blown gt40p or N/A 347?

95five-oh · Apr 20, 2007

As the title suggests, I'm trying to decide which direction to go with the car. The current engine has 159k on her so i'm gonna start fresh either way.
What are the advantages/disadvantages of these combos?
I'd either be getting a complete gt40p longblock with under 75k and slapping on a 13-14psi procharger and necessary hardware.....or i'll get a 302w block and stoke it to 347 with full HCI and remain N/A. I want about 415 at the wheels (is that even possible N/A?) which I think is still safe for the stock block. From what i've gathered, the price will be similar for either buildup and I plan to start within the next two months or so, but don't plan on installing it until probably this time next year. I know alot of you guys have 347's so feel free to jump in here with input if you would like. Anybody running a blown gt40p combo i'd really like to hear from.

Pokageek · Apr 20, 2007

You are not going to get 415 n/a at the wheels with a 347....unless you want no power at 0-3000rpm and a whole bunch from like 4000-6000 which is a driveability nightmare and prob cost you $$ for..what?

I would go forced ind. gt40. Cons there? Potential issues that everyone encounters with forced like tuning, blown gaskets, gremlins, etc... but i you can ge it matched right it will work...as long as you dont get too frustrated with it.

Good luck.

cbarr300 · Apr 21, 2007

you want seat of the pants for intown driving....go with a 347.

You want seat of the pants on the highway and a cool noise, go centri. supercharger

orrr.....you could get a kenne bell which starts making its boost realllly low and would be pretty fun to drive around.

My vote of the 3...kenne bell. If you can't do kenne bell...I'd do HCI

just my .02

Black95GTS · Apr 21, 2007

http://www.fordmuscle.com/archives/2005/02/YellowFever/

If I had money, I'd copy this build almost exactly, except I'd use a big bore 8.2 deck block and make a 364 instead of a 347. 3.4 stroke, 4.125 bore. You'll reach your goals NA with this combo.

Adam

OrangeMustangGt · Apr 21, 2007

i agree.....347 is gonna be more fun to drive.

I had 10psi with my current gt40p combo, and dont get me wrong it was fast as hell at 10 psi most likely 400+ wrhp, however P heads are a tricky head because they have a small combustion chamber for boost. I kept blowing HG's using my stock cam because it had too much static compression....i had to use my crane 2031 to bleed away some compression and it caused a drop in power. I ended up getting it very reliable with my cometic mls gastekts though.

IMO nothing beats the low-end fun of stroker car.....dont gotta wait for revs and boost!

Pokageek · Apr 21, 2007

But also, who needs 400rwhp when that car in the link can run 10.9's? It is set up as a drag car basically..Make it street without slicks and other parts and it will lose a second. Then put some other driver behind the wheel and you are at 12.5's lol. Lots of factors, depends on what you really want..

A radical 364 will get you very close to 400rwhp and might be street driveable too.

RAD · Apr 21, 2007

Pokageek said:
But also, who needs 400rwhp when that car in the link can run 10.9's? It is set up as a drag car basically..Make it street without slicks and other parts and it will lose a second. Then put some other driver behind the wheel and you are at 12.5's lol. Lots of factors, depends on what you really want..

A radical 364 will get you very close to 400rwhp and might be street driveable too.

364CI streetable and only 400rwhp? wow that is weak , I was thinking about 364 and still street friendly with something around 450 rwhp , looks like is time to change goals crapola

95five-oh · Apr 21, 2007

would about 370-380 rwhp be more realistic for a 347? By the time this project gets finished next year the car will no longer be my DD, so driveability isnt my top priority but i would def. like it to be streetable. What kinda numbers are you 347 guys putting down and what heads/cams/intakes are you running?

Pokageek · Apr 21, 2007

According to grady there is a 1 to 1 ratio with c.i. and RWHP for a fairly streetable car n/a. Once you head above that, you get into more track oriented.

I agree with this philosophy because I have seen the results. Streetable by MY definition may NOT = YOUR definition, but to me that is around that 1 to 1 ratio.

So a streetable combo by MY definition meaning good low end, not a lot of shakey idle, 93 octane max needed, and other factors for a 347 would be anywhere from 347rwhp - 360rwhp max potentially for example.

Grn92LX · Apr 22, 2007

Black95GTS said:
http://www.fordmuscle.com/archives/2005/02/YellowFever/

If I had money, I'd copy this build almost exactly, except I'd use a big bore 8.2 deck block and make a 364 instead of a 347. 3.4 stroke, 4.125 bore. You'll reach your goals NA with this combo.

Adam

Yep!

So much poor 347 info in this thread

Oh well, its beautiful out and i'm about to go take my pump gas street car 347 out for a spin

Gearbanger 101 · Apr 22, 2007

Blower combo > all motor combo

Blower car will allow you to retain stock drivability and fuel economy until "you" decide otherwise by stuffing your foot into it. That's a luxury you won't retain on a high horsepower all motor 302 based engine. You’re always feeding 347cid and you’re always at the mercy of the aggressive cam specs, and cavernous exhaust and intake compromises needed to retain 400+rwhp with an all motor combination.

Black95GTS · Apr 22, 2007

Gearbanger 101 said:
Blower combo > all motor combo

Blower car will allow you to retain stock drivability and fuel economy until "you" decide otherwise by stuffing your foot into it. That's a luxury you won't retain on a high horsepower all motor 302 based engine. You’re always feeding 347cid and you’re always at the mercy of the aggressive cam specs, and cavernous exhaust and intake compromises needed to retain 400+rwhp with an all motor combination.

An HCI 302 will get better mileage then a stock 302. Stuffing air into a less efficient stock setup will result in worse mileage. What do you think gets better mileage? A 302 with a blower at 10 PSI making 300 HP or a 302 with an HCI making 300 HP? I'll bet my next pay check that the 302 HCI gets much better MPG. I would cringe at the mileage that a supercharged 302 would get trying to compete with the mileage of an HCI 347.

If this were not true, then how come a 346 LS1 knocks down 25+ mpg? Displacement has nothing to do with gas mileage. Its all about the tune, the quality of the parts, and how well they work together.

A 427 ci Z06 is putting out 500 HP and gets 30 MPG, despite "feeding" that displacement.

And if anyone thinks a 364 with 400 rwhp is weak, drive one. There is some shady info going down in here....

Adam

Pokageek · Apr 22, 2007

"And if anyone thinks a 364 with 400 rwhp is weak, drive one. There is some shady info going down in here....

Adam"

+1. 400rwhp is weak if 400 # bench press is weak. Sorry but what are you smoking man!!

RAD · Apr 22, 2007

Relax guys I was hoping that my future 364 will hit something around 450 rwhp and will be streetable but ... anyway I have to do some search

99FiveOh · Apr 22, 2007

Regardless of what you have, HP= reduction in gas mileage. That Z06 is a product of alot of research and EXPENSIVE parts that make it work like it does. You won't get that kind of efficiency with anything you can buy off the shelves for any V8 Mustang.

When you have a blower and you're not making boost, it's almost like not having it at all. Sure it takes like 4 or 5 HP to free spin it but so does your alternator and A/C compressor when their running, but I don't EVERYONE ripping their alternators and A/C systems out to gain a mile or two per gallon.

And don't kid yourself, that H/C/I-stroker setup will drink the gas right down just as fast as a boosted car when you're making the power. Remember, to get HP we have to increase air AND fuel, there's no if's ands or but's about it! Sure a properly built N/A setup will save you a little fuel IF you're not in the throttle all the time, but get real! It's a Mustang, we buy them to DRIVE them, not pu$$y foot them around all the time...

Black95GTS · Apr 23, 2007

The_Mustang said:
Regardless of what you have, HP= reduction in gas mileage. That Z06 is a product of alot of research and EXPENSIVE parts that make it work like it does. You won't get that kind of efficiency with anything you can buy off the shelves for any V8 Mustang.

When you have a blower and you're not making boost, it's almost like not having it at all. Sure it takes like 4 or 5 HP to free spin it but so does your alternator and A/C compressor when their running, but I don't EVERYONE ripping their alternators and A/C systems out to gain a mile or two per gallon.

And don't kid yourself, that H/C/I-stroker setup will drink the gas right down just as fast as a boosted car when you're making the power. Remember, to get HP we have to increase air AND fuel, there's no if's ands or but's about it! Sure a properly built N/A setup will save you a little fuel IF you're not in the throttle all the time, but get real! It's a Mustang, we buy them to DRIVE them, not pu$$y foot them around all the time...

If you read my post, my whole point is that if your components are more efficient, it takes less fuel and less air to make the same or more power.

I don't know how you drive on the street, but when taking my girl out for ice cream or driving my niece home from school I tend to take it easy. I don't pull my car out to terrorize the neighborhood.

An '05 mustang gets around 25 mpg and puts out 300HP... with a 281. Those are stock parts available to any V8 mustang. Thats less displacement, more HP, and better mileage then our stock junk. Better parts, better tuning, and a better combo. The advantages of modern technology shouldn't be overlooked when selecting parts for a combo.

Adam

Pokageek · Apr 23, 2007

RAD said:
Relax guys I was hoping that my future 364 will hit something around 450 rwhp and will be streetable but ... anyway I have to do some search

Hey no problemo. But I would recommend more research. What your asking out of that many cubic inches...is never going to happen. Low 5.0 is running jus tover 450+rwhp with a 408 n/a and anymore than that is pushing driveability for a 408. Honest question though: Have you ever driven in a car with 400rwhp? You are really throwing us with the comment about 400rwhp being weak, lol.

final5-0 · Apr 23, 2007

Seems to be a good many of these kind of threads going around lately
don't it

For now ... I'll limit my findings to what I've done with my GT

That guideline of 1rwhp for each cubic inch is ............
Just that .... a guideline

I can say it holds pretty true while staying within these parameters:
302/306 ci short block with no blueprint or balance
Parts selection geared toward street or light strip use
100% legal or all emissions in place and functioning
No trickery at dyno like no belt in place during pull, etc

With a good tune ... the above type of combo should behave well
enough that it ... COULD ... be used for a dd.

I've seen two words used here ... Drivability & Streetable
They can mean different things to each us

For me and how I use my weekend toy only Stang

I found I could go more aggressive with my combo than I first would
have thought and the drivability ended up being just like stock which
I would not have at first believed as well.

So having said that ... that little 1 to 1 rule held true for my first
attempt at building a Stang with pcm controlled stuff that has
both Drivability and is Streetable.

Now ... Lets lean more toward the word Streetable than Drivability

Sure ... You can sneek anything out on the street and raise a little
cane ever now and then .............. but

I would not want a Stang that could not obtain a Sticker which legally
allows me to drive it on public roads

I'm just trying to stay practical here guys

I do feel I could go beyond what I've done with a 302-306 and still
pass emissions testing ........... but

The Question is ??? ... how much more beyond ......... can I go
My gut says 350 to 375 rwhp ..............but

Even though you might obtain a sticker and be ... "Streetable"
I got a sneeking suspicion ...... drivability is not gonna be like stock

Now ... If you go stroker ... You may be able to elevate that 1 to 1 ratio
a bit and still stay in that ... Stock Like Drivability Category

If you got another car to get around in for day to day activities ......
The words drivability and streetable don't have as much bearing on
you as if your Stang is your only car

Each application can be different since some peeps may:
Live where strict emission testing is in place
Not care if they deal with drivability issues
Focus more on Strip than Street
and so forth

To me ... these comparison threads can sometimes be misleading
if
We don't be pretty specific about our idea of what .......
We think a successful combo is

One last quick thing here is this ............
You will not obtain maximum power and drivability
With dizzy twisting and fuel pressure changes alone
if
Going with an "aggressive" h/c/i combo like talked about above

Grady

Gearbanger 101 · Apr 23, 2007

Black95GTS said:
An HCI 302 will get better mileage then a stock 302. Stuffing air into a less efficient stock setup will result in worse mileage. What do you think gets better mileage? A 302 with a blower at 10 PSI making 300 HP or a 302 with an HCI making 300 HP? I'll bet my next pay check that the 302 HCI gets much better MPG. I would cringe at the mileage that a supercharged 302 would get trying to compete with the mileage of an HCI 347.

If this were not true, then how come a 346 LS1 knocks down 25+ mpg? Displacement has nothing to do with gas mileage. Its all about the tune, the quality of the parts, and how well they work together.

A 427 ci Z06 is putting out 500 HP and gets 30 MPG, despite "feeding" that displacement.

And if anyone thinks a 364 with 400 rwhp is weak, drive one. There is some shady info going down in here....

Adam

Well Adam, I'd say you need to re-read my post. I didn’t compare a H/C/I 302 to a stock 302 HO. I was reffering to a heavily modified 347cid engine (which it would need to be to accomplish 400rwhp +) to a blown stock or near stock 302. H/C/I alone won’t net you 400rwhp+ on a big displacement 302 based OHV Ford…..even stroked and poked out to 347cid, it’s gong to require a fairly aggressive head, cam and intake combination to reach those kinds of power levels. In doing so you’re going to reduce drivability and as a result decrease fuel economy in the lower levels. Not only that, but in order to take full advantage of a combination like this, you’ve got to step up the rear gear ratio (usually in the 3.73-4.30 range), which reduces highway mileage further. I didn't state it wouldnt' be a good daily driver, but I know plenty of daily drivers that don't get outstanding gas mileage....and a combination like this would easily fall into that category.

A blown, normal bolt on 302cid OHV Ford, with a set of decent flowing heads/intake will be able to reach similar power levels while being able to retain near stock fuel economy and drivability since engine characteristics haven’t been altered a lot and the added performance is achieved via the power adder. Bypass valves ensure that unneeded airflow isn’t screwing with fuel economy under normal driving conditions and only when called upon does the power make itself apparent.

It’s not a guess, it’s a fact and the major reason most people choose the power adder over the all motor route.

The 346 LS1 is a completely different animal than the 302 Ford and you’re comparing apples to oranges here. First off, they’re saddled with much higher flowing (yet still very streetable) heads, cam and intake combination, with comparable intake and exhaust upgrades as well as a much higher compression ratio over the stock 302 and HO components. Accompany that with the GM’s 3.42 axle ratio and a .50:1 6th gear O/D and it’s no surprise that the LS1’s knock off great gas mileage while still providing equally great performance.

The LS6 based ZO6 shares similar engine characteristics with the LS1. Great flowing engine components, high compression ratio, great transmission and rear end gearing. Not to mention it’s only hauling around a little over 3,100lbs with 505hp and like amounts of torque on tap. Great highway mileage since the engines barely able to surpass 1,500rpm on the highway….but check it’s in town mileage. It’s not all that impressive. Close to a 10mpg drop.

I’m almost insulted by your “shady info” comment. Just because an opinion differs from your own, doesn’t mean it’s “shady” or incorrect. Perhaps you just need to open your mind up to different perspective than your own and come to grips with the reality that just because you hadn’t though of it, doesn’t mean it isn’t correct.

Pokageek · Apr 23, 2007

"My gut says 350 to 375 rwhp ..............but"

Grady, I have never seen a 350-375 RWHP n/a 302 stang in our cars..ever. Have you?..on alcohol or something?

edit - the most I have ever seen was something like 317rwhp...

As to the 347 n/a, I have not seen any 400rwhp examples either...

I found some of those on this thread...But the driveability sounds like it starts to go with a guy at 11.5:1 on one of the links...as far as my definition...that aint pump gazz. I still have never seen a 375rwhp 302 but I am sure it is nothing I would want to drive either..

http://www.mustangworld.com/Forums/printthread.php?t=401863

blown gt40p or N/A 347?

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