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4.3L v8 (L99)

V

vortec

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i came across a 4.3L v8, supposedly from a 94 caprice. i've seen these engines before, but never driven one. the power numbers look about the same as a vortec 4.3L v6, but at slightly different rpms. is the torque curve flat enough for a truck? would it even mate up to my 700r4? i hate to replace a broken 350 with something smaller, but with gas getting so expensive, it may be the logical thing to do. that's assuming it can actually drag the beast around without me giving it too much right foot. based on the numbers i've seen, i'd be giving up some torque. not cool.
 
i may be wrong but from what i have resurched if you was to use the cranck out of the 4.3v8 in a 350 block you would basicaly have the same thing as the camaro 302 from 67-69 witch is a very short stroke hi reving engine id say the 4.3 in stock form would be a little small for a fullsize but to build the 302 would put the power in the lower end of the rpm curve (with the right cam that is) and might do well in a 4x4

balzer
 
Huh???

A 4.3 V8??---I think you had better count the plug wires again!---they make a 4.3 V6,but as far as I know they never had a 4.3 V8 motor-(but I dont know every motor chevy's made in the 90's--I might be wrong)--older Caprices sometimes had 267 V8 motors,they would be approx.4.3 liters-they are like a 305 with thimble pistons..only 3-1/2" bore if I remember right..not very tourquey at all...

-I'd avoid using one of those in a full size truck..the V6 would actually be better than a 267,I've driven trucks with both,and the V6 had more guts and got better gas mileage!...sometimes,in a heavy vehicle,a LARGER motor gets better fuel economy than a smaller one straining just to keep it moving all the time will...I gained 4mpg when I put a 305 in place of a 250 six in my 79 C10,and a 454 I put in a 74 C10 got 2-3mpg more thn the 350 I yanked out of it...so the "smaller motor==better mileage" theory doesn't always pan out.. :crazy:
 
Yes, they did make them. Go look up Caprice or Impala specs for the 90's. (not sure if both cars could have them though) IIRC, on the 9C1 website, they list that as one of the engines for the police cars, it may have even been the base engine for certain years.

I'll save you the work
 
Suprise!!

I haven't seen one of those yet!(until today!)...but then,I dont poke my head under too many 90's vehicles...I like old rusty iron better :p: ...

It's interesting to see they do have such a "tiny" V8 ...but I still say 200hp wont propel a 5000+ lb truck too well,especially if it has high gears in it,like 2.73's or 3.08's...a guy I know had me put in a "305" in his 83 C10 in place of the straight six it had..we later found out it was actually a 267!..it was pretty sluggish,but he used it mostly as a commuter vehicle,and rarely carried any weight,so it was not that bad...

But adding a riding mower and some tools to the bed slowed it down quite a bit..the owner remarked he thought it went better with the six!...and regretted the expense of swapping motors..he later had me put a 350 in it instead..he loved that motor,and said he got better gas mileage and lots more power than the 267 ever had...
 
If the motor is out of a 94 then it is a baby LT1, you will have all the same problems people have with LT1s in trucks ie, optispark and cost, but not the power.
 
the 3" stroke makes it a good revving engine, but not a good torque engine.

the 3.75" bore is very bad about shrouding the valves. if you could make it work in stock form, it *might* work for you with the proper gearing, but its doubtful.
 
diesel4me said:
...but I still say 200hp wont propel a 5000+ lb truck too well,especially if it has high gears in it,like 2.73's or 3.08's...
Click to expand...


200 hp will propel a stock rig no problem(29 inch tires)... especially if you upgrage the t/c to a higher stall speed. Even with 35's the only complaint i had with my stock motor was having to be in third whenever i hit a hill on the highway.

Hp isn't the problem, its torque. I thought you owned a diesel :D

Keep in mind by the time the transam series 302 penske camaroes rolled off the line at the shop they were pushing 600 hp n/a with very little changes from stock. If you really wanted to you could get the 4.3 v8 to work but would probably be spending enough money on it to buy a 383.
 
The torque peaks at like 2400rpm which is kind of nice. I'd still rather have a 305, especially a roller one out of a Caprice.
 
CyberSniper said:
The torque peaks at like 2400rpm which is kind of nice. I'd still rather have a 305, especially a roller one out of a Caprice.
Click to expand...

the L99 is a roller engine, along with having an injection setup that is far superior to TBI. just takes a bit more work to get it to work in a truck.
 
yes the v8 does exist, but i do like the v6

i don't have much concern on hp. has more than my old 350. they sure did rob the horses out these early eighties v8's. but the 4.3 v8 torque does seem lacking, although it does appear to make it at decently low rpms. the optispark does concern me, as well, since i enjoy some mud.

for those who doubt it exists, it is often called the "little lt1" or "baby lt1" as mentioned earlier, and is 265cid, not 262 like the 4.3L v6. a lot of people knock the v6, probably simply because it is a v6. but it's served me very well in my 94 c1500, and i know at least 5 other people who love them in various fullsize and s-series trucks. no, my truck won't run 12 second 1/4 miles, but it doesn't seem to mind spinning the tires from a stop, towing 7000lbs, or cruising at 90+ on the highway.
 
not so....

My van has a 1973 307 V8 that puts out 200hp,and 300 ft.lbs of torque...it has 2.73 gears and "stock" 235/15 tires..it will go 65 mph in low before it starts to "wind out"!..when I had a 4 barrel carb on it,it would not open the sceondaries until it hit that speed!..I put a 2 bbl carb back on it for better fuel economy--(it had a 2bbl manifold,and the 4bbl didnt work good with an adapter--)..but even 300 ft lbs is anemic when your pulling a 5000+lb van uphill at highway speeds..it often downshifts into second at any speed below 75 mph on the highway if your climbing a hill..its pretty slow on takeoffs too,(can you say SLUG-gish! :rotfl: )..but I doubt any high stall speed converters will make it any better--only slip more and waste more gas...bigger tires would kill it even more..

You just cant argue with physics...a 5000 lb vehicle with high gears needs LOTS of torque and HP..yes,I do have a diesel--but you cant compare a diesel engine's torque to a gas engine's...my 6.2 has the exact same rating as my 86 305 in my C10,(140HP,240 ft lbs)..but they are as different as night and day in actual driving and how they "feel"...and its not all due to the gear ratio being a bit different between the 2 of them..I still say bigger is better when it comes to motors in GM trucks...no worse on fuel,most cases better,and NO lack of power to do whatever you want it to do.. :D
 
Only reason i said that was because the 6.2 has about 170 hp at the flywheel(gm took their ratings from the back of the tranny) but the tq makes up for it.

My dad had an old 1973 chevy van too but with a 383, and it was still slow as hell... probably because of stock gearing and the th400.

Personally anything short of 327 cu in. won't cut it for me. Like i said before... you could probably have a 383 for the same price of making the 4.3 "work".
 
beater_k20 said:
the L99 is a roller engine, along with having an injection setup that is far superior to TBI. just takes a bit more work to get it to work in a truck.
Click to expand...

Who cares if it has a superior injection setup. It has oddball bore and stroke, probably an oddball cam, et cetera. It's not like you're going to turn it into a horsepower monger. It probably costs a lot to work on as well. A TBI 305 has similar numbers and probably gets the same gas mileage in a truck.

Did they make LT1 305s? Seems like they did. I ran across some oddball 305 in a Caprice at the junkyard. My memory is failing me. I think it's the heat.
 
ya know, i was just up there in Livonia and if i recall it was fairly warm... :haha:
Now i'm over here in Limon,Co. and it's 110 outside my truck...... :yikes:

I think the Z-28 had a LT-1 engine, i know it had a MPFI 305

You can make BIG power with a small displacement, but ya gotta rev it to 8500 rpm to do it..............that 4.3 V-8 doesn't have the bore/stroke relationship or rod length to do that as you stated.

But it does sound like a good candidate for a turbo if someone makes low comp pistons for it. :crazy:
 
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