[the black widow]

im want to build an engine for my daily driven 90 gt. i want to know the differences in gas mileage, realiability, durability, and power output of a 306, 331, and 347 engines. anyone that can shed light on the subject, thanks.

[1slo5.0]

Bigger engines use more gas. Reliability is about the same between all three of them.

[mt50guy]

do u really build a v8 for gas milage?

[ninedee-coupe]

a 306 isnt stroked its just bored.

[Kingcater]

408 FTMFW!!!!

[the black widow]

i heard the cylinder walls in the 347 wear faster because the crank spins twice as fast as a stock crank or something.

my bad, i knew a 306 isnt stroked.

[1slo5.0]

Originally Posted by the black widow i heard the cylinder walls in the 347 wear faster because the crank spins twice as fast as a stock crank or something. my bad, i knew a 306 isnt stroked.

No that is totally false. Idiots that don't have any experience tell people this crap. Whoever told you that should go kill himself.

[ken5_0]

Once again Darrell straight to the point!!!

[mustangman9550]

My 331 Stroker is somewhat streetable. I use her for my daily driver, but it's like having a high-maintence girlfriend! Kiss your gas mileage bye-bye too once you start upgrading the rest of the car to match the performance of the engine. I have a friend with a 347 that goes through the same problems as I do but seems to burn more oil and not idle as street worthy. Could all be in the build or the tune though.....

[the black widow]

can you tell me how much more gas is used with a 331 or 347 as opposed to a 306?

[mustangman9550]

Originally Posted by the black widow can you tell me how much more gas is used with a 331 or 347 as opposed to a 306?

With my fuel cranked up just enough so she doesn't starve AND my lead foot I prolly run around 13 to 14 miles to a gallon......prolly even worse than that when I'm feelin frisky with her.

[94' Cobra 351]

if it is your daily driver and you still want to retain decent gas mileage, you would be better off going the nitrous route IMO.

I get about 12mpg's in the city with my 351.

[1slo5.0]

Originally Posted by mustangman9550 My 331 Stroker is somewhat streetable. I use her for my daily driver, but it's like having a high-maintence girlfriend! Kiss your gas mileage bye-bye too once you start upgrading the rest of the car to match the performance of the engine. I have a friend with a 347 that goes through the same problems as I do but seems to burn more oil and not idle as street worthy. Could all be in the build or the tune though.....

You have issues somewhere. A friend of mine has a carbureted 347 in his 88 GT. He gets 24mpg on the highway. I've had fuel injected 347s get similar fuel economy. A 331 or 347 is just as streetable and reliable as a 302.

[NottyBoy93]

Originally Posted by Darrell Originally Posted by the black widow i heard the cylinder walls in the 347 wear faster because the crank spins twice as fast as a stock crank or something. my bad, i knew a 306 isnt stroked. No that is totally false. Idiots that don't have any experience tell people this crap. Whoever told you that should go kill himself.

I love it! 347's do push a stock block to it's outer limits strength wise, and you can get better rpm ranges out of strokers, but crank speed otherwise known as RPM's are not a funtion of cylinder wall failure. To answer the original question, gas mileage has never been a consideration in any motor I have ever built, but it does vary depending on cam, intakes etc. I have gotten as good as 15-18mpg on a well modified 408 and as little as 10. I have little experience with 302 formats as I don't mess with them.

[the black widow]

goddayumm! 24 sounds like alot even with a stock 302 i dont get that much. maybe if it was supercharged.

[mustangman9550]

Originally Posted by the black widow goddayumm! 24 sounds like alot even with a stock 302 i dont get that much. maybe if it was supercharged.

That's what I was thinking! Ofcourse we all don't have Big "D" cashflow either. lol I took a guesstamate on my gas mileage anywho.....and I'm not in the habit of cruising heavily on the highway all the time. Guess I need to do a decent gas mileage check one day. 24 though I barely got in my old 03 GT with bolt-ons!!! Maybe this deep South heat is really that much of a bitch.......lol

[1slo5.0]

Originally Posted by mustangman9550 That's what I was thinking! Ofcourse we all don't have Big "D" cashflow either. lol I took a guesstamate on my gas mileage anywho.....and I'm not in the habit of cruising heavily on the highway all the time. Guess I need to do a decent gas mileage check one day. 24 though I barely got in my old 03 GT with bolt-ons!!! Maybe this deep South heat is really that much of a bitch.......lol

He doesn't have big cash flow. He works at a paper mill for $13 an hour. He has spent alot of hours tuning his carb and the rest of his combination. Street manners is a big thing for him. There is alot more to fuel economy than cubic inches. I got 25mpg on the highway with my EFI 91 GT and it ran 11s....

[StangAddiction]

Originally Posted by the black widow i heard the cylinder walls in the 347 wear faster because the crank spins twice as fast as a stock crank or something. my bad, i knew a 306 isnt stroked.

The crank spins twice as fast?

So the car turns over 8,000 rpm instead of 4,000, or 10K instead of 5?

[ken5_0]

Originally Posted by StangAddiction Originally Posted by the black widow i heard the cylinder walls in the 347 wear faster because the crank spins twice as fast as a stock crank or something. my bad, i knew a 306 isnt stroked. The crank spins twice as fast? So the car turns over 8,000 rpm instead of 4,000, or 10K instead of 5?

Ya its true! It has that new K&N RPM Multipliar Filter! And yes that spelling is trademarked.

[GTXRacing]

Originally Posted by ken5_0 Originally Posted by StangAddiction Originally Posted by the black widow i heard the cylinder walls in the 347 wear faster because the crank spins twice as fast as a stock crank or something. my bad, i knew a 306 isnt stroked. The crank spins twice as fast? So the car turns over 8,000 rpm instead of 4,000, or 10K instead of 5? Ya its true! It has that new K&N RPM Multipliar Filter! And yes that spelling is trademarked.

Also... "prolly"? Sounds like some kids toy from PBS Kids.