modern engine choices

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alright this was a question i had in one of my threads and it didnt get any attention so im making a thread so someone can see it. im explorin into the choices of modern fuel injected engines for my 72 firebird in the quest to get some better mpg from it. i was wondering what your guys suggestions would be. i want a nice stout engine. but nothing as extreme as like a new ls7. something reliable and prefferably something where tbi can be set up so i can still have the caburator/aircleaner look. also im looking for a good 4 speed auto to replace the th350 so hopefully that 4th gear will give me some better mpg too. cause its ashamed that the thing has been in my garage for as long as it has.

posted by  72firebird

So, in my opinion carburetors are outdated, if you want something with good gas mileage and power go FI or go home.

Find yourself an LT1 still bolted to a 700R4 from an F-Body and put it in. My brother had a '95 LT1 Formula Firehawk and managed 32 mpg on a trip to Vegas at about 75-85mph... granted he had the 6spd, but you get the idea.

posted by  Bino

no i was talking about fuel injection. you much not know a whole lot. i was talkin about tbi throttle bodie injection. found like on 80s 350s. it looked like a carb and had an aircleaner like the 60s 70s 350s but it wasnt a carb it was the throttle body.

posted by  72firebird

The TBI was just a complicated carburator. Seriously it wasn't a very good injection system. The Holley aftermarket on is much better, but you're gonna spend a LOT of money to keep the carburator look. If you're looking at better fuel mileage, it'll take well over a decade to make up the cost difference. In fact, that's true for any engine swap to get beter mileage, as the difference will be fairly minor at this level (your'e only going to gain about 5 mpg in the best case, so think of how many years you could drive on the cost difference between what you have and what you're looking to put in there).

posted by  ChrisV

5 mpg more would help out alot. right now i only get like 12-14 mpg. id like to either keep the engine or try to get a fuel injected engine and mate it to a 4 speed and try to bring the mpg up into the 20s. i just dont like the new intake system. i never liked the down pipes and square or cone filters.

posted by  72firebird

Yes, but what he's saying is by the time you buy/pay for the new engine/trans/etc and say you gain 5-7 MPG, ya thats good, but say a gallon is like $2.40 and you spent say $1,500 for everything, it'll take awhile before what you save in gas makes up for what you paid for the parts.


Hope that makes sense, it does in my mind anyways.

posted by  car_crazy89

It does make sense. i got that part. even though for me an lt1 with the wiring would cost me 1200 and the transmission would another 500. i got the money and i can do the work myself. itd just be nice to get more than 14 mpg with conservative driving. and fuel injected is better anyways. and thats why i was also asking on your guys sugestions on a nice 4 speed auto. cause as you probably know the th350 is a 3 speed and a 4th gear will lower your rpms 15-30%. so what would you guys think for a good trany for the 350 i got in there now. also i kinda need it to handle 500-600 flt lbs of torque cause although im only in the 400 range now thats what my goal ratings are gonna be 500-600 hp/ 500-600 ft lbs

posted by  72firebird

Alright, well i dont know a whole lot and for now dont care about fuel mileage (maybe i will when i can drive). If you have plans for that much hp/tq then your still gonna be using alot of gas, especially the more your on the throttle. Like my first vehicle is going to have a 350 like yours but with a 400 automatic transmission (not sure gas mileage though). If you have the time/money and plan on having your car for a long time or drive it alot and you like the engine/trans swap idea then i'd say go for it, but keep the 350 incase you change your mind.

If i were you i'd definately wait for knowledgeable people lol. Hope you find the best setup for your needs :thumbs:

posted by  car_crazy89

lol yea when you start paying for your own gas and your car only get 13 mpg and work is a 60 mile round trip and you work 5 days a week you start worrying about mpg. and ive had the car for 6 years already and in all honesty i plan on keeping it till i either total it and in which case ill salvage the good parts and rebuild it with a new frame. or if i die. so thats also why im thinking about the swap cause i plan on keeping it for another good 50-60 years and itd be a little easier on the wallet in the long run. especialy if prices stay the way they are or if even worse in the future gas starts getting used less and less and it becomes a rare commotity

posted by  72firebird

Well sounds like you drive alot so it wouldnt be a bad investment to make some changes to get better mileage, and i dont blame you for wanting to keep the car for as long as possible, i'd feel the same if i had something i really liked and had a special meaning. Its good your thinking ahead kinda, gas mileage is getting more and more important.

posted by  car_crazy89

At that hp range, you're looking at 10-13 mpg with the overdrive. And yp're gonna spend a few grand to get there. if you're concerned with fuel mileage, buy a $500 economy car beater that get 25-30 mpg and build the Firebird for fun. Seriously, leave mileage completely out of the equation, as it ain't gonna happen at that hp level in that car.

Just being realistic. Occasionally you'll hear claims of somebody's brother's wife's uncle's big block musclecar that got 20-25 mpg with 500 hp, but in the real world, it requires a car like the new Z06 to come close to that, and spending $60k+ to try to be "economical" is hardly realistic... :screwy:

posted by  ChrisV

yea that is unrealistic. but i only do engine mods every once in a while. i mostly work on the suspension and body every chance i get. but still id like to know what your guys opinions would be on a good 4 speed. and like im saying and i should have clarified. itll be a good 5-10 years before i make it pump out that much hp. im not in a hurry. i want a transmission though that can handle that much just so that down the line i dont have to build it up or change it. im just looking for better gas milage now because by the time i get that much hp into it itll be strictly a weekend warrior car for cruisin. im just thinking ahead. it helps to plan it out ahead and try to keep the suprises/problems down to a minimum

posted by  72firebird

for as long as im gonna have this car every little bit is gonna help. i know with 500 hp its gonna get shitty gas milage no matter what. but the difference between using a 3 speed and only getting 9-10 mpg and using a 4 and geting 13-15 mpg is still a good thing. its not a major money saver but every little bit helps. id rather not be driving my car due to mechanical problems. not because it just sucks too much gas down. which is again why i made this thread i wanna hear your guys opinions

posted by  72firebird

Well then stop beating your head against the wall and get a freakin' LT1 with a 700R4 still bolted to it. So... LT1 + 700R4, 4spd transmission that really has a pretty extensive aftermarket for your hp aspirations, plus fuel injection... and all parts are common as hell and a dime a dozen.

posted by  Bino

Upon further examination it appears that the LT1's were also available with the 4L60E 4spd AT as well.

posted by  Bino

Sorry about my rather unpleasant posting earlier.

Anyway, just a thought since you seem concerned with gas mileage you could go the L99 route from a Caprice. Most of the LT1 technology just in a smaller package. Plus you could upgrade to an LT1 anytime as they are very similar motors.

Just another thought.

posted by  Bino

well, you could be creative and original and retrofit port injection to a pontiac 400 w/ 4-speed... :thumbs:

posted by  dodger65

thatd be a nice idea except i dont like pontiac motors all that much except the ra 400s and the 455s. i like the chevy 350s better. maybe i could go with the older fuelie style like on the ram jet 350s and 454s.

posted by  72firebird

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