel curves) WITHOUT the laptop or computer. :mrgreen: On the 411 tip, the PCM (programmable computer memory) on later vehicles (95-up, I think), you can send them your pcm for modification for just $150! The PCM mod was mentioned ALOT on various forums. Nothing but glowing praise......which led me to find the EBL FLASH for ECMS. It still costs roughly the same as a reburn chip...... but, if you want to modify more in the future....... you dont have to keep buying chips EACH time. :banana: Also, sorry about not figuring out how to post links. The EBL flash home page is alot more articulating and would of taken less wording. Regardless, I'm intrigued. THIS product is worth saving up for! Hope this info helps in some way form or fashion. G'day :greetings-wavingyellow:

 

[astro355]

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. 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.

:2:

 

[rev_les]

Amen Astro355, a Magnaflow cat and a good catback............

 

[madmax]

No beef, astro 355...but "the obvious" upgrades ie: 4 bbl carb, edelbrock v6 intake,cam, v6 headers (long, or shortie style) ARE expensive, questionable that the part will even FIT in the space its meant for ( headers) , and the amount of down time to install it. The after market is flooded with OVER-PRICED parts as well. Selling products for YEARS that have little to no improvements in them based solely on their name. Yeah you could try flea bay for bargains, but then theres the modern axiom ..."you MIGHT get what you pay for." Parts could be warped, pitted, missing something etc. No offense....but I actually did a few searches on this forum, and most of the parts previously mentioned kept turning up for v8s. I dont hate on v8's, there cool. I just like to see big power out of a small package.Also, the only reason torque was even mentioned was because someone else stated they had an issue with a bigger exhaust causing problems. My 91' runs very well due to these simple modifications, which can be done by yourself and bought one at a time when money is available. Just offering a different perspective on how to make some linear, affordable power. Unfettered, I'd do a 4.3 with a custom DEMON carbs, tri power set up. (3 two bbls belong on a six anyway), with A hotter roller cam, ported vortech heads, 1.6 roller tip rockers, forged crank/pistons ,and JBA headers. No computer, w vac adv distributer.

 

[madmax]

Also, I didnt say to use TRUE duals, I meant to say use a good straight thru muffler after the factory "y-pipe",followed by a "y-pipe" terminating into dual outlets. Most custom exhaust shops around here do a very good job with this scenario. Very typical. My bad if you misunderstood my intent.

 

[astro355]

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.

 

[madmax]

Astro 355, I agree with you that I may have jumped the gun by going straight to the TBI upgrades......mainly because I wanted to let people know they dont have to be limited by stock engine management. basic tune-ups ( distributer cap w rotor, sparkplug wires and spark plugs) ARE a fundamental , prerequisite for over all good, engine driveability. I probably SHOULD have started the thread with just that aforementioned sentence. Again, my apologies......When I get passionate about a problem, I gets tunnel vision. Actually, I was gonna do a short PART FIVE on ignition.....most folks are already aware of whats available. But, what to AVOID should be beneficial to all.

 

[madmax]

Also, I wasnt trying to tell the obd II guys to swap out their manifolds for carbs OR tbi's...................just offering info I found that may help someone who feels limited performance wise, like I did when I first bought my astro. ( it was SOOOO slow!) Besides, dont obd II 4.3's have more aftermarket programming options as well as the highest horsepower rating anyway, right? (200hp I think.)

 

[AstroAustin]

Now this is what I call good healthy debate. I like reading both of your views. Nobody is all-knowing when it comes to this topic, just express your suggestions and let the people decide what they want to do. Great information either way you choose to go about it. :2:

 

[generaljake01]

I agree...VERY entertaining and also a little informative...A+ :ty: