383 Gas and Daily Drivability.

[r0nin89]

Comments? I am thinking about building one at around 400hp (to the wheels) and was wondering what I can get for gas mileage. I am considering this route because its proving itself alot cheaper than building a forged 355 and putting a turbo on it. I've kinda forgotten I have a tight situation with money and would like to get an engine built asap. I'm interested in MPG and how streetable a 400hp 383 would be.

PS: Would a 400hp be considered "mild" for a 383?

[WildBillyT]

Depends on your trans and rear gears. What have you got?

[Ian]

gas mileage, big power and budget dont go together. you need to determine which is most important and go from there

[r0nin89]

700r4 and 3.43's. Its going to be an around town car for the most part. If I can get 12 I'll be happy.

[sleeperMULLET]

with my setup i get about 8mpg, i haven't driven it on the highway much

[r0nin89]

Eww thats no good... What are you putting to the wheels? Anyone else on what I could get for mileage on a 400hp 383?

[BonzoHansen]

With a carb?

[sleeperMULLET]

Eww thats no good... What are you putting to the wheels? Anyone else on what I could get for mileage on a 400hp 383?

no sure what i'm putting to the wheels becasue i haven't dynoed it yet. my machinist estimated 600hp at the crank, but i think it a bit lower then that. plus i'm running a bit rich becasue of the tune. ive just been doing WOT pulls to get the rings to seat.

[Pampered-Z]

As Ian stated, big HP and mileage don't go together. BUT, with 3:42s, the right convertor and you should be able to get at least close to your HP and mile goals.

I think a 383 with a something like the 305 cam, 2800-3000 stall convertor, and 3:42 gears should get about 12-14 MPG.

On my old N/A motor I went from 3:23 to 3:42 and noticed only minor gas mileage change, but when I went to 3:73 I did notice far less miles per tank.

I haven't done allot of easy cruising with my 383/blower, but I can tell you that under boost it uses allot of fuel!

[78camaro]

this may not help at all but, why not build a forged 355 and juice it that way you'll have the better gasmilage around town yet the power when you really want it nothing rediculous just like a 100shot on a well build 355 and you be set.

[Ian]

werd, juice is safe if you do it right and you'll get good gas mileage if you stay out of it.

[r0nin89]

All throttle no bottle... I am not a fan of hitting a button for my power especially when it costs money everytime you use it. With how frequently I'd be using it it would add up to the cost of the lost gas mileage if I had that power. A 305 cam seems a little small... I can get 400horse from it?

[Ian]

All throttle no bottle... I am not a fan of hitting a button for my power especially when it costs money everytime you use it. With how frequently I'd be using it it would add up to the cost of the lost gas mileage if I had that power. A 305 cam seems a little small... I can get 400horse from it?


probably not a cam from a 305, but a CC305 from comp cams.

[WayFast84]

All throttle no bottle... I am not a fan of hitting a button for my power especially when it costs money everytime you use it. With how frequently I'd be using it it would add up to the cost of the lost gas mileage if I had that power. A 305 cam seems a little small... I can get 400horse from it?
Dude you need to relax, seriously, I might be a little biased but you can get 400 horses from a 355 with vortec heads easily, 425 hp with a 383.. He was sugesting nitrous for the track, No offence but any one that sprays on the street is asking for trouble.


Not a fan of hitting a button? tell that to the people who have 9 second street cars :lol:

Edit: I xe273 cam is can net you 400 hp with vortecs in a 355.

EDIT Its a XE274 my bad

[unstable bob gable]

He was sugesting nitrous for the track, No offence but any one that sprays on the street is asking for trouble.


Why is anyone using N20 on the street asking for trouble? I've had N20 on everything from a Z-24 Cav to a Procharged 94 Trans Am, and I've never had any trouble. Ya just gotta know what ya are doing, and not get too greedy with the power levels.

[r0nin89]

Dude you need to relax, seriously, I might be a little biased but you can get 400 horses from a 355 with vortec heads easily, 425 hp with a 383.. He was sugesting nitrous for the track, No offence but any one that sprays on the street is asking for trouble.


Not a fan of hitting a button? tell that to the people who have 9 second street cars :lol:

Edit: I xe273 cam is can net you 400 hp with vortecs in a 355.

EDIT Its a XE274 my bad

Just saying I'm not a fan... Alright sounds good so I can run a 355 and not destroy my gas mileage with a stroker motor but still get the 400hp easy?

[WayFast84]

Why is anyone using N20 on the street asking for trouble? I've had N20 on everything from a Z-24 Cav to a Procharged 94 Trans Am, and I've never had any trouble. Ya just gotta know what ya are doing, and not get too greedy with the power levels.
I dont mean one or two times, I mean excessively like 2-3 times on the street a week. and if you get cought ur ****ed if the valve is even open, let alone if you have a permit or not

[unstable bob gable]

I dont mean one or two times, I mean excessively like 2-3 times on the street a week. and if you get cought ur ****ed if the valve is even open, let alone if you have a permit or not


You think 2-3 times a week is excessive? If you can't speak from experience, you should keep yer cyber piehole shut. :grin: :laugh:

[WayFast84]

You think 2-3 times a week is excessive? If you can't speak from experience, you should keep yer cyber piehole shut. :grin: :laugh:
http://i13.photobucket.com/albums/a286/Wayfast84/NXdrug-1.jpg

[unstable bob gable]

http://i13.photobucket.com/albums/a286/Wayfast84/NXdrug-1.jpg



A lot more fun than crack, I must add!

[Savage_Messiah]

word on the street is the ewingites love their crack

[unstable bob gable]

word on the street is the ewingites love their crack


OH SNAP! :grin:

[unstable bob gable]

N' to get back on track...
I would build the largest engine you can afford. A larger engine won't have to work as hard to make the power levels you want, thus you can go easier with cam specs and compression. A nice pump gas 383 should satisfy your needs nicely. if you want MPG, stick a 6 cylinder in it, or learn to keep your right foot out of it...:grin:

[r0nin89]

Well if I can pull 12mpg driving like I'm about to croak I can manage. So what do you think I should do 355 or 383? I need at least 400hp and 12mpg.

[WayFast84]

Well if I can pull 12mpg driving like I'm about to croak I can manage. So what do you think I should do 355 or 383? I need at least 400hp and 12mpg.
no you dont.

j0ns famous quote:

Cheap, fast, reliable you can only have 2.


You dont need 400hp. no one does. YOU WANT 400hp, and you havent even explained if its rwhp or to the crank..

[r0nin89]

I'm hoping rwhp so I can sail a 12 flat. We'll see though.

[unstable bob gable]

HELL-OH? Is this thing on???? Do the 383, broh...you won't regret it.

[r0nin89]

HELL-OH? Is this thing on???? Do the 383, broh...you won't regret it.


Alright so say I pick up a 383 crank and put it in my 355 will there be any compression or any other issues??

[Tru2Chevy]

400 rwhp should send a decently setup 3rd gen into the 11's without much effort.

- Justin

[WildBillyT]

400 rwhp should send a decently setup 3rd gen into the 11's without much effort.

- Justin

X2. Good chassis tuning is imperative.

[BonzoHansen]

X2. Good chassis tuning is imperative.Subframe connectors FTW, along with other neato stuff.

[r0nin89]

Yeah subframs are next after rear. Then springs then comes the 355. I'm gonna drop it with 300hp at first then upgrade heads for the gain. Its got a hot cam limited by the heads right now.

[Pampered-Z]

Alright so say I pick up a 383 crank and put it in my 355 will there be any compression or any other issues??


Not sure if you realize you can't just drop the crank in. The block will need to be clearanced. The oil pan rail area and bottom of the cylinder bores need to be cut so that the crank weights will clear them. Likewise the oil pan will need to be hammers ( or replaced ) to clear the crank as well.

For the rotating assembly, you will need piston designed for a 383, which has a relocated wrist pin, and shorter piston skirts to again clear the crank. Stock piston on a stroker crank will put the piston into the valves or bind against the crank. I'm not even 100% sure the 5.7 rod will even work, might be some interference issues with the rod bolts? Most strokers 383/396 are 5.85" or 6" rods, and again, piston design and rod legnth need to be matched.

One other thing you need to look at is the cam lift. On my motor after the block was decked and the heads machined I did not have enough piston to valve clearance for the 600 lift cam I was planning to use. I didn't want to run an excessively thick head gasket or have material removed from the pistons to notch them so I went with a lower lift cam (544 lift).

My .02

JB

[r0nin89]

Yeah right now I know everything clears fine. Its got a hot (but not rediculous) cam in it that is obviously small enough to flow with the paper weights heads on it. When I upgrade to vortecs I may buy a new cam just to know the exact numbers I have.