More Power! 4.3L

Hello all. I have a 2002 GMC Sonoma. It has the 4.3L and an automatic. I bought it with 40,000 miles on it, so it's still fairly new. This is pretty much the GMC equivilent of an S-10 Extreme. It's lower than stock, has bilstien shocks, big front and rear swaybars, and 16" x 8" Wheels stock. Now, this truck was VERY fast, for a truck at least, in stock trim. I have also added some perfomance parts to it to pick it up some. I had a Flowmaster 50 on it, but removed it and straight piped it. It was much to quiet. Had the Y pipe changed to a larger one at the local muffler shop. Installed cold air intake, TB spacer, K&N. I even rapped my cold air intake with insulation to keep the engine heat off of it. My mileage has increased about 4 mpg with all of these upgrades. I was at 19mpg, in town, and lead-footing it, of course. Now i'm up to about 23 in town. Now here's my problem. I recently raced an '03 S-10 in stock trim identical to mine, except for a diff. brand of tires. It was DEAD EVEN. I know there isn't any changes from '02 to '03, so why is my truck not faster than his?? My truck feels more powerfull than when I bought it, but that didn't matter much in a race. Now, I have beaten a 3000GT, non-turbo, of course. What gives?

well was he in a stick? what kind of injection do you have, and what are the rear end gears, thats the big one, if hes geared better, you lose

My injection is CPI. He had an automatic. Our gears were the same. The only thing I can think of is I had a passenger, full tank of gas, and a big subwoofer box behind my seat. Maybe the extra weight slowed me down enough.

aim your sub backwards the extra base will help you excelerate! LOL

It could be the weight, or it could be that his might be in a little better tune.
Some people luck out and get a more powerfull motor right from the factory.
There are also some dogs that hit the streets.

I don't know about the auto industry but motorcycle companies like Honda actually pull aside their best motors (known as factory perfects) and they'll end up on their race bikes. This is so they have the strongest motors, and they still qualify as stock.
They send their next best motors out on the bikes that reporters test

have you had the computer unlocked yet? if not i would this will remove the top end kill point and release a few more HP

Haven't gotten a programmer, yet. The 4.3L doesn't seem to have much on the top end anyways, although with all of the upgrades, it certainly has improved.

get a turbo, then youll have every other 4.3 l beat, the other question is did he have the baby lt 4.3l its a v-8 4.3 ive heard rumors about them but never accualy seen or worked on one

Haven't gotten a programmer, yet. The 4.3L doesn't seem to have much on the top end anyways, although with all of the upgrades, it certainly has improved.

Years ago, had 2 friends, both had 67 Dodge Chargers 440 automatics, identical except for color, in a drag race they would run dead even, did it many times.

One night I was with one of them, he took his air breather off and we went looking for the other friend, he said I know I can beat him with the breather off.

Well we found him, he beat him over 4 car lengths, the other friend could not believe this, did it again with same results.

A few nightslater I was talking to the one who lost, we were talking about this and I finally told him about the air breather.

He took his off and we went looking, this time he beat the other friend more than 4 car lengths.

Many people say breather off does not help, but back in the 60's I can guarantee you it did, I feel sure they be tricks out there that people are using to get the edge, maybe this fellow has found one.

My injection is CPI. He had an automatic. Our gears were the same. The only thing I can think of is I had a passenger, full tank of gas, and a big subwoofer box behind my seat. Maybe the extra weight slowed me down enough.


Actually you have CSFI not CPI... That said, you have the VIN X motor or the VIN W? Which one did he have? You sure he was geared the same? Do you granny shift? Tire sizes? lots of factors.

^ just gunna add a few while im thinking, what was your engin temp compaired to his, is he on synthetic oil, running a different octain, or an octain booster, did he have a tunno cover and you dont, or his tail gate down and yours up, as you stated the extra weight in your vehical, how hard you normally drive your truck to how hard he drives his, just to name a few, you could go on for hours and hours with small differences like that... and im just woundern, but if all the trucks are csfi, what is the difference between vin x and w anymore, i know it use to be throttle body or cpi, but what is the difference now?

I have synthetic oil, he didn't. My temp was normal, about 200*, he didn't have any mods on his truck whatsoever. I was also running premium fuel. The only major difference besides the color, was he had a... flareside??... bed. A normal short bed. I have the stepside. I don't think that should have made a diff though. Tire sizes the same, but diff brands. He had cheapos and i have Goodyear Eagles. And what the hell is "Granny Shift???"

"I had a Flowmaster 50 on it, but removed it and straight piped it" = lack of back pressure. On smaller engine a little back pressure is better than none. Lowering your back pressure will change your torque curve. Put a high flow cat on it and a nice muffler and you'll beat his a** with no problem.

"I had a Flowmaster 50 on it, but removed it and straight piped it" = lack of back pressure. On smaller engine a little back pressure is better than none. Lowering your back pressure will change your torque curve. Put a high flow cat on it and a nice muffler and you'll beat his a** with no problem.

Yeah. I still have my cat. Actually my truck has two. Even with no muffler, the exhaust isn't very loud at all. As for the torque curve: mine is now much more even. I'm sure you may know how "torky" the 4.3L is. With the cold air intake and the exhaust done, my low end torque is a little less, but the engine pulls a lot better now in the higher RPMs. I think a power programmer would really open her up, but i don't have that kind of cash, right now al least.

for one, our trucks dont need premium, its flat out a waist of money to put higher grade fuel into a s 10, they are set up to run on 87. and all i can really say is sorry, you got beat, it happens, no matter what you do, how many mods, or how much money youve put into your vehical, there is alwase someone faster, stronger, bigger then you, im not saying this in an angry tone more as a sorry, i dont know what else to tell you, like i had said b4, there are a million factors to play into every race, sometimes you win, sometimes you dont, either way, when its done its doen, and you move onto the next

Yeah. I still have my cat. Actually my truck has two. Even with no muffler, the exhaust isn't very loud at all. As for the torque curve: mine is now much more even. I'm sure you may know how "torky" the 4.3L is. With the cold air intake and the exhaust done, my low end torque is a little less, but the engine pulls a lot better now in the higher RPMs. I think a power programmer would really open her up, but i don't have that kind of cash, right now al least.

You only have 1 Cat, the other is a resonator... Just thought I'd point that out.,.

You're right bro. I ordered some power pulleys from Summit that I need to put on. I am curious to see how much that helps. I am also trying to bump up my mileage, too. I've already had to take out a second morgatge on my house to fill my tank last week. ;-) ROTFL

if you wanna gain some miles, put an e fan on it

When I was a teenager, that was a lng time ago, had a friend who always had the best and fastest cars, all one had to do is ask him and he would tell you his was the best and the fastest!

For some reason he did not win all of his drag races, but he would still claim that his was the best & fastest!

I suppose they be one like him in ever town!

if you wanna gain some miles, put an e fan on it

That is next in line. I'm thinking of going with a perma-cool (Jegs part #771-19115). It seems to have the most CFM. And it doesn't have a shroud. Has anybody ran one of these fans? or similar??

i suggest a fan from a torus, will be the cheapest from a j yard, you wont need to turn a lot of air, your not in a muscle car thats putten out a grand for horses

That is next in line. I'm thinking of going with a perma-cool (Jegs part #771-19115). It seems to have the most CFM. And it doesn't have a shroud. Has anybody ran one of these fans? or similar??

Go with a ford taurus 3.8 e-fan, much cheaper (35 bux) and runs at 2800 cfm on low, 3600 cfm on hight and allows you to use your stock shroud...

That much air???? The highest aftermarket fan I could find in Jeg's or Summit was the one mentioned above. 2900CFM, 16" Perma-cool. And I still have to buy the thermostat for it, also.

That much air???? The highest aftermarket fan I could find in Jeg's or Summit was the one mentioned above. 2900CFM, 16" Perma-cool. And I still have to buy the thermostat for it, also.


Standard hayden thermostat switch which does well runs about 15 bux at most autoparts stores.

all rightey... I've done some mileage calcs, and i'm now getting 23MPG in town! not bad. That is with a set of power pulleys that I isntalled. Out of everything I've done to my truck, they seemed to make the biggest difference. They pumped up the HP a little, too. The only thind i don't like about the pulleys is my alt doesn't produce enough power at idle with the stereo on anymore. Not a big problem, but a little bothersome.

i was talking to a guy about getting more power out of the 4.3 and he said talk to someone that builds motors for a living, cause you should be able to bore the motor to put 350 pistons in it.

going to talk to a friend that does racing motors tonight will post his reply about doing this

i was talking to a guy about getting more power out of the 4.3 and he said talk to someone that builds motors for a living, cause you should be able to bore the motor to put 350 pistons in it.

going to talk to a friend that does racing motors tonight will post his reply about doing this

The pistons in your 4.3 are already the same size (4" diameter) as those in a 350. This is exactly what GM did to make the 4.3 -take a 350 and chop out two cylinders.
350cu.inch = 5.7 Liter.
5.7L / 8 cyl = .713 Liter per cylinder.
Then take .713 Liter x 6 = 4.3 Liter.
So , What's your point?

you CAN get from what ive been told up to and over 500 ponies out of a 4.3, think base, start with your bloc, flat top or domed pistons, i personally would go flat top 350 pistons with 4 way relief valvs, call up GM, Comp Cams or Crain cam and tell them EXATLY what you have and what your intentions are, they need to know every thing from break style (ie drums in back or 4 wheel disk) tire/rim size, radio size, e fan or clutch style, if you dont mind lobe, they can give you even more power, have the heads port n' polished, have the heads gasket matched, and machined so there is no difference in hole size in either intake or exhaust ports, put either a turbo or blower onto it, 5 speed manual transmission, race setup, not the stock 8" (or whatever it is) flywheel, if you put big bucks into your 4.3 you can make her scoot, and the advantage is, the stroke cycle will never be long enough to sound like an 8, so you could blow that mid 80's monty away at the stoplights and all they will think is, damn i got beat by a 6 cyl.

Wow DMB..51, You've got a Vision.
Don't forget, NONE of that extra power will help you "blow that mid 80's monty away at the stoplights" unless you tub it and put in a narrow rear end with FAT tires. Even a stock Blazer has traction problems in an off-the-line race.

my vision is a 350 on a stand in my garauge... im just saying it is possible