Difference between 4.3L vs. 350 weight?

[PJTPW]

What's the difference in weight between a stock 350 with all the accessories and a stock 4.3L with all the accessories? (alt, ps pump, etc)

Does the 4.3 come with a cast intake manifold or AL?

By the time I add headers, AL intake, etc to a 350, how much actual weight savings am I looking at versus a 4.3L with AL intake, headers, etc?

Thanks,

Ryan

 

[gambit420s]

since it basically the same block, just missing 2cyls; most of your accessories will be the same, so if you have similar setups carb/fi, etc, the weight diff would only be 4" of cam, crank, head, etc and 2 pistons and rods, so a 4.3 would be 80-75% of a 350 theoretically.

and it depends on what year 4.3. older carbs would have iron intake, but later mpfi have cast AL maybe even plastic, not sure on tbi but probably either iron or AL depending on year

if everything was similar prob about 20-25% less

anyone know if they ever made an AL block 4.3? i thought i saw one in the gmpp cat
edit* yep they make a couple different ones P/ns 10134371, 10134351, 14011069, all with splayed m/c's

from gmpp cat
90 deg v6 bare iron block 163#
90 deg v6 bare AL block 78-75#
SBC bare iron block 202-167#
SBC bare AL block 89-101#
the sbc ##s are for various deck heights and bores but you get the picture

i always thought it would be cool to run a s-10 4x4 set up like a Sy-Ty in SCCA Pro-rally there is a truck class that the 4.3 w/turbo would just make based on their cc limit * 1.6 for the turbo and with an Al block and IRS you could spank the ranger and tacoma crowd

 

[HarryH3]

The factory intake on our '91 4.3 TBI motor was aluminum. The one on our '94 5.7 TBI is also aluminum.

 

[dirtwarrior17]

older carbs would have iron intake, but later mpfi have cast AL maybe even plastic, not sure on tbi but probably either iron or AL depending on year

who told you gm made a plastic intake manifold or even they might have made one? Plastic is not much lighter than aluminum. they would have to make the thing so damn thick to hold up under torquing, the weight would probably be the same. Not to mention how easy it is to strip out a plastic manifold. Carbon fiber i could see but good luck finding one.

 

[jhellwig]

Some plastics like bake light or whatever they call it are stronger than aluminum and lighter. And they actualy did have plastic manifolds on some v6 in cars.



Done de railing

 

[dirtwarrior17]

Some plastics like bake light or whatever they call it are stronger than aluminum and lighter. And they actualy did have plastic manifolds on some v6 in cars.



Done de railing

what about gm?

sounds alot like carbon fiber. Having owned a 91 and a 96 jimmy and blazer with a 4.3 I would be real suprised to find one on a 4.3

 

[4X4HIGH]

Now let me throw a wrench into the mix. Are we talking about a 4.3 V/6 or a 4.3 V/8?

Everyone is so quick to assume he is talking about a V/6.

 

[sled_dog]

what about gm?

sounds alot like carbon fiber. Having owned a 91 and a 96 jimmy and blazer with a 4.3 I would be real suprised to find one on a 4.3

GM uses and has used plastic intakes since 1996. All MPFI Vortec cars and trucks have them, as far as I know. Its some type of composite plastic, they break, it happens. LS1s have them, the 6.0/5.3/4.8, the 4.3s had them, 5.7/5.0 vortecs had them. People have blown them out by puting too much boost to them, or if you misadjust the timing on one, you can blow that intake to pieces.

 

[dirtwarrior17]

Damn.... I learned somethin today.

Do all ls1's have em? I always thought it was aluminum with some sort of coating on it.

 

[sled_dog]

nope, all LS1s are plastic intakes. They make aftermarket aluminum ones that can take boost pressures and nitrous backfires and such, but they are $$$.

 

[gambit420s]

I was thinking maybe they used plastic on the 4.3's near the end but i wasn't sure, i know they use plastic(or some composite) on the late v-8s. but the latest 4.3 i have is 96 TPI vortec(50K on a stand any takers?)and i thought they might have plastic on some of the last s-series, or maybe even f/s before the sbcIII.

Composite seems like a good idea as it doesnt conduct heat like metal, for better charge temp, but like sled_dog said they prob don't like a lot of boost or backfires. plus you prob cant enlarge or port the runners. prob good as is but not a lot of room for improvment.

More to the point of PJTPw's original question they would be lighter if they ever existed.

 

[sled_dog]

as I look around, it looks like the 4.3Ls used aluminum top plates with steel lowers. So I was wrong there, no composite. But the V8s do, and the intakes flow very well for being stock pieces. Many many people are making well over 500 horse through a stock intake.

 

[73k5blazer]

My '86 4.3l has a high rise cast intake. Carbuerated.
I'm in the middle of rebuilding it right now (waiting for parts), switching to aftermarket AL intake, late model vortec heads.

 

[ryan22re]

all 96 up 4.3, 5.0 and 5.7's have an alum. lower intake and a plastic upper intake. the upper only seals around the fuel meter block for the injectors and only has to seal airflow. if you are planning on fuel injected 4.3 try to find a 4.3 with a vin number X. instead of having central injectors feeding poppet valves (the 4.3 with vin W). the X motors have the injectors mounted down at the cylinders which is far better than the injector poppet valve combo.
all 5.0 and 5.7s have the injector/poppet valve setup (although i believe GM makes a kit to install the X motor style injectors).

the 4.8-5.3-5.7 and 6.0's have a full plastic intake. but since they only have to seal air and fuel, not coolant and oil they work just fine.

ryan

 

[vortec]

my friend's 4.3l v6 in his 96 c1500 had a plastic intake manifold. worked just fine until he hit the nitrous one time and blew the crap out of it.

i'd say don't think too much about engine weights. the 4.3 is a good engine and lighter, but, the 350 has enough additional torque and hp to compensate for its extra weight. the main advantage of the v6 would probably be if you have to sit in traffic a lot, since it definitely uses less fuel just idling. on the highway or offroad, you might lose your mileage benefit from having to use more right foot to get the same speed or climb the same hill.

 

[dirtwarrior17]

the 4.3 is a good motor but i wouldn't consider dropping one in the k5. Yeah i am a powerhungry teenager but a 4.3 can't move a 5000 lb truck with 35's too well. Not to mention a 350 has alot more potential if you want to hot rod it.

So the 4.3's had AL/plastic intakes or what?