What GM engine is the easyest on fuel? I sold my 402 today, gas was killing me and need to look for a more fuel efficent platform which should be almost anything. What engine should I replace it with? Power unfourtunatly isnt an issue I just need pure city milage.

Thanks!

 

2.2L Ecotech engine out of a 02-03 Caviler!!!

A well tuned small block that is built conservatively will yield good mileage and have some decent power to. It all lies in the proper equipment and the tune...

 

LS1 gets my vote. Pricey though.

 

any modern EFI engine combined with a economy drivetrain should get you the miliage you are looking for...



so feel free to swap a eco tech with a T56 and some 3.43 gears.

 

I would say it depends on how heavy the vehicle is you intend to put it in. A little 4 banger in a 3500 lb car isn't going to be "easy on gas" because you are going to be working it twice as hard as a V8.

 

true...

the key is more efficency then it is anything else.

but in city driving, i think a geared low smaller motor would work better..


on the hwy, the larger engine with its higher TQ running thru a overdrive would work better...

 

Yea, it's got to be larger displacment then a 4 banger that fits an already V8 platform. What I really need is somthing that driven farily hard (I dont trust myself) and still gets good fuel economy. 1bbl setup baby!

 

a iron duke would fit in there.

put a small 2bbl carb on it, and you wont get any speeding tickets....


i donno... for ciy driving you want somthing that doesnt waste fuel at idle, and all the power below 3k..... *shrug*


i would just stick with a V8 because it already fits in there... 305s are cheap. a used 305 with a peanut cam would work fine...

if you dont trust yourself to keep your foot out of it, but a 2bbl on it..

couple that with some hwy gears in the rear and you'll get decient mpg...

 

305 with some higher gears would help alot. Those 4.56s are half your problem. Get some 3.42s or so. with a decent 305 with a 2 barrel and you should do pretty good on gas.

 

You should be able to pick up a 267 for $5 or less.

They have the long stroke of a 350/305 with a 3.5" bore, so the torque is OK.

I had a '81 Malibu with one in it, and it wasn't bad after I took out the 2.56 gear and put in a 3.42.

Put a Edelbrock #3702 cam in it with some cheap headers and it'll pull pretty good.

Or if you REALLY want to be different, use a 307 crank in it to make a 250 cid.

 

could u get a 4bbl carb and disconnect the secondaries to save gas. then when more power is wanted, just reconnect them?

 

Geo Metro 3-cil...........!!!???

 

My vote is a LS1. You can find them on eBay with an auto tranny for $2500. A LS1 gets 25 mpg highway, weights 150lb’s less then a Gen I SBC and has 320 hp at the rear wheels stock.

 

Yes, an LS1 CAN NET 25MPG but it can also get GPM wide open. I found an LS1 local $2500 just for the engine. Wiring would be a nightmare. I just need suggestions for a realistic engine, cheap easy to install great on gas, too much to ask for.

Heres another question since Ive never pulled a 2GC, what spread pattern is it? Holley or motor crap 2bbl fit it or is it like the old rectangle style. I know those motorcrap 2bbls are easyer on fuel then most 2bbl's.

 

Well, the best engine I've had for MPG (V8 wise that is) was in my 79 T/A, 26 MPG on the highway. It was the Olds 403 with minor mods, velocity stack under the shaker scoop, headers and duel exhaust, Rochester carb rebuilt and fine tuned.

If you can get it to fit you may want to look into getting a 3.5 or 3.8 V6, they each had over 200 hp, 215 for the 3.5 and 205 for the 3.8.

 

You sold the 402???

Now the task is calculating cost/benefits ratios. How much will it cost you to get good mileage, and how long will it take to pay back the cost of getting that good mileage?

My votes:

Non-CC:
305 with q-jet or dual-jet. Rochester 2bbls are rotten carbs, will suck more gas than a q-jet. Dual-jet is primaries-only of a q-jet.

CC:
If you're willing to go through the conversion hassles, LO3. If you can't find one of those cheap, you ain't tryin'...

 

Way back in the day when Car Craft ran the "Street Car Shoot Out" yearly, there was a guy with an 89 T/A that swept the entire "shoot out" with a 350 TPI engine, and got an astounding 35 MPG (highway) and ran the 1/4 in the 12's.
They do a whole run down on what each car's engine/ suspension is comprised of, if you could find the issue that it was covered in you could try setting up an engine like that.

 

Well in your signature it says you have a 3 speed, 4.56 gears. If you are looking for gas mileage then you should ditch the 3 speed and get some lower gear ratio gears.

 

Id say a 350 with a aftermarket OD trans with a lockup TC, like a probuilt or a TCI 4l60 with some higher ratio rear gears like 3.42's, which should be a good to help it get going in the city and still provide reasonable highway economy. As for the engine, id say a 350 with a small cam with less than 200 degrees of duration at the intake lobe, small runner heads, like L98 tpi heads, small primary headers, and an efi system or a small carb, but the efi will do much better when set up properly. Someones always dumping their tbi system around here to go to carb so theyre available. Get the ecm and wire harness and get an aftermarket holley tbi. Theyre somewhat of a pain to put in but itll be tight internaly and come with the delphi injectors, which are the best injectors available for the tbi IMHO. With my 350 i average around 23-25 mpg (put over 500 miles a week on the car commuting), which is only slightly less then the L03. This is with very little tuning since i havnt had much time to work with it. I should be able to at least get another 2-3 mpg more. Also, the car was a total dog with that 305. It would bearly even move when i floored it. It was like driving my crappy eclipse all over again. Even the plain jane 350 i have totally buries the L03 in every way.

PS: some people have done much better with fuel economy then this. Sometimes getting into the mid 30s with the efi. If you dont mind the severe lack of power, though, a good running L03 will deliver good fuel economy.

 

well, my old 350 tpi with 24# inj's 305 tpi heads with 1.94 valves, slp roller cam (480. lift one) and a tbi 5-speed running 3.23 gears got great gas milage it was getting around 25+ mpg hwy maybe more if I was not always on it when ever a mustang would get next to me. and yes I drove it 200 miles each day going from my house in WI to chicago and back. I would have never done that in my old pontiac 6000 $$$

I think the higher comp. helped and the overdrive ratio with 3.23's
oh and the car moved very fast almost the same as the 400 in it now (same stuff on the 400)

oh, I also had the slp 1 3/4" headers on it

 

Yes 57 I sold it, my friend with the 72 Nova was in need of an engine.
He had lots of $$$$ and was willing to pay for an 11 second setup. I however had no cash to finish the SD BB 396 for the Malibu. Its too rusted and needs everything done to it. That and the added funds will most likely cover 70% of its restoration.
$5 a day for fuel just to drive 3 miles 3 times a day


Here are some options I have on hand, 4, 327's, 5, 350's one is recent from my bird, 357, the 305 with MTC-1 cam installed from my bird and actually have the ported and valved 416's that were on my 355 avalible.
Parts range from stealth intakes to HO OEM's, a set of headders 1, 5/8 & 1, 3/4 and a few dozen different 4bbl carbs.

I could make a fuel efficent combo from any of these if anyone can suggest a fairly guranteed combo.

 

My stock 305 gave me 18 mpg city with a TPI and T5. The only work done to it was some chessy exhaust it had on it when I bought it and I cut the air cleaner boxes and installed KNs. No PROM tuning, no porting, nothing...

On the HWY it would lay down close to 30mpg with my lame "ram air" I made from drier ducts. It was only used on one road trip of about 3000 miles.

So, there's my suggestion, a stock 305 TPI with a slightly enhanced induction and exhaust...oh, and an overdrive tranny...

 

One of the 327's, especially if one is a 2bbl version. A factory q-jet intake manifold with a well-tuned q-jet, and the 1-5/8" primary headers.

(Don't suppose you'd be willing to part with a 327 or 350 shortblock, by any chance...)

 

How about a 4.3L V6? Hooks up to the V8 tranny and with TBI it would get great mileage. Or maybe even a 2bbl carb.

 

The 4.3 in my s-10 does very well on fuel. Just make sure you dont use the CPI.

 

fuel economy... brake specific fuel consumption...

hundreds of things to change if you want fuel economy. What everyone said so far is correct. your gears and tranny need to go if you plan on getting better than 10 MPG, no matter what engine you put in there.

it takes horsepower to move a car down a road. simple enough..
and horsepower is a function of torque and rpm.
torque basically cylinder pressure, or fuel and air (in proportion by mass not volume) and rpm is just application rate.

so if we need x horsepower to keep a car moving, that translates directly to y torque and z rpm. most engines make better brake speicific fuel consumption right at their peak torque area, according to crossfire this is what im told. fuel atomazation (EFI) helps BSFC alot, as does running a 14.7:1 or 15:1 a/f ratio.

but there are other factors. slippage in the drivetrain (non-lockup converter) eats fuel up. Weight (hp = weight moved distance.. less weight = further distance less time). drivetrain loss like heavy converters, heavy driveshafts, big gears, big tires, all play a roll in the final driveline loss of power %. things like tire pressure and just how new and greased the wheel bearings are also play a roll in fuel economy. drag coefficient is a big one, going from 20mph to 40mpg would be 4 times harder for the vehicle to maintain, since i beleive the exponent is ^4 from what ive read.

did i say hundreds of things affect fuel economy? i can go on all day. if you search you will find ive done this sort of thing before...

 

(Don't suppose you'd be willing to part with a 327 or 350 shortblock, by any chance

Actually I have a 350 4 bolt block at the machine shop that needs align bored if you want to swap your rods and crank.

The top end build I did a few weeks ago that I wasent impressed with apperently ran well enough for him to smoke the bottem end.

"I was going down the road at 2am south end of Denver and it overheated and stopped running"
Yea at what speed? "I dunno the speedometer only reads 85 but I think around 5000rpm." Lets see 2600RPM is 75MPH, dare to guess what 5k is?

BTS.

The 3 speed is actualy a close ratio and I do have the complete factory 12 bolt 3.73 and a 3.42 gear set. Ive always been under the asumption that the numerical higher you were with the gears (lower) the less the engine has to struggle and the more effecinet it would run city wise at least.

 

All I've got is 1-piece rear seal stuff.
That's true, if keeping the power enrichment system out of the picture is the intention.