Jproz1167

iTrader: (3)

OK first off I searched and my brain hurts from all the fighting involved in this swap!
Now then the patient is my gas guzzling 82 trans am. Currently it has a L-98 with LO-3 TBI system & a 5 speed with 3.73 gears, so we can leave the wiring/transmission since it will all support the 4.3 TBI motor.

Since I love this Trans Am and it's main purpose isn't for racing just my fun daily driver with the downside of a long work commute I'de like much better fuel economy out of it. Would I get much better fuel economy from this swap? My car generally averages 17-19mpg so if a 4.3 will knock off much better economy I am going to swap it. I figure with my gearing it should still be responsive enough for a fun daily driver and if I ever want to I can put the 350 back in.
So to the question .... I have yet to see anyone who has ever completed this swap and my concerns are obviously limited to the exhaust manifolds and Y-pipe & and my serpentine system working. Will I actually see a MPG improvent and is it significant enough to warrant the price of a new 4.3? If it could make 25mpg then the 350 will be history.

Just a few more questions ..... Will my stock air cleaner be in the same position so I can retain my cowl induction? will the motor clear my A/C box?

Now then refrain from drop a LSx LTx in the car because I'm not going through that hassle & leave out sell the car and buy a V-6 f-body because I love my car LOL .... However I am up to building the 4.3 up a little but not too much that it gets lousy gas mileage. Which again what this thread is about GAS MILEAGE !!!!!!!!!!

KrisW

iTrader: (5)

No one knows what the mileage would be because no one has done it. If you do it and post the results we will all know then. Some of us are very interested!!

I love the six cylinders and would love to see this done but I would not do it if I were you. I feel that it is always best to stay within the series of what you have so here's my two cents.

The 2.8 and 3.1 cars usually get in the 20's for mileage. The V8 cars can break into this plane. What you are doing doesn't have much practical use because of the situation you are in.

The bigger V8 cars don't have to use all of their power to cruise fairly economically if they are not too radically modified. The V6 cars have to be kicked in the butt more to move down the road or else for their displacement would give much better mileage. You are seeking to meet in the middle and the middle is a small place here. Switching from 19 MPG to 25 MPG is not a drastic difference.

It is a positive difference as far as budget concerns go, so here are my suggestions.

If you really are romantically inclined to use 4.3 V6 then do it. All of the V6 guys here will benefit from your experiences. On our end, we can help a little. You should be able to strip the entire front off of the engine and re-use your accessory drives and brackets from your V8. If you have an odd bolt pattern on your heads and this doesn't work then use a complete S-10 setup. you can most likely re-use all of the S-10 accessories with little modification to your car.

Use the S-10 or full size truck manifolds for the 4.3. They look like they dump out fairly close to factory V8 locations. Bite the bullett and pay the exhaust shop to fit your y-pipe if you are off a little. Don't take a side trip to chevy donut gasket hell on your way to an engine swap. Use the factory V8 mounts and shells for your motor mount setup and re-drill the crossmember to match.

Your air cleaner is going to sit to the rear a little more than the V8. Modify as necessary for power bulge fresh air use.

OPTION B:

If you are just interested in displacement then get one of the smogger 4.3 V8 engines from the late 70's and early 80's. You can use a 305 block with a smaller crank. It becomes a no-brainer that a 4.3 liter V8 is a lot easier to put into your engine bay since you are already V8. The last advantage is computer chip. Your V8 chip will run your V8 car just fine. You may have to switch to a 4.3 V6 S-10 or 1500 pickup chip to run your car properly...

Good luck and keep us posted!!

TheScaryOne

iTrader: (3)

I dunno about in a coupe, but in a truck those 4.3's get lousier gas mileage than I get with my 350. My buddies Blazer gets somewhere around 15. Much larger car though. For better gas mileage in your TA you might want to change the rear gears down to a 3.27 or a 2.73. You'd notice increased mileage then. I get about 24 Highway and 19-20 around town (not driving during rush hour. Driving during rush hour I get somewhere around 10 mpg. >.<) with my 3.27 gears. Then again, I also have TPI.

Heck, do it if you've got the parts laying around, then let us know if you got better mileage!

Cronic3rd

You aren't going to see a strong MPG increase going to a 4.3. Less power doen not mean better MPG just that the motor has to work harder to make the car move.

Swapping your rear gears to a 2.73 will have an immediate effect of increasing your mileage. Your car will be a dog from a dig but like you said it isn't a race car.

I know you said that you don't want to do a LS! or LT1 swap and I agree but your best power + mileage is going to come from modern technology. Look into a gen 3 4.8 or 5.3 truck motor swap. either will net you excellent mileage, as much power as your choked 350 (if not more) and either can be picked up, complete with PCM and harness, pretty inexpensively.

I checked ebay and either motor, with 60-70k on it, is going for about $550 plus shipping and bolt on acessories.

KrisW

iTrader: (5)

I don't know if I'd drop to 2.73 but any milder gear set will increase mileage a lot in these cars. 3.73s are gas eaters and not really necessary with the low first gears we get in the transmissions.

Jproz1167

iTrader: (3)

Thescaryone

Your fortunate to see 24 highway. I put about 80-100 miles a day on my car plus generally put maybe a 100-200 miles on the weekend. Commuting at night running 65-70mph my car in no traffic conditions only average 19mpg, in gridlock it's real bad LOL .... I'm 40 now so it's not like the car is raced or run hard I just like the looks of it and thats why I am extremly hesitant selling it or buying a economy car. Don't get me wrong I will miss the power of the 350 but I put alot of miles a week on this car so economy superceeds power now.

Krisw

a 70's 4.3 V-8 is taboo since this is a california car LOL .... so to be legal the donor motor must be newer then my body and retain all host emmisions equipment.

Cronic

I have to disagree with your statements, I once had a ungodly underpowered 4 banger 4 speed camaro that could get around 32mpg hwy and about 26'ish city. I wouldn't consider my 350 choked, well except for the LO-3 intake ... It passes smog with ease so it's just my combination that is whats killing me is all. However this combination beats MPG wise the original LG-4 3 speed automatic with 3.23 gears that the car had originally.



My plans for this swap is this

Mildly built 4.3 and have the heads ported
aftermarket intake
better then stock cam
modified edelbrock headers that I have to fit the 4.3
change to 3.23 gears
retain my TPI exhaust

I've been at pickapart looking for a nice donor engine and searched the web for info. The oil pan is another potential problem that I could forsee. I really want to keep my 350 serpentine system so my engine harness doesn't need any alterations that become a nuisance. everything under my hood is currently 1990 stuff so that is why I'm choosing a 4.3 swap I figure aside from the fabbing of the Y-pipe this could be installed in a weekend easily and running verses weeks swapping a say 3.8 4th gen motor or LSx type. And to return the car to smallblock chevy this isn't a irreversible swap.
This weekend I have off work so I am going to check out some 4.3 car/trucks and really see what all I need to do it. I think my best bet is to go with a 90-93 engine and stock prom.

Now another question I have is this. Does the 4.3 use a 7747 ecm like my TBI has and did the 90-93 car/trucks have VATS? VATS is one thing that I am very hesitant on removing from my car. Now if these applications did have VATS will my 90 vats system work with something as late as a 93 prom?

OddyseusDSM

L99 4.3l or LT1? Drill it for a dizzy and use a TPI setup? Just a thought.

Jproz1167

iTrader: (3)

OK I pulled this up to be a smog legal swap. Now it has reference to body classification to be legal. So that eliminates using a S-10 type 4.3 in my car.

So what 4.3 TBI engines were found in cars? and what kind of GM cars were the found in through the 89-93 model years. I'm using these years since I want the 1 piece RMS and serpentine drive.


“Engine changes are legal as long as the following requirements are met to ensure that the change does not increase pollution from the vehicle:
• The engine must be the same year or newer than the vehicle.
• The engine must be from the same type of vehicle (passenger car, light-duty truck, heavy- duty truck, etc.) based on gross vehicle weight.
• If the vehicle is a California certified vehicle then the engine must also be a California certified engine.
• All emissions control equipment must remain on the installed engine.

After an engine change, vehicles must first be inspected by a state referee station. The vehicle will be inspected to ensure that all the equipment required is in place, and the vehicle will be emissions tested subject to the specifications of the installed engine.

Note that there are two emission systems to consider: Exhaust and Evaporative. The former consists of burning (and reburning) the fuel and air to the cleanest state possible, and then reburning yet again through the catalytic converter in the exhaust circuit. Evaporative emissions consist of how the unburned fuel is stored and transferred in the vehicle. The principal piece of hardware used here is a charcoal canister that absorbs fuel fumes as they slowly evaporate from the tank and lines. Upon starting the engine, the cannister is purged of these fumes through engine vacuum and the temporary opening of a purge valve.

Jproz1167

iTrader: (3)

when I said 4.3 I meant 4.3 V-6 with TBI

Apeiron

No 4.3 was ever put in a car.

Jproz1167

iTrader: (3)

well seems 90-92 caprices could have had the 4.3 V-6 TBI engine. So I guess that would be in the same classification as my car. I would also think since it is a 90 degree engine my 350 serpentine brackets will fit.

Apeiron

No, Caprices had a 4.3L V8 engine, not a V6.

327_TPI_77_Maro

iTrader: (8)

Putting an underpowered engine in will not necessarily increase gas mileage because you will have to use a lot more throttle to go the same speed. I doubt you will see any noticeable MPG increase with the 4.3 TBI. Plus you are effectively ruining a 3rd gen putting a slug TBI V6 in it.

A much smarter swap would be a multiport EFI setup, get a wideband O2, and burn your own chips. That would be time well spent.

RacerX13

1990 and older Caprice/Impala came with 4.3 V6's, and so did G bodies(Monte Carlo/ElCamino). My 95 Chevy fullsize pickup has a 4.3 and it has adapter plates that bolt on to the frame to move the motor mount back. The motor mounts look to be pretty much the same as F body. You will probably need a G or C body oil pan to have room for the crossover pipe.

As mentioned before, change the gears-it makes a big difference, and you should be able to get a big improvement in mileage with your current engine. My L03/T5/3.08 gear Camaro gets 28mpg highway and it's bone stock right down to the muffler-you should be able to get at least that. Changing the gear and prom tuning should get you 90% of the gains you would get from a motor swap for a lot less money and effort, and if you swap motors you are pretty much going to have to do some tuning anyway.

Do the math and figure out how much the swap is going to cost you and then figure out how many miles you have to drive before you actually recoup your outlay and come out ahead. If it takes several years of driving before you see a gain it's not worth it. Might be cheaper just to buy a beater v6 Firebird for cheap and keep your T/A in the garage and nice for the weekends. Keep us posted- I think a 4.3 F body with a stick would be a great car.

Jproz1167

iTrader: (3)

1989 Chevrolet Caprice
4.3 liter V-6 VIN "Z"
----------
MOD'S LOCK THIS ... IT'S TURNING INTO THE SAME UNPRODUCTIVE THREAD AS ALL THE OTHERS

THANK YOU

OkanaganIroc

I realize you probably have your heart set on a 4.3 V-6 but have you considered a buick 3.8? These were the same engines that came in buick grand nationals and t-types (turboed opf course.) the non-turboed versioned showed up in buick regals and other mid-sized cars. (didn't 4th gen camaros get this engine as well?)
I've heard you can get very good mileage out of one of these and they're a fairly tough unit as well.

five7kid

iTrader: (14)

From what I can gather, you are looking for better fuel economy in a fun daily driver. You asked specifically about the 4.3l V6, which I personally do not have much exposure to. I know it's a Chevy 350 with two fewer cylinders, but I don't know exactly how they did it.

From what I've been able to gather, they didn't leave anything in place - engine mount bosses are moved, induction (TBI, carb) is centered on the new set of cylinders rather than left in the same place relative to either end of a 350. It's those things that make it the red-headed step-child of the engine swap crowd.

How well is your current induction system tuned? Improper tune can make a big difference in fuel economy. Have you considered 3.42 or 3.23 gears instead of your 3.73's? Economy would improve, and you'd still have V8 power for the fun times.

Also, have you ever calculated how much fuel you can buy for the cost of this engine swap? The break-even point for gear would come a lot quicker.

327_TPI_77_Maro

iTrader: (8)

I don't think he wants to hear these (good) arguments for keeping and tuning the V8. Alas! I have a 305 peanut cam coming out of an 87 TPI motor you can have for free. That is one hell of a gas mileage cam (0.350" intake gross lift, anybody?).

OddyseusDSM

I'm just afraid he'll find that he may have wasted his $$ with a lesser engine. not that the 4.3L is a lesser engine cause its a great engine. Con though is my friend has it in a '92 stick 2wd s-10 which should be the perftect recipe for gas milage with that engine and he just hits 19-20 driving to work which is a long sweeping constant speed drive. Not to mention the s-10 has to be 400-500 lbs less. i think the only swap you will save on gas with is going the newer V8 route.

I only brought up the L99 because eevenn though it is a marginal savings over the LT1 (which was a leap fron the 305 TBI) its still a savings and you still end up with the same power as the 4.3L HO V6 if not a little more. On top of all that AX THE TBI, Multi PortFuel Injection is vastly superior in terms of efficiency with concern to gas milage depending on how you tune it.

duckmanquacker

Sounded to me like he was done.

Jproz1167

iTrader: (3)

No

Actually I am not done. I started the thread for only certain problematic areas of installing a 4.3 in my car. You see by bringing up 3.8, LT-1, L-99, etc. etc. means nothing nor does tuning the car. ...... It is plain and simple the 4.3 is the easiest V-6 swap for the car and thats what is going in the car, I really don't care how fast this car is. And by comparing a S-10's MPG to a trans am with the same motor can't be same. You are dealing with a brick going through the air compared to a arrow going through the air.

Now then if I want muscle for the weekend I have my corvette so there is no need for two gas guzzlers.

As for weight only a guestimate but I say my trans am would be lighter then a s-10 here is factory shipping weights on my car when new. When new it had a 305 and a automatic. ....... 3186lbs ..... Now if you take into consideration the different weight of the 5 speed verses automatic and weight difference between a 4.3 and 5.0 where would that put me as compared to a s10?

So like I said I am only interested in what oil pan to use

What exhaust manifolds to use

will my 305 TBI ecm run the 4.3 or will I need a 4.3 ECM and chip

did the 4.3 ever come with VATS

Just the basics my car is setup for TBI and thats why a 4.3 is the easiest and most convienant engine to swap in since it will all bolt up and electronically speaking the stuff can run a 4.3 with little work.

So can a 4.3 in a aerodynamic car achieve 25mpg with say 3.08/3.23 gears yes or no? or could it have the potential for slightly more if tuned good?

KrisW

iTrader: (5)

When I was in CA my friend and I put a 76 400 in his 90 firebird. We even passed the visual. We were using 350 TPI heads and from the outside only the dipstick was wrong. Our test guy didn't notice...

Anyway, even if you are an environmentalist wacko (just kidding) you could put a 70's vintage 4.3 V8 in there and you could maintain a clean, green conscience with all of your systems running fine. Again, just my two cents...

Good luck with your swap. I have been waiting for someone to put a "Z" engine in a third gen for a while now.

kanexpl

The l99 4.3 v8 was in 94 to 96 caprices. It has a one piece rear seal. In stock form, the l99 was made by taking a 305 bore size lt1 block (3.736) and putting a 3.0 crank in it. It uses 5.94 rods, so you can use standard compression height pistons. Just get a 305 short block and put the crank and rods from the l99 with a set of 305 pistons and you now have a 262. Put in a set of 305 or 4.3 tbi injectors and you are set. Another option is what I did. I put that crank in a 350 block with kb105 pistons making a 302. The long rods help reduce friction. Go real small on the cam. The intake vacuum is 2 to 3 inches lower. The motor will rev instead of being a slug like a 305. I don't how they got it to run good in a caprice with 2.56 gears. My monte was a 4.3 and got 22 to 24 with 2.41 or 3.08s. My c1500 get 19.2 with 4.10 and 31.5 tires. Montes have tubular exhaust manifolds on the 4.3.

Jproz1167

iTrader: (3)

kanexpl

This is what I'm looking for ........ was this 4.3 a TBI motor and is your 1500 a vortech 4.3?

so mid 20's are possible any idea on the weight of this monte? what trans did it have?

I am curious of these headers, what year was this monte?

I wonder why GM never made a 4.3 f-body

duckmanquacker

OIL PAN & EXHAUST.

When I had my 92 S-10 Ithought of doing the very swap you are considering.
I had measured the exhaust manifold outlet ports and they were only an 1/8" off from my 84 Z28. the oil pan to crossmember clearance would give you plenty of room since the S10 V8 swap moves the mounts forward. which brings to mind that if the S10 moved the mounts forward you may need to move them backwards in the camaro.

KrisW

iTrader: (5)

The L99 4.3 V8 was a baby LT1 with LT1 style fuel injection, reverse cooling and that crazy optispark distributor.

Sounds like you should just buy a crank for that engine and put it in your 305. Then you have a TBI 4.3 V8....

duckmanquacker

I thought the journals were way different between the L99 and the 305?????

kanexpl

My truck is a 91. It has a roller cam, pre vortec headed 4.3 tbi. I think a tbi small v8 is a better option because it will generate more low end torque and can handle taller gears. Jtr says that a 8v s10 swap add 112 pounds to the truck. So by going to a 4.3 v6 you lost 112 pounds off the front end. Edelbrock makes a performer tbi intake for the 4.3 v6 with matching cam. Compcam and crane also make cams. 3.23 or 3.42 would be a good gear ratio for the 4.3 v6. The throtle body is the same size for 4.3 to 350.
The v8 could use all the parts you have now. I think a 305 block, l99 crank and rods, small balancer, a set of al vette heads, 3.08 gears and stock 350 tpi cam would make a good running mpg engine. DD shows 272 hp at 5000 rpm 320 ft/lb 3000 rpm with that combo, but you know DD is always dreaming.

Jproz1167

iTrader: (3)

I just saw a picture of a 87 monte carlo 4.3 tbi motor with the tubular exhaust manifolds even if they are a bit off they would be easier to modify then cast manifolds.

would the engine really move ??? afterall if the trans remains in the same place the motor would be as far back as a 305/350 correct? the bolt patters on the block for the mounts were the same as a 305/350 so my stock mounts should work correct?

kanexpl

The l99 crank is the same as any other one piece rear seal and uses the same bearings. There is no difference when ordering 383 cranks. They don't specify l98 or lt1. L99 cranks weights 43 pounds. 8 pounds light than the 350 crank I had. It took 4 slugs to balance with 350 pistons! The 4.3 v6 uses special rod bearing that are narrowed for room on the crank for the pin offset. They are 2.2 instead of 2.1.

Jproz1167

iTrader: (3)

so with the difference in weight from a automatic to 5 speed and the loss in weight from a 4.3 my car should weigh in at right around 3,000lbs. since my front and rear shipping weights added up to 3186lbs.

so if I can pull 170-180hp out of this combination it should be a much better package then a 2.8/3.1 f-body.

right now at 65 my car with 5 speed and 3.73's turns about 2100-2200rpm, I'de like to get this cruising rpm down to about 1700-1800 rpm which should be attainable with 3.23 gears

kanexpl

You could use the monte or caprice engine mounts. The frame has plenty of holes, something should line up. The 4.3 mounts I got to so I can replace them in my truck look the same as v8 mounts, but more narrow. The clutch setup would bolt right to the 4.3. I when 4.3 to 350 in my monte. All the wires were long enough. The engine with set back 4.4 inches. The trans mount and torque decide that. You could use a caprice prom in your computer. Both camaros and caprices use the same computer ( 1227748 ), just change proms and cal packs. Use the monte 4.3 rad hoses. I used a f body fan in my monte swap, so the rad is the same width. The monte used a engine driven cooling fan. You have a electric fan. The fan should be controlled From the temp sensor, not the ecm. Caprices had engine drive cooling fans, so you don't need a extra long fan shroud. My 4.3 monte used a egr temp switch and did not have a mat. I know camaros and caprices use mats, but i do not know if 4.3 caprice uses egr temp switch. Old c1500s 4.3 and 305 trucks use the same exhaust so the caprice manifold spacing got to be close to what the 305 tbi uses. It should be a easy swap.

archemedes

your car weighs about the same as my awd bravada. The 4.3 is going to be about the same mileage as the 5.0 (I have done a similar swap into a camaro and got about 16 mpg) if you have the engine go ahead and do it (realize that the top level 4.3 was only 195 hp so getting 3000 lbs moving will take some fuel)

kanexpl

All wheel drive is why your Bravada get 16 mpg and my 4200 pound truck gets 19. The window sticker was 19/21 for my truck. The syclone could of been so much fast without the dead weight of a front axle and transffer case constantly binding up.

duckmanquacker

my 92 S10 averaged around 23-25 with campershell. I think it would do much better in a firebird.
1. the car weighs about half what my truck did.
2. the aerodynamics are way better (comparing a brick to a knife)
3. keeping it fuel injected is always better than a carb for fuel milage, cold starts, and just plain ole drivability.

If your bravada weighs the same as his bird what did you do totally strip it out? the bravada is a luxury S10 blazer and the blazer comes in around 5000+- LBS.

darkride86T/A

I dont know if the oil pan question was answered, but I believe you can use the 85-89 caprice or the 85-88 monte oil pan in your T/A with no problems.
The K-member in these vehicles are very close, if not the same. I know you didnt want to retain the 350, but dropping down to 2.73's should give you
a dramatic increase in MPG's. My 86 T/A has an LG4 w/edelbrock performer
intake and flowmaster 80 series muffler. She has the stock 2.73 open diff.
rear end. Right now I have a 700R4 that's on it's last leg, I get 18-20 city and damn near 25 mpg on the hwy. This is without TCC lock up. When my
original tranny was in the car, the mpg's were 19-20 city,28 hwy. When I
drove it like I stole it it still got like 17-23 mpg. My motor's got 198,850 miles on it also. I'm like you, my car's racing days are over, so dropping to lower
numerical gears is the easiest and most economical solution. You could do a gear swap in an afternoon.

archemedes

the 16 was in an '84 camaro my bravada gets about the same

Jproz1167

iTrader: (3)

Ok, I've been researching old reviews of s-10 for information and this is what I have come up with and this is a 1991 s-10

Standard Engine 4.3L 160 hp V6
Horsepower 160
Torque (lb-ft) 235

City (mpg) 17
Highway (mpg) 23 (specific gearing isn't mentioned)


Here are some general weights I came up with

1992 bravada 4.3
Curb Weight, lbs. 3939

1991 chevy s-10 regular cab short bed
Curb Weight - Manual (lb.) 2648


Duckquackmaster claimed 23-25hwy which based on this info seems credible. However the 16mpg in the bravada verses s10 is quite obvious were talking a 1,300lb weight difference ..... Granted my Trans am is going to be guestimated at say 3100lbs after a 4.3 is installed I still have the aerodymics on my side verses the s-10 and going down the road that is what makes or breaks MPG

I say with a good prom tune and a little porting and nice cam and exhaust I should have a very nice 4.3 combination. The power levels are faily consistant with a LO-3 so it should have decent acceleration

Klortho

As I have not had any dealings with a 4.3 with what you have posted up there you can honestly put an LT1 (direct bolt in) into the car with a 6-speed or 5-speed (6-speed recommended) and get close to 25-27mpg highway. I drive my GTA 60 mile round trip every day and average around 340-350 miles out of a tank which is around 24-25mpg. at 80mph in 6th gear, I'm turning 2200 rpm with a 3.70 gear in the car, no air on both windows down. Don't call an LT1 a gas guzzler before you do some checking on those and the LS1 cars, it's nice to have both the power and the economy that can be had with the more modern engines.

Also there isn't any hassle in doing an LTx/LSx swap, no more than what you're wanting to do with putting a 4.3 in the car.

327_TPI_77_Maro

iTrader: (8)

This pretty well describes why you should just set up your V8 properly. There are a LOT of V8 3rd gens getting 25 mpgs highway, carbureted even! You aren't going to be doing anything special getting 25 mpg with a V6 in this car.

People are giving you very good advice, whether you choose to listen to them or not.

Yes going to a 4.3 is going to smaller displacement. However, smaller displacement can only net you so much mpg gain, when the 4.3 has such outdated technology. TBI is only going to get you so far. You really need to be looking at multiport EFI (like a TPI) if gas mileage is important to you. In that case, just sticking a TPI on top of the V8, and using 273 gears will already get you to your 25 mpg goal, and still leave you with some power.

You're not looking at the whole picture, just decreasing displacement, but keeping TBI "because it's easy".

Jproz1167

iTrader: (3)

I think thats awsome you get that with your LT1 maybe I will put one in my 82 corvette!!!!!! the trans am is getting a 4.3 so lets keep this on topic for these simple reasons

(1) I am not rewiring the car again
(2) who's to say 25mpg is all it will really get
(3) No hassle doing a LT1/LSx swap verses unbolting my 350 from my transmission and bolting a 4.3 to it and dropping it in????

Lets talk about the cost of a lt1/lsx swap verses the cost of a Y-pipe and a few miscelaneous parts to do a 4.3 swap shall we? And in the end the 4.3 will net the same fuel economy or more, granted technology isn't on it's side but the ease of installation is. .... My 350's real world mpg average is 18mpg meaning everyday driving, different conditions after each fill up thats its average. I don't think under the same conditions I honestly dont think even 305TPI's do much better ..... So run your V-8's for me all day around town a little on the freeway, throw in some gridlock etc. etc. then fill it up and tell me what you averaged.

with that said post up your REAL world day to day average MPG of your V-8's ... I say this because thats what I am interested in since my car takes my son to school, to the stores, to work, stuck in traffic. So plain and simple how can I not benefit from going from a 350 L98 with throttle body injection and not see a jump in fuel economy swapping to a 4.3 throttlebody V-6? I honestly drive mmy car nowadays on average 700 miles aweek OK gas mileage was never a priority when I put the car together since I used my escort all the time but now this is my everyday car not just a hey I'm going to drive the trans am a couple days this month.

As I've said this is about simplicity and economy and still using my car everyday so you can see why the 4.3 is the engine of choice.

Klortho

Real world average MPG of my V8 is 25mpg, 295hp 375 torque 6-speed and 3.70 gears. As for rewiring the whole car again, 8 wires is all that has to be hooked up for either an LTx or LSx to run TBI has never been the best for fuel economy, port injection with sequential firing will always do better MPG than TBI or TPI (since it's batch firing) because the fuel gets injected directly into the cylinder one at a time instead of firing all 4 cylinders at once, or dumping fuel at a constant rate with TBI like a carburator does. You could change your L98 over to TPI and pick up around 5mpg right there alone.

Jproz1167

iTrader: (3)

klortho

so to say you average 25mpg every fill up then theres times your car is getting apprx. 30mpg? Tell me your secret because I had a 97 v-6 camaro with A4 and 3.42 and its average was only about 24.5mpg. So share with me your secrets how a LT-1 with 3.70 gears beats a 3.8 camaro in fuel economy. I'm going to go out on a limb here and ask how emmisions legal it is, I've used a 96 Z-28 for a week and it never averaged over about 22mpg

327_TPI_77_Maro

iTrader: (8)

1. Rewiring is not a big deal, I've done it
2. The TBI says you won't get more than 25 mpg on that engine

Klortho

Well, since I don't have to worry about emissions, no egr, no air pump, no cat. The trick is the 6-speed tranny, at 55mpg I'm just above idle but lugging the engine, 5th gear is around 1800 or so. You said real world driving, I drive my car 30 miles one way to work on the interstate, then about 5 miles city driving. I get between 340-350 miles on a tank and it's around 15 gallons to fill it up every time.

Jproz1167

iTrader: (3)

Then drive out here and do it for me and I will be glad to drop a LS-1 in the car. It would take a stick of dynamite to get me to go through that again.

Anyways I found a guy with a 92 4.3 that will make a good rebuilder and starting point so the outcome will be a 4.3 in this car. I suppose I could adapt port injection to it, that wouldn't be to hard but like I said aside from bolting it in and starting it up these days is to much work for me.

duckmanquacker

how do you determine that? (see my other post) the S10 is a brick and it got 25MPG fairly easy for Hwy miles.

Jproz1167

iTrader: (3)

I'de still like to know why since it would be feasibly cheaper since a 4.3 uses a small block trans why they went the route of a 2.8 then a 3.1 .... There certaily wasn't a shortage of them.

I'm curious what the monte's caprices el caminos of the day got with this 4.3 granted most of them early on had 3 speed auto's

duckmanquacker

I believe it was originally due to the emissions that they were put in the heavier vehicles only. the good thing nowadays is the smog guru cant tell the difference between them other than ones a V6 and the other is a V8.

by the way does your car use electric fans or the mechanical style?

Jproz1167

iTrader: (3)

the car has all 1990 electronics. the car has a factory 90 electric fan