306ci vs 331ci vs 347ci ???

[blake_colvin]

I appoligize in advance for the long a** post.

Okay so ive been into mustangs a long time now. Ive had a 97 gt and a procharged 97 cobra. Im now looking into getting a 90-93 notch (maf models)

My goal here is to build a car under 10k (hopefully including the price of the car) and make it run 11.99 or better N/A. the only work ill have done for me is the machine work and tranny work and rear end work.

The car will be a weekend only car and will only need air condition and two front seats and a whole lot of speed on the straight lines and in the curves.

This is what i had in mind originally, 347 stroker h,c,i built t5 tubular k member coil overs 3.90rear with 31 spline axels striped interior. and nothing over a 125 shot of gas to scoot down the track.

This is what ive been battling. built 306ci port polish shaved heads, wild cam, the best intake money can buy 3.90rear with 31 spline axels and a built t5 with the same suspension goodies. and the same shot of gas.

I only put the 331 stoker in the mix because i know i also want longevity.
as in id like to get 50-75k very hard ridden miles out of the motor.
but i want the car very very capable of a 7 hour road trip.

the things i put in bold are the things i have strong feelings about wanting. If anyone can shed some light on this and maybe fill me in on there 306 or 347 build and how much power you make n/a id greatly appreciate it.

 

[FISHTAIL]

A notch, with over 400rwhp (possible N/A with a well built stroker) will be in the 11's, especially with some weight reduction.

When I started my fox build, I had originally intended to use it as an open track toy, and went for a 331 with the goal of hitting 400rwhp N/A. The engine is built, but I can't tell you how much power it makes, because the car hasn't left the garage yet. It went from a open track project, to a clean street car project, and it's not done yet (although it's extremely close to where I can at least enjoy it again). I wish I could tell you my setup makes my intended hp goal, but I can't, since it hasn't seen a dyno yet.

The engine builder that helped me spec it all out claims it'll break 400hp, but I'm skeptical as hell. For a starting point, here is what I've got:
331 Stroker (~11.1 Static compression)
RPM Rods
Scat crank
Probe Pistons
AFR 185's w/ 58cc chamber
Custom Ground Cam
Harland Sharp Rockers
Trick Flow Intake, 70mm TB, EGR spacer and 75MM MAF.
Timing chain is some custom order piece with roller bearings on it.
Car has lots of other mods, but they aren't relevant to this discussion.

If you want to go around corners, look into a Maximum Motorsports or Griggs suspension setup. 31spline axles will be fine.

 

[yzracer931]

id like to get 50-75k very hard ridden miles out of the motor.

I believe that you answered your own question there. Nitrous is out of the picture.

 

[blake_colvin]

FISHTAIL : im not trying to knock the 331 stroker making 400whp but im also real skeptical considering ive seen several 347's including a recent build in fast fords magazine that made 340whp but with a 2800 stall it went down the track in 11.9X which is where i intend to be.

yzracer931 : depending on the actual cubic inch and final compression i chose to run will determine if ill need nitrous to push it below 11.3X
i was thinking a wild 306ci at 10.1cr with a 125 shot should do the trick.

 

[OBGT]

89's are maf too...just putting it out there in case you come across an 89

 

[blake_colvin]

89's are maf too...just putting it out there in case you come across an 89

ahh okay good looking out man

:beer:

 

[Project X]

89's are maf too...just putting it out there in case you come across an 89

And 88' California cars....

 

[OBGT]

And 88' California cars....

Yeah forgot about those

 

[truebluedevil02]

You'll be better off doing a 351, lightly boring it out to 357 (saves a good amount of $$ not having to buy a stroker kit/machine work) using the stock crank and football rods, some forged pistons, roller cam, jic jr or afr 185/205 heads, appropriate intake, etc. 400whp can SOMETIMES stress a 302 block with a weak casting spot but it wont touch a 351 at that power level, you'll EASILY get your 11.99 but probably a good bit faster than that and still be able to keep the set up calm enough for having a great driver/road racer plus you'll also be able to lower your static compression a bit to be able to safely run pump gas.

From what ive seen 331-347 just have a hard time making the power NA while retaining reliability. Honestly if you want the ability to go for 50K+ miles then I would go 396/408 stroker, with a good set of heads you'll be way over your HP goal but that just makes it easier to reach your other goals on a safer/milder setup. The more mild the setup the longer it lasts and there is no replacement for displacement. GL with your build.

also worth a note, my car making 340whp went 11.79@118 at elevation (over 7500ft DA) at 3275lbs race weight. My car makes 429whp at sea level and would be able to run 11.00 or even 10's NA. So if your just looking for an 11.99 car, stick with a 306 with a good H/C/I/E set up and with some suspension work you'll have it.

 

[blake_colvin]

You'll be better off doing a 351, lightly boring it out to 357 (saves a good amount of $$ not having to buy a stroker kit/machine work) using the stock crank and football rods, some forged pistons, roller cam, jic jr or afr 185/205 heads, appropriate intake, etc. 400whp can SOMETIMES stress a 302 block with a weak casting spot but it wont touch a 351 at that power level, you'll EASILY get your 11.99 but probably a good bit faster than that and still be able to keep the set up calm enough for having a great driver/road racer plus you'll also be able to lower your static compression a bit to be able to safely run pump gas.

From what ive seen 331-347 just have a hard time making the power NA while retaining reliability. Honestly if you want the ability to go for 50K+ miles then I would go 396/408 stroker, with a good set of heads you'll be way over your HP goal but that just makes it easier to reach your other goals on a safer/milder setup. The more mild the setup the longer it lasts and there is no replacement for displacement. GL with your build.

also worth a note, my car making 340whp went 11.79@118 at elevation (over 7500ft DA) at 3275lbs race weight. My car makes 429whp at sea level and would be able to run 11.00 or even 10's NA. So if your just looking for an 11.99 car, stick with a 306 with a good H/C/I/E set up and with some suspension work you'll have it.

alot of good sugestions here. i never thought a 351 would be more cost effective than a 331-347. (i know its power capabilities are greater just never researched the cost and what it takes to drop a 351 into a notch) it is deff something i will look into and consider though along with a mild built 306-347 considering im going to do alot of weight reduction. im hopeing to come in at around 2850 with me in it and i weigh about 165.

 

[Boomer182]

displacement, displacement, displacement. 408 is going to give you a lot more power, then a 347, 331, 306. I have ran a DSS 347, and I currently have a 306 in my coupe. They make good power, but if you want to run with the big boys, a 351 based motor is where it is at.

 

[blake_colvin]

yea im deff all for displacement but how hard is it to swap a 351 into a foxbody a bolt a t-5 behind it?

on the same note if i can run a 125 shot on a h,c,i,e 306 and make around 430-450whp that will give me my 11.99 or better n/a and hopefully a 11.00 or better on the nitrous.
im not planning to hit the juice every time i get in the car just every other time lol..

however if its the same cost to go 351 .20 over and forged and pull the same 400+whp and run at least 11.00 then id rather do that and stay n/a

 

[yzracer931]

We just had two 347s come off the dyno, one made 380 and was a very mild build, the other was tested for hot rod magazine and make close to 500. It can be done, the heads were CNC ported, and supposedly flowed in the 300+ cfm range.

 

[truebluedevil02]

yea im deff all for displacement but how hard is it to swap a 351 into a foxbody a bolt a t-5 behind it?

on the same note if i can run a 125 shot on a h,c,i,e 306 and make around 430-450whp that will give me my 11.99 or better n/a and hopefully a 11.00 or better on the nitrous.
im not planning to hit the juice every time i get in the car just every other time lol..

however if its the same cost to go 351 .20 over and forged and pull the same 400+whp and run at least 11.00 then id rather do that and stay n/a

As far as I know It jsut a set of motor mounts, an aftermarket oil pan, and thats it. I didnt do the swap in mine.

On another note, I just sold my 408 car and Will probably be buying a 92 coupe with a H/C/I/E set up and adding my 125hp shot of N2O to it, Im sure that will put me in the 12.0's-11.7's at my altitude so at sea level your looking at low 11's im sure, depending on the head/cam profiles. You wont be sorry going with a 351 though. I LOVED my 408.

 

[blake_colvin]

We just had two 347s come off the dyno, one made 380 and was a very mild build, the other was tested for hot rod magazine and make close to 500. It can be done, the heads were CNC ported, and supposedly flowed in the 300+ cfm range.

Thats alot more than ive ever heard of a 347 making. Fast ford magazine did a budget 347 build and the total cost of the engine was around 6700 and it made 338whp thorough the aod and with a 2800 stall it went 11.9X with a 1.8 60ft

i guess that sounds about right though if it was a 5spd it would have prob made 375+whp. my question is could i have the stock heads from a 5.0 port and polished enough that with a custom cam it will make in the 375+whp range?
im trying to stay as cheap as possible

As far as I know It jsut a set of motor mounts, an aftermarket oil pan, and thats it. I didnt do the swap in mine.

On another note, I just sold my 408 car and Will probably be buying a 92 coupe with a H/C/I/E set up and adding my 125hp shot of N2O to it, Im sure that will put me in the 12.0's-11.7's at my altitude so at sea level your looking at low 11's im sure, depending on the head/cam profiles. You wont be sorry going with a 351 though. I LOVED my 408.

that seems easy enough, ive been looking for 351's locally and found a 351 with a c6 trans for around 3k and i found a 351 block and heads for 200 bucks.
where im looking 5.0's are hard to come by, but its really going to come down to the deal i find and how much i can save. id love to do a 351 and make well over 400 n/a but if i can make close to 400 with the 347 as stated above then my only worry will be how long before the block goes, because i may not hit the nitrous all the time but i deff have never done the speed limit.

 

[FISHTAIL]

FISHTAIL : im not trying to knock the 331 stroker making 400whp but im also real skeptical considering ive seen several 347's including a recent build in fast fords magazine that made 340whp but with a 2800 stall it went down the track in 11.9X which is where i intend to be.

yzracer931 : depending on the actual cubic inch and final compression i chose to run will determine if ill need nitrous to push it below 11.3X
i was thinking a wild 306ci at 10.1cr with a 125 shot should do the trick.

I'm skeptical also. We'll see what happens when it gets tuned. However, the car you quote was an AOD, so that's giving up a good bit of power there, with a 5spd you are probably looking at 370+. I didn't see that article either, so I'm not sure what parts they used, or what type of compression they were running. Were they using AFR heads? What kind of cam? Custom grind or off the shelf?

Having said all that, I do agree with the others here. A 351 based build would probably be a better fit for what you want.

 

[blake_colvin]

I'm skeptical also. We'll see what happens when it gets tuned. However, the car you quote was an AOD, so that's giving up a good bit of power there, with a 5spd you are probably looking at 370+. I didn't see that article either, so I'm not sure what parts they used, or what type of compression they were running. Were they using AFR heads? What kind of cam? Custom grind or off the shelf?

Having said all that, I do agree with the others here. A 351 based build would probably be a better fit for what you want.

Im not sure of the month but it was a recent issue. it was a budget junkyard build or something of the sort. im not close to the issue right now so im not sure of the parts used but the total cost of parts was around 6500.

If a 347 can net 370+whp on a mild build then id be more than happy going that route to cut down on the cost and weight for the corners (so i can afford some suspension goodies and of course some sort of tranny that will hold the power)

for saving money im hopeing to use the stock 5.0 heads and block and just have the heads port, polished, shaved if needed and buy a stroker assembly and a nice intake mani. hopefully staying around 4k for the engine cost. (ive looked into the 351 and i found several blocks and whatnot for the cheap but im concerned that the weight will be a little much for what i truely intend to used the car for. (50% street(twisties) and 50% street raceing(straight line acceleration)

 

[truebluedevil02]

for saving money im hopeing to use the stock 5.0 heads and block and just have the heads port, polished, shaved if needed and buy a stroker assembly and a nice intake mani. hopefully staying around 4k for the engine cost. (ive looked into the 351 and i found several blocks and whatnot for the cheap but im concerned that the weight will be a little much for what i truely intend to used the car for. (50% street(twisties) and 50% street raceing(straight line acceleration)

Stock 5.0 heads will not do the trick from everything ive ever seen/read. Even ported there way to restrictive. To meet your goal you'll have to get a good set of heads. Edelbrock Victor Jrs are great for a smaller engine, along with the AFR 185's. Since your not going forced induction you probably wont be able to skimp on the heads. Also IIRC the 351 block isn't much heavier than a 302 block, i think its only about 10-15lbs heavier but the added CI makes it well worth it. Glad to see your doing your homework. You'll be glad you did:beer:

 

[blake_colvin]

Stock 5.0 heads will not do the trick from everything ive ever seen/read. Even ported there way to restrictive. To meet your goal you'll have to get a good set of heads. Edelbrock Victor Jrs are great for a smaller engine, along with the AFR 185's. Since your not going forced induction you probably wont be able to skimp on the heads. Also IIRC the 351 block isn't much heavier than a 302 block, i think its only about 10-15lbs heavier but the added CI makes it well worth it. Glad to see your doing your homework. You'll be glad you did:beer:

okay well the edelbrock victor jrs arent too expensive so i may be able to swing that in my budget.
and the 351 block being around 15lbs more.. my next question is what about efi.
if i go with a 351 im going to try and find at least a block and heads to keep down on the cost.. would i be able to use the stock 5.0 fuel system and cpu on the 351? (94 up 351) ive seen a few 351 blocks for 100 to 200 bucks and then one with block and heads for 200 bucks.
i know efi kits can run from 1500-2500 and thats going to hurt my budget.

cheap fast reliable? its a battle between reliable and cheap for me. im hopeing to be somewhere in between.

 

[95PGTTech]

you're all over the place - you want a car that does everything (strip, cornering, and street) on a budget. you want a/c but a gutted interior. you want 11.99 N/A but then talk about nitrous. you want a built motor/trans/rear/suspension car to last 50-75K...on a budget.

first, figure out what you really want, and concentrate on that goal. 11.99 is going to require a 6pt, so if the street manners are more important to you, start rethinking everything. is 100lbs of A/C really worth it in a caged, gutted, built T5 car with a wild cam?